the spatial relationship between physical features and the utilization ...

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EARTH SCIENCES CENTREGÖTEBORG UNIVERSITYB157 1998

THE SPATIAL RELATIONSHIP BETWEENPHYSICAL FEATURES AND THE UTILIZATION

OF LAND-A Land Capability Classification within the Regencies of Sleman &

Gunung Kidul, Special Province Yogyakarta, Indonesia

Marie-Charlotte Enryd

Department of Physical GeographyGÖTEBORG 1998

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GÖTEBORGS UNIVERSITETInstitutionen för geovetenskaperNaturgeografiGeovetarcentrum

THE SPATIAL RELATIONSHIP BETWEENPHYSICAL FEATURES AND THE UTILIZATION

OF LAND-A Land Capability Classification within the Regencies of Sleman &

Gunung Kidul, Special Province Yogyakarta, Indonesia

Marie-Charlotte Enryd

ISSN 1400-3821 B157 D-geografi Göteborg 1998

Postadress Besöksadress Telefo Telfax Earth Sciences CentreGeovetarcentrum Geovetarcentrum 031-773 19 51 031-773 19 86 Göteborg UniversityBox 46 Guldhedsgatan 5A Box 460413 81 Göteborg S-413 81 Göteborg

SWEDEN

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1. SUMMARYThe physical features within the study area, embracing parts of the regencies Sleman andGunung Kidul, Special Province Yogyakarta, Java are distinct. The southern slope of theMerapi volcano in the Northeastern part of the Sleman regency consists of a more uniformcomposition of material with volcanic origin together with a thick soil, which makes the landsuitable for cultivation. The opposite situation occurs in the karstic areas of Gunung Kidul. Marland limestone dominate the more heterogeneous lithologic compositions and the soil layer areusually very thin, with exception for some parts receiving deposits from upslope. Thetopography is hilly and sometimes very steep.

Soil profiles located along the volcanic slope contain pyroclastics from the lasteruption in November 1994, and the layers between the horizons were diffuse and thereforedifficult to separate. Profiles taken further down the slope have according to the normalprocesses in a catena coarser texture and therefore also higher drainage and lower shearstrength. The very thin and clayey soil profiles within the limestone areas of Gunung Kidul havemoderate to low infiltration rates in most of the cases and accumulation of calcium carbonate isalso common.

Even though the soil profiles along the Merapi slope indicates very advantageousconditions, further laboratory analysis of the soil characteristics showed that the amount ofexchangeable cations along the Merapi is low, especially potassium. This may be a result ofleaching losses that usually occurs within coarse-textured soils along slopes and can in a long-term result in degradation of land. Soils in Gunung Kidul have more exchangeable cationsbecause of its calcic parent material and clayey texture, although extremely severe sodicconditions were also noted for most of the sites. Sodium soils have deleterious effects on soilstructure, and therefore also on the infiltration. This together with the accumulation of calciumcarbonate is therefore an important factor that together with the hilly topography increases theerodibility of land.

Soil erosion within the regency of Sleman is hardly existing except in the steep conearea of the volcano were slides occur. Estimations with Universal Soil Loss Equation (USLE)although point out some of the drylands along the upper slope to be highly subjected forerosion. This may be the case if degradation of the land will continue, but present land utilizationso far seem to have a good effect promoting soil loss to occur in larger quantities. The soils inthe regency of Gunung Kidul are in contrast very exposed for soil erosion.

Erosion hazard mapping carried out during fieldwork indicates severe to extremelysevere hazards in a dominant part of Gunung Kidul, especially the coastal region together withsites located along river Oyo positioned in the centre of the regency. Vegetation is an importantfactor to offset the effects of erosion, and several revegetation programmes therefore occurwithin the study area.Since the whole study area is under intensive cultivation, the human impact has the mostsignificant influence on soil erosion including land utilization as well as the management of land.

The very different physical conditions existing within the study area is in response to thatdeciding the distribution of the economical profits for the farmers. Farmers in Gunung Kidul forthat reason have a very low income, and poor villages have been priority for community forests.However, the very high population pressure and economical situation has in big extensionalready resulted in an exceeded land capability in Gunung Kidul with the results that theproductivity together with the thickness of the soil layer according to the farmers is decreasingfor every year.

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2. INTISARIDaerah penelitian meliputi kabupaten Sleman dan Kabupaten Gunung Kidul, DIY mempunyaikarakteristik phisik yang berbeda. Lereng sebelah utara gunung Merapi pada KabupatenSleman sebelah Norheastern mengandung banyak material Volcanic origin dan lapisan tanahyang tebal. Sehingga lahan tersebut cocok untuk pertanian. Situasi berlawanan di Gunung Kidulyang merupakan kartic. Marl dan Limestone medominasi komposisi litholosi lebih heterogendan lapisan tanah biasanya sangat tipis, dan beberapa tempat menerima endapan dari ataslereng (upslope). Topograpi berbukit dan kadang sangat curam.

Profil tanah di lereng Merapi tampak sangat menguntungkan, berdasarkan analisakarakteristik tanah memperlihatkan bahwa jumlah pertukaran kation di daerah Merapi adalahrendah terutama potasium. Keadaan ini mungkin hasil dari leaching loss yang biasa disebabkanpada tanah bertekstur coarse di daerah lereng. Dan pada jangka panjang bisa menyebabkandegradasi pada tanah. Tanah di Gunung Kidul mempunyai banyak pertukaran kation sebabdaerah tersebut mempunyai material calcic dan tektur clayey meskipun beberapa daerahberkondisi sodic sangat ekstrim.Tanah Sodium mempunyai efek merusak pada struktur tanahdan peresapan . Sodium bersama dengan akumulasi kalsium karbonat faktor yang pentingbersama dengan topografi yang berbukit meningkatkan erodibility lahan.

Erosi tanah di Kabupaten Sleman rendah kecuali pada daerah cone vulkanik terdapatlongsoran tanah. Perhitungan erosi dengan USLE (Universal Soil Loss Equation)memperlihatkan dryland sepanjang lereng bagian atas potensial terjadi erosi. Hal ini akanmenjadi masalah apabila degradasi tanah terus berlangsung, tetapi penggunaan lahan di daerahtersebut kelihatan mempunyai pengaruh baik untuk menanggulangi erosi tanah dalam jumlahyang besar. Tanah di Kabupaten Gunung Kidul sangat kontras memperlihatkan erosi tanah.

Pemetaan bahaya erosi dilaksanakan selama fieldwork menunjukkan tingkat parah ketingkat ektrim sangat parah pada sebagian besar daerah Gunung Kidul, khususnya pada daerahpantai bersama lokasi sepanjang sungai Oyo yang terletak di pusat kabupaten Gunung Kidul.Vegetasi merupakan faktor penting untuk penanggulangan erosi dan beberapa programpenghijauan dilaksanakan di daerah penelitian. Kondisi daerah penelitian adalah lahanpengolahan intensif maka faktor manusia sangat berpengaruh terhadap erosi termasukpemanfaatan lahan dan juga manajemen lahan. Kondisi phisik yang sangat berbeda terdapat didaerah penelitian menghasilkan keputusan distribusi keuntungan secara ekonomi bagi petani.

Petani di Gunung Kidul mempunyai pendapatan rendah dan miskin telah menjadiprioritas community forests. Bagaimanapun tekanan penduduk dan situasi ekonomimenyebabkan melebihi kemampuan lahan di Gunung Kidul dimana produktifitas dan lapisanketebalan tanah berkurang setiap tahunnya.

Profil tanah yang terletak di sepanjang lereng vulkanik mengandung pyroclastics dariletusan merapi pada bulan November 1994, dan lapisan antar horison sangat dalam sehinggasulit dibedakan. Profile sepanjang bawah lereng menunjukkan proses normal mempunyaitekstur coarser catena dan juga karena dranasi yang tinggi dan kekuatan shear yang rendah.Profile tanah sangat tipis dan clayey di daerah limstone Gunung Kidul mempunyai peresaman(infiltrasi) moderat sampai rendah dan akumulasi kalsium karbonat sangat umum.

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3. ACKNOWLEDGEMENTDuring the preparation, practical performance and the final compile of this thesis a great deal of people hasbeen involved. They have all in some way with great concern contributed to innumerable solutions ofpractical, theoretical and emotional problems that appeared in the sometimes most unexpected moments.

At home, Göteborg University, Department of Earth Sciences/Physical Geography, I would like toexpress my very big appreciation and respect to my supervisor Dr. Margit Werner, lecturer in Geography.Her enthusiasm and concern has by far extended outside the usual supervision procedures.

During my intensive 4-month period in Indonesia I was stationed at the Faculty of Forestry,Gadjah Mada University in Yogyakarta, Java. Many people have during that time been involved in myresearch in a sometimes overwhelming way. I would therefore now like to pay them some attention.

Firstly I would like to thank the Dean at the faculty of Forestry, Dr. Ir. Sambas Sabarnurdin. MSc.,for giving me the very pleasant opportunity to study at the faculty. My practical training there was underthe supervision of Dr. Ir. Agus Setyarso MSc. This admirable and unselfish man simply did everything tofacilitate my visit down there and I am very grateful for that.I would further like to thank all other people that has contributed to this thesis.

In Sweden;

At Department of Human Geography, Umeå University, Umeå:• Margit Söderberg & Fred Hedkvist for their contribution to the received grant by Sida.At Department of Earth Sciences/Physical Geography, Göteborg University, Göteborg:• Dr. Mats Olvmo, Vice Chancellor and lecturer in Physical Geography for the lending of Field Equipment

In Indonesia;

At the Head Office for Foreign Affairs, Gadjah Mada University, Yogyakarta• Dr. Hurdoyo, head responsible for foreign matters, for the approval and extension of my practical training at the

university• Mrs Suhartini, assistant of foreign academic matters, for the facilitating help concerning my practical trainingAt Faculty of Forestry, Gadjah Mada University, Yogyakarta• Dra. Ninik Supriyantini, head of academic affairs, as well as other assistants at the Dean's office for helping me with all

administrative matters.• Dr. Ir. Fanani & assistant Sarifudin for matters concerning GIS.• Agus Cahyono, assistant in Soil Science for theoretical material• Djoko Supriadi S.Hut for assistants of several matters within the research• Ari Susanti & Wijonarko Suhari (my left and right hand) for 24-hours assistance, including practical, theoretical and

emotional matters.• The very friendly students and other people concerned, at the Biometrics Laboratory of Forest Management, for

support within all kinds of matter.At Faculty of Geography, Gadjah Mada University, Yogyakarta• The Dean Dr. Ir. Sutikno MSc Geography for the approval of GIS application at the faculty's GIS laboratory• Dr. Ir. Hartono, head responsible for the GIS laboratory who in the first place suggested me to stay at the faculty for

the GIS application• Ir. Heru, lecturer in geography at the faculty who with great concern guided me through the sometimes confusing

moments of the GIS application• Junun Sartohadi M.Sc. Geography for lending me the Soil Profile Description sheet• The very helpful students within the GIS laboratory for practical helpAt Department of Soil Science, Faculty of Agriculture, Gadjah Mada University, Yogyakarta• Dr. Ir. Dja´far Shidiq for the generous lending of field equipment together with other data concerning the research• All people concerned at the soil laboratory, for help with the analysis of my samples

To all other People Concerned• Jozsef Micski, Deputy Director at Forest Liaison Bureau, who in the first helped me to established contacts in

Indonesia• All people concerned at the Office for Province Development Planning (BAPPEDA), Yogyakarta for help with

permissions concerning the performance of the research• All people concerned at the Offices for the Gunung Kidul respective Sleman Regency Development Planning

(BAPPEDA), Yogyakarta for help with permissions concerning the performance of the research• All people concerned at the Offices for social and politics in Yogyakarta, Sleman respective Gunung Kidul, Yogyakarta

for the help to get permissions for samplings and Interviews within the Study Area• All people concerned at the Province office (Kantor Wilayah), Department of Forestry in Yogyakarta for giving the

approval to study satellite images, maps and other data• Ir. Sukasno, Ir. Suparto, Ir. Suharsono & Ir. Sutamto and all other people at the Rehabilitation and Land Conservation

Bureau (RLKT), Department of Forestry, Yogyakarta for their kindly cooperativeness concerning maps, literature,statistics and interviews.

• All people concerned at the Forestry office (Dinas Kehutanan), Department of Forestry, Yogyakarta for help with thecollection of maps and statistics

• All people concerned at the Province office (Kantor Wilayah), Department of Agriculture in Yogyakarta for helpwith the collection of maps and statistics

• Reidar Persson, Project Leader at CIFOR (Centre for International Forestry Research), for recommending ofliterature

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I would also like to pay my respect to the very courteous farmers within the study area, and all other peoplenot earlier mentioned that all in some way have been involved during the process.

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LIST OF CONTENTS

1. SUMMARY

2. INTISARI

3. ACKNOWLEDGEMENT

LIST OF FIGURES AND TABLES p.3

I. INTRODUCTION p.4

1. Statement of the problems p.6

1.1 Historical Influences p.6

1.2 Contemporary Situation p.6

2. Research Objectives p.8

II. GEOGRAPHICAL OVERVIEW p. 9

1. Indonesia p.9

2. Java p.9

3. Daerah Istimewa Yogyakarta (Special Province) p.10

III. THEORETICAL FRAMEWORK p.12

1. Land Degradation p.12

2. Land Evaluation System p.12

2.1. Land Capability Classification p.13

2.2. Erosion Hazard Assessment p.13

3. Factors Influencing Erosion p.14

3.1. Relationships between Land Use and Erosion p.15

3.2. Land Management and Soil Conservation p.15

IV. RESEARCH PROCEDURES p.17

1. Delineation of Scope of Work p.17

2. Methods p.17

2.1. Data Collection Phase p.17

2.2. Fieldwork Phase p.17

2.3. Compile Phase p.18

2.4. The Application of GIS p.20

V. RESULTS p.23

1. The Study Area p.23

1.1 Physical Features p.24

1.2. Population Status p.29

1.3. Summary of Results p.31

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2. The Area of Focus p.33

2.1. Sampling Sites p.34

Soil Profile Description p.40

2.2. Soil Characteristics p.42

3. Land System Analysis p.44

3.1. Erosion Hazard Assessment p.44

Soil Loss p.44

3.2. Land Capability Classification p.47

4. Local Knowledge in Land Management p. 47

VI. DISCUSSION p.50

VII. CONCLUDING REMARKS p.54

VIII. REFERENCES p.56

IX. APPENDIX p.59

1. Geographical Description p.59

1. Indonesia p.59

2. Java p.60

3. Daerah Istimewa Yogyakarta (Special Province) p.61

3.1. Physiographic Conditions p.61

Geomorphology p. 61

Topography p.61

Climate p.62

Vegetation & Land Use p.62

Soils p.64

Hydrology p.64

3.2. Population Status p.65

Demography p.65

Socio-Economic & Cultural Parameters p.66

2. TP-formula p.67

3. Universal Soil Loss Equation (USLE) - Calculations p.67

4. Questionnaires p.68

5. Common Crops and Vegetation Types within the Study Area p.70

6. Soil Survey p.71

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List of Figures & TablesFig.1 The Plain Field of Daerah Istimewa Yogyakarta (Special Province) with Mount Merapi in the Background.Fig.2. Republic of Indonesia, and Java's geographical location in Indonesia.Fig.3. Erosion risks across Central Java, and D.I. Yogyakarta. 1990.Fig.4. Wet Paddy Rice Cultivation on the Coastal Plain, Sempor, Central Java.Fig.5. Administrative Map of Daerah Istimewa Yogyakarta (Special Province)Fig.6. Land Evaluation SystemFig.7. Dryland with Multiple Cropping of a great various of species in the hilly areas, terraced wet paddy rice fields in lower altitudes, Gunung KidulFig.8. Flowchart over the Operational Steps within the Research.Fig.9. Flowchart over the Operational Steps for Creation of the Land Capability MapFig.10. Flowchart over the Operational Steps for Creation of the Recommended Land Use MapFig.11a,b,c.Geographical Overview of the Study Area.

a) Special Province Yogyakarta with Limitations for the Study Areab) The Study Areac) The Area of Focus

Fig.12. Geomorphology Map of the study areaFig.13. Slope Map of the Study AreaFig.14. Rainfall Map of the Study Area.Fig.15. Land Use within the Study AreaFig.16. Soil Map of the Study AreaFig.17. Orange coloured Soil Deposits dominates the Landscape in Patuk, Gunung Kidul.Fig.18. Groundwater MapFig.19. The distribution of Land Utilisation Types in the Sleman Regency (1996).Fig.20. The distribution of Land Utilisation Types in the Gunung Kidul Regency (1996).Fig.21. Map of Sampling SitesFig.22. Land Mapping Units within the Study Area.Fig.23. Landslides along the Volcanic Cone.Fig.24. Wet Paddy Rice Field in Turi, Sleman (Not a Sampling Site)Fig.25. Mud Cracking in PatukFig.26. Eroded Kayu Putih CultivationFig.27. Calcic ground in BaronFig.28. Soil Profiles within the Study Area.Fig.29. Erosion Hazard MapFig.30. Soil Loss Map of the Study Area.Fig.31. Land Capability MapFig.32. Map of Recommended Land UseFig.33. Monthly averages precipitation for each of the regencies with average monthly temperature and relative monthly humidity given for the whole area (D.I.Yogyakarta)Fig.34. River Oyo running through in Playen, Gunung Kidul.-----------------------------------------------------------------------------------------------------------------------------Tab.1. Physical Features within the study AreaTab.2. Population Status within the Study AreaTab.3. ESP- Value for the Different Sites.Tab.4. Description of the Physical Features within the Sampling Sites.Tab.5. Soil Characteristics.Tab.6. Original and Present Forest Cover in Java.Tab.7a,b. a) Distribution of Land Area Based on Altitude in Special Province Yogyakarta. b) Distribution of Land Area Based on Slope Degree for Each Regency/Municipality.Tab.8. Number of rainy days (1996), in each regency.Tab.9. The spatial distribution and quantity of forest for each regencyTab.10. Area of wetland and dryland by utilisation in D.I.Yogyakarta (1996), and its distribution for each regency/municipality in percent.Tab.11. Population distribution, density and growth for each regency/municipality in D.I.Yogyakarta, 1996, and its total land area and administrative sub-divisions.Tab.12. TP-Calculations based on Agroforestry within each of the Regencies.Tab.13. Soil Loss Estimations within the Study Area.Tab.14. Plant Species within the Study Area, and their Main Use.

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I. INTRODUCTION

In comparison to many other developing countries, Indonesia appears to be relatively rich inland, population and natural resources. With an estimated population of 201.5 million people(Microsoft Corporation, 1998), this archipelago ranks fourth among the world's most populouscountries. Indonesia is also the world's largest island nation, and although most of the islandsare sparsely populated the distribution of people is exceedingly uneven. Census data from 1990show that approximately 60% of the Indonesian people live on the island of Java (Fig.2), anarea amounting to a mere 7 % of the total land area of the country (Marcoux, 1996).

This situation is causing several environmental problems and therefore also social andeconomical problems, and vice versa, within the country. One of the most urgent problems thatoccurs is concerning the high population pressure in relation to the capability of land, includingland degradation, such as soil erosion and decreasing productivity.

My personal interest in Indonesia, and to get working experiences with Land EvaluationSystems, therefore led to this M.Sc. thesis in Geography, combined with a Minor Field Study(MFS). The study was financed through a grant from Sida (Swedish International DevelopmentAgency) via the Department of Human Geography at Umeå University.

This thesis is concerning a so called specific purposed land evaluation that is a complexsubject field suitable for people with a multidisciplinary background of which geography isincluded to a great extent. These specific purpose processes in this case comprise interpretationand comparison for two areas with different physiographic features. Since studies within LandEvaluation Systems include several problem areas, I decided to concentrate on physiographicfeatures of the land in relation to human impact.

The overarching aim within this study is therefore to indicate how these physiographicfeatures affects the people and people's respond to the characteristics of the land system. Forthat reason I chose to focus on an area in the most overpopulated and fertile part of Java,where the historical influences has been of great importance for the situation occurring today(Fig.1).

Fig.1 The Plain Field of Daerah Istimewa Yogyakarta (Special Province) with Mount Merapi in the Background(Photo M. Enryd 1998).

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Fig.2. Republic of Indonesia, and Java's geographical location in Indonesia.

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1. Statement of the problemsProblems occurring today, concerning land degradation on Java are mainly considered to be ofhistorical influences. A short historical resume, taken from Witten et al. pp.328-331, willtherefore first be presented below.

1.1. Historical InfluencesPeople have lived on Java and Bali for about one million years, and human impact on the forestand the flora began as soon as cutting tools and fire were available. The first major loss ofnatural forest probably occurred after teak was introduced (200-400 AD). By the time theHindu-Buddhist temples of Central Java were being built, appreciable areas of forest hadprobably been cleared. Irrigated rice culture was introduced over 1,000 years ago, probablyconfined to the lower slopes. Major change began in 1830 during the Dutch control, whenfarmers were forced to grow export crops among the food crops, usually on forested grounds.The people had to grow cash crops at the expense of food to satisfy the desires from Europe.The human population grew rapidly and the land became crowded, forcing farmers to use moreintensive forms of agriculture. In 1870, more than 300.000 ha of Java were used for coffeeplantations, especially in the east and central regions.

The northern half of the island, with malaria-infested alluvial coastal plains, remaineduncultivated until between 1850 and World War I, when these land was brought undercultivation. Between 1898 and 1937, some 22.000 km2 of natural forest were lost, because ofthe building of the railway network. During World War II, there was widespread anduncontrolled deforestation, and during the difficult years of the 1940s and 1950s. In the 1980sall Javanese and European farmers were required to protect the soil on sloping fields with theresult that large areas were terraced. The area under cultivation although increased so rapidly,and on to more and more marginal land by poorer and poorer farmers, that it was impossible tocontrol land management.

1.2 Contemporary SituationAgriculture is the most important sector in Indonesia and is characterised by family based, smallfarm holdings. The average farm size in Java is about 0.20 ha while on the outer islands it isapproximately 0.80 ha (Martaamidjaja 1996). Java has fertile volcanic soils but even so thereare limits to its human carrying capacity and a voluntary resettlement scheme, now called theTransmigration Program, has been operating ever since 1905 as an attempt to reduce thetremendous pressure (Marcoux, 1996).

As a consequence of population pressure and intense development activities, theindustrial and housing sector's need for land is rapidly increasing. More and more, agriculturaland forest areas are being encroached to meet this need. In 1991, the remaining forest area inJava comprised only 4.6 percent of the total land (Martaamidjaja 1996). Central Java isIndonesia's least-forested province, with an average population density of 833/km2 (MicrosoftCorporation 1998).

About 50% of the rural Javanese farmers, whose income is solely from agriculture, donot have enough land for farming (Muhamud 1996, p. 6). Such a condition combined with theincreasing demand for food and other products from the land has forced the farmers to useland, which is not suitable for agriculture. When demand for land is not matching the landcapability this will result in an increasing pressure, finally forcing the land to its carrying capacity.

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This has resulted in degradation of land through the process of soil erosion, especially occurringin steep hilly areas. The degradation of land is strongly connected with the high populationpressure of the island, and its physical environment. Java experiences some of the highest ratesof erosion in the world and the soil loss is enormous. It is beneficial to consider that 15% or 1.9million ha of Java is regarded as 'critical' or subject to serious erosion (Fig.3), and that this areaare inhabited by some 12 million people (Whitten et al. 1996, pp. 45-46).

Fig.3. Erosion risks across Central Java, and D.I. Yogyakarta. 1990. (Simplified after Whitten et al).

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2. Research Objectives

Scope of work

The overarching aim of this study is to indicate how the physiographic features of land affectsthe people and people's respond to the characteristics of the land system, and can be split intoseveral significant objectives as follows:

One purpose is to estimate and classify the land capability, with special focus on erosionhazards, for two areas with different physiographic conditions. This is carried out to assess thephysical limitations of the land.

In order to get this assessments transformed to a statement or indication of how fast therate of soil loss is the Universal Soil Loss Equation (USLE), based on field data, will be used asa further purpose. The use of USLE also requires more knowledge about crop management and erosioncontrol practices in the area of concern. Therefore, another purpose was to study the effect ofhuman impact on the land, especially with focus on existing land use and land management, andits relationship and influence on physical and chemical soil properties in terms of degradation,erosion and fertility.

Since the requirements and quality of land not always match it is also of great importanceto understand the socio-economic and cultural situation in the area. For that reason animportant purpose, as a step towards more knowledge, is an attempt to understand how thephysical features of the land affects the people, and people's respond to the characteristic of thephysical land system.

ObjectivesI. Elaborate land utilisation type.II. Classify terrain stability with focus on erosion risk and slope stability.III. Indicate land capability with respect to erosion hazards and soil characteristics.IV. Estimate land capability with GIS by the use of erosion mapping and other data.V. Identify the influence of socio-economic & cultural factors as well as land management and

conservation practices on land degradation.

As a further important purpose in this research a recommendation map concerning land usewithin the area was made. The aim with this map was to indicate how balanced conditions, ormatching between the physical features and utilization of land within the study area can beachieved. A combine of my own field data together with some local knowledge about the studyarea was used. That achieved a creation of a more realistic situation.

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II. GEOGRAPHICAL OVERVIEWThis thesis concerns a study area positioned in the regencies of Sleman respective GunungKidul within Daerah Istimewa Yogyakarta (special province), which is located in the centralparts of Java Island, Indonesia. A short overview of Indonesia, Java and Daerah IstimewaYogyakarta will firstly be introduced for a better understanding of the actually study area inrelation to the local, regional and national environment For further details see app.1 pp. 59-66).

Indonesia, an archipelago with a population density of 103 people/km2, is stretchingfrom 94°45' to 141°05' E, and 6°08' N to 11°15' S, crossed by the line of Equator (Fig.2). Itis the world’s largest archipelago with a total of about 13 600 islands occupying a total area ofabout 1 .919.400 km2. The South China Sea borders in the west and the south by the IndianOcean and in the west by the Pacific Ocean and in the north the country

A chain of volcanic mountains, many of them still active, is rising to heights of more than3568 m extends from west to east through the southern islands from Sumatra to Timor. Each ofthe northern islands has a mountain mass, with plains around the coasts. The most extensivelowland areas are on Sumatra, Java, Kalimantan, and Irian Jaya (Diercke Weltatlas 1992).

The climate is tropical, with a wet season from November to March and a dry seasonfrom June to October. Humidity and temperature is relative high and the precipitation variesfrom low in the lowlands to very high in the mountain areas (Microsoft Corporation 1998).

About two-thirds of Indonesia is covered with forests and woodland, mostlyconcentrated on Kalimantan, Sumatra, and eastern Indonesia. About 12% of Indonesia isunder cultivation and about 55% of the country's approximately 70.4 million workers areengaged in agriculture, either as owners of small farms or as labourers on estates (BPS, KantorStatistik Jawa Tengah 1996).

Java is located between 114°04' E, and 104°48' S to 7°12' S longitude, with a size ofabout 130.000 km2, split into different regions (Fig.2), is the economic, social, political andcultural hub of Indonesia, with one of the densest concentrations of population anywhere in theworld. In 1995, Java had about 114 million inhabitants living at an average density of 862people/km2, ranging from nearly 40.000 in some parts of Jakarta, the capital of Indonesia, tovirtually zero in some of the remaining wild areas (Microsoft Corporation, 1998).

The island is the most volcanically active island in the world (Microsoft Corporation1998). Mountains ranging between 3.000 and 3.800 m.a.s.l can be found (Indonesia-a countrystudy, 1992). A low coastal plane (Fig.4), with an average height of 250 m (FAO-Unesco1974, p.47), adjoins the mountains on the north, and the southern part of the island is a serie oflimestone ridges (Microsoft Corporation, 1998), forming a landscape of tropical karst.

Winds are moderate and generally predictable, with monsoons usually blowing in fromthe south and east in June through September and from the Northwest in December throughMarch (Indonesia-a country study 1992). Dry season in Java normally last from March toAugust, wet season from September through March (travel-Indonesia 1996). About 90 % ofJava and Bali receive at least 1,500 mm in annual precipitation, and the temperature usuallyranges between 20°C and 30°C, the humidity between 60% to 90%. (Indonesia-a case study1992).

The present remaining forested area on Java is less compared with other islands, only coveringless than 10% of the land area (Ross 1984, p.10). Dominating utilization types includeswetlands, tree crops, and upland farming which also is specific for this island (World Bank,1994).

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Fig.4. Wet Paddy Rice Cultivation on the Coastal Plain, Sempor, Central Java (Photo M. Enryd 1998).

Daerah Istimewa Yogyakarta (special Province, located between 7° 33' until 8°12' E, and 110 °00' until 110° 50', on the central part of Java is divided into four Kabupaten(Regencies) and one Kota Madya (Municipality), with a total land area of 3.185.80 km2

(0.17% of the total land area of Indonesia), split into several Kecamatan (Sub-districts) andDesa (Villages). Yogyakarta is the municipally of the province, surrounded by the regency ofSleman in the north, Kulon Progo in the west, Bantul in the Southwest, and Gunung Kidul inSoutheast (Fig.5).

Each of the regencies has a very specific geomorphic location, but the structure of theYogyakarta area and its surroundings is strongly influenced by plate and tectonic movements,and volcanic deposits from the still active strato volcano. (Sutikno 1996, p.3). The topographywithin the special district varies from flat to mountainous with about 65% of the total areahaving an elevation between 100-500 m.a.s.l. Steep areas (>40%) is mostly found in the conearea, west Kulon Progo, and the coastal south. The central of the special province consists of abig plain area. Remaining areas are varying a lot on a local scale between 2-15% in steepness.Special Province Yogyakarta is located in a humid tropical area with average humidity andtemperature as described for Java in general. Amount of precipitation is depending on altitude,showing significant higher amounts in the volcanic area.

Dryland cultivation's is the dominating land utilization type within all regencies, mostlyconsisting of dryfields. Forests are more concentrated to the Bantul and Gunung Kidul regency.Irrigated wet paddy rice embraces most of the wetland areas and the majority of the rice fieldsare concentrated along the volcanic slope in the Sleman regency.

12

Fig.5. Administrative Map of Daerah Istimewa Yogyakarta (Special Province). (Source: Peta Fisiografi. PropinsiD.I.Y., scale1: 250.000, Mitojat dkk (1987)).

Volcanic Regosols (inceptisols & entisols) dominates the slopes of Mt. Merapi, litosols(entisols) is more common in the plain areas, and a great variation of grumosols (vertisols),Litosols (entisols) and Rensina (entisols) is found in remaining areas. There are several riverswithin the special district, as well as underwater rivers.Big parts of the special district are non-aquifer or comprise a shallow depth of the groundwater(<7m). This with exemption of the Merapi slope and Wonosari plateau, having considerabledeeper levels.

D.I. Yogyakarta, located on the fertile foot plain of Mt. Merapi, is considered as thecradle of the Javanese culture, which makes it one of the most popular tourist destinations in theIndonesian archipelago. The municipality Yogyakarta also has a long established reputation asthe educational centre of Indonesia with several privates and government owned universities.Therefore, D.I. Yogyakarta is one of the most densely populated areas in Indonesia, with adensity of 999.87 persons per km2 (Tab.6).

Most of the people within the Special Province are in some way depending onagriculture for their living. The economical situation varies a lot on a relative local scale, ofwhich the volcanic influenced areas together with the city have higher income.

The traditional thinking among farmers within the regencies is strong, and the use ofplants for a wide range of medicinal cures is common.

13

III. THEORETICAL FRAMEWORK

1. Soil DegradationSoil degradation is a common problem all over the world and in recent decades the global rateof soil degradation has increased dramatically, and is likely to increase further as we approachthe twenty-first century. The term Soil degradation refers to the decline in soil productivitythrough adverse changes in for example nutrient status, organic matter, structural stability andconcentration of toxic chemical. It incorporates a number of environmental problems includingerosion, compaction, water excess and deficit, acidification, salinisation and sodifiction, toxicaccumulations of agricultural chemical etc. These factors have led to serious decline in soilquality and productivity (Ellis & Mellor 1996, pp. 238-239).

Soil degradation in Indonesia is one of the nations most serious degradation problems,and varies a lot between the many islands. Kalimantan, with large quantity of forest suffers fromlow productive soils due to deforestation and other qualities of the soil characteristics. Areaswith more fertile soils such as the areas within the volcanic chain, stretching from Sumatra innorth down to The Smaller Sunda Islands, have high amount of soil loss because of the moresteep topography together with a lack of dense vegetation cover. Specific for these areas isalso the periodic burial of soil profiles together with the burning of existing vegetation caused byvolcanic eruptions (Oral Setyarso 1998).

This thesis has its focus on soil erosion, which, according to Morgan (1995) is a hazardtraditionally associated with agriculture in tropical and semi-arid areas. Defined by Trudgill(1983) it includes the removal and transport of material from its original site by an agency suchas water, wind or ice. Various types of erosion can be found and specific for a tropicalenvironment is, according to Morgan (1995) rainsplash erosion; overland flow (sheet),subsurface flow, rill erosion and gully erosion.

Soil erosion on Java is mainly a result of inappropriate land management, and mucherosion occurs from fields, bare roads, and roadside paths, open villages areas, landslides,incised riverbanks (Witten et al. 1996, p. 142).

2. The land Evaluation SystemLand systems analysis is used to compile information on the physical environment. The processof identifying a certain land system is by comparing the present land use, or Land UtilizationType with the natural features of the land and its significant influence on the potential land use. ALand Utilization type, including its technical specifications within a given settling of physical,environmental, and social parameters will have certain requirements on the land. This as wellas certain limitations that will adversely affect the potential of land for a specific use(Swedforest International AB & PT. Wahanabhakti Persadajaya, 1995, p. 16).

To be able to compare land and land use, or evaluate land for specific use, the land hasto be classified into areal units or land systems, which are made up of smaller units, or landmapping units (LMU) (Morgan 1995, p.54). Land mapping units refers to a land unit of anysize that can be delineated as long as the features it reflects are uniform, and particularly landform, soil and vegetation cover is of great importance (Swedforest International AB & PT.Wahanabhakti Persadajaya 1995, p. 29).

In order to evaluate the sustainability of a specific land unit for a certain land utilizationtype, the land units will be described in quality terms, which in turn can be compared with therequirements of the land utilization type. Land Quality must then be broken down into LandCharacteristics e.g., properties of the land that can be measured or estimated and thus make itpossible to compare the specific land use requirements. In the comparison, or matchingknowledge on land use is combined with the information of the land into Land Use Systems.

14

These are defined as a specific land Use type, including its inputs and outputs, applied on aspecific Land Unit (Fig.6) (Swedforest International AB & PT. Wahanabhakti Persadajaya1995, p.16).

The Land Evaluation System

Fig.6. Land Evaluation System (Source: Setyarso 1998).

2.1 Land Capability ClassificationThis method is used for assessing the extent to which limitations such as erosion risk, soil depth;wetness and climate hinder the agricultural use that can be made of the land. The aim ofdeveloping land capability classification is to use the land in accordance with its capability sothat optimal productivity is attained without destruction taking place on the land (Muhamud1996 p.31). The objectives are to regionalize an area of land into units with similar kinds anddegree of limitation (Morgan 1995 p.47). The capability unit is the basic unit. It consists of agroup of soil types of sufficiently similar conditions of profile form, slope, soil structure, soiltexture, drainage and other physical properties, such as degree of erosion as to make themsuitable for similar crops and warrant the use of similar conservation measures (Muhamud1996, p.31). ''The capability units are then combined into sub-classes according to the natureof the limiting factor and these, in turn, are grouped into classes based on the degree oflimitation'' (Morgan 1995, p.47).

2.3 Erosion Hazard AssessmentsMany of the factors examined in land systems analysis are relevant to the soil erosion system, interms of erosion risk evaluation. The assessment of erosion hazard is a specialised form of landresource evaluation, the objective of which is to identify those areas of land where the maximumsustained productivity for a given land use is threatened by excessive soil loss. The assessmentaims at dividing a land area into regions, or land mapping units, similar in their degree and kindof erosion hazard (Morgan 1996, p.40). The degree of soil erosion hazard will indicate on theintensity of soil degradation in a specific area, and can then be used to determine priority for soilconservation practices. In order to get a better understanding of the dynamics of erosion further

LAND USE

LMU Utilization Type

Influencing FactorsSocial

CulturalEconomicalTechnical

Physical FeaturesGeomorphology

TopographyClimate

Vegetation/CropsSoils

Hydrology

RequirementsLand Characteristics&

Land Qualities

Matching

Land Capability

Erosion Manageability

15

mapping of both the erosion features and the factors influencing them is necessary. Anotherimportant issue is to find relationships between the two.

3. Factors Influencing Erosion The factors controlling soil erosion are according to Morgan (1995) the erosivity of the erodingagent, the erodibility of the soil, the slope of the land and the nature of the plant cover. Otherfactors taken under consideration are land management and utilisation of land. "Land utilisationis perhaps the most significant factor influencing soil erosion, for two main reasons. First, manyland use practices leave the soil devoid of a protective vegetation cover, or with only a partialcover, for significant periods of time and second, they involve mechanical disturbance of thesoil" (Ellis & Mellor 1996, p.243). Thus, it is likely that the balance of the different degradationfactors in different areas will vary (Yanda 1995, p.35).

Erosivity is a measure of the potential of the eroding agent to erode and is commonlyexpressed in terms of kinetic energy (Ellis & Mellor 1996 p. 242). High erosivity of tropicalrains is attributed to its intensity, big drop size, and to wind velocity that increases the energyload (Boodt & Gabriels 1980, p.143). The rain also contributes to soil loss through surfacerunoff.

Erodibility of the soil is a measure of its resistance to detachment and transport, anddepends on many factors, which fall into two groups; those which are the actual physicalfeatures of the soil; and those which are a result of human use of the soil (Selby 1993, p.226).Erodibility varies with a number of soil characteristics, particularly texture, organic content,structure and permeability (Ellis & Mellor 1996, p.242), and also on its shear strength,infiltration and chemical content (Morgan 1995, p.29).

Although a soil's resistance to erosion depends in part on topographic position, slopesteepness and the amount of disturbance, for example during tillage (Morgan 1995, p.29). Theproperties of soil horizons determine the rate of infiltration and the amount of water thatpenetrates further into the soil and eventually down to the ground water. Also, different soilhorizons have different erodibility (Yanda 1995). In terms of both water and wind erosion, themost erodible soils tend to be characterised by low clay and organic contents, and poorstructural stability (Ellis & Mellor 1996, p.242). The resistance of soil to detachment byraindrop impacts depends upon its shear strength, that is its cohesion and angle of friction(Selby 1993, p.226).

The topographic factor is evident in the steepness and length of slopes. Raindropsplash will move material further down steep slopes than down gentle ones, there is likely to bemore runoff, and runoff velocities will be faster. On steeper slopes the process can be intenseenough to form gullies. Because of these combinations of factors the amount of erosion is notjust proportional to the steepness of the slope, but rises rapidly with increasing angle (Selby1993, p.224). Long slopes are more affected and particularly those which drain a largesubcatchment area (Yanda 1995, p.66).

The vegetation factor offsets the effects on erosion of the other factors-climate,topography and soil characteristics. The major effects of vegetation fall into different categories:(A) The interception of rainfall by preventing the drops from reaching the soil and harm thestructure. It also allows water to be evaporated directly from leaves and stems, (B) Decreasingof runoff velocity and hence the cutting action of water and its capacity to entrain sediment, (C)Increasing soil strength, granulation, and porosity, and therefore also the root effect, (D)Stimulates biological activities associated with vegetative growth, influencing the porosity of thesoil, (E) More transpiration of water, leading to the subsequent drying out of the soil, (F)Insulation of the soil against high and low temperatures, (G) Compacting of underlying soil(Selby 1986, p.226). Vegetation also reduces the shear velocity of wind by impartingroughness to the flow of air (Morgan 1995 p.37).

16

3.1 Relationships between Land Use and ErosionUtilisation of land depends on different requirements with respect to land conditions. For asustainable production basis, the land should be managed so that its production capacity ismaintained or improved for future generations. When people get forced into the marginal landsfor their survival or have special requirements on land not suitable for a certain kind of land usethe matching with the characteristics and quality of land fails (Muhamud 1996, p.38). Changesin Land utilisation and erosion are strongly related and whenever land is misused consequenceslike accelerated soil loss is very common. The rate, spatial and temporal distribution of soilerosion depend on the interaction of physical and human circumstances and is therefore anintegral part of both the natural and cultural environment (Morgan 1995, p. 6).

Agricultural practices are of great significance in erosion. All operations reducing thevegetation cover, including cultivation, grazing and burning, logging and deforestation, roadconstruction etc. increase the rate of erosion. Compared to cultivated land, grassland andforests seem to provide good protection against erosion.Overgrazing is no problem in the tropics but on soils lacking in humus, overcrowding on wetground causes puddling and packing, increased sediment yield and runoff. Burning before theonset of intense rains also induces accelerated erosion.A consequence of clear cutting in many humid areas is a raised water table (Jansson 1982,pp.38-40).

Soils play a central role in the effective operation of land use systems. The soilproperties have great influence on the productivity of the land and are as well affecting thenature and timing of mechanical operations. The characteristics of the soil also have an impacton the behaviour of fertilisers and pesticides, and other related agricultural chemicals (Ellis &Mellor 1996, p.199).

3.2 Land Management and Soil Conservation PracticesFor a more permanently productivity, land should be used wisely within its capability.Economical stability, income, labour, educational level, culture, attitude, ownership of land andso on are important factors affecting the management of land, and therefore also conservationpractices (Muhamud 1996, p.48).

Crop and vegetation management is agronomic measures effectively used for soilconservation. The differences in density and morphology within the species will differ in theirability to protect the soil and reduce erosion. Several conservation measures is practised, suchas rotation, cover crops, strip cropping, multiple cropping (Fig.7), high density cropping,mulching, revegetation and agroforestry (Morgan 1986, pp. 113-128). The correct choice ofcrops or vegetation mostly depends on physical essential elements such as soils and climate.The choice made must although take account of special requirements like financial factors aswell. Sometimes a conversion to another kind of land utilization type gives more obviousfinancial advantages or disadvantages easily measured in money terms, other may be equallyimportant in the long term, but more difficult to access financially (Davies et al. 1982, pp.102-103).

Strip cropping is a new method and not yet so very common conservationmeasurement on Java, but this method is considered to be a cheap and suitable managementmethod with long protection and good effects, especially for runoff control, and as animal food.Another suitable alternative, as a cheap and easy conservation method against erosion andsedimentation, is alley cropping. Alley cropping is, according to the Department of Forestry,Yogyakarta especially useful on bench terraces in dryland cultivation's, and also contributes to

17

an increase of mulch and organic content. It is in addition to that useful as animal food andfirewood.

Soil management is another important strategy for erosion control, including applicationof organic content, tillage practices, and use of soil stabilisers (Morgan 1986 pp.130-135).According to Davies et al. (1982) soil management has two aims: to grow crops for profit andto maintain or improve soil fertility in the long term. The techniques used should increase theresistance of soil to erosion, and focus mainly on the improvement and maintenance of soilstructure (Ellis & Mellor 1995, p. 248).

A third strategy for erosion control is mechanical methods, which normally are inconjunction with agronomic measures. Mechanical techniques aim to reduce the energy of theeroding agent and often involve the modification of surface topography (Ellis & Mellor 1995 p.249). Contouring, contour bunds, terraces, waterways, windbreaks, and other stabilisationstructures are commonly used to fulfil this purpose (Morgan 1986, pp. 137-152).

Agroforestry is a very common on Java. Research on Java has showed that the soilerosion rate is not significantly different between forests and agroforestry areas with the reasonthat crops and trees planted together in this way will have same conditions like a multilayerednatural forest. Erosion measurements within a forest area usually show on low rates. Otherresearches has although indicated that the kinetic energy from the raindrops that usually isreduced by a high canopy tree will have time to reach more than 95% in speed in a free falldistance of eight meters. The drop size may also be increased through accumulation and fallingfrom the leave surface. Severe erosion has also occurred within some teak plantations as aresult of that (Kusumandari & Mitchell 1997, pp.376-380).Fig.7. Dryland with Multiple Cropping of a great various of species in the hilly areas, terraced wet paddy rice fields in

lower altitudes, Gunung Kidul (Photo M. Enryd 1998).

18

IV. RESEARCH PROCEDURES

1. Delineation of Scope of Work.This research was carried out from December 1997 until April 1998 in the regency of Sleman& Gunung Kidul in D.I.Y Yogyakarta, and can be divided into three phases, the data collectionphase, the fieldwork phase, and the compile phase (completed in Göteborg during late springand summer same year). Two study areas, with different land system, within the two regencieswere chosen for comparison.

The physiographic units of the complete study area are located along the southern slopeof the Merapi volcano in the north-eastern part of the Sleman regency, stretching further downto the karstic plateau area of Wonosari, in the Gunung Kidul regency, finally reaching Baron inthe coastal area. Great variations in the soil forming factors can be found in every physiographicunit between the slope of Mt. Merapi to Baron coast, especially due to topographic, lithologicand vegetation factors. In this respect influence on the soil development have given rise todistinctive distribution of soils within the study area.

2. MethodsSince the overarching aim of this study is to investigate relationships between physical featuresand different land utilisation types, split into several miner purposes, following methods andmaterial have been chosen for accomplishment of this study (see also Fig.8 Flowchart overthe Operational Steps within the Research on p.19).

2.1 Data Collection PhaseThe first step of the research included many visits to different departments, offices, faculty's etc.for textural and spatial background material about the area of concern including:a) Collection of literature, maps, satellite images about physiographic conditions, land utilisation

types, statistic data of demography, socio-economic and cultural conditions, and othersecondary data used as theoretical background information, and for the planning of theresearch.

b) Preparation of fieldwork by delimitation of the research area, field orientation, andformulation of questionnaires for interviews.

2.2 Fieldwork PhaseDuring fieldwork a survey method was used, consisting of soil sampling, soil profiledescriptions, and interviews with the local people about the socio-economic andphysiographical conditions in the area (for questionnaire see app. 4. p.68). The survey spotswere chosen based on primary data, Dr. Ir. Agus Setyarso. M.Sc., and field observations as tobe representative for the surrounding areas with similar conditions. Following procedures andmaterial were used during the fieldwork:

a) Land use map (Penggunaan tanah, Propinsi D.I.Y, 1994/95, scale 1:100 000), and GPS (Magellan Nav 5000) were used for orientation and determination of position for eachsurvey site. The altitude was then noted with the help of an altimeter.b) Soil profile descriptions was carried out with the help of the Munsell colour chart, together

with a survey sheet (app.6, p.70) used for description of the physical and chemical soilproperties. The soil profile description included 6 of the total 13 sample sites. (For moredetailed information see the section Profile description on p.40).

c) Totally, a number of 26 soil samples were taken from different depth, usually at a depth of 5cm, 50 cm, and from the subsoil, if possible by drilling or digging. Soil samples taken from

19

sites without soil profile description were carried out in an adjoining area, with another kindof land utilisation type. This was done in order to compare areas with different kind of landuse located within the same LMU, and also be able to find possible relationships betweensoils and land utilization type. Determination of pH was then made from all sites by the useof a pH-indicator (0-14) put into a solution of soil and distillate water (1+4). Colour andother characteristics of the soil were then noted using same survey sheet as for the soilprofile description.

d) Shear strength tests were taken from 3 different depth (5 cm, 50 cm, and from the subsoil, ifpossible whenever a soil profile description was carried out. This with the aim to measurethe cohesion of the soil. ELE International Torvane soil test was used for this matter.

e) Measurement of the infiltration was the carried out with the help of an infiltrometer consistingof an inner and outer steel cylinder ring with the 6,8 cm respective 11,8 in wide, and 13,1 inheight. A plastic can with the volume of 3 Litre was also used. The infiltration rate was thenoted for every minute until no water was left in the can, which varied a lot between thedifferent survey sites. The position of the infiltrometer was in connection with the samplingsite, and also 15 m above respectively below the site in the slope for more references.

f) With help of a measuring tape, a radius of 15 m was taken out in the surrounding areaaround the soil sample site, as to be representative for a certain land utilization type withinthe land unit, classified by RePPProT (1989). The relative relief, local climate, type anddensity of the vegetation and ground cover were then determined in detail with the help ofmy talented field assistants, Ari Susanti and Wijonarko Suhari, from the Faculty of Forestry,Gadjah Mada University, Yogyakarta, and also by the very courteous local farmers. Otherfield checks concerning above described matters was also carried out to make sure that thesurrounding area with same kind of land use had similar conditions as the sampling site.

g) Slope inclination and slope aspect was measured by the use of a Suunto and a compass.h) The degree of erosion and other visible land degradation, if any was noted and classifiedaccording to the survey sheet (app.5, p.70).i) Land management was observed concerning crop and vegetation management, soilmanagement and mechanical methods. Interviews was carried out with the help ofquestionnaires and interpretation by Ari Susanti and Wijonarko Suhari (app.4, p.68) among 30random chosen farmers of different age and sex, and also with other people that have localknowledge about the study area. The questions concerned socio-economic, cultural and landconditions for farmers with different land utilization types, and had an important function as abase for the fulfilment of the result section.

2.3 Compile PhaseThe third phase embraced several kind of data analysis, including soil analysis carried out at theDepartment of Soil Science, Gadjah Mada University. Another software used was Ilwis, a GISprogram for digitalisation and creation of maps (For a more detailed description about theapplication of GIS on p.20). To fulfil some of these maps, estimation and evaluation of theland capability and erosion hazards with the help of USLE was necessary. Questionnaires andother data were then analysed as a further step towards the final compile of the essay.

20

Fig.8. Flowchart over the Operational Steps within the Research.

Attribute DataPhysicalSocialCulturalDemographicalEconomicalTechnological

Determination &Limitation of

Research Process

TexturalSpatial

ResearchPlanning

Statement of the ProblemScope of WorkQuestionnaries

Selection of theStudy Area Data Identification

FieldObservation

Data Collection

Primary Data Secondary Data

Field WorkErosion Hazard MappingSoil SamplingSoil Profile DescriptionInterviews with Farmer etcDescription of Land Characteristics

Data Arrangement

GIS Textural Soil Analysis USLE-Calculations

Compile ofResearch

21

2.4 The Application of GISIn order to evaluate the land capability of the study area the GIS-program Ilwis 1.4 was usedas a convenient tool for that fulfilment. Ilwis (Integrated Land and Water Information System) isa GIS-software that integrates image processing and spatial analysis capabilities, tabulardatabases and conventional GIS characteristics. Data acquisition from aerospace images is alsoenabling effective monitoring (ITC 1993). This software is a common tool used especially forland use planning in Indonesia.

Due to time limit a total number of 8 maps over different physical features within thestudy area were digitalized with the intention to let the land capability depend on so manyfactors as possible (See further fig.9). Scoring, concerning high potential erosion hazard, of theland characteristics was then carried out.

Furthermore, the scoring tabular were linked together with the digitalized maps, and anoverlay of all maps showing high potential erosion hazard areas resulted in a high potentialerosion map. An overlay with the land use map were done in order to get a more clearly mapindicating high potential erosion hazard within the different types of land use. Matching betweenthis map and the erosion hazard map (made during the fieldwork phase) were further carriedout, finally resulting in a land capability map after an overlay.

Since the land capability map almost is a result of map studies a further purpose withthe GIS application was to create a recommendation map for forest land use (Fig.10), partlybased on my own data collected during fieldwork. An administrative map over the study areawere digitalized together with two (by me modified) erosion hazard maps made by RePPProT(Land System with Land Suitability & Environmental Hazards, Sheet Jawa 1407, Jawa1408 1989), and an already existing forest land use map (TGHK) made by the Department ofForestry D.I.Y. (1992). After an overlay between these three maps, matching between theforest land use map and the erosion hazard map were done with the purpose to exclude areasfor conservation.

The remaining areas showed on the map were then overlaid with a soil loss map,created from USLE-calculations based on the field data. This resulted in the split up in twocategories, high and low potential erosion hazard areas, within the study area. Areas with highpotential erosion hazard were considered to be most suitable for reforestation and afforestation.The low potential areas were all regarded as productive, and therefore a further split includingnon-forest respective forest areas were done. Finally, an overlay between productive-nonforest areas, production forest, and conservation forest was carried out resulting in arecommendation map for forest land use within the study area.

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Fig.9. Flowchart over the Operational Steps for Creation of the Land Capability Map

Digitalisationof Maps

Maps of Physical FeaturesGeomorphologySlopeRainfallSoilGroundwaterLand UseErosion Hazard Map

Scoring ofLand

Characteristics-High PotentialErosion Hazard

Data LinkageScoringTabular

DigitalisatedMaps

Overlay

High PotentialErosion

Hazard Map

OverlayLand UseMap

Land Use Mapwith High

Potential ErosionHazard

Matching ErosionHazard Map

LandCapability

Map

Overlay

24

Fig.10. Flowchart over the Operational Steps for Creation of the Recommended Land Use Map

Digitalisationof Maps

Adminitrative MapErosion Hazard Map

Forest Land Use Map (TGHK)

Administrative Map Overlay

Erosion Hazard Mapwith Administrative

Details

Forest LandUse Map(TGHK)

Erosion Hazard Map

Overlay

Matching Erosion Hazard MapForest Land

Use Map(TGHK)

ConservationArea

RemainingArea

Overlay USLE-Map

High PotentialHazard

Low PotentialHazard

Production

Yes

Area forProduction

ForestNon Forest

OverlayArea for

ConservationForest

Forest

RecommendationMap for Forest

Land Use

Reforestation&

Afforestation

25

V. RESULTS

1. The Study AreaThis part of the thesis will be a closer presentation of the study area, located in the regency ofSleman respective regency of Gunung Kidul (Fig.11a). These two areas will be introducedseparately but in direct connection to each other. This is done for a better comparison and alsofor a more integrated context. Finally, a more detailed summary in tabular form over thephysical features respective population status will also be presented in the end of this section.

This section of the results mainly is based on interviews with farmers made duringfieldwork. Furthermore it is also supported by interviews with people educated within the frameof this research as well as with more detailed and specific data taken from other literaturesources and maps, than presented earlier in the overview of the special province.

Note that Fig.11b shows a larger area than the actual sampling area (Fig.11c). Thereason of that is to give a better overview as a way to simplify for further understanding of theorigin of different physical features. This area is mainly based on field observations, togetherwith RePPPtoT's LMU-mapping from 1989, but also with the support of different maps.

Fig.11a,b, c. Geographical Overview of the Study Area.

The numbers within map b is the elevation in m.a.s.l. The names in the same map show somesub-districts as well as larger rivers within the study area.

(Source: Peta Fisiografi. Propinsi D.I.Y., scale: 1: 250.000, Mitojat dkk (1987)).

The Sleman regency, with a total area of 574.82 km2, is located north to Northeast ofD.I.Yogyakarta between 7° 30' to 7° 50 ' S, and 3° 25' to 3° 45' E.

26

Stretching from south to Southeast within the special province, enclosing a total areaof 148.536 km2, is the regency of Gunung Kidul between 7° 50' to 8° 10' S, and 3° 10' to 4' E.It is bordered by the Sleman regency in the Northwest (Fig.11a) but embrace totally differentphysical conditions.

1.1 Physical FeaturesThe regency of Sleman is strongly influenced by volcanic activity, and due to eruptions of theMerapi volcano, the landscape has continually altered over time, and greatly influences the soiltypes and patterns. Eruptions have occurred several times during recent years and the latest bigeruption was at 22 November 1994. Freshly erupted materials accumulated near the volcaniccone as a debris avalanche. During heavy rainstorms, the unconsolidated and very hot materialfrom the volcanic slope flowed down as lahar, or 'glowing avalanche' with a velocity of about300 km/h as far as 7 km from the summit burning everything in its path (Sudibyakto & Abasi

1996). Fig.12. Geomorphology Map of the study area (Source:Peta Geomorphology.D.I.Y. Scale 1:250.000 Laboratorium Kartografi, Fakulats Geografi, Universitas Gadjah Mada (1990)

The parent material within the area is of volcanic origin with a relative homogenous composition(Tab.1, p.31 ). Morphologically, the regency is divided into 5 units: the cone, the upper slope,the middle slope, the foot plain and the alluvial plain area (Fig.12).

The regency of Gunung Kidul is mostly located in a karstic area and has a more heterogeneouscomposition of parent material, dominated by limestone and marl (Tab.1). The north toNorthwest part of the regency, bordering the Sleman regency, is influenced by material ofvolcanic origin. Further south a mix of sandstone, volcanic and limestone material can be found,finally more south reaching the large limestone and marl area.The regency is generally hilly from north to south, as a result from land upheaving. Due to thefault and flexure occurring, basins were formed, and within the basins a flat to undulating karstic

27

plain area can be found. Erosion and solution processes then formed a negative topography ordepression. Alluvial deposits forming a karstic alluvial plain later filled the depression (Sutikno1996 p.8). A huge gently to strongly undulating karstic plateau area, the Wonosari plateau, islocated in the centre of the regency. The karstic features of the area are characterised bykarstic dome hills, dolines, uvalas, underground rivers and caves with stalactite/stalagmite(Tab.1, p.31).

The volcanic slope of Mt. Merapi,reaching an altitude of 2911m.a.s.l. at the cone dominates thetopography in the northern part ofthe regency. A large plain area islocated in the south to Southeast.The southern slope of the volcanohas very steep areas withinespecially the nearness of thecone, but also on the upper slope(Fig.13). The continuing slopebelow is then gradually decreasingin angle, finally reaching the plainarea.Approximately 25% of the areavary between 100-500 m.a.s.l.(Tab.1) and the rest of the landare almost equally divided intoareas below 100 m.a.s.l.respective areas between 500-1,000 m.a.s.l.Fig. 13. Slope Map of the Study Area

Source: Peta Kemampuan Tanah Prop. D.I.Y, scale1: 100.000, Kanwil Badan Pertanahan Nasional. Prop.D.I.Yogyakarta 1994/95).

In the regency of Gunung Kidul, the steepest areas are concentrated to the hilly parts in south toSouthwest. Although, some areas in the northern part of the regency among limestone ridges isalso very steep.

The Wonosari plateau in the centre is rather flack with surrounding steep areas(Fig.13). Areas with an altitude between 100-500 m.a.s.l. dominate within the regency coveringabout 90% of the land areal. Other areas are located below 100 m.a.s.l. in altitude, withexemptions of some few areas having an elevation that varies between 500-1,000 m.a.s.l.(Suharsono et al. 1996, p.8).

The climate within the volcanic area is characterised by a mean monthly temperaturevarying from approximately 25°C to 28°C (BPS, Kantor Statistik, Kabupaten Sleman DalamAngka 1996). The mean annual precipitation shows on a high amount of rainfall at the cone(Fig.14), and also on a relative gradually decrease in amount of rainfall with altitude furtherdown the slope.

The relative humidity is high, reaching about 78 %, and during the rain season an increase with10% is normal. A decrease in sunshine duration (0.00 a.m. to 04.00 p.m.) with 15 -20 % toabout 45% is also usual at this time of the year (Woro 1990, p.28). The

28

Mean monthly temperature within the regency of Gunung Kidul is approximately 26 °C, whichis a little bit, less than theplateau unit (see Tab.1). Themean annual precipitation isvarying on a relative localscale between 2.000-4.000mm. In general the north partof the regency have a few 100mm less rain a year than thecoastal south, and the plateauin turn receive a few 100 mmless than the northern part.(Woro 1990, p.28).The mean monthly humidity isalso a few percent higher thanthe northern part, reachingalmost 90%. The coastalZone in the very south isalthough exceeding this ratewith a few percent(RePPProT 1989).

Fig.14. Rainfall Map of the StudyArea. (Source:Pola Curah hujan

prop. D.I.Y Scale: 1:100.000. Dinas Pertanian dan Dinas Pengairan Kabupaten Dati II se Prop. D.I.Y(1982/92))

The vegetation in some parts of the Sleman regency is not more than 3 years old because of'glowing avalanches'. On the steep upper volcanic slope, considered as the dangerous zone, athick natural forest conservation area with growing tree species like pine, salak and rattan(app.5, p.70) can be found. Dryland forest dominates further down on the upper to middleslope, containing a varying mix off species. Large areas of irrigated paddy rice are located onthe middle slope down to the foot plain (Fig.15). Wetland cultivation, especially paddy rice alsodominates on the alluvial plain area together with maize.

Compared with the other regencies, Sleman has less dryland and wetland dominates inthe regency (see D.I.Yogyakarta section), with approximately 43 % of the total land areacovered by irrigated paddy rice (Fig.19, p.32). This is in general also the only land utilisationtype used in the wetland areas of Sleman (Fig.15). Home garden is the most common landutilisation type in the dryland areas followed by dryfields or garden. Areas covered with forestsor forested lands are much more unusual compared with the other regencies within the specialprovince, only comprehensive an area of about 4 %.

Gunung Kidul is the most forested regency within the special province with about 43% of thetotal land area covered by dense forests and forest lands (Fig.20, p.32). The most commontree species is shown in Tab.1.

29

Acacia is used very frequentespecially in the more hilly areaswere community forests hasbeen created as a way topromote revegetation programs(Oral Setyarso 1998).

Compared with theSleman regency, cultivation withpaddy rice is rare, onlycomprehensive about 4% of theland use in the area (Fig.20). Itis usually the more steeplyslopes, located in the lowaltitude areas within the regencythat are cultivated with paddyrice and maize. Dryland forest,rich in species, is the mostcommon land utilisation type,covering approximately 55% ofthe regency (BPS Fig.15. Land Use within the Study

Area (Source:Penggunaan Kantor Statistik D.I.Y. 1996).tanah, Propinsi D.I.Y, scale 1:100. 000(1994/95) & Field Mapping 1998).

.Regosols, with its origin from thevolcanic parent material,dominates on the volcanic slope(Fig.16). The soil usually with asoil depth of 1-2 m or more, isvery fertile and has a highporosity, which makes it suitablefor cultivation (for detailedinformation see the section SoilCharacteristics on p 42).Coarser material was depositedupslope, and the finer materialwas transported to lower parts.Therefore, soils with finer textureare find on an increasing distanceFig.16. Soil Map of the Study Area

(source: Jenis Tanah Kabupaten from the volcanic cone.DATI II Gunung Kidul. Scale 1:100.000 (1988/89), Jenis Tanah Kabupaten DATI II Sleman. Scale 1:50.000(1989/90), Penggunaan Tanah DATI II Gunung Kidul. Scale 1:100.000 (1988/89), Penggunaan Tanah DATI IISleman. Scale 1:50.000 (1991/92)). PPT-Indonesian Soil Classification System

Cambisols dominates further down on the fluvial plain area at the volcanic foot, with a ratherdeep soil depth in places receiving deposits from the slope above. Combined with rathershallow groundwater various wetland crops can be cultivated in this area with great success.The soil distribution within the regency of Gunung Kidul is very varying, mostly consisting of lowdrainage and more acid litosols and luvisols, with exception for the karstic plateau of Wonosari,located in the central part of the area. Vertisols, litosols and rendzina dominate in this area

30

(Fig.16). In general, the soils within the regency are low in fertility, especially in south, with avery shallow soil depth varying between approximately 10-30 cm. An exemption is the morefertile areas at the border to the Sleman regency, having a soil depth of more than 1 m (Fig.17)because of volcanic influences (for more information see the section Soil Characteristics on p.42).

Fig.17. Orange coloured Soil Deposits dominates the Landscape in Patuk, Gunung Kidul.(Photo M. Enryd 1998)

Fig.18. Groundwater Map. Peta Airtanah D.I.Y. Scale 1:250.000 Laboratorium Kartografi, Fakultas Geografi, Universitas Gadjah Mada. Yogyakarta).

The river systems of Merapi consist of Progo, Dengkeng, and Opak river system. During theeruption of Merapi in 1994, Boyong river, which is under the Opak system received huge

31

quantities of volcanic material and played a very big role in the distribution of various volcanicmaterial in form of Lahore or mudflows that occurred after heavy rainfall (Sudibyakto & Abasi1996, p.2). As a consequence, river water was generally polluted to such an extent that it wasunfit for any use. The groundwater depth on the long slope is approximately 7-15 m, withexemptions for the non-aquifer cone and upper slope, and the fluvial foot plain with a depth ofmore than 25 m (Fig.18). The Oyo river is running through the regency of Gunung Kidul with a west to Southwestdirection causing occasionally flooding, and therefore also erosion in the catchment areas. Theunderwater rivers and the relative shallow groundwater with a depth less than 7 m that can befound in especially the more central parts of the regency (Fig.18) are of great importance forwater supply to the local cultivation, and many wells therefore exists within that area.

1.2 Population StatusThe Sleman regency is administratively divided into 17 sub-districts, including a total of 86villages. Sleman has the highest population density of all the regencies within the specialprovince, and is also in possession of the highest population growth (see the D.I.Yogyakartasection Socio-economic & Cultural Parameters). Approximately 25% of the total populationalso live within this regency, of which about half are concentrated in the more urban areas(BPS, Kantor Statistik Kabupaten Sleman 1996).

The regency of Gunung Kidul is divided into 15 sub-districts, including a total of 144villages, in which about 23% of the total population within the special province lives. It is alsothe most rural regency with only approximately 4% of its population living in more urban areas(Tab.2, p.31). The population density is lower compared with the other regencies, which also isthe case for the population growth that is about 50% less (BPS, Kantor Statistik KabupatenGunung Kidul 1996).

The economical situation in the regency of Sleman is relative good compared with theother 3 regencies because of the more fertile soil. Most of the land in Sleman is highlyproductive and, according to the interviews and other field data, it also indicates on an increasein productivity of the cultivation with none to slight erosion for most of the farmers.

This affects the economical profits for the households and an approximately income isas a result between Rp.500.000-1.000.000 (60-120 US) a year which is 3-10 times more thanfor a household located in a karstic area of Gunung Kidul. Although, a low-paid side-incomeselling food crops in the city, work as a shepherd or own a small shop in the village is verycommon among farmers.

One household usually comprises of about 4-6 people in Sleman, compared with 5-8 inGunung Kidul, cultivates a land area of approximately 0.2-1.5 ha which, according to theinterviews, and is the regular size within the whole study area.

The nearness to the active volcano have also given the result that areas have beenconverted to conservation forest and tourist areas, providing the local people with some extraincome. People seem to have no problem with erosion or other degradation of their land, butfigures based on the TP-formula (app.2, p.67) although indicates on an increasing populationpressure within the regency.

Opposite the situation occurring in the Sleman regency most people within the regencyof Gunung Kidul, according to the interviews, have problem with erosion, and other landdegradation resulting in a decreasing in productivity. This is affecting their economy and poorvillages have been priority for community forests. Community forests serve the local peoplewith fire wood, fruits, vegetables, food for the animal's etc. It is also of cultural importance,providing the people with many kinds of species used for different ceremonies and traditionalmedicine (Oral Setyarso 1998).

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People living near the privet research forest Wanagama in Wonosari, owned by GadjahMada University, also have the privilege to bring firewood from the forest. In return they usuallyprovide the research area with dung from their animals and therefore also contribute to themaintenance of the forest. There is also some kayu putih forest plantations owned by thegovernment within Gunung Kidul. Some farmers work extra within these areas and cantherefore make some economical profits by collecting the leaves from the tree that containsvaluable resources of oil used in medicine.

The economic situation for the farmers in Gunung Kidul varies mostly depending on ifthe cultivation is located on the volcanic soil as a dominant factor. Most of the land area isalthough located in less fertile areas and the farmers are working hard for its survival withoutany special economical profits. The economical situation also tends to get worse since themajority of all interviewed farmers complained about a decrease in production, and in somecases also about more erosion. The majority of the people does not know the reason of that, orcan not do anything about the occurring situation because of limitation in their economy.

The lifestyle in the villages is simple but all farmers' claims that they have enough ofmoney to support their household, and that they are relative satisfied with their social andeconomic situation.

1.3. Summary of Results

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Tab.1. Physical Features within the study Area.

PhysicalFeatures

Sleman Gunung Kidul

Geology Old Volcanic Deposits: basalt containingaugite-hyperstene, hornblende, andesiteYoung Volcanic Deposits: augite,hyperstene andesite

Andesite, breccia, sandstone, tuff,limestone, marl

Morphology Volcanic Slope. Karstic features: Plateau, dome hills,dolines, uvala, underground rivers,stalactite/stalagmite caves, ridges

Elevation 6.203 ha (11%) <100 m.a.s.l. 43.246 ha(75%) 100-500 m.a.s.l., 6.538 ha (11%)500-1000 m.a.s.l., 1.495 ha (3%) >1000.Top of Merapi: 2911 m.a.s.l.

11.515 ha (8%) <100 m.a.s.l. 1134.171 ha(90%) 100-500 m.a.s.l., 2.850 ha (2%) 500-1000 m.a.s.l.

Steepness Cone: >40%, Upper slope:15-40% (also>40%), Middle slope: 2-15%, Foot plain 0-2%

Hills in S-SW, N: >40%, S-SW, N: 15-40%,N-NW-2-15%, plateau: 0-2%

Climate: Am North:Am, plateau:AwRainfall (mm) Mean Annual:4.500-3.000 cone & upper

slope, 3-2.500 middle slope, 2.000-1.500foot plain

Mean annual in plateau:2.073 (1500-2000),Remaining areas 2-2.500

Temperature(0C) Mean Monthly: 25-28 Mean monthly: 26.35Humidity (%) 78%(Sept)-86%(Jan) Mean: 87.23Land Use Homogenous: Cone: Conservation Forest,

Upper slope: Dryland, Middle slope to plain:wet paddy rice

Heterogeneous: NW (low altitude):wetpaddy rice, forest: plateau and adjoiningareas, Dryland: remaining area

Soils*(USDA): Entisols & Inceptisols Entisols, also alfisols & vertisols in plateau

Hydrology: Opak river, Shallow perennial rivers.Groundwater depth: non-aquifer at cone,upper slope:15-25 m, middle-foot plain:7-15m

Oyo river, Shallow perennial rivers.Groundwater depth: N-NW, S, parts ofplateau: non aquifer, south part ofplateau:>25m,

Tab. 2. Population Status within the Study Area

Population Status Sleman Gunung Kidul

Population (thousands) 804.4 729.7

Male population (%) 49.3 48.9

Female population (%) 50.7 51.1

Urban Population (%) 48.2 3.8

Rural Population (%) 51.8 96.2

Population Density (thousands per km2) 1.399.34 491.2

Population Growth (%) 1.27 0.68

Annual average income per household(farmers)in $US

60-120 25-35

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Fig.19. The distribution of Land Utilisation Types in the Sleman Regency (1996). (Source: BPS, Kantor Statistik D.I.Y. 1996.)

Fig.20. The Distribution of Land Utilisation Types in the Gunung Kidul Regency (1996) (Source: BPS, Kantor Statistik D.I.Y. 1996.)

2. The Area of Focus

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The first part of this section is based on analysis and observations made during the fieldworkphase together with theoretical background information about the sampling sites (Fig.21). Thestudy area is divided into different land mapping units showed in Fig.22. Land Mapping Unitswithin the study Area below and a unit usually include more than one land utilization type.Therefore, sampling sites where chosen as to be representative for each land utilization typewithin every Land Mapping Unit. Furthermore, section 2.2. Soil Characteristics, a moredetailed description of the soil properties, is a result of soil laboratory analysis and other datacollected in field.

Fig.21. Map of Sampling Sites

Site 1. Hutan Wisata, Kaliurang, Sleman (Conservation Forest) Site 2. Turgo, Kaliurang, Sleman (Dryland Cultivation) Site 3. Agro Wisata, Turi, Sleman (Dryland Cultivation) Site 4. Batur, Cangrigan, Sleman (Dryland Cultivation) Site 5. Ngemplak Asem, Ngemplak, Sleman (Wet Paddy Rice Field) Site 6. Gemawang Putat, Patuk, Gunung Kidul (Dryland Cultivation) Site 7. Gemawang Putat, Patuk, Gunung Kidul (Wet Paddy Rice Field) Site 8. Forest Police Resort, Playen, Gunung Kidul (Forest) Site 9. Keduriggereis, N'glipar, Gunung Kidul (Forest) Site 10.Department of Forestry-Forest Research, N'gleri, Gunung Kidul (Forest) Site 11.Wanagama, Gadjah Mada University Research Forest P5, Wonosari, Gunung Kidul (Forest) Site 12.Wanagama, Gadjah Mada University Research Forest P17, Wonosari, Gunung Kidul (Forest) Site 13.Palang Racuk, Baron, Gunung Kidul (Dryland-'Bushland')

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Fig.22. Land Mapping Units within the Study Area (Source: Jawa Sheet 1408 Yogyakarta. Land Systems/LandSuitability. Land Systems with Land Suitability & Environmental Hazards. Scale 1:250.000. Serie RePPProT (1989) &Jawa Sheet 1407 Parangtritis.Land Systems/Land Suitability. Land Systems with Land Suitability & EnvironmentalHazards. Scale 1:250.000. Serie RePPProT (1989)

2.1 Sampling SitesThis section will be a closer presentation about the physical features of the totally 13 samplingsites (Tab.4, p.35). Soil profile descriptions, almost taken on a strait diagonal line from north tosouth were also carried out from 7 of the sampling sites with the purpose to describe atoposequence, or catena (see further Soil profile Description below). Remaining 6 sites weretaken from the adjoining area of each profile site comprising another kind of land utilisation type(see Fig. 21).

Starting from the north part of the study area is sampling site 1, the conservationforest, located on the cone of Merapi. The thick vegetation that mostly consists of pine andzalucca is about 3 years old as a result of the eruption in November 1994. Even if thevegetation layer has a high density, evidence of slides are common. During the rain season thatoccurred at the time of the fieldwork, more slides were noted (Fig.23). The terrain is verysteep, reaching more than 45 degree at the sampling site.

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Fig.23. Landslides along the Volcanic Cone. (Photo M. Enryd 1998)

This conservation forest attracts many tourists with the interest to see the active volcano, but thearea was recently (July 1998) evacuated because of an expected eruption. Within the veryporous and granular soil stones with its origin from earlier eruptions are found through the wholeprofile (for more details about the soil profile see Soil Profile Description on p.40).

Site 2, located in Turgo a few kilometres Southwest of the conservation forest belongs toanother LMU. This dryland area was also affected by the 1994 eruption and therefore thevegetation is young. Some native species like kaliandra and sengon is cultivated, and alsocoffee. Elephant grass dominates on the ground together with large volcanic blocks in the onlyslight sloping area. The soil depth is only 40 cm but appears to be very fertile, and no visibleevidence of soil degradation occurs.

Fig. 24. Wet Paddy Rice Field in Turi, Sleman (Not a Sampling Site) (Photo M. Enryd 1998)

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Next LMU includes 3 sampling sites (3, 4, 5) along the middle to foot slope. Site 3 is a largetourist area cultivated with salak pondoh, a native fruit tree. The area is flat and its position islocated more to the west than the other sites that is following the steeper southern slope ofMerapi. The cultivation is supported by a local groundwater source and is, according to themanagers, very productive.

Site 4 also includes dryland, but its position on the Southeast slope comprises a moresteep topography than site 3 mentioned above. The age of the cultivation is unknown and has abig variety of species, such as melinjo, avocado and cassava. The area contains terraces ofmore than 1 m in height, with local stones in the top layer. The soil is about 1 m in depth and itsstructure and other characteristics indicate on very fertile conditions. Although some soil losshas been noted within the area by the local farmers.

A small and young irrigated paddy rice field in the volcanic foot area encloses site 5,which is a converted fishpond since in December 1997. Since the cultivation is located in a flatarea, because of terracing, no erosion is found and the soil depth is more shallow comparedwith site 4, but similar conditions concerning the visible soil characteristics occurs (Fig.24).

Sampling site 6 will represent next LMU. Still located along the foot slope is site 6, the mostvarious sampling area, comprising a dryland cultivation of unknown age with a random mix ofspecies like cacao, melinjo, maize, sengon, rambutan, coffee and banana trees. The cultivationis terraced with the same technical used for the earlier mentioned site 4. The degree of the slopeis although more steep varying from 9 to 250 on a 30 m distance between the lower and uppermeasuring point.This LMU contain a more various lithology of volcanic and sedimentary origin, also including amixed mineralogy of intermediate, basic and calcareous material.The very bright orange to reddish coloured soil with a depth of more than 150 cm has visiblesoil characteristics that indicates on good growing conditions for the vegetation. The owner ofthe land although complains about an ongoing increase of soil loss through runoff since a fewyears back in time.

Fig.25. Mud Cracking in Patuk. (Photo M. Enryd 1998)

Samples were also taken from a LMU comprising a terraced wet paddy rice field (site 7),located further south to Southwest on a moderately, dissected, tilted plateau. The composition

40

of the lithology and mineralogy is similar as described above, and soil conditions seem to befavourable for the cultivation. The rice fields position in direct nearness of a river also makesadvantageous conditions for irrigation. The more sparsely precipitation that occurs within thisarea although gives rise to mud cracks direct outside the rice field (fig.25).

A miner LMU, including site 8, also with its position on the tilted plateau is located less than 1km south of Opak River. The area is forested with species like mahogany, acacia, andteakwood growing on a calcareous ground. It is not a very steep area but small slides, andgullies were although found within this area. Within the 32 cm thick soil profile transformation ofiron to ferric material and formation of calcretes is distinct. The incorporation of the bedrockwithin the highly weathered profile also creates aggregates through the accumulation of calciumcarbonate, and therefore the drainage is very high resulting in even more weathering especiallyoccurring during rain season.

From a rather hilly area, located on the karstic Wonosari plateau, 3 sampling sites were chosen(site 9,10,11) as to be representative for next LMU. Site 9 and 10 are since a few years backin time converted teak plantations cultivated on calcic ground. The productivity is according tothe farmers lower now after the change to kayu putih, a tree used for the making of naturalmedicine. These two forest areas, located above a flood plain, have seasonally flooding fromthe same river at the end of the slope. The slopes is moderately steep, but the low qualitylimestone terraces as well as the low density of trees is hardly preventing runoff, which makesthese 2 areas highly eroded (Fig.26).

Fig.26. Eroded Kayu Putih Cultivation (Photo M. Enryd 1998)

The soil depth is very thin only comprising 12 respective 7 cm, and even if the structure consistsof single grains for site 9, and aggregates for site 10 the drainage is moderate to low because ofsaturated conditions.

Site 11 is part of the Gadjah Mada forest research also positioned on calcareous ground on thehilly karstic plateau. The thick forest embraces species such as teakwood and lamtoro (local

41

firewood), and has a function as community forest. The forestland is terraced but its position onthe moderately slope still give rise to small slides. The depth of the soil is 15 cm, and consists offerric material and accumulation of calcium carbonate within the profile. The structure isgranular and porosity and drainage conditions are relative favourable. Revegetationprogrammes have since the early 70´s been practised here and in surrounding areas, some hasresulted in success others with failure without any particular known reason. The reforestationprogramme included among one thing the introduction of new and more tolerant species, andhilly areas were usually prioress for forest.

Site 12 is also part of the Gadjah Mada forest research, however in anotherLMU. This is a eucalyptus forest, planted in rows along a slightly sloping area. No apparenterosion is visible and the soil conditions also seem to make advantageous conditions forcultivation of this kind. The soil depth is although only 10 cm.

The last LMU includes site 13 (Baron), an extremely eroded hilly karst area in the coastal zone.The slopes are sparsely covered with vegetation and only bushes with a very superficial rootsystem together with grass manage to survive in the hardly existing soil layer along the slopes. Inthe plain areas between the slopes cultivation with maize is common. The low quality limestoneterraces are hardly visible among all different salient calcic formations (Fig.27). The reddishbrown soil at the sampling site has a depth of 20 cm at the sampling site. Visible conditionswithin the soil indicate on bad conditions, such as very low drainage, low porosity etc. andevidence of erosion by both wind and water is obvious. Fig.27. Calcic Ground in Baron (Photo M. Enryd 1998)

Soil Profile DescriptionExternal factors like volcanic eruptions has from time to time dramatic changed the patternsamong the slope influencing the soil formation by the burial of already existing soils in north.

42

The areas in south are instead strongly affected by degradation due to chemical andphysical processes occurring in the calcic parent material.

The cross-section contains some further information about the soil profiles within thestudy area than presented in the former section, and falls under a typical description of a catena,concerning geomorphic processes occurring among the slope.

Fig.28. Soil Profiles within the Study Area.General DescriptionProfile 1: Volcanic Influenced. Mineral horizons with diffuse boundaries. Gradually colour change to approximately~50 cm (dark brown-brown). Volcanic stones within the whole profile. Moderate Shear Strength.

Profile 2: Volcanic Influenced. Mineral horizons with diffuse boundaries. Gradually colour change to approximately~50 cm (dark brown-brown). More volcanic stones after ~50 cm. Low shear strength.

Profile 3: Volcanic Influenced. Eluvial horizons mottled gley until ~45 cm. Calcic accumulation until ~50cm. Darkerred colour at a depth of 100 cm. Subsoil at unknown depth (>150 cm). Moderate shear strength.

Profile 4: Weathered calcic profile. Mottled until ~25cm with a mix of organic matter until ~15cm. Calcretes andwithin the whole profile, mostly concentrated on ~15cm from the surface. Thin profile (32cm), moderate shearstrength.

Profile 5: Very thin and calcic profile (7 cm). Calcic and ferric accumulations. Shear strength test not accurate.

Profile 6: Very thin calcic profile (15 cm) with organic matter until ~5 cm. Calcic accumulations make soilunconsolidated.

Profile 7: Very thin profile (12 cm). Brown red soil with incorporated calcic bedrock. Shear strength test notaccurate.

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2.2 Soil Characteristics

44

Totally, 15 different laboratory analysis from each soil sample was carried out from everysampling site in order to give a more detailed analysis of the physical and chemical features ofthe soil (Tab.5). A summary of the analysis pointing out the most distinguishing features withineach sampling site in comparison with other studies will now be presented together with sometheoretical comments.

• The texture along the slope of Merapi is coarse with sandy loam to loamy silt at the coneand upper slope. Further down sandy soils occurs as a result of water transfer. Clayeymaterial dominates in the regency of Gunung Kidul.

• The amount of exchangeable potassium is in general low within the whole study area, withexception for site 6, Gemawang Patuk (dryland). Potassium as well as magnesium belongsto the clay minerals and is according to Rowell (1994) usually occurring in higher amountswithin soils formed on sedimentary material, which also is the case. The lack of potassium,especially occurring along the Merapi slope, may be a result of leaching. Fertilisers are alsofrequently used, which in a large concentration can reverse the effect, causing the potassiumto be non-exchangeable (Rowell 1994, p.177). Losses also seem too large in more acidand coarse-textured soils (Armson 1979, p.134) that occur along the slope. Site 6, withhigh amount of potassium, is located on the foot plain of Merapi receiving large quantities ofthe very minerogen volcanic soil transported downslope.

• Exchangeable calcium in the Sleman soils is moderate, while sites in Gunung Kidul havesubstantial higher amount. This is very distinct due to the difference in lithology between thetwo regencies.

• The presence of exchangeable magnesium is low on the Merapi slope, and moderate in theGunung Kidul sites. Although Site 6 & 7, located in Gemawang Patuk on the foot plain,have significant higher amount of magnesium. Leaching processes occurring on the slopecould, as well as for the higher potassium conditions earlier mentioned for the Patuk area,give rise to the higher amount of magnesium. Excessive amount of potassium also reducethe uptake of magnesium (Davies, et al. 1982, p.42), and in addition to this these soils haveclayey texture together with sesquioxides which contributes to the held of exchangeablecations (Rowell 1994, p.176). Magnesium occurs together with calcium in dolomite(Armson 1979, p.134), but on lime-rich soils calcium is antagonistic to magnesium (Davieset al. 1982, p.42) which could be the case for the soils located in the calcic regency ofGunung Kidul.

• Exchangeable sodium values are considerable higher in sites located in Gunung Kidul. Thelow amount of sodium in the volcanic slope is increasing further down, and since sodium islost through leaching more easily than other cations it could be the case. Sodium can betoxic to many plants species, and it also has a deleterious effect on soil structure, promotingthe dispersal of aggregates (Ellis & Mellor 1995, p.49), although calcium protects the soilfrom deterioration, and also defends plants against the toxic effects (Rowell 1994, p.280).This to a certain limit and in order to evaluate if sodic conditions occurs, calculations withthe Sodium Adsorption Ratio (SAR) formula was necessary to fulfil this. SAR representsthe total amount of exchangeable sodium relative to total exchangeable calcium andmagnesium, and is determined as follows:

SAR, that according to Davies et al. (1982) gives an approximately determination of theExchangeable Sodium Percentage (ESP) of the soil. Although, it has long been realised that

45

this is an arbitrary figure among soil scientists. Several classifications and threshold levelsconcerning the sodicity of a soil exists within the literature, but a threshold of 15 (ESP) is ingeneral used as an indicator of sodic conditions, of which all sites within Gunung Kidulexceeded with a striking marginal (Tab.3). According to Landon (1991) a soil with theexchangeable Na > 1 me/100 g should be regarded as potentially sodic. This in additionalconfirms the already calculated ESP-values.

Results from calculations showed that sites located in the regency of Sleman had anESP ranging between approximately 6-18%, while the sites with its location in the GunungKidul regency have an ESP varying between approximately 24-42% (Tab.3). The SARcalculations indicate that the most sodic conditions occur in especially forested areas, such asfor site 8-11. Tab.3. ESP- Value for the Different Sites.

• The Cation Exchange Capacity (CEC) along the Merapi slope is relative low. The forestedareas of Gunung Kidul shows considerable higher CEC, while the remaining areas withinthe regency have medium too high values. A certain pattern between the CEC values andthe estimated ESP values above exist, together with an obvious relationship with thetexture, indicating that clayey soils have significant higher CEC values.

• Amount of organic matter and the percentage of total carbon within the soils areconsiderable higher in site 1 respective site 8, which also is covered with thick forest.

• The acidity of the soils in the Sleman regency are in general slightly acid while the sites inGunung Kidul varies from slightly acid to slightly alkaline. The more alkaline soils of GunungKidul are located in the forested areas, which also have the highest CEC values.

• Ease of dispersion is an important factor influencing the erodibility of soils. The DispersionRatio Value in clayey soils is considerable lower compared with the more coarse-texturedsoils. Site 8, the forest in Playen have low infiltration capacity that has resulted in calcretes.In turn this give rise to the very low existing dispersion ratio occurring within the upper partof the profile.

The Sleman sites have a less amount of exchangeable macro nutrients and therefore also lowerCEC. The texture is coarse and increases with lower altitude. The dispersion ratio, foremostdepending on the texture, is very high and the soils are slightly acid. The soil is although fertilewith an increase in productivity. Sites in Gunung Kidul have clayey texture and therefore higherCEC and amount of macro nutrients (also depending on the lithology). Extremely sodicconditions occur and the dispersion ratio is also low The soils varies from slightly acid to slightlyalkaline. Soil conditions within these sites are less favourable, and indicate severe degradationthat also occurs today.

3. Land System Analysis

Site1 12.4%Site2 18.5%Site3 6.2%Site4 12.5%Site5 11.3%Site6 26.5%Site7 23.3%Site8 36.8%Site9 34.6%Site10 41.7%Site11 40.3%Site12 24.6%Site13 25.0%

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Following chapter is a compile of erosion hazard mapping, USLE-calculations, and theapplication of GIS. This includes the presentation of totally 4 maps. The first map presented insection 3.1 is an erosion hazard map, which is the result of field observations. Section 3.2 a soilloss map is the result of USLE-calculations based on field data. The land capability map insection 3.3, and the recommended land use map in section 3.4 was created with the help ofGIS applications. Maps and other theoretical information together with data collected duringfieldwork were combined in order to give a more accurate interpretation.

3.1 Erosion Hazard AssessmentDuring the fieldwork phase mapping and classification of erosion hazards were made withineach land mapping unit.

According to the field observations the steep forest covered cone of Merapi isclassified as an area with severe erosion hazard with many slides occurring (Fig.29). Humanimpact is not so significant in this matter and the hazard is depending on the steep topographycombined with a high amount and intensity of rainfall that contributes to slides in the fine-textured soil. However, the natural thick forest layer offsets most of the erosion. The remainingsites located along the long volcanic slope had none to only slight erosion hazard all the waydown to the permanently inundated foot plain area. The erosivity along the slope is high,although suitable soil conditions, mentioned in Factors Influencing Erosion on p.14, give riseto a high erodibility.

Areas with moderate to high erosion hazard vulnerability dominate the foot plain ofMerapi and the northwestern part of the Gunung Kidul regency, including site 6. This LMU isdominated by a steep hilly topography, but does not affect the sampling site showing no visiblesign of erosion. This site, chosen for a more linear soil profile description, is positioned in thefoot plain of the volcano and therefore have deposits of material transported from above.

A plainer LMU, mostly cultivated with wet paddy rice, is located in the regency ofGunung Kidul further down. This LMU is classified as a non-to-slight erosion hazard area.Even though, the precipitation is relative low in the area were site 7 is positioned and some drycracks in the clayey soil earlier mentioned can be found in the adjacent dryland of theinvestigated rice field.

In the nearness of the Opak river is site 8, included in a LMU considered as an areawith extremely erosion hazard. This forested sampling site is relative protected from erosion dueto the dense vegetation that offsets the effects, while evidence of gullies and small slides occursespecially in areas more close to the river.

Located on the forest covered Wonosari plateau with a rather hilly topography togetherwith a thin soil layer is site 9-12, which has various conditions concerning erosion. Site 9 & 10cultivated with kayu putih is highly eroded, while other areas higher up on the plateau isconsidered as moderate. The change from teak to Kayu Putih increases runoff and splasherosion. The reason of that is the lack of canopy on the Kayu Putih tree that also will have othereffects on the soil characteristics. Finally, the very south part of the study area is classified asextremely severe erosion hazard area, containing large hilly areas with lack of vegetation.Soil LossThe soil loss map (Fig.30) is a result of the universal soil loss equation, with calculations basedon field data collected in the study area (app.2 p.67). Most of the sample sites within the studyarea indicates on a rather low amount of soil loss. Although some parts of the area in the upperslope of Mt. Merapi, utlilizated as dryland have higher loss of soil. The highly eroded LMU inthe very south is also effected by severe soil loss due to the loss of vegetation and to thecharacteristics of the topography.

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Fig.29. Erosion Hazard Map (Source: Field Mapping)

Fig30. Soil Loss Map of the Study Area. (Source: USLE-calculations based on field data).

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Fig.31. Land Capability Map (Source: GIS-applications, see further in the GIS section on p.20) Fig.32 Map of Recommended Land Use (Source: GIS-applications, see further in the

GIS section on p20)

3.2 Land Capability Classification

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The evaluated land capability, with focus on erosion risk, within the study area is showed inFig.31. A matching method based on a total of eight maps over physical features split intodifferent criteria’s has been used to accomplish this matter.

The map indicates that areas with forest and wet paddy rice usually have low potentialerosion hazard. An exception is some rice fields located in more steep areas at the border ofthe Sleman and Gunung Kidul regency. Most of the areas covered with dryland are of lowpotential erosion hazard, but dryland located in the rather steep areas within foremost theregency of Gunung Kidul, and also in the upper volcanic slope, although have high potentialerosion hazard.

3.3 Recommended Land Use within the Study AreaThe final and most important purpose with this research is to indicate how balanced conditions,or matching between the physical features and utilization of land within the study area can beachieved. Therefore, a recommendation map for land use (Fig.32) was made in order tofacilitate the presentation of this matter. These suggestions or recommendations are, in contrastto the land capability map, totally based on interpretations and mapping of land characteristicsas well as analysis of soil samples and USLE-calculations. Local knowledge in landmanagement and other socio-economic and cultural factors has also been taken underconsideration. The recommendations are as follows:

The cone, already covered with a dense natural conservation forest, seems to be the bestalternative for protection of the soil against erosion. Due to flooding and sedimentationconservation practices can also be suitable in river zones within the whole study area. Furtherdown on the upper slope a dryland area with high potential erosion hazard is found. This areais, according to the USLE-calculations partly liable to severe soil losses. Therefore, aconversion to forest, with the function as a water holding zone, is recommended to be the bestalternative.

According to Jansson (1982) agricultural practices reducing the vegetation coverincreases erosion. A large area, for the time being cultivated with wet paddy rice, along themiddle to lower Merapi slope could therefore be replaced with forest in order to reduce therapid drainage of water occurring. The plain wetland areas at the end of the slope couldalthough remain cultivated with paddy rice, or other crops suitable for wetland cultivation. Thelower slope of Merapi down to the foot plain mostly consisting of wet paddy rice fields couldinstead be converted to dryland areas if the zone above has a function as water holding forest.

The very north part of the regency of Gunung Kidul is in general cultivated with highpotential erosion hazardous dryland. A land use change to forest with the function as aproductive protection area is an alternative. This would increase the protection against therelative high erosion by a higher amount of organic matter and other soil characteristics thatimproves the soil structure. A reduce of chemicals, such as pesticides and herbicides will alsofollow by that.

According to the land capability map, the majority of dryland that exists within GunungKidul is classified as low potential hazardous. If parts of these areas are reforested orafforestated an increase of the less favourable soil conditions will be improved of same reasonsmentioned earlier. Finally, the large eroded coastal area in the very south of the regency, andalso the similar classified regions in the nearness of the river Opak, could be converted tonature reserve because of its very disadvantageous cultivation conditions. These areas areaccording to the land capability map of low potential hazard, but the very thin soil depth andother less favourable soil characteristics have not fully been taken under consideration duringthe creation of the map.

4. Local Knowledge in Land Management

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This section of the results is based on interviews made during the fieldwork period with farmersand engineers in conservation practices from the study area.

The attitude among farmers concerning management of the soil, crops and other vegetation isvery traditional. The land is usually inherited for many generations and not many changes in landuse or management of the land has been done through the years. According to the interviewsmost of the people are afraid to try another kind of cultivation to improve their economicalsituation. They usually have the same kind of cultivation all the life.

All of the farmers have done some kind of conservation practice to protect their landagainst erosion. Mechanical methods dominated by terracing with local stones are frequentlyused within the whole study area. People in general have stone terraces made of pyroclastics inareas near the volcano, and limestone from the bedrock in the other areas. The local people inSleman also use sand, pebbles, gravel and other coarse material, that comes down the volcanicslope during rainfall, as construction material.

Since many of the terraces are old and therefore less effective because of weathering, itseems like the maintenance of already existing terraces is the most common way to protect theland against erosion. This occurs especially in the regency of Gunung Kidul were limestoneterraces are destroyed, due to rainfalls, which dissolve the calcic material.

Research done in Gunung Kidul (Oral Setyarso 1998) although shows that terraces onsome steep slopes having a shallow soil depth may be deeper than the subsurface flow. As aresult water runs out of the riser face and on to the terrace below, with the result that 90% ofthe rainfall becomes runoff causing serious erosion. Cultivations located along the slope of Mt.Merapi also use waterways as a further alternative to control the land against intensive rainfall.

Contouring by ploughing, planting and cultivation is also practised among most of thefarmers to protect their land against soil loss in slope areas. Contour bounding and earth banks,is other methods frequently used as a barrier to runoff.

Crops and vegetation management practised in the area is strongly depending on theland utilisation type. Multiple cropping by intercropping is generally used in dryland areas,which is considered to be a favourable alternative recommended by the Department of Forestry(Oral Sutamto & Sukasno 1998). Strip cropping and multiple cropping by sequential cropping,is more common among the interviewed people in the regency of Sleman, and can be related toland utilisation types like salak cultivation.

Strip cropping is a relative new method and not yet so very common conservationmeasurement on Java, but this method is considered to be a cheap and suitable managementmethod with long protection and good effects, especially for runoff control, and as animal food(Oral Suparto, 1998).

Another suitable alternative, as a cheap and easy conservation method against erosionand sedimentation, is alley cropping. Alley cropping is, according to Mr. Suharsono at theDepartment of Forestry, Yogyakarta especially useful on bench terraces in dryland cultivation's,and also contributes to an increase of mulch and organic content. It is in addition to that usefulas animal food and firewood.

Regular weeding and applications of fertiliser's etc. is carried out. Row crop cultivationis according to Morgan (1986) usually give rise to more erosion problems due to the highpercentage of bare ground, particularly in the early stages of crop growth. However, row cropswithin the study area are combined with high density planting of other vegetation to preventerosion. This management (agroforestry) is very common among farmers and also seems tohave advantageous effects.Combination with forest management or other rotational cropping is also done all over the areaas a way of controlling erosion.

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Conventional tillage such as ploughing together with the adding of animal dung is most commonin soil management. Soil stabilisers also occur in some cases. Numerous studies concerning theeffects on convention tillage on soils have according to Morgan been done. The results showedthat conventional tillage sometimes causes problems, especially on structureless soils with a highsodium content but no explanation about this statement is given.

VI. DISCUSSION

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This thesis concerns a specific purposed land evaluation of which the specific purposes in thiscase comprise the interpretation and comparison between two areas with differentphysiographic features. The overarching aim that concerns the relationship between the physicalfeatures and utilization of land will be discussed, as well as the objectives that were put up toanswer that aim.

The first objective achieved was the elaboration of land utilization types within the studyarea. This were carried out by semi-detailed mapping based on field observations and a landuse map from 1994/95, and due to relative homogenous utilization types this were done withoutany specific problems.

Next objective concerned the terrain stability, which included erosion hazard mappingas well as slope stability. Since the study area comprised an approximately 60*20 km largearea and the Land Mapping Units, classified by RePPProT (1989), were in scale 1:250.000,the mapping of the erosion hazards therefore had to be generalised for each unit even thoughsome minor variation occurred.

Erosion hazards in Sleman are rare and visible soil conditions are favourable. Thisbecause of the volcanic influence within this area that creates advantageous growing conditionsdue to the minerogen deposits increases the erodibility of the soil that offset factors like highamount and intensity of rainfall as well as a sometimes rather steep topography exists. The veryhigh rainfall that usually occurs in volcanic areas as a result of the relief in turn promoteinfiltration and reduce the shear strength and by this also that minerals can be weathered andtherefore become more available for the vegetation.

Conditions in Gunung Kidul, concerning erosion hazards, is a contrast to the Slemanarea. Cultivation land within the karstic limestone-rich areas indicate disadvantageous growingconditions and also severe to extremely severe erosion in a dominant part of the regency. Lime-rich areas are more sensitive to chemical weathering that dissolves the calcium carbonate, andtherefore also cause leaching due to the high amount and intensive rainfall that occurs. Theevapotranspiration within the area also exceeds the precipitation, causing the calcium and othersalts to accumulate, especially at the surface. This will contribute to the severe erosion ratesoccurring as a result of runoff. This is according to Reading, Thompson & Millington (1995) acommon problem recognised in especially humid tropical areas

The slope stability was in field indicated with measurements of shear strength within thestrategy chosen soil profiles. These tests gave relative accurate indications of the stability, withexemption for some areas were the soil layers were to thin and therefore not possible to carryout. This type of testing (field shear box) is according to Selby (1993) particularly useful instudies of soil erosion, and for comparing the strength of soils under different kind of vegetation.The results of the test shows that the shear strength is especially low in the steep and morecoarse-textured volcanic slope with dryland as land utilisation type. With exception for therainfall and topography as depending factors, a vegetation cover with low organic content, as inthis case, can sometimes increase infiltration and interflow along root channels.

Calculations with USLE, based on field data, were performed as a further complement,or indication to slope stability, showing the potential soil loss within the area. The reliability ofUSLE has been discussed in numerous cases before because of its restriction to USAcontributing to limitations in application within other parts of the world. However, this method iscommonly used for long-term prognosis and is also specific for rill and sheet erosion that occursin a great extent in a tropical environment.Estimations with USLE point out same drylands earlier mentioned concerning shear strength tobe highly subjected for soil loss. In reality some soil loss within this areas has been noted, but atthe time being agroforestry with high density planting of many various species exist. This is sofar promoting soil loss to occur in larger quantities.

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Unfortunately this large study area is represented by to few sampling sites as referencefor the whole area. The variation in both land utilization and topography varies a lot on a relativelow scale which results in deviating values calculated on the whole region. This especially withthought of the more heterogeneous conditions existing in the regency of Gunung Kidul.

Another objective was to indicate the land capability. In order to achieve that, visibleand further analysed soil characteristic together with other land characteristics were taken underconsideration. The earlier described erosion hazard mapping as well as interviews with localfarmers were also used for this matter. The interviews concerned land conditions, landmanagement, socio-economic and cultural conditions.

Since the productivity of land, according to the majority of all interviewed farmers in theregency of Sleman is increasing the capability of land is not exceed and indication of soil lossestimated in a long-term was, as told earlier, only noted for some parts along the slope.According to Sudibyakto & Abasi (1996) the long-term prognosis for this area can also be animprovement of the micro-climate as a result of the fresh and dense vegetation growth.

All other visible characteristics of the soil indicates on favourable conditions, but furtherlaboratory analysis showed that the level of exchangeable macro nutrients, such as potassium,magnesium and sodium were low. This could be the cause of leaching processes that iscommon in acid-coarse textured soils like this. A possible overuse of fertilisers and otherchemicals, which is frequently used along the slope, can also contribute to a reverse effectpromoting a decrease in soil fertility by the leaching of important nutrients. This has beenconfirmed in several cases around the world.

The north to Northwest part of the regency of Gunung Kidul, positioned in the footplain area have soil layers that reaches more than 1,5 meter. The colourful orange-reddishprofiles have good growing conditions, which also were confirmed by the laboratory analysis.The colour of the horizon indicate on a high amount of sesquioxides that may have dissolvedaway the quartz which also contribute to the held of exchangeable cations. Input of soil from theslope above, together with a finer texture is reducing the possibility of leaching. Therefore, theland capability within this part of the regency is not exceeded.

Further south, including the limestone-rich areas of Gunung Kidul the productivity of thesoil is, according to the local farmers, decreasing since a few years back in time. The amount ofmacro nutrients although shows normal conditions according to several classifications of soils insimilar environments. However, extremely high values of exchangeable sodium were foundwithin these sites. Since sodium soils according to Landon (1993) are noticeable in itsdeleterious effects on soil structure a connection between the low infiltration rate that alreadyexists can be an important factor influencing the already exceeded land capability.

One example is the highly eroded area in the nearness of river Oyo that embraces themost sodic conditions. They are both positioned in moderate slopes above a flood plain andflooding is also common during the wet season. According to Ellis & Mellor (1996) this istypical condition for sodic soils in an environment like this.

Estimation of the land capability was the following objective to this. The methodchosen for this was theoretical with exemption for the included erosion hazard map done duringfieldwork. Based on eight important maps over physical features this was carried out with thehelp of GIS. This resulted in a map indicating high potential erosion hazard areas as well as lowpotential areas within the study area.The results received with this method indicated on less high potential areas than expected. Withthe fulfilment of the former objective in mind I could clearly see the importance of the analysedsoil characteristics as well as the farmers indications on the productivity. No considerationconcerning the very sodic soil conditions was taken by the application of this method, which isof great importance and relevance for the estimation of land capability within this area. Thefarmers living within areas, classified as low potential for erosion, has although noted a decrease

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in productivity, which not have been considered with the application of GIS. Therefore, acombination between the GIS application and the field data, including interviews and soilsampling, is necessary to give a more complex presentation of the actual potential areas.

GIS is a very useful tool in the creating of maps, and the applying of GIS in landevaluation analysis will facilitate the linking between all depending factors that usually exists.However, the combination of physical maps and demographic maps, such as population densityis seldom used in the creation of for example a land capability map. This could be used in abigger extent since demographic data concerning this matter in most of the cases is relativeavailable. One of the negative sides is although that the demographic data usually is in tabularform, which like in my case can cause problems due to limitation in time. Another suggestioncould be to apply the TP-formula (app.2 p.67), which is a common formula used in Indonesiansocio-economic analysis for calculations of the carrying capacity of land. A map of TP, thepopulation pressure could result in an accurate land capability map when overlaid with othermaps.

Since the interviews are of great importance for further land use planning as well as forconservation practises a try to understand how the physical features of land affects the peopleas well as people's respond to the land system were done. By using the information concerningland management and socio-economic conditions, together with cultural aspects, in combinationwith indications of land capability conditions a further objective could be fulfilled.

The farmer's interest to obtain the maximal output from the land has an influence on theland capability. In areas were the capability of land is exceeded, the introduction of newconservation practices or a conversion to another kind of land utilization type should be carriedout. Many researches on especially Java have according to Kusumandari & Mitchell (1997)suggested agroforestry as a favourable alternative for prevention of particularly the soil loss.Erosion although occur within these already existing agroforestry areas of Gunung Kidul but animprovement of this utilization type by planting trees of less height will, as earlier mentioned inthe theoretical background on p.16 give a further protection from runoff.

However, the attitude among the majority of farmers concerning introduction of newcrops or vegetation, as a way to increase the productivity of land, is traditional. They mainproblem is that these farmers are insecure if they will be able to make a profit at the market ifthey have other species and therefore prefer to only improve or maintenance the managementof land. The requirements of commercial crops and other traditional medicine plants also have astrong influence within this area. This confirms an already recognised problem all over theworld. Farmers in poor rural areas are according to Morgan only willing to adopt soilconservation practices if they perceive an immediate economic benefit, which sometimes isdifficult to estimate. That adoption of new conservation methods is although only possible if theyhave necessary labour, capital and technological inputs.

Morgan further points out another conservation problem by referring to a situation thatoccurred in Java in the 1980s. Six government organisations with different responsibilitiesworked alongside in a watershed project. The little co-ordination of activities as well as thecompetition to work on different aspects between these organisations became confusing for thefarmers and other people involved. To avoid a situation like this project and other research onboth high and lower level must be better organised. To achieve that further understanding andprojects with people of different disciplines is necessary.

Successful government projects within the regency of Gunung Kidul although exists.The idea to have community forests prioress within the poorer areas have a positive influenceon the land as well as a safety function with benefits for the farmers that are depending on anextra income. The achievement of the research within the area might also lead to the adoptionof sometimes more suitable conservation measures than the usual ones.

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Sometimes an improvement of the management of land is not enough. As told earlier inthe section for management on p. 48, evidence of load caused by terraces in some parts ofGunung Kidul have been noted and therefore a conversion of the land to another kind ofutilization is a further alternative.

Suggestions concerning land use was in the form of a recommendation map for land usepresented earlier in the results. The aim with this map is to combine my own field data togetherwith some local knowledge about the study area, and by that create a more realistic situation.Most of the maps I have studied concerning land use are mainly based on two or three mapsover physical features such as slope, rainfall and soil type. During my period of fieldwork Irealised that the matching between reality and theoretical seem to differ a lot in some cases. Itherefore believe that the importance of applying more actual field observations together withfield mapping is necessary in order to give a more accurate illustration, meaning that morepriority should be given to fieldwork within research concerning land evaluation systems.

The discussion above concern problems related to the degradation of land. Clear ishowever that external factor especially including volcanic eruptions have great impact within thisenvironment. At the time of the compile of this thesis (August 1998) disquieting newsconcerning another severe eruption from Mt. Merapi, affecting parts of the study area has beenreported. Lava flows and the throw out of gas has already occurred, and so far 3,000 peoplefrom the volcano's surrounding has been evacuated. The severity and damage caused by theeruption is difficult to estimate but it will for sure have an impact on the cultivated land by theburning of vegetation and the burial of land. I would therefore like to finish this discussion bysaying that land use planning within this unstable area is difficult to apply concerning the karsticareas that includes special features and sodic soils as well as along the volcanic slope having afrequent and sometimes unexpected volcanic activity.

VII. CONCLUDING REMARKSThe physical features within the study area is distinct and the overarching aim within this study isto indicate how these physiographic features affects the people and people's respond to thecharacteristics of the land system. Several objectives have therefore been put up as a way toanswer this key question. Conclusions regarding these objectives will be presented below

I. The elaboration of land utilization types within the study area was classified into threemain groups of cultivation including several kinds of species. The utilization of landwithin the regency of Sleman is homogenous with conservation forest at the cone,dryland along the upper slope, and wet paddy rice field along the remaining part of thevolcanic slope also covering big parts of the plain area. A more heterogeneousdistribution of land utilization occurs in the regency of Gunung Kidul. Wet paddy rice

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fields cover the low altitude areas in the north to Northwest of the regency. Forests arefound on the karstic Wonosari Plateau as well as in the adjoining areas, mostly coveringthe hilly parts. Remaining areas consists of dryland.

II. No visible evidence of erosion exists along the Merapi slope, with exception for theslopes located on the very steep cone were several landslides occurs. Potential soil lossis although indicated by USLE-calculations for some coarse-textured drylands alongthe upper slope, and the shear strength is also very low. According to the soil analysissome nutrition losses of for example potassium occur, which can be the results ofleaching processes.The karstic areas of Gunung Kidul are exposed to soil erosion in different degree. Sitesin the nearness of Opak River have evidence of gullies, slides, weathering, compaction,calcretes, stoniness, drought and a very thin soil layer. Occasionally flooding alsohappens in some cases. A huge part of the region in the very south of the regency isclassified as extremely severe erosion hazard area with steep hills almost bare from soiland vegetation. Besides this the whole area suffers from severe sodic conditions. Thehuman impact has the most significant influence on soil erosion including land utilizationas well as the management of land.

III. The land capability within the study area based on observed erosion hazards, visiblesoil characteristics and other land characteristics, together with the interviews madewith local farmers and indicates on an exceeded land capability in all sites in GunungKidul. Local farmers within the karstic areas on the whole consider their land to be lessfertile even with a decrease in productivity. Therefore, this regency is considered tohave the most disadvantageous conditions concerning cultivation within the specialdistrict. This with exception for the volcanic influenced region in north and theWanagama forest research area.

IV. Estimation of the land capability with the help of GIS included interpretation ofphysiographic maps. The application of GIS partly confirm the above mentionedindications of land capability but is not taking the less favourable analysed soilcharacteristics into consideration. Furthermore, no regards concerning the statements ofa decrease in productivity of the land made by the local farmers is done. The landcapability map shows high potential erosion hazards for the drylands in the upper slopeas well as some wet paddy rice fields located in steeper slopes in the Northwest of theregency of Gunung Kidul. Remaining areas is classified as low potential hazard areas.

V. Clear is that the very different physical conditions that exists within the study area also isdeciding the distribution of the economical profits for the farmers.Some socio-economic & cultural factors influencing the degradation of land within thestudy area are mainly considered as a result of the farmers intention to obtain themaximal output from the land without considering the land capability. The Governmentalso owns big parts of the forested areas. This can with thought of the earlier conclusionhave a positive influence on the land as well as a safety function with benefits for thefarmers that are depending on an extra income. The achievement of the research withinthe area might also lead to the adoption of sometimes more suitable conservationmeasures than the usual ones.

The very different physical features within the study area affects the people in several ways andhave a considerable influence on the erodibility of the soil and therefore also on the productivity.Generally speaking, sites located in the volcanic slope have advantageous cultivation conditionswhile sites within the limestone-rich areas have less favourable conditions. People's respond to

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these land conditions is still to keep the land under intensive use because of economicalreasons. This has resulted in an exceeded land capability in big parts of the regency of GunungKidul.

IX. REFERENCES

Literature• Armson, K (1979) Forests Soils, Properties and Processes. University of Toronto Press.

Toronto 390 p.• Boodt, M & Gabriels, D (1980) Assessment of Erosion. John Wiley & Sons. Great

Britain. p. 563• BPS, Kantor Statistik (1996) Daerah Istimewa Yogyakarta Dalam Angka 1996.

D.I.Yogyakarta• BPS, Kantor Statistik (1996) Kabupaten Gunung Kidul Dalam Angka 1996.

D.I.Yogyakarta• BPS, Kantor Statistik (1996) Kabupaten Sleman Dalam Angka 1996. D.I.Yogyakarta• BPS, Kantor Statistik (1996) Jawa Tengah Dalam Angka 1996. D.I.Yogyakarta

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• Data PertanianWilayah Propinsi D.I.Y (1996).Departemen Pertanian, Kantor WilayahD.I.Yogyakarta.

• Davies, B, Eagle, D, Finney, B (1982) Soil Management. Page Bros (Norwich) LTD.,Norwich. P. 287

• Department of Forestry, Yogyakarta Daerah Aliran Sungai Opak-Rencana TeknikLapangan Rehabilitasi Lahan dan Konservasi Tanah Sub Daerah Aliran Sungai Oyo1993)

• Diercke Weltatlas. (1992) WestermannSchulbuchverlag GmbH, Braunschweig. 275 p.• Ellis, S & Mellor, A (1995) Soils and Environment Routledge. Great Britain. 364 p.• Indonesien, Länder i fickformat. (1994) Utrikespolitiska Institutet. Stockholm. p. 40.• Jansson, M (1982) Land Erosion by Water in Different Climates. UNGI Rapport Nr

57, Uppsala University, Department of Physical Geography. Borgströms tryckeri AB.Motala. 151 p.

• Kusumandari, A & Mitchell, B (1997) Soil Erosion and Sediment Yield in Forest andAgroforestry Areas in West Java, Indonesia. Journal of Soil and Water Conservation.Vol. 52 No 5. p. 376-380

• Lamporan - Pengadaan dan Penggambaran Paper Print Citra Satelit dan Peta-petaPenafsirannya Untuk Penyebaran Potensi Kayu Rakyat Propinsi D.I.Yogyakarta-Dalam Rangka Perencanaan Pengelolaan Hutan Rakyat. Fakultas Kehutanan &Kanwil Kehutanan D.I.Y. (1996) 22 p.

• Morgan, R (1995) Soil Erosion & Conservation. Longman Malaysia. 198 p.• Muhamud, N. (1996) Directions of Soil Conservation as a way of Conserving the

Capability of the Environment in Sedayu Sub-District-Bantul District, Yogyakarta. GadjahMada University. Yogyakarta. 204 p.

• Reading. A, Thompson. R, Millington. A (1995) Humid Tropical Environments.Blackwell. Great Britain. 429 p.

• RePPProT (1989) Review of Phase 1. Results. Java and Bali Vol.2 Annexes 1-5. LandResources Department ODNRI, Foreign & Commonwealth Office UK, Government of theTransmigration Directorate, General of Settlement Preparation. United Kingdom.

• Ross. M (1984) Forestry in Land Use Planning -policy for Indonesia. University ofOxford. Great Britain. 266 p.

• Rowell, D (1994) Soil Science, Methods and Applications. 1994. Longman. Singapore.350 p.

• Selby, M (1993) Hillslope Materials and Processes. Oxford University Press. GreatBritain. p. 451

• Soil Map of the World. Vol.1Legend (1974) FAO-Unesco. Paris. p.59• Sudibyakto & Abasi, S (1996) The Eruption of Merapi Volcano, November 22, 1994,

The Geographical Review. The Indonesian Journal of Geography Vol.28, No.72. Facultyof Geography, Gadjah Mada University, Yogyakarta. pp.1-10

• Suharsono et al (1996) Bahan Seminar. Departemen Kehutanan D.I.Yogyakarta.• Sutikno (1996) Geomorphology of Yogyakarta Area and its Surroundings proposed as

a geomorphological Field Laboratory. The Indonesian Journal of Geography Vol.28,No.71. Faculty of Geography, Gadjah Mada University, Yogyakarta. pp.1-10

• Swedforest International AB & PT. Wahanabhakti Persadajaya (1995) Final Report.Regional Management Plan. Part 1, Fundamentals of Regional Planning, EastKalimantan Province. Departemen Kehutanan, Direktorat Jenderal Pengusahaan Hutan.Jakarta. 109 p.

• Trudgill, S (1983) Weathering and Erosion, Sources and Methods in Geography.Butterworths. London 192 p.

59

• User's Manual, ILWIS 1.4. (1993) ITC-International Institute for Aerospace Survey andEarth Science Netherlands.

• Whitten, T, Soeriaatmadja, R, Afiff (1996) The Ecology of Java and Bali. PeriplusEditions. Singapore. 969 p.

• World Bank, (1994) Indonesia-Environment and Development. The International Bankfor Reconstruction and Development. Washington D.C. 294 p.

• Woro, S (1990) Toposequence of Soils on the South Slope of the Merapi Volcano toBaron Coast, Yogyakarta. The Indonesian Journal of Geography Vol.20, No.59. Facultyof Geography, Gadjah Mada University, Yogyakarta. pp.25-39

• Yanda (1995) Temporal and Spatial Variation of Soil Degradation in MwisangaCatchment, Kondoa, Tanzania. Stockholms Universitet. Edsbruk Akademitryck.Stockholm.

Data Bases

CD-ROM• Encarta 98, Encyclopedia. 1998. Microsoft Corporation. USA.

Internet• Martaamidjaja.(1996) Group-based Extension Programmes for Natural Resource

Conservation in Java. Ministry of Agriculture, Indonesia.http://www.fao.org/WAICENT/FAOINFO/SUSTDEV/EXdirect/EXan0012.htm

• Marcoux (1996) http://www.cgiar.org/cifor/publications/occpaper/occpaper9.html• ID/ID: Indonesia (1993). ID/ID: Indonesia . http://www.adfa.oz.au/CS/flg/wf93/id.html.• Indonesia-a case study (1992), http://www.umanitoba.ca/indonesian/indo-in-b.html• Indonesia-a country study (1992) Indonesia - a country study. http://lcweb.2.loc.gov/c...dy:

@field(DOCID+id0043).• Sunsite (1996) http://sunsite.ui.ac.id/about_indonesia/physio.html.• Surabaya International School (1996) Indonesia, rich in culture.

http://www.rad.net.id/users/personal/s/siscoord/indo.html• Travel-Indonesia (1996) Introducing Yogyakarta . http://www. travel-

indonesia.com/yogya/ygy_home.htm

Maps• Jawa Sheet 1407 Parangtritis.Land Systems/Land Suitability. Land Systems with Land

Suitability & Environmental Hazards. Scale 1:250.000. Serie RePPProT (1989)• Jawa Sheet 1408 Yogyakarta.Land Systems/Land Suitability. Land Systems with Land

Suitability & Environmental Hazards. Scale 1:250.000. Serie RePPProT (1989)• Penggunaan tanah, Propinsi D.I.Y, (1994/95), scale 1:100 000• Peta Airtanah D.I.Y. scale 1:250.000 Laboratorium Kartografi, Fakultas Geografi,

Universitas Gadjah Mada. Yogyakarta).• Peta Dati II, Jenis Tanah, Kabupaten GK, scale 1:100.000 (1988/89).• Peta Fisiografi. Propinsi D.I.Y., scale1:250.000, Mitojat dkk (1987).• Peta Geomorphology.D.I.Y.. Scale 1:250.000 Laboratorium Kartografi, Fakulats Geografi,

Universitas Gadjah Mada (1990).• Peta Kemampuan Tanah Prop. D.I.Y, scale1:100.000, Kanwil Badan Pertanahan Nasional.

Prop. D.I.Yogyakarta.(1994/95)

60

• Peta Paduserasi Rencana Tata Ruang Propinsi dan Tata guna Hutan D.I.Y (TGHK).Badan Perencanaan Pembangunan Daerah (Bappeda) Prop. D.I.Yogyakarta. (1992).

• Peta II.3.Sebaran janis-janis tanah di prov. D.I.Y, scale 1:250.000 (1992).• Pola Curah hujan prop. D.I.Y Scale: 1:100.000. Dinas Pertanian dan Dinas Pengairan

Kabupaten Dati II se Prop. D.I.Y (1982/92))

Oral Sources• Setyarso, A. (1998) Dr. Ir. Forestry MSc. Faculty of Forestry, Gadjah Madah University,

Yogyakarta• Sukasno, Ir. at the Rehabilitation and Land Conservation Bureau (RLKT), Department of

Forestry, Yogyakarta• Suharsono, Ir. at the Rehabilitation and Land Conservation Bureau (RLKT), Department of

Forestry, Yogyakarta• Suparto, Ir. at the Rehabilitation and Land Conservation Bureau (RLKT), Department of

Forestry, Yogyakarta• Sutamto, Ir. at the Rehabilitation and Land Conservation Bureau (RLKT), Department of

Forestry, Yogyakarta

Visited Faculties & Offices• Department of Soil Science, Faculty of Agriculture, Gadjah Mada University, Yogyakarta• Faculty of Geography, Gadjah Mada University, Yogyakarta• Faculty of Forestry, Gadjah Mada University, Yogyakarta• Faculty of Social Science, Gadjah Mada University, Yogyakarta• Office for Province Development Planning (BAPPEDA), Yogyakarta• Offices for Social and Politics in Gunung Kidul, Yogyakarta• Offices for Social and Politics in Sleman, Yogyakarta• Offices for Social and Politics in Yogyakarta, Yogyakarta• Offices for the Gunung Kidul Regency Development Planning (BAPPEDA), Yogyakarta• Offices for the Sleman Regency Development Planning (BAPPEDA), Yogyakarta• Province office (Kantor Wilayah), Department of Agriculture, Yogyakarta• Province office (Kantor Wilayah), Department of Forestry in Yogyakarta• Rehabilitation and Land Conservation Bureau (RLKT), Department of Forestry, Yogyakarta• Statistic Bureau (BPS), Yogyakarta• The Forestry office (Dinas Kehutanan), Department of Forestry, Yogyakarta

61

IX. APPENDIX

1. Geographical Description

1.1 IndonesiaThere are five large islands and four of them are collectively known as the Greater Sundaislands; Jawa (Java) is the main island with about 115 million inhabitants (MicrosoftCorporation 1998). This is the most fertile and rich island, in terms of its contribution to nationalsectoral gross domestic product (ID/ID: Indonesia 1993). Sumatera (Sumatra) with about 40million inhabitants ranks second in economic terms with large rubber plantations, Sulawesi(Celebes) with about 14 million inhabitants and Kalimantan, the Indonesian part of Borneo issparsely populated with about 14 respective 10 million inhabitants. The fifth large island is IrianJaya, the eastern most part of New Guinea, shared with the independent state of Papua NewGuinea. Extending eastwards from Java are the Lesser Sunda Islands, including Bali, Flores andTimor. Another island chain is the Moluccan Island, located between Sulawesi and Irian Jaya.

Indonesia is also home to the worlds largest Muslim population (87% of the population)(Surabaya International School 1996), but wide waters and high mountains have helpedperpetuate cultural distinctions and differences, resulting in 300 discrete ethnic clusters, over250 individual languages, and just about every religion practised on earth (UtrikespolitiskaInstitutet 1994 pp.7-10). Centrifugal political forces have been powerful and, on more than oneoccasion, nearly pulled the country apart. One of the most important political episodes everhappen within the nation is at the moment, spring 1998, taking place with former PresidentSuharto's suddenly retirement after 32 years of power.

Many volcanoes in Indonesia are still active, and earthquakes also occur. Volcanicflows, that periodically have occurred over many centuries have deposited fertile volcanic soilson the lowlands, particularly on Java, which makes ideal conditions for cultivation. Somevolcanic mountains, included in the volcanic chain stretching from Timor up to Sumatra, exceedheights of more than 3568 m. The highest mountain in Indonesia (5030 m) is located in PuncakJaya, in the Sudirman Range of Irian Jaya (Diercke Weltatlas 1992).

The weather between the monsoons is moderate. The northern parts of Indonesia haveonly slight differences in precipitation during the wet and dry seasons occurring in November toMarch respective June to October. Humidity is generally high averaging about 80%. The dailytemperature ranges about 20-320C and varies little from winter to summer. Rainfall in thelowlands averages about 1780 to 3175 mm annually and about 6100 mm in the mountainregions" (Microsoft Corporation 1998).

Tropical rain forest vegetation prevails in the northern lowlands, mangrove trees andnipa palm dominate the forests of the southern lowlands. The hill forests consists of oak,chestnut, and mountain plants. Forestland covers about 60-70% of the total land area and themajority of the forest is state owned.

Cultivation's covers about 12 % of the land area and about 55% of the country'sapproximately 70,4 million workers are engaged in agriculture, either as owners of small farmsor as labourers on estates. The small farms, which produce most of the subsistence crops, alsocontribute substantial proportions of the nation's rubber crop, tobacco crop, and total exportproduction. Plantation estates produce rubber, tobacco, sugar, palm oil, coffee, tea, and cacao,mostly for export. Rice is the major staple food of the country, other important crop areCassava, maize, sweet potatoes, coconuts, sugarcane, soybeans, peanuts, tea, tobacco andcoffee (BPS, Kantor Statistik Jawa Tengah. 1996).

62

1.2 JavaThe Indo-Australian plate dips beneath the Sunda Plate along the Java trench, causingearthquakes and a landscape dominated by volcanoes (Witten et al 1996 p.87). The island isalso the most volcanically active island in the world, with 35 active craters (Indonesia-a countrystudy 1992). The southern part, and also the northern parts of the island chain consists ofsedimentary rocks that provides the country with oil and natural gas resources (MicrosoftCorporation 1998). The island can be divided into four physiographic regions: The northernalluvial plains, the northern Foothills and Plains (karstic), The central Volcanic Mountains, andthe southern Dissected Plateaux and Plains (karstic) (Witten et al. 1996, p.105).

Yearly climatic variations are governed by the oscillations of air masses within the ITCzone (Whitten et al. 1996, p. 119). Monsoons are usually blowing in from the south and east inJune through September and from the Northwest in December through March (Indonesia-acountry study 1992). Dry season in Java normally last from March to August. The wet seasonusually last from September through March with the heaviest rainfall usually starting fromNovember through February (travel-Indonesia 1996).

The climatic conditions in Java varies on a relative local scale, depending on the islandstopography and prevailing wind patterns (Indonesia-a case study 1992), but over 90 % of Javaand Bali receives at least 1,500 mm in annual precipitation. There is also a big variety intemperature and humidity. The temperature decreases with altitude by about 0,6 0C every 100m and usually ranges between 200C and 300C, and the humidity, often disturbed in those areasaffected by trade or monsoon winds, varies between 60% to 90% on the island. Temperatureand humidity vary more between night and day than between months or years.

The total number of plant species on Java, including weeds and cultivated species, isover 6500, with about 4500 native species (Whitten et al 1996 pp.119-125). The presentremaining forested area on Java although indicate on a more than 90 percent decrease in forestcover since around 200-400 AD (Whitten et al 1996 p.328), as a consequence of humanimpact, volcanic eruptions, earthquakes, and strong winds (Tab.6.).

Tab.6. Original and Present Forest Cover in Java. (Simplified after Witten et al 1996)

Java is only forest covered with approximately 9% compared with 60-70% for the wholenation. Most of it is converted to national parks and recreation areas (Ross 1984 p.10).Wetlands mostly cultivated with paddy rice are the dominating land utilisation type, covering23% of the land area. Tree crops (and estates) as well as upland farming is also very commonfor the island (World Bank 1994). Tree crops together with estate crops covers approximately19% of the totally cultivated land, upland farming about 18% (Whitten et al 1996 pp.9-11).

3. Daerah Istimewa Yogyakarta (Special Province)

3.1. Physiographic Conditions

Vegetation Type Original Area

(km2)

Present Area

(km2)

Present Remaining Area

(%)Evergreen Rain Forest 26.949 1.902 7.00Semi-evergreen Rain Forest 22.235 1.764 7.90Moist Deciduous Forest 61.292 1.436 2.30Dry Deciduous Forest 4.902 167 3.40ASeasonal Montane Forest 3.065 907 29.6Seasonal Montane Forest 13.704 4.227 30.8

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GeomorphologyThe very specific geomorphic features within the regencies are mostly depending on its locationto the volcano or the coastal area. The regency of Sleman is located in the volcanic cone, slopeand foot of Mt. Merapi: Yogyakarta in the volcanic footplain of Mt. Merapi; Bantul in the fluviovolcanic plain and coastal area; Gunung Kidul in a karstic and coastal area; Kulon Progo in ahilly and mountainous area, and coastal alluvial plain (Sutikno 1996, p.2).

As well as for other places along especially the West Coast of Java Island, platetectonic movement between Eurasian and Indian-Australian plate influences Special ProvinceYogyakarta. Volcanic deposits from the still active strato volcano Mt. Merapi covering bigparts of especially the regency of Sleman and Bantul. Fold and fault therefore occurs in theregency of Gunung Kidul respective Kulon Progo (Sutikno 1996, p.3).

Topography

The topography within the special district varies from flat to mountainous with about 65% of thetotal area having an elevation between 100-500 m.a.s.l. (Tab.7a). The altitude in the northernpart, located in the volcanic slope area of Mt. Merapi varies from 80-2911 m.a.s.l. (BPS,Kantor Statistik D.I.Y. 1996). In the southern part of D.I. Yogyakarta, including the regency ofBantul and Gunung Kidul, the altitude is less with 0-500 m.a.s.l. Some parts of the large karsticWonosari plateau, located in the central part of Gunung Kidul, although reach an altitude of 900m.a.s.l (see further details in the result section on p.25). Finally, the western part, Kulon Progo,has an altitude between 0-786 m.a.s.l. (Sutikno 1996, p.3).

Climate

64

The climate within the Special Province is, as well as for whole Java, is varying on a relativelocal scale. The average temperature varies between 23,6-31,7 0C, with an average yearlyhumidity between approximately 75-88 % (BPS Kantor Statistik D.I.Y. 1996). Theprecipitation in the area is between 1750-3000 mm annually, but higher rates of precipitationoccur in the volcanic slope and cone of Merapi, located in the northern part of the area(Sutikno 1996, p.2). Fig.33 indicates a relative constant monthly temperature and humidity overthe year. The rainfall, also seen in the figure is depending on the monsoon, with a dry periodfrom May to August, which is considered to be a little longer period than Java in general (seeJava section).

Fig.33. Monthly averages precipitation for each of the regencies with average monthlytemperature and relative monthly humidity given for the whole area (D.I.Yogyakarta) (Source: BPS, Kantor Statistik D.I.Y. 1996., Suharsono et al 1996).

During May-September, the number of rainy days for each of the regencies is less than 10 daysand more than 10 days during October-April (Tab.8). According to RePPProT (1989), themean daily Penman evapotranspiration, is relative constant through the year with an average of4,1 mm/day, and the monthly Penman evapotranspiration is estimated to 1502 mm. Theaverage wind speed within the special province is estimated to 3 m/s, but depends on thetopography and distance from the Indian Ocean.

Tab.8. Number of rainy days (1996), in each regency.Regency J F M A M J J A S O N DKulon Progo 17 17 15 18 7 4 1 6 10 15 19 15Bantul 20 12 8 14 6 4 2 5 6 9 14 12Gunung Kidul 14 14 17 15 5 4 3 5 8 12 12 11Sleman 20 16 15 16 7 3 2 6 8 13 13 13

(Source:Fakultas Kehutanan & Kanwil Kehutanan D.I.Y. 1996)

Vegetation & Land UseThere are many kinds of tree species within each of the regencies, such as teak, mahogany,pine, lamtoro (local firewood), hibiscus, coconut and mango trees (App.?). There are alsoplanted trees, especially in the hilly areas, to create community forests, with the aim ofpromoting the afforestation policy. Acacia is a common tree used for this aim (Oral Setyarso1998).

Totally, an area of about 25,6 ha. (80%) within the special district is covered by forest,distributed different between the regencies (Tab.9). Gunung Kidul is the most forested regencywith more than 40% of the area covered by forest, while the regency of Sleman only is coveredwith less than 12 %, including forest lands.

65

Tab.9. The spatial distribution and quantity of forest for each regencyRegency Area

(ha)Area (%) Volume

(m)Density(m/ha)

Kulon Progo 5.881 22,9 243.061 41,32Bantul 5.667 22,1 173.992 30,70Gunung Kidul 11.072 43,2 927.106 83,73Sleman 3.030 11,8 103.667 34,21Total 25.639 100 1.447.826 56,46Simplified after Fakultas Kehutanan & Kanwil Kehutanan D.I.Y. 1996.

Different types of seasonal crops are grown in the area including paddy rice, cassava, salakpondoh, maize, soy beans, sugar canes, bananas, and potatoes as leading crops (app.5, p.70).These kinds of crops are more commonly cultivated on the Island of Java compared with theother islands. About 19% of D.I. Yogyakarta is covered with wetland, and irrigated sawah(wet paddy rice fields) is the most usual land utilisation type, dominating the flat areas of fertilevolcanic deposits, especially in the Sleman regency. More than 50% of the dryland areas islocated in the regency of Gunung Kidul (Tab.10) and dryland plantations dominate in the entirespecial district, mostly occurring in hilly areas and close to settlements. Tegal (dry paddy ricefields) is also common in these areas. Nearly all temporary fallow land (98,2%) and land usedfor commercial crops (96,7%) can be found in the regency of Kulon Progo (BPS, KantorStatistik D.I.Y 1996).

Tab.10. Area of wetland and dryland by utilisation in D.I.Yogyakarta (1996),and its distribution for each regency/municipality in percent.

Land byUtilisation

Area(Ha)

Distribution for Each Regency(%)

D.I.Yogyakarta K* B* G* S* Y*1. WETLAND 60,671 17,9 27,6 13,3 40,5 3,21· Irrigation 50,304 18,2 28,9 5,08 48,9 3,88· Rain fed 10,307 16,1 21,1 53,4 0,00 0,00· Others 60 0,00 100 0,00 0,00 0,002. NON-WETLAND 257,909 18,5 13,1 54,4 12,7 1,18· Home Garden 84,28 23,2 23,5 29,1 21,9 3,20· Dry field/Garden 112,343 16,4 5,97 73,5 5,53 3,56· Pond 295 6,44 21,0 20,7 50,2 3,73· Temporary fallow land 112 98,2 0,00 1,80 0,00 0,00· Private woods/Forested lands 18,406 14,2 10,6 63,8 6,60 0,00· Forest 16,527 6,19 56,4 79,9 8,08 0,00· Commercial Crops 1,649 96,7 0,00 32,5 0,00 0,00· Others 23,975 19,2 19,4 36,1 23,8 149

TOTAL 318,58 18,4 16,0 46,6 18,0 1,00

Source: BPS, Kantor Statistik D.I.Y. 1996.* K-Kulon Progo, B-Bantul, G-Gunung Kidul, S-Sleman, Y-Yogyakarta

Statistic figures from 1993-1996 (BPS, Kantor Statistik D.I.Y. 1996) indicate relative similarland utilisation conditions in the area through the years. Since 1995 a change concerningcommercial crops lands, according to statistics, occurred in the regency of Gunung Kidul,which at the moment have 55 ha compared with none in 1994. This because of conversion ontemporary fallow land (Oral Setyarso 1998). The regency of Gunung Kidul also embraces themajority of the forest-covered areas and private forestland.

Soils

66

High fertile volcanic soils mixed with minerogen ashes dominates the slopes of Mt. Merapi, inthe northern part of the province, and Regosols (inceptisols &entisols) is the most common soiltype, with a pH-value between 5,5-6,5 (Peta II.3.Sebaran janis-janis tanah di prov. D.I.Y,scale 1:250.000 1992). A recent eruption from the volcano (1994) has resulted in a soil depthof more than 2 m in some places. The regency of Gunung Kidul, stretching from the foot of thevolcanic slope down to the Indian Ocean in the south, in general consist of low drainage, andmore acid litosols (entisols), with exception for the karstic plateau of Wonosari, located in thecentral part of the area (Peta Dati II, Jenis Tanah, Kabupaten GK, scale 1:100.000 1988/89).grumosols (vertisols), litosols (entisols) and rensina (entisols) having a pH-value between 5,5-7,5 dominate this area (Peta II.3.Sebaran janis-janis tanah di prov. D.I.Y, scale 1:250.0001992). Similar soils can be found in the west part of the district, including the regency of KulonProgo and major parts of the Bantul regency. (Peta Dati II, Jenis Tanah, Kabupaten GK,scale 1:100.000 1988/89) with a pH-value between 7,5-8,0 (Peta II.3.Sebaran janis-janistanah di prov. D.I.Y, scale 1:250.000 1992).

HydrologyDuring periods of heavy rainfall, flooding occur in the down stream areas, especially of thelargest rivers Progo, Opak (Fig.34), and Serang, causing erosion on the river banks and theburying of rice fields with deposits. Droughts is the main problem of the karstic area, especiallyconcerning water supply, although some dolines are filled with rainwater, function as reservoirsfor the local people (Sutnikno 1996, p.8). This area also embrace several underwater rivers, asa result of the land upheaval, which supports the area with water.

In general, the groundwater level in the regency of Bantul and Kulon Progo is shallowwith a depth less than 7 meter. The middle slope of Merapi has a groundwater depth between7-15 m reaching more 15-25 m in the volcanic footplain. The Wonosari plateau in the regencyof Gunung Kidul has a groundwater depth between 7-15 m, while the surrounding areas withinthe regency are non-aquifer (Peta Airtanah D.I.Y. scale 1:250.000 Laboratorium Kartografi,Fakultas Geografi, Universitas Gadjah Mada. Yogyakarta). Fig.34. River Oyo running through in Playen, Gunung Kidul. (Photo M. Enryd 1998)

3.2 Population Status

Demography

67

As a result of the large concentration of universities and other education centres the SpecialProvince Yogyakarta is one of the most densely populated areas in Indonesia, with a density of999,87 persons per km2 (Tab.11.). The province further attracts tourists because of its specifichistory, which also contribute to a higher density of people.

Tab.11. Population distribution, density and growth for each regency/municipality in D.I.Yogyakarta, 1996, and its totalland area and administrative sub-divisions.

Regency/Municipality

Totallandarea(km2)

Number ofsub-

districts

Number of

villages

Total popu-lation

(Thousands)

Malepopu-lation(%)

Femalepopu-Lation

(%)

Popu-lation

density(pers/km

2)

Popu-lation

growth(%)

Totalurbanpopu-lation(%)

Totalruralpopu-lation(%)

Kulon Progo 586,3 12 88 431,6 48,7 51,3 736 0,69 8,00 92,0

Bantul 506,9 17 75 748,5 48,8 51,2 1,476,80 1,07 59,3 40,7

Gunung Kidul 1,485 15 144 729,7 48,9 51,1 491,2 0,68 3,8 96,2

Sleman 574,8 17 86 804,4 49,3 50,7 1,399,34 1,27 48,2 51,8

Yogyakarta 32,50 14 45 471,3 51,5 48,5 14,502,62 1,07 100 0,00

D.I.Yogyakarta

3,185,80 75 438 3,185,474 49,4 50,6 999,9 0,98 42,9 57,1

(Source: BPS, Kantor Statistik D.I.Y. 1996. and Departemen Pertanian, Kantor Wilayah D.I.Y. 1996).

One problem is within the special province is the increase in population pressure (TP)Calculations of TP in areas with agroforestry as land utilisation type (Tab.12) show thatespecially the regency of Sleman are under an intensive influence of TP with about 85% of allvillages included. Kulon Progo is although under less influence. Bantul and Gunung Kidul alsoso far comprise a less pressure.

Tab.12. TP-Calculations based on Agroforestry within each of the Regencies.

RegencyTotal

Number ofVillages

TP>1 TP<1

Gunung Kidul 13 6 7Bantul 17 7 10Sleman 15 13 2Kulon Progo 12 1 11(Source:Suharsono 1996)

Socio-economic & Cultural Parameters

68

Many people within the Special province are in some way involved in agriculture giving a bigvariety of incomes among the people. According to statistics (BPS, Kantor Statistik 1996)people with the highest income, not surprisingly, tend to live in the city. Among farmers,households located on the volcanic soils of Mt. Merapi in general have a more high income,sometimes reaching more than 3-10 times more, compared with the other areas.

The higher education levels are concentrated among the city people, and people livingin the surrounding regencies of the municipality Yogyakarta in general have lower educationlevel. The reason of that is lower income together with more traditional and 'simple' thinking.Although, research made in the area (Bahan seminar 1996) indicates on a relationship betweeneducation and productivity. Farmers with agroforestry that get educated in agribusiness willaccording to the research be able to use their natural resources better and also to make a betterprofit, but people that get educated and adept new techniques with success also tend to moveto the city renting out their land.

The traditional thinking among farmers within the regencies is very strong, and the useof plants for a wide range of medicinal cures is common. These plants are usually grown inhomegardens and are usually cultivated for their role in religious ceremonies. Alang-alang (wildgrass) sometimes regarded as a scourge for some, is managed and sometimes cultivated amongtraditional farmers to produce fodder for animals and thatching. The traditional belief on Mt.Merapi is also that the topmost grasslands on the volcano are the property of the spirits and cannot therefore be cut (Whitten et al. 1996, p. 676-677).

2. TP-formula

69

TP (=population pressure) is a common formula used in Indonesian socio-economic analysis tocalculate the carrying capacity of the land. This formula can be applied on any kind of land use.

TP >1: Severe problems, TP = 1: Under control, TP <1: Good conditions.

3. Universal Soil Loss Equation (USLE) - Calculations

Tab.13. Soil Loss Estimations within the Study Area.Site R K LS C P USLE (USLI)1 474.97 0.20 289.82 0.01 1.00 275.31 27530.64

2 474.97 0.10 0.8400 0.60 0.40 9.5300 39.71000

3 474.97 0.20 1.0000 0.20 0.50 9.500 94.99000

4 546.64 0.20 188.27 0.60 0.04 494.00 20583.54

5 546.64 0.30 1.0000 0.20 0.40 13.120 163.9900

6 752.96 0.20 1.0000 0.20 0.40 12.050 150.5900

7 492.56 0.20 0.8900 0.20 0.04 0.7000 87.74000

8 321.16 0.15 0.7000 0.15 0.30 1.5200 33.85000

9 338.80 0.30 14.320 0.15 0.40 87.320 1455.340

10 321.16 0.20 12.750 0.15 0.40 49.14 819.0100

11 429.55 0.20 12.970 0.15 0.40 66.860 1114.400

12 429.55 0.20 11.130 0.15 0.40 57.370 956.1100

13 418.68 0.15 10.220 0.15 0.40 256.640 641.5900

A = R X K X LS X C X P

A = Soil Loss in mass/unit area (ton/ha/year)

R = Rainfall and Runoff erosivity FactorK = Soil Erodibility FactorL S = Topographic Factor for Slope Length and SteepnessC = Crop Management Factor*P = Erosion Control Practices Factor*

• (USLI) = USLE-calculations excluding the P-factor• The USLE-calculations are based on the top layer (Depth: 5cm) from the soil samples.• Classification (ton/ha/year): Very Low (<15), Low (15-60), Moderate (60-80), High (180-480), Very High (>480)*(Source: Department of Forestry, Yogyakarta Daerah Aliran Sungai Opak-Rencana Teknik LapanganRehabilitasi Lahan dan Konservasi Tanah Sub Daerah Aliran Sungai Oyo 1993)

70

4. Questionnaire

². ². Identity of Respondent1. Location:

a. Village:b. Sub-District:c. Regency:

2. Name:3. Sex:4. Age:5. Number of Members in the Household:

²I. ²I. Land Conditions1. What is the approximately size of the cultivated land area that you own?2. Is all land under cultivation? If not, what is the reason of that?3. What kind of crops or vegetation do you cultivate?

In what size is the cultivation? Since when have you cultivated this land?4. Why did you choose this kind of cultivation?5. What is your main crop?6. Would you like to introduce another crop or vegetation in the future? If yes, what kind? If not, any reason of that?7. Have you ever had another kind of cultivation in the past? If so, when and why did you change?8. Do you think that your land is more fertile now or earlier? If yes, since when? If not, since when?9. Do you have any problems with soil loss because of the rainfall, erosion, decrease in fertility, or other? If so, what scale? If so, do you know what the problem is?10. What is the most time consuming with your cultivation?11. What is the most difficult work to do within your cultivation?12. Do you use fertilisers? Insecticide? Pesticide? Weedkiller? 13. Have you done anything to prevent or reduce erosion? If so, what did you do?14. Do or did you get any help from the government to prevent or reduce erosion? If so, what kind of help? (Financial help, management programs etc.) When?

15. What kind of management do you use for your crops or vegetation?• Rotation

Row crop cultivationGrazing land managementForest management

• Cover crops• Strip cropping• Multiple cropping

Sequential?Intercropping?

High density planting• Mulching• Revegetation

AfforestationReforestation

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Natural revegetation• Agroforestry16. What kind of management do you use for the soil?• Apply organic matter• Tillage practices

Conventional tillageNo tillageStrip tillageMulch tillageMinimum tillage

• Soil stabilisers?17. What kind of mechanical methods do you use?• Contouring• Contour bounds• Terraces• Waterways• Stabilisation structures

²II.²II.Socio-Economic Conditions1. Are you able to get some income from your cultivation? If so from what? a. Food crops b. Vegetables c. Fruits d. Fuel wood e. Wood for constructionf. Honey beeg. Others, What?2. Are you a full time farmer? If not, are you working anywhere else?3. Do any another members of your household have some side incomes?4. Do you have an employee helping you with your cultivation?5. Are you able to make a profit by selling? If so what do you sell?6. How much is the profit for your cultivation?7. Do you have enough land to support one household?8. Is your cultivation irrigated? If no, other kind of water resources?9. Do you use firewood? If yes, from where?

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5. Common Crops & Vegetation Types within the Study Area

Tab.14. Plant Species within the Study Area, and their Main Use.No Indonesian English Latin Main use1 Pinus Pine Pinus merkusii Pulp, Gum, Furniture2 Salak Pondoh Zalacca palm Zalacca sp Fruit (food)3 Rotan Rattan Calamus sp Furniture4 Paku-pakuan Fern Marattiaceae5 Ubi Kayu Cassava Manihot utilisima Root crop (food)6 Padi Paddy rice Oryza sativa Cereal (food)7 Kelapa Coconut Cocos nucifera Fruit (food & drink), wood (construction)8 Sukun Bread fruit Artocarpus communis Fruit (food)9 Melina Gmelina Gmelia arborea Pulp10 Nangka Jack fruit Artocarpus integra Fruit (food), furniture11 Meniran Phyllanthus niruri12 Secang Caesalpinia sappan Fire wood13 Sengon Paraserianthes falcataria Pulp, furniture14 Kaliandra Caliandra calothyrsus Fodder15 Kopi Coffee Coffea canephora Bean (food & drink)16 Randu Cotton tree Ceiba pentandra Clothes17 Melinjo Gnetum gnemon Fruit, leaves (food)18 Jagung Maize Zea mays Vegetable (food)19 Rumput Teki Cyperus rotundus Fodder20 Putri malu Sensitive plant Mimosa pudica21 Mindi Melia azadarach Furniture22 Apokat Avocado Persea americana Fruit (food)23 Coklat Cacao tree Theobroma cacao Bean (food & drink)24 Gamal Gliricidea sepium Firewood25 Sonokeling Dalbergia latifolia Furniture26 Formis Acacia Acacia auriculiformis Firewood27 Leda Eucaliptus Eucaliptus alba Furniture28 Klampis Acacia Acacia tomentosa Firewood29 Jati Teak wood Tectona grandis Construction, furniture, plywood30 Kayu Putih Melaleuca leucadendron Distillated oil (medicine)31 Kerinyu Eupathorium pallescens32 Alang-alang Imperata cylindrica Fodder33 Kacang tanah Peanut Aracis hypogaea Nut (food)34 Pisang Banana Mimosa pudica Fruit (food), leaves (wrapping)35 Bambu Bamboo Bambusa sp Furniture36 Kalanjana King grass Panicum muticum Fodder37 Petai Parkia speciosa Vegetable (food), Firewood38 Rumput Gajah Elephant grass Pannisetum purpureum Fodder39 Lamtoro Leucaena leucocephala Firewood40 Mahoni Mahogany Swietenia mahagoni Furniture41 Rambutan Nephelium lappaceum Fruit (food)42 Johar Casia siamea Firewood(Source: Susanti 1998)

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6. Soil Survey

Sources to survey sheet

# Soil profile description: FAO Soil description (1988).# Subsoil description (texture): RePPProT (1989).# Slope inclination, exposure and form: FAO Soil description (1988).# Erosion type (and cause): Morgan (1994).# Soil erosion classification: (Dep. of soil science UGM):

None, slight, moderate, severe, extreme• Degree of deposition (Dep. of soil science UGM): none, slight, moderate, severe,extreme• Deposited material (Dep. of soil science UGM)

# Field check within a 15 m radius: FAO soil description (1988), Ari Susanti, WijonarkoSuhari, local farmers.

• Exposure of tree roots• Crusting on the soil surface• Formation of splash pedestals• Type of ground cover• Density of ground cover (%)• Type of canopy cover• Density of canopy cover (%)

Soil samples

Only soil sample:

1 soil sample from A respective B-horizon, if anypH-test from topsoil and subsoil (1s + 4 dest.)Colour, brightness, intensity classification with Munsell colour chartClassification of texture

Soil profile description:

1 Sample from A, B, respective C horizon, if any, for soil profile descriptionpH-test from A, B, respective C horizon (1s + 4 dest.)Colour, brightness, intensity classification with Munsell colour chartClassification of texture, structure and wetnessShear strength test from horizon, if possible.Measure of infiltration rate(FAO Soil description etc.)

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