Eng3

Jfuas No.2 December 2013

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Composition and Structure of Boswellia papyrifera Standsand their Sustainability in Jebel Marra, Western Sudan

Mohamed A. Khamis¹, Siegfried Uhlig² and Huberts Pohris²

1- Department of Forestry, Faculty of Environmental Sciences & Natural Resources,University of Al-fashir

2- Institute of International Forestry and Forest Products, Tharandtو Faculty of Forest, Geo-and Hydro Sciences, Dresden University, Germany

بجبل واستدامتها اللبان صمغ اشجار مشاجر وتركيب تكوينالسودان،مرة غرب

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Abstract

The present study was conducted in Boswellia papyrifera stands in

Jebel Marra area, which is located in the western part of the Sudan.

Boswellia Papyrifera (Del.) Hochst. is a multipurpose tree that grows

on the rocky shallow soils of the hilly elevated areas. It produces gum

resin that has various local uses, pharmaceutical and industrial

applications. In addition to the multiple uses of its wood, the leaves

are used as fodder and it appears to play a great ecological role. The

area covered in this study was 224 hectares. Systematic sampling

technique with camp unit was used. Where two clusters were

established and a total of 84 sample plots were obtained. Diameter and

height of the trees with diameter equal to and greater than seven

centimeter were measured in each plot. Boswellia stand characteristic

parameters such as species richness, species area curve, stem number,

basal area and importance value index (IVI) for the total stand were

analyzed. The results revealed about 28 tree species, 19 genera and 15


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families in the sampled area. The analysis of species area curve

showed that the different species are not homogeneously distributed

throughout the stand. Boswellia papyrifera exhibited the highest

values of abundance (114), frequency (80), dominance (31.24), and

importance value index (184.8). Only three young seedlings were

observed for Boswellia papyrifera species in the sampled area, while

Dichrostaschys cinerea showed the highest percentage of natural

regeneration (68.1%) followed by Acacia gerrardii (6.7%), Grewia

villosa (5.3%), Combretum collinum (4.2%), Grewia

flavescens(3.9%), Acacia seyal (3.8%), Albizia amara (2.8%) and

Acacia Senegal (1.5%). The absence of regeneration of Boswellia

papyrifera trees and the domination of regeneration by Dichrostaschys

cinerea, as an invasive species, may jeopardize the future

sustainability of this stand. Also the domination of Acacias indicates

the direction of successional change of these stands towards the

Acacia wood land savannah, which requires the adoption of other

management strategies.Key words: Boswellia Papyrifera; composition and Structure;sustainability; important value index; Jebel Marra.

Introduction

Sudan is characterized by a diversity of natural woody perennials

which produce wood and non-wood forest products. However, gums

and gum resins are among the products that contribute significantly in

the livelihood of the local inhabitants and in the economy of the


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country as a whole. Boswellia Papyrifera (Del.) Hochst. is one of the

important tree species, which is found in most states of the Sudan,

south of latitude 14° N (El Amin 1990, Vogt 1995, Wickens 1976

Khamis 2001 Adam 2004 and Khamis 2008). It is a multipurpose tree

that produces gum resin. In addition to the multiple uses of its wood in

local carpentry work and other wood related industries (match-boxes,

pencils, air-conditioning particles, etc.) the leaves are used as fodder

for livestock during the dry season. Despite its apparent ecological

and economic roles in rural areas of the Sudan, Boswellia papyrifera

stands lack adequate planning and proper management and utilization,

as is the case in other African countries. In Sudan, there are number of

factors, which jeopardize the development of the Boswellia papyrifera

stands such as fires, agricultural encroachment, uncontrolled grazing,

insects and diseases, which also affect the natural regeneration

(Ogbazghi, 2006, Eshete et al, 2012) .

Jebel Marra Forests (JMFs) is located in Western Darfur State in

Sudan. It was established in the 1950s as a division of the Forests

National Corporation (FNC), formerly known as Department of

Forests (DF), with the responsibilities of managing and conserving the

forest resources in the area. The most interesting feature of Jebel

Marra is its Island-like position amidst the lowlands of the Sahelo-

Sudanian transition zone, in the very heart of the African continent, in

the low rainfall Savannah zone (Wickens 1976). It receives average

annual rainfall that ranges between 500-900 mm, with a recorded

maximum of 1066 mm and minimum of 294 mm. The forests and


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woodland savannah in Jebel Marra area cover an area of

approximately 196000 hectares (Khamis 2001). It constitutes a very

important element of the Sudan’s natural heritage and biological

diversity - hosting about 400 species of plants. Boswellia Papyrifera

(Del.) Hochst. is one of the important tree species, which occupies the

western sub-hills of Jebel Marra and covers an area of

approximately17500 ha. Reliable information about the stand

composition and structure and growing stock is lacking. Therefore no

management plans have been constructed for proper and sustainable

management of these stands. Also the present utilization practices

have led to severe deterioration of the Boswellia papyrifera stands.

This situation has been aggravated by improper tapping practices by

inexperienced people, which may lead to more deterioration of these

stands. Accordingly the aim of this study was to carry out an

inventory to assess the structure and composition of these stands and

their future sustainability. However, this study mainly emphasized on

the management of the Boswellia papyrifera stands with the objective

of providing reliable information about stand composition and

structure that form bases for adequate planning and proper

management of these stands.

Materials and methods

Jebel Marra is located between latitudes 12 º 30′ and 13º 30′ N and

longitudes 24º and 24º 30′ E, in the low rainfall Savannah zone in the

western part of the Sudan. It covers an area of about 196000 hectares


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(ha). The average temperature range is 20-30º C. The rainfall in the

area ranges between 500-900 mm per annum fluctuating from year to

another. The soils in Jebel Marra are classified into three categories as

follows; first is the basement complex, Aeolian sands and the volcanic

mountain complex soils. The geology of the area is characterized by

the formation of the basement complex, which is over lied by the

volcanic massif. The area is covered by many small isolated or groups

of hills, which form the Jebel Marra Mountains (Andrew 1948).

The study area is relatively rich in vegetation cover with

considerably high diversity. It is characterized by montane vegetation

zone which consists of three groups of vegetation, namely; hill

savannah, upland steppe and meadow and gallery forests (Wickens,

1976). Boswellia papyrifera stands fall in hill savanna vegetation

group with Boswellia papyrifera trees dominating the hill catena,

either as pure stand or in association with other species such as

Sclerocarya birrea, Sterculia setigera, Acacia gerardii, Anogeissus

leiocarpus, Lanea fruticosa, Commiphora africana, Stereospermum

kunthianum, Terminalia brownii, Combretum golutinosum and Albizia

amara. The shrubby species include Dichrostachys cinerea,

Combretum molle, Combretum collinum, Grewia flavescense, G.

villosa, and Adenium obesum. The ground vegetation includes;

Eragrostis cilianensis, Pennnisetum pedicellatum, Acanthospermum

hispidum and Cenchrus biflorus.

Reconnaissance survey was carried out first covering the study area.

Observations concerning Boswellia papyrifera stands were made,


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which include general stand condition, regeneration and the visible

factors affecting the stand. This was followed by management

inventory where systematic cluster sampling with camp unit was used

and two clusters were established. The area covered in this study was

224 ha and 84 sample plots were established. The sample plots are

circular in shape and with two radii; the first is 17.84 m (area = 0.1 ha)

where all trees with diameter at breast height (DBH) equal to and

greater than seven cm were measured. The second radius is five

meters (area = 0.008 ha) in which the number and heights of stems of

the regeneration were measured.

The measured variables in each sample plot included number of

trees, diameter at breast height (dbh), total height (th) for (trees with

dbh ≥7 cm) and the number of regeneration (dbh < 7 cm).Then species

richness, species area curve (it is ��

��

�� obtained by counting the number of species in each five sample

plots (0.5 ha)), stem number (Abundance (AB)), number of

individuals per species (Absolute abundance (AAB)), percentage of

each species of the total stem number per hectare (Relative abundance

(RAB)), occurrence or absence of a given species in a sample plot

(Frequency (FR)), percentage of occurrence of a certain species

(Absolute frequency (AFR)), percentage of the total of absolute

frequencies �Relative frequency (RFR)), basal area �Dominance

(BA)), the sum of the individual stem basal areas (Absolute

dominance (ABA)), the percentage of a given species of the total stem


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basal area measured (Relative dominance (RBA)) and importance

value index (IVI) (sum of the relative abundance + relative frequency

+ relative dominance) for the total stand, as a measure of ecological

significance of a species in a certain forest type were analyzed,

according to Curtis and McIntosh, (1951) and Kershaw, (1978).

Results

The results of analysis of Boswellia papyrifera stands presented in this

study include; species richness, species area curve, stem number, basal

area and importance value index (IVI) for the whole stand. There

were 28 species in total (six species as regeneration), comprising 19

Genera and 15 Families, in the sampled area including the

regeneration (Figure 3). The highest number of species were found in

the first five sample plots which was seven species, followed by four

new species in the second five sample plots, then the number

decreased towards the end of the last five sample plots. Zero indicates

no further new species was found in five sample plots (0.5 ha), as

shown in (Table 1) and (Figure 1), ��

��

Results of this analysis also included the abundance, absolute

abundance, relative abundance, frequency, importance value index,

the stem number and the basal area per hectare for all species in the

Boswellia papyrifera stands, for the trees with dbh ≥7 cm, as

presented in (Table 2). For Boswellia papyrifera, it shows the absolute

abundance of 956, abundance of 114, relative abundance of 75 %


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(percentage of species) and it was found in 80 sample plots

(frequency), absolute frequency 95, relative frequency 30.9,

dominance of 31.24, relative dominance of 78.9 and importance value

index (IVI) of 184.8, which was the highest importance value index

(IVI) found in the sampled area. The co-dominant species are

Anogeissus leiocarpus, Acacia gerardii, Albizia amara, Sclerocarya

birrea, Sterculia setigera and Albizia amara with IVI of 30.9, 14.0,

11.9, 11.06, 10.77, 7.06 and 6.84 respectively. The rest of the species

showed IVI of less than 5, as shown in (Table 2 and Figure 2).

Results have also shown that the average number of trees per

hectare (abundance) for all species with dbh ≥ 7cm is about 152

trees/ha, of which Boswellia papyrifera constitutes 114 trees/ha about

75% (relative abundance). The average basal area per hectare for all

species was estimated to be about 39.6 m² per hectare (Table 2).

Concerning the natural regeneration, only 3 seedlings of Boswellia

papyrifera were observed in the sampled area. The regeneration was

dominated by the Acacias and shrubby species, namely

Dichrostaschys cinerea which showed the highest percentage of

natural regeneration (68.1%) followed by Acacia gerrardii (6.7%),

Grewia villosa (5.3%), Combretum collinum (4.2%), Grewia

flavescens (3.9%), Acacia seyal (3.8%), Albizia amara (2.8) and

Acacia senegal (1.5%). While the rest of the listed species exhibit less

than 1% regeneration. For Boswellia papyrifera species there was

almost total absence of regeneration (0.4%) (Figure 3).


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Table 1: No. of new species discovered in each 5 plots for trees with dbh ≥ 7

cm in the sampled area of Boswellia papyrifera stand, Jebel Marra,

SudanArea (ha) Number of species Area (ha) Number of specieso.5 7 5 21 4 5.5 11.5 1 6 02 3 6.5 02.5 1 7 13 0 7.5 13.5 1 8 04 0 8.5 04.5 0 Total 22

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Figure 1: Species-area curve for Boswellia papyrifera stand, trees with DBH≥ 7 cm in the sampled area, Jebel Marra, Sudan


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Table 2: composition and structure, for trees with DBH ≥ 7 cm in the B.papyrifera stand, Jebel Marra, Sudan.

Species A B C D E F G H IAcacia gerrardii 43 5.1 3.30 23 27.4 8.92 0.73 1.8 14.0Acacia nilotica 3 0.4 0.26 1 1.2 0.39 0.05 0.1 0.75Acacia senegal 2 0.1 0.07 2 2.4 0.78 0.22 0.6 1.45Acacia seyal 19 2.3 1.51 14 16.7 5.44 0.02 0.1 7.05Albizia amara 29 3.5 2.30 20 23.8 7.75 0.77 1.9 11.9Anogeissus leiocarpus 107 12.7 8.36 41 48.8 16 2.60 6.6 30.9Azanza garkeana 1 0.1 0.07 1 1.2 0.39 0.01 0.03 0.49Balanites aegyptiaca 5 0.6 0.40 5 6 1.95 0.21 0.5 2.85Boscia salicifolia 2 0.1 0.07 2 2.4 0.78 0.06 0.2 1.05Boswellia papylifera 956 114 75.00 80 95 30.9 31.24 78.9 184.8Comb. glutinosum 13 1.5 0.99 6 7 2.28 0.21 0.5 3.77Comb. molle 1 0.7 0.46 1 1.2 0.39 0.01 0.03 0.88Commiphora africana 12 1.4 0.92 8 9.5 3.09 0.21 0.54 4.55Dalbergia melanoxylon 6 0.1 0.07 5 6 1.95 0.08 0.2 2.22Ficus glumosa 1 0.01 0.07 1 1.2 0.39 0.08 0.2 0.66Lanea barteri 3 0.4 0.26 3 3.6 1.17 0.13 0.13 1.56Lanea fruticosa 19 2.3 1.51 11 13 4.23 0.2 1.1 6.84Sclerocarya birrea 26 3.1 2.03 15 17.9 5.83 1.26 3.2 11.06Sterculea setigera 22 2.5 1.64 15 17.9 5.83 1.3 3.3 10.77Terminalia brownii 1 0.1 0.07 1 1.2 0.39 0.03 0.07 0.53Terminalia laxiflora 1 0.1 0.07 1 1.2 0.39 0.03 0.07 0.53Ziziphus abyssinica 2 0.2 0.13 2 2.4 0.78 0.02 0.05 0.96Total 127 152 307 39.62Absolute abundance (A), Abundance (B), Relative abundance (C), Frequency (D),Absolute frequency (E), Relative frequency (F), Dominance (G), Relative dominance (H)and Importance value index (I)


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Tree species

Figure2: Importance Value Index (IVI) for trees with DBH ≥ 7 cm in theBoswellia papyrifera stand, Jebel Marra, Sudan.


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Tree species

Figure3: Regeneration in Boswellia papyrifera stands, Jebel Marra, Sudan

Discussion

The species composition in the Boswellia papyrifera stands is

relatively rich compared to the rocky shallow poor soils of the hill

slopes. They were also comparatively rich in comparison to 37 species

in more or less similar stands in South Kordofan, as presented by

Khamis (2008).

It is obvious from the results above that the dominant species is

Boswellia papyrifera with 184.8 IVI, but it shows very low or total

absence of regeneration. While the domination of regeneration by

Dichrostaschys cinerea and Acacia gerardii (Acacias) indicates a

gradual change of this stand from Boswellia papyrifera stand to


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Acacia and shrubby woodland in the future. Dichrostaschys cinerea

which is of low value, is considered to be an invasive species and

strong competitor in this stand and may jeopardize the growth and

future development of the valuable species.

Also as shown by the results, there were about 152 trees per hectare in

average for trees with dbh ≥ 7, which is higher compared to 60 trees

per hectare stated in (Khamis, 2008) in South Kordofan with more or

less similar environmental conditions, especially the Boswellia stands.

Boswellia papyrifera constitutes about 75% of the total number of

trees in the sampled area which is very high and indicates its

domination at the present time but the absence of its regeneration may

jeopardize its future sustainability, if no managerial intervention is

taken to reverse the situation.

The findings of this study also show that, there were about 98

seedlings per hectare as regeneration of different species. This amount

of regeneration is comparatively sufficient to sustain the stand in

mixed forest. But the domination of regeneration by the Acacias

indicates the direction of successional change of these stands towards

the Acacia woodland savannah. In conclusion, the stand of Boswellia

papyrifera is endangered by the absence of regeneration of this

species and invasion by non-economic ones.

However, the execution of prescribed silvicultural measures which

should include enrichment planting of Boswellia papyrifera trees,

after releasing the stands from the competing undesirable species, like

Dichrostachys cinerea and promoting an integrated management of


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the valuable ones like Boswellia papyrifera for resin, Acacias for gum,

and Combretaceae sps. for wood, within the stands of Boswellia

papyrifera are highly recommended. Effective measures should be

worked out against forest fire, grazing and browsing, cutting and

chopping of trees and the other negative impacts. Also, the

requirement for encouragement, motivation and increasing the

awareness of the direct users of these forests who cause damage to

Boswellia papyrifera stands, through extension and training programs

to participate in planning, protection and sustainable management of

these stands.

References

1. Adam, A. A. 2004. Aspects of Ecology and Management of Boswellia

papyrifera in Jebel Marra mountain area, Ph D thesis, University of

Khartoum, Sudan.

2. Andrew, F. W. 1948: The vegetation of the Sudan. In Agriculture in

the Sudan, pages 32-61.

3. Curtis, J. and Mcintosh, R. P. 1951. Interrelation of certain analytic

and synthetic phytosociological characters. Ecology, 31, 434-445 pp..

(In: KERSHAW, K. A. 1978: Quantitative and Dynamic plant

ecology 2nd edition. ELBS and Edward Arnold (Publisher) Ltd).

4. El Amin, H. M. 1990. Trees and Shrubs of The Sudan, Ithaca Press,

Biddles Ltd, Guildford and Kims Lynn, England.


36

5. Eshete, A., Teketay, D., Lemenih, M. and Bongers, F. 2012.

Effects of resin tapping and tree size on the purity, germination and

storage behavior of Boswellia papyrifera (Del.) Hochst. seeds from

Metema District, northwestern Ethiopia. Journal of Forest Ecology

and Management 269 (2012) 31–36

6. Kershaw, K. A. 1978. Quantitative and Dynamic plant ecology, 2nd

edition. ELBS and Edward Arnold (Publisher) Ltd).

7. Khamis, M. A. 2001. Management of Boswellia papyrifera stands for

Resin Production in Jebel Marra Area, Present Situation and Future

Prospects, M.Sc. Thesis, Dresden, Germany.

8. Khamis, M. A. 2008. Assessing the Potentials of Boswellia

papyrifera stands for Sustainable Management in Southern Kordofan

State, PhD Thesis, Juba University, Khartoum, Sudan.

9. Ogbazghi, W. 2006. The Distribution and Regeneration of Boswellia

papyrifera In Eritrea, British Ecological Society, Journal of Applied

Ecology, 43, 1188–1195

10. Vogt, K. 1995. A field worker’s guide to the identification,

propagation and use of common trees and shrubs of the Sudan; (SOS)

Sahel international London, UK.

11. Wickens, G. E. 1976. The flora of Jebel Marra (Sudan Republic) and

its geographical affinities.-Kew Bull. Add. Ser.5.-London

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