Mediterranean Desertification:A Mosaic of Processes andResponses

Edited by

N.A. GeesonKing’s College, University of London, UK

C.J. BrandtKing’s College, University of London, UK

and

J.B. ThornesKing’s College, University of London, UK

Innodata0470856866.jpg

Mediterranean Desertification

Mediterranean Desertification:A Mosaic of Processes andResponses

Edited by

N.A. GeesonKing’s College, University of London, UK

C.J. BrandtKing’s College, University of London, UK

and

J.B. ThornesKing’s College, University of London, UK

Copyright 2002 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester,West Sussex PO19 8SQ, England

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Library of Congress Cataloging-in-Publication Data

Mediterranean desertification: a mosaic of processes and responses / edited by N.A.Geeson, C.J. Brandt, and J.B. Thornes.

p. cm.Includes bibliographical references (p.).ISBN 0-470-84448-5 (alk. paper)1. Desertification–Mediterranean Region. I. Geeson, Nichola. II. Brandt, C. Jane. III.

Thornes, John B.

GB618.68.M43 M4 2001333.73′6′091822–dc21 2001046911

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 0-470-84448-5

Typeset in 9/11pt Times by Laserwords Private Limited, Chennai, IndiaPrinted and bound in Great Britain by Antony Rowe Ltd, Chippenham, WiltshireThis book is printed on acid-free paper responsibly manufactured from sustainable forestryin which at least two trees are planted for each one used for paper production.

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Contents

List of Contributors ix

Preface xv

Part 1 Thematic Issues 1

Section I Introduction 3

Chapter 1 The Evolving Context of Mediterranean Desertification 5

J.B. Thornes

Section II Climate, Processes and Responses 13

Chapter 2 Extreme Climatic Events over the Mediterranean 15

M. Conte, R. Sorani and E. Piervitali

Chapter 3 Potential Effects of Rising CO2 and Climatic Change on MediterraneanVegetation 33

C.P. Osborne and F.I. Woodward

Chapter 4 Use of NOAA-AVHRR NDVI Data for Climatic Characterization ofMediterranean Areas 47

Giovanni Cannizzaro, Fabio Maselli, Luciano Caroti and Lorenzo Bottai

Section III Land Use, Processes and Responses 55

Chapter 5 The Effect of Land Use on Soil Erosion and Land Degradation underMediterranean Conditions 57

C. Kosmas, N.G. Danalatos, F. López-Bermúdez and M.A. Romero Dı́az

Chapter 6 Agro-pastoral Activities and Land Degradation in Mediterranean Areas:Case Study of Sardinia 71

G. Enne, G. Pulina, M. d’Angelo, F. Previtali, S. Madrau, S. Caredda andA.H.D. Francesconi

Chapter 7 Landscape Protection from Grazing and Fire 83

N.S. Margaris and E. Koutsidou

Chapter 8 Bioengineering Principles and Desertification Mitigation 93

J.N. Quinton, R.P.C. Morgan, N.A. Archer, G.M. Hall and A. Green

vi Contents

Section IV Physical Processes and Responses 107

Chapter 9 Differing Responses of Greek Mediterranean Plant Communities toClimate and the Combination of Grazing and Fire 109

A. Dalaka, E. Papatheodorou, G. Iatrou, T. Mardiris, J. Pantis,S. Sgardelis, C. Lanara Cook, T. Lanaras, M. Argyropoulou,K.J. Diamantopoulos and G.P. Stamou

Chapter 10 Vegetation Cover Assessment in Mediterranean Semi-arid Landscapes 119

F.J. Garcı́a-Haro, J. Meliá, M.A. Gilabert and M.T. Younis

Chapter 11 The Impact of Rock Fragments on Soil Degradation and WaterConservation 131

B. van Wesemael, J. Poesen, C. Kosmas, N.G. Danalatos and J. Nachtergaele

Chapter 12 Aridification in a Region Neighbouring the Mediterranean 147

Ádám Kertész, Tamás Huszár, Dénes Lóczy, Béla Márkus, János Mika,Katalin Molnár, Sándor Papp, Antal Sántha, László Szalai, István Tózsaand Gergely Jakab

Chapter 13 Soil Salinization in the Mediterranean: Soils, Processes and Implications 163

L. Postiglione

Section V Tools for Exploring Desertification 175

Chapter 14 Environmentally Sensitive Areas in the MEDALUS Target Area StudySites 177

A.C. Imeson and L.H. Cammeraat

Chapter 15 Investigation on Environmental Characteristics to Underpin the Selectionof Desertification Indicators in the Guadalentı́n Basin 187

L.H. Cammeraat, A.C. Imeson and L. Hein

Chapter 16 MEDRUSH: A Basin-scale Physically Based Model for ForecastingRunoff and Sediment Yield 203

M.J. Kirkby, R.J. Abrahart, J.C. Bathurst, C.G. Kilsby, M.L. McMahon,C.P. Osborne, J.B. Thornes and F.I. Woodward

Part 2 Regional Studies 229

Section VI The Guadalentı́n Basin, South-east Spain 231

Chapter 17 Natural Resources in the Guadalentı́n Basin (South-east Spain): Water as aKey Factor 233

F. López-Bermúdez, G.G. Barberá, F. Alonso-Sarría and F. BelmonteSerrato

Chapter 18 Local and Regional Responses to Global Climate Change in South-eastSpain 247

C.M. Goodess and J.P. Palutikof

Contents vii

Chapter 19 The Impact of Land Abandonment on Regeneration of Semi-naturalVegetation: A Case Study from the Guadalentı́n 269

J.A. Obando

Chapter 20 Lithology and Vegetation Cover Mapping in the Guadalentı́n Basin asInterpreted through Remote Sensing Data 277

M.T. Younis, J. Melı́a, M.A. Gilabert, F.J. Garcı́a-Haro and A.J. Bastida

Chapter 21 Changing Social and Economic Conditions in a Region UndergoingDesertification in the Guadalentı́n 289

Asunción Romero Dı́az, Pedro Tobarra Ochoa, Francı́sco López-Bermúdezand Gonzalo González-Barberá

Chapter 22 Management Plan to Combat Desertification in the Guadalentı́n RiverBasin 303

L. Rojo Serrano, F. Garcı́a Robredo, J.A. Martı́nez Artero and A. Martı́nezRuiz

Section VII The Agri Basin, Southern Italy 319

Chapter 23 General Description of the Agri Basin, Southern Italy 321

F. Basso, E. Bove and M. del Prete

Chapter 24 The Agri Valley – Sustainable Agriculture in a Dry Environment: CropSystems and Management 331

F. Basso, M. Pisante and B. Basso

Chapter 25 Soil Erosion and Land Degradation 347

F. Basso, M. Pisante and B. Basso

Chapter 26 Social and Economic Conditions of Development in the Agri Valley 361

E. Bove and G. Quaranta

Chapter 27 Characterization of Soil Hydraulic Properties in a Desertification Context 369

Alessandro Santini and Nunzio Romano

Chapter 28 Aspects of Forestry in the Agri Environment 385

Agostino Ferrara, Vittorio Leone and Malcolm Taberner

Chapter 29 Modelling Large Basin Hydrology and Sediment Yield with Sparse Data:The Agri Basin, Southern Italy 397

J.C. Bathurst, J. Sheffield, C. Vicente, S.M. White and N. Romano

Section VIII Conclusions 417

Chapter 30 Emerging Mosaics 419

J.B. Thornes

Glossary 429

Index 433

List of Contributors

R.J. Abrahart School of Geography, University of Nottingham, University Park,Nottingham NG7 2RD, UK

F. Alonso-Sarrı́a Laboratorio de Geomorfologı́a, Universidad de Murcia, Campus de “LaMerced”, c/Santo Cristo 1, E-30001 Murcia, Spain

M. d’Angelo Centro Interdipartimento di Ateneo NRD (Nucleo di Ricerca sullaDesertificazione), Dipartimento di Scienze Zootecniche, Universitàdegli Studi di Sassari, Facoltà de Agraria, Via de Nicola, I-07100,Sassari, Italy

N.A. Archer Division of Environmental and Applied Biology, Biological SciencesInstitute, University of Dundee, Dundee DD1 4HN, UK

M. Argyropoulou Department of Biology, Aristotele University of Thessaloniki,GR 540 06 Thessaloniki, Greece

B. Basso Dipartimento di Produzione Vegetale, Università degli Studi dellaBasilicata, Via Nazario Sauro 85, 85100 Potenza, Italy

F. Basso Dipartimento di Produzione Vegetale, Università degli Studi dellaBasilicata, Via Nazario Sauro 85, 85100 Potenza, Italy

A.J. Bastida Departamento de Geologı́a, Universtitat de València, Spain

J.C. Bathurst Water Resource Systems Research Laboratory, School of CivilEngineering and Geosciences, University of Newcastle upon Tyne,Newcastle upon Tyne NE1 7RU, UK

F. Belmonte Serrato Laboratorio de Geomorfologı́a, Universidad de Murcia, Campus de “LaMerced”, c/Santo Cristo 1, E-30001 Murcia, Spain

L. Bottai FMA, Via Einstein 36, 50023 Campi Bisenzio, Firenze, Italy

E. Bove Dipartimento Tecnico-Economico perla Gestione del TerritorioAgricolo-Foresstale, Università degli Studi della Basilicata, ViaNazario Sauro 85, 85100 Potenza, Italy

L.H. Cammeraat IBED-Fysische Geografie en Bodemkunde, Universiteit van Amsterdam,Nieuwe Achtergracht 166, NL 1018 WV Amsterdam, The Netherlands

G. Cannizzaro TelespazioSpA, Via Tiburtina 965, 00156 Rome, Italy

S. Caredda Centro Interdipartimento di Ateneo NRD (Nucleo di Ricerca sullaDesertificazione), Dipartimento di Scienze Zootecniche, Universitàdegli Studi di Sassari, Facoltà de Agraria, Via de Nicola, I-07100,Sassari, Italy

L. Caroti CeSIA-Accademia dei Georgofili, Logge Uffizi Corti 1, 50122 Firenze,Italy

x List of Contributors

M. Conte (deceased) Formerly at Istituto Fisica Atmosfera CNR, PZA L. Sturzo 31, 00144,Rome, Italy

A. Dalaka Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

N.G. Danalatos Department of Agriculture, University of Thessaloniki, 38221 Volos,Greece

M. del Prete Dipartimento di Produzione Vegetale, Università degli Studi dellaBasilicata, Via Nazario Sauro 85, 85100 Potenza, Italy

K.J. Diamantopoulos Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

G. Enne Centro Interdipartimento di Ateneo NRD (Nucleo di Ricerca sullaDesertificazione), Dipartimento di Scienze Zootecniche, Universitàdegli Studi di Sassari, Facoltà de Agraria, Via Enrico de Nicola,9-07100, Sassari, Italy

A. Ferrara Dipartimento di Produzione Vegetale, Università degli Studi dellaBasilicata, Via Nazario Sauro 85, 85100 Potenza, Italy

A.H.D. Francesconi Centro Interdipartimento di Ateneo NRD (Nucleo di Ricerca sullaDesertificazione), Dipartimento di Scienze Zootecniche, Universitàdegli Studi di Sassari, Facoltà de Agraria, Via Enrico de Nicola,9-07100, Sassari, Italy

F. Garcı́a Robredo Fundación Universidad Empresa de Murcia, Escuela de Negocios de laRegión de Murcia, Campus de Espinardo, 30100 Espinardo (Murcia),Spain

F.J. Garcı́a-Haro Remote Sensing Unit, Universitat de València, Dr Moliner 50,46100-Burjassot, València, Spain

M.A. Gilabert Remote Sensing Unit, Universitat de València, Dr Moliner 50,46100-Burjassot, València, Spain

G. González-Barberá Departamento de Coservacion de Suelos y Agua, CEBAS-CSIC, CampusUniversitario de Espinardo, Apartado 4195, 30080 Murcia, Spain

C.M. Goodess Climatic Research Unit, University of East Anglia, Norwich, NorfolkNR4 7TJ, UK

A. Green National Soil Resources Institute, Cranfield University, Silsoe, BedfordMK45 4DT, UK

G.M. Hall National Soil Resources Institute, Cranfield University, Silsoe, BedfordMK45 4DT, UK

L. Hein FSD, PO Box 570, NL 6700 AN Wageningen, The Netherlands

T. Huszár Dept of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112 Budapest, Hungary

G. Iatrou Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

A.C. Imeson IBED-Fysische Geografie en Bodemkunde, Universiteit van Amsterdam,Nieuwe Achtergracht 166, NL 1018 WV Amsterdam, The Netherlands

List of Contributors xi

G. Jakab Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

Á. Kertész Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

C.G. Kilsby Water Resource Systems Research Laboratory, School of CivilEngineering and Geosciences, University of Newcastle upon Tyne,Newcastle upon Tyne NE1 7RU, UK

M.J. Kirkby School of Geography, University of Leeds, Leeds LS2 9JT, UK

C. Kosmas Laboratory of Soil Chemistry, Agricultural University of Athens, IeraOdos 75, 11855 Athens, Greece

E. Koutsidou Department of Environmental Studies, University of the Aegean,“Xenia” Building, 81100 Mytilini, Lesvos, Greece

C. Lanara Cook Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

T. Lanaras Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

V. Leone Dipartimento di Produzione Vegetale, Università degli Studi dellaBasilicata, Via Nazario Sauro 85, 85100 Potenza, Italy

D. Lóczy Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

F. López-Bermúdez Department of Physical Geography, Laboratorio de Geomorfologı́a,Universidad de Murcia, Campus de “La Merced”, c/Santo Cristo 1,E-30001 Murcia, Spain

S. Madrau Centro Interdipartimento di Ateneo NRD (Nucleo di Ricerca sullaDesertificazione), Università degli Studi di Sassari, Facoltà deAgraria, Via de Nicola, I-07100, Sassari, Italy

T. Mardiris Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

N.S. Margaris Department of Environmental Studies, University of the Aegean,“Xenia” Building, 81100 Mytilini, Lesvos, Greece

B. Márkus Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

J.A. Martı́nez Artero DGCONA, Ministerio de Medio Ambiente, Avda. Alfonso X El Sabio 6,30008 Murcia, Spain

A. Martı́nez Ruiz Fundación Universidad Empresa de Murcia, Escuela de Negocios de laRegión de Murcia, Campus de Espinardo, 30100 Espinardo (Murcia),Spain

F. Maselli IATA-CNR, P. le delle Cascine 18, 50144 Firenze, Italy

M.L. McMahon Infocom (UK) Ltd, York Science Park, York, UK

J. Meliá Remote Sensing Unit, Universitat de València, Dr Moliner 50,46100-Burjassot, València, Spain

J. Mika Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

xii List of Contributors

K. Molnár Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

R.P.C. Morgan National Soil Resources Institute, Cranfield University, Silsoe,Bedfordshire MK45 4DT, UK

J. Nachtergaele Laboratory for Experimental Geomorphology, Katholieke UniversiteitLeuven, Belgium

J.A. Obando Department of Geography, Kenyatta University, PO Box 43844,Nairobi, Kenya

C.P. Osborne Department of Animal and Plant Sciences, University of Sheffield,Sheffield S10 2TN, UK

J.P. Palutikof Climatic Research Unit, University of East Anglia, Norwich, NorfolkNR4 7TJ, UK

J. Pantis Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

E. Papatheodorou Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

S. Papp Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

E. Piervitali CRATI s.c.r.l., Università della Calabria, Rende (CS), Italy

M. Pisante Dipartimento di Produzione Vegetale, Università degli Studi dellaBasilicata, Via Nazario Sauro 85, 85100 Potenza, Italy

J. Poesen Laboratory for Experimental Geomorphology, Katholieke UniversiteitLeuven Redingenstraat 16, B-3000 Leuven, Belgium

L. Postiglione Faculty of Agriculture, University of Naples Federico II, via Universitá,100, 80055 Portici (NA), Italy

F. Previtali Dipartimento di Scienze dell’Ambiente e del Territorio, Università diMilano–Biocca, Milano, Italy

G. Pulina Centro Interdipartimento di Ateneo NRD (Nucleo di Ricerca sullaDesertificazione), Dipartimento di Scienze Zootecniche, Universitàdegli Studi di Sassari, Facoltà de Agraria, Via de Nicola, I-07100,Sassari, Italy

G. Quaranta University of Basilicata–DITEC, Via Macchia Romana, I-85100Potenza, Italy

J.N. Quinton National Soil Resources Institute, Cranfield University, Silsoe,Bedfordshire MK45 4DT, UK

L. Rojo Serrano DGCONA, Ministerio de Medio Ambiente, Gran Vı́a de San Francisco4, 28005 Madrid, Spain

N. Romano Department of Agricultural Engineering, Division for Land and WaterResources Management, University of Naples “Federico II”, ViaUniversita’, 100, 80055 Portici (Naples), Italy

M.A. Romero Dı́az Department of Physical Geography, University of Murcia, Campus de“La Merced”, c/Santo Cristo 1, E-30001 Murcia, Spain

List of Contributors xiii

A. Sántha Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

A. Santini Department of Agricultural Engineering, Division for Land and WaterResources Management, University of Naples “Federico II”, ViaUniversita’, 100, 80055 Portici (Naples), Italy

S. Sgardelis Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

J. Sheffield Department of Civil and Environmental Engineering, PrincetonUniversity, Princeton, New Jersey 08544, USA

R. Sorani Servizio Meteorologico dell’Aeronautica, Rome, Italy

G.P. Stamou Department of Biology, Aristotele University of Thessaloniki, GR 54006 Thessaloniki, Greece

L. Szalai Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

M. Taberner c/o Institute for Environment and Sustainability, Ispre, Italy

J.B. Thornes Department of Geography, King’s College London, the Strand, LondonWC2R 2LS, UK

P. Tobarra Ochoa Department of Fundamentals of Economical Analysis, University ofMurcia, Spain

I. Tózsa Department of Physical Geography, Geographical Research Institute,Hungarian Academy of Sciences, H-1112, Budapest, Hungary

B. van Wesemael Département de Géographie, Université Catholique de Louvain, PlaceLouis Pasteur 3, B-1348 Louvain-la-Neuve, Belgium

C. Vicente C/Cafetos #4, Col. Campestre, Cordoba, Veracruz 93653, Mexico

S.M. White Institute of Water and Environment, Cranfield University, Silsoe,Bedfordshire, MK45 4DT, UK

F.I. Woodward Department of Animal and Plant Sciences, University of Sheffield,Sheffield S10 2TN, UK

M.T. Younis Remote Sensing Unit, Universitat de València, Dr Moliner 50,46100-Burjassot, València, Spain.

Preface

Desertification has been recognized as one of the biggest problems facing the European Mediter-ranean countries. By desertification we mean land degradation resulting from various factors, includ-ing climatic variation and human impact, and it is the long history of human intervention, fromClassical times onwards, that has particularly shaped the landscape here. Water resources have beenexploited unsustainably, resulting in chemical pollution, salinization and exhaustion of aquifers. Aseconomic activity has flourished in coastal areas so abandonment and degradation of land in theinterior, previously sustained by traditional farming practices, have continued. Portugal, Spain, Italyand Greece are all now signatories to the United Nations Convention to Combat Desertificationand implementation of the convention within national and regional action plans will require furtherorganization of research and monitoring.

The European Commission has funded a number of projects within the Environment Programme(DGXII), aimed at improving the understanding of the whole range of desertification issues. Thisbook is based on the results of one of those projects, MEDALUS II, where 44 different universitiesand other institutions combined their expertise to clarify the processes of desertification operating inthe Mediterranean environment, and the responses to those processes. Scientists of many disciplines,ranging from remote sensing to microbiology, researched climate, land use and the physical processeswithin soil and vegetation systems in order to design tools to describe and monitor desertification.Part 2 of this book describes how these processes and tools have been applied specifically. Theregional studies illustrate how the application of remedial action cannot usually be uniform, butmust respect the mosaic of physical environments and social and historical variations that interactwithin the geographical space of two of the target areas: the Guadalentı́n Basin of south-east Spain,and the Agri Valley of southern Italy.

The editors feel privileged to have had the opportunity to work with the MEDALUS projects andto edit this book. All the authors should feel very proud of the unique spirit of co-operation that theprojects have engendered. Each individual contribution makes up a part of the mosaic of our currentknowledge, and the years of work behind this achievement are very much appreciated.

Nichola GeesonJane Brandt

John B. Thornes

Department of Geography, King’s College, University of London, UK

November 2001

PART 1 THEMATIC ISSUES

Section I Introduction

1 The Evolving Context of MediterraneanDesertification

J.B. THORNESDepartment of Geography, King’s College London

1 INTRODUCTION

In the last 10 years, the issue of desertification has not only become more widely recognized, bothinternationally and regionally, but the social and political framework has changed dramatically in away that makes a change in the research approach crucial. It is the purpose of this chapter to outlinethese changes in order to set the context for further assessment of the problem. There have been anumber of major syntheses that reflect the wider consciousness and appraisal of the problem.

Despite these changes, the UNEP (United Nations Environment Programme) definition of deser-tification as “land degradation in arid, semi-arid and dry sub-humid areas resulting from variousfactors including climatic variations and human activities” remains as helpful today as it was in1990 (UNEP 1990). Bearing in mind that “land” means the terrestrial bioproductive system thatcomprises soil, vegetation, other biota and the ecological and hydrological processes that operatewithin the system, the definition is particularly relevant. “Land degradation” means reduction andloss of the biological and economic productivity caused by land-use change, or by a physical processor a combination of the two. If anything, it would be useful to incorporate the rural depopulationimplied in the French language usage, especially in a European context, where desertion of ruralareas has been stressed as a pivotal problem in European Agricultural Reform.

More light was spread on the problems of desertification in southern Europe by the conferenceheld jointly by the Directorate General for Research of the European Commission and the GreekGovernment from 29 October to 1 November 1996. The proceedings have been published in two vol-umes (Balabanis et al. 1999, 2000). Another source is the documentation arising from the ConcertedAction on Mediterranean Desertification, funded by the Research Directorate under Framework Vand published in three volumes (Burke and Thornes 1998, in press a, b). A further important con-tribution, in addition to the publication of the two major books on the MEDALUS Project (Brandtand Thornes 1996; Mairota et al. 1998), is van der Leeuw’s brilliant synthesis of the ArchaeomedesProject (van der Leeuw 1998).

2 AGENDA 21 AND SUSTAINABILITY

At the international level, the UNCED Rio Conference of 1992 urged signatory nations to “repositiontheir economies, their societies and their collective purpose to maintain all life on earth, peacefully,equitably and with sufficient wealth to ensure that all are content in their survival” (O’Riordan andVoisey 1998, p. xiii). In Europe, this requirement was foreseen in the Fifth Environmental Plan, aprecursor to the Rio Conference’s position on sustainability. Although progress has been relativelyslow in some European countries and almost non-existent in others, the plan anticipates a level ofpublic empowerment in environmental matters that will, in the longer term, enlighten environmentalaffairs. In Portugal, the establishment of Environmental Protection Associations at four different

Mediterranean Desertification: A Mosaic of Processes and Responses. Edited by N.A. Geeson, C.J. Brandt and J.B. Thornes 2002 John Wiley & Sons, Ltd

6 Mediterranean Desertification

levels (Reibeiro and Rodrigues 1998) has strong affinities with the Land Care approach of Australia,in its emphasis on community and end-user involvement. This bodes well for the future contemplationof measures against desertification. Greece has been somewhat slower to act, according to Greekauthors (Fousekis and Lekakis 1998), but the difficulties are the same: the lack of familiarity with,and acceptance of, consultation of the people; the late development of institutions of government,especially those concerned with environment; and the shortage of basic data that are required fordecision making at the local level.

Another major change since the start of the MEDALUS Project has been the shift in the CommonAgricultural Policy (CAP) as a result of changing public awareness of the failures of the agriculturalprice support system and, specifically, the negotiations in 1992 of the General Agreement on Tariffsand Trade (GATT).

3 AGRI-ENVIRONMENTAL MEASURES AND AGENDA 2000

Perhaps the largest socio-economic change to occur in Europe that may be expected to have a bearingon the desertification problem is the Cork Declaration. In this, Commissioner Fischer stated hisdetermination to reform the CAP into a more broadly based rural policy, integrating environmentalissues. This was to bring to an end 40 years of price support and potentially affect an area of141 million hectares, 44% of the total land surface of the 15 European Union states and probablychange the landscape of Europe forever. There is a close link here to Agenda 21, because the need forsustainable agriculture is one of the key forces driving the reform of the CAP. This reform is calledAgenda 2000. Here sustainable use means “The use of components of biological diversity in a wayand at a rate that does not lead to the long-term decline of biological diversity, thereby maintainingits potential to meet the needs and aspirations of present and future generations” (according to theInternational Convention on Biodiversity, Rio 1992).

In their assessment of the new CAP proposals, Birdlife International (1997) described the oldCAP as “the engine of destruction in the countryside”. The productionist philosophy, with its link toregional and national development, led to the intensification of agriculture after the Second WorldWar, through increased mechanization, fertilizer application and the promotion and extension ofirrigation, that was so notable in the Mediterranean, leading to the conversion of dry farming todense, fast-growing, heavily fertilized and pest-treated crops. It also led to a sharp increase inthe demand for irrigation water and massive extraction of groundwater resources (see below). Theoriginal CAP (arising in the earliest days of the Community from the Treaty of Rome) was “anoutdated, expensive, inefficient, inequitable and environmentally-damaging collection of policiesthat by 1992 was in need of further reform”. This was urgent for several reasons:

• the proposed enlargement of the European Community;• the requirement to meet the needs of the Uruguayan round of GATT and to prepare for the

next round of World Trade negotiations with an emphasis on the reduction of trade-distortingsubsidies;

• the commitment at the Rio Conference to promoting sustainable agriculture and protecting andenhancing the natural environment, as well as helping to meet the needs of rural communities;

• public demand for economic reform, relating to the budgetary costs and the economic inefficiencyof the CAP.

The Commission decided to follow the McSharry approach to reforms by reducing support paymentsto world levels and replacing production incentives with direct payments. For example, the sharpcuts in beef and cereal prices are designed to allow food to be exported into world markets withoutsubsidy enabling an enlarged EU to sell off its surpluses in these commodities. The East Europeancountries that are joining will need to develop their agricultural systems in a sustainable way whilemeeting the needs of their rural communities.

It is too early to see the outcomes of these policy shifts, which tend to be obscured by short-termfluctuations, such as the rise in grain prices that enabled export without subsidy in 1995–1996. The

The Evolving Context of Mediterranean Desertification 7

increased harvest in 1996 and the subsequent fall in world grain prices have reintroduced the needfor export subsidies. The potential for significant increases in production brought some difficultiesin meeting GATT limits on subsidized exports, requiring a significant increase in the set-aside rates.

What is clear is that rural depopulation remains an important issue. A key objective of Agenda2000 is to maintain the viability of rural communities by maintaining employment and incomesin rural areas through sustainable long-term use of resources. According to Birdlife International(1997), the number of people employed in agriculture in the 12 member states of the EU declinedfrom 16.3 million in 1970 to 7.0 million in 1994, falling from 13.5% to 5.5% of total employment. Atthe same time, farm sizes and agricultural production have increased, resulting in increased levels ofsubsidies going to smaller numbers of farmers. As employment in agriculture continues to decline,the benefits of the (original) CAP are becoming less apparent.

This valuable appraisal goes on to say that “Europe’s rural development problems cannot beaddressed by support for agricultural production alone. They require a more integrated approachto rural policy, which places agriculture within the context of the whole rural economy” (BirdlifeInternational 1997, p. 19). It is hard to disagree with this view and it must be added that the failureto address the most severe crisis in southern Europe, land degradation, highlights this lack of an inte-grated approach. The Agenda 2000 reforms are a great opportunity to couple economic regulationswith environmental reforms. This has been done directly, to some extent through the “extensifica-tion measures” and indirectly through Environment Impact Directives. The ideal agri-environmentalprogramme would, among other things, provide opportunities for all farmers to manage land forerosion mitigation rather than allow them to pass externalities (such as reservoir siltation) to thetax payers.

4 LAND ABANDONMENT

It is often claimed that land abandonment invariably leads to land degradation and desertification,partially at least through the failure to maintain agricultural terraces. However, as Baudry (1991)points out, land abandonment is not a new phenomenon. It has been constantly occurring in Europesince 1950 and has been widespread in eastern North America since 1920. Rather than simply blameland abandonment on European Union policy, we need to know better what lessons can be learnedfrom history. In the Mediterranean, there have been phases of strong outward migration. These havebeen both local (such as the impact of the Phylloxera plague on vines in the Spanish Alpujarra inthe early years of the 20th century), and regional (as in the out-migrations for employment fromsouthern Spain to northern Europe in the mid-20th century).

Land abandonment does not necessarily mean that land is no longer used, either by agricultureor any other rural economy; it means a change in land use from the traditional or recent patternto another, less intensive pattern. Nevertheless, we need to be able to identify how the landscapewill change in relation to our knowledge of the erosion risk. Perhaps it is self-evident that theland at greatest risk is most likely to be abandoned. There are two sides to the coin: land aban-donment occurs either because of external stresses and/or because of its inherently low productivecapacity.

Land abandonment occurs as a result of external driving forces, such as market changes, orinternal changes that are “intrinsic”, for example if the system crosses some invisible threshold,such as the critical soil depth for plant growth. Once crossed, the tendency is for change to benegative, self-reinforcing and irreversible. Over the years, farming practice has brought the farm-ing systems more stability, making them more resilient to changes. It is claimed that the mixedtree–grass–herb–grazing system of Extremadura, Spain (the dehesas) is highly stable to changebecause of its need for very low external inputs, its high biological diversity and the highly par-titioned tree and herb layer (Bernaldez 1991). On the other hand, ecosystems are more unstableand susceptible to change when there is a strong competition between components. Thus Thornes(1990) was able to demonstrate the low stability in Mediterranean ecosystems where plants and soilscompete for water, a situation that can lead to catastrophic changes as a result of small changesin the inputs and outputs (rainfall and grazing take-off, respectively). Progressive slow degradation

8 Mediterranean Desertification

can move the system towards an unstable state without the dangers being recognized. The trick isto identify the “position” of the threshold in state-space, so that trajectories towards instability canbe recognized. The trajectory towards instability becomes apparent over time. After fire, it oftentakes 8–10 years before the pre-fire equilibrium between vegetation cover and sediment yield is re-established. Unfortunately, abandonment and the associated neglect often bring the system rapidlyto a threshold that, when crossed, may lead to irreversible erosion. Abandonment after ploughingresults in a succession that requires about 20 years to reach equilibrium as a mature ecosystemunder the prevailing grazing. Alpha diversity increases with succession and niche amplitude tendsto diminish, the new plant species becoming specialists of increasingly narrower habitats (Pinedaet al. 1981).

Traditional sylvo-pastoral systems are subjected to either increases or decreases in grazing pres-sures. The former leads to destruction of natural pastures and the replacement of valuable grassesand legumes by unpalatable nitrophilous vegetation as has occurred at the MEDALUS field sitein north-west Lesvos Island, Greece, observed by Kosmas et al. (1998). Replacement of nutritiousherbs by rough pasture has also been described in Spain (De Miguel 1989). If this “matoralization”process proceeds unchecked, it eventually induces a decrease in biological diversity and a decreasein stability, as described by Naveh and Whittaker (1974), and an increase in fire risk.

5 WATER RESOURCES

Problems of water resources are inextricably bound to, but not synonymous with, desertification. Asland degradation occurs, soil storage capacity is reduced, runoff increases and erosion thresholds arepassed. The high inter-annual variability of rainfall moves Mediterranean soils inexorably towardsthe thresholds of land degradation as the pressure on vegetative cover increases through lack of soilmoisture. The gathering pace of confidence in the observation of the existence of global warmingand revised estimates by the ICCP indicate more difficult times ahead for hillslope hydrology assystems dry out. MEDALUS research suggests significant reductions in the biomass of grass andbushlands in areas having more than seven rain-free months per year in the Iberian Peninsula, astemperatures and atmospheric CO2 rise (Diamond and Woodward 1998), and estimates made by theSpanish Ministerio de Obras Publicas indicate important (17–20%) reductions in the flow of majorSpanish rivers. Even accepting the scope for errors in these model estimates, the contemporarydata already show that the supply of water for river flow replenishment and aquifer recharge isdecreasing.

In Mediterranean regions with average rainfalls of less than 300 mm per year, high inter-annualvariability and high summer temperatures, there is a more or less continuous threat of water scarcity.In meteorological droughts this is caused by failure of precipitation, as has occurred in Italy, Greeceand Spain in the last two decades of the last century. The whole of Italy was affected by severedrought during 1988–1999. A sequence of three years with low rainfall were accompanied byhigh temperatures; snow depths were also considerably reduced, with lower snowfalls than nor-mal, combined with high temperatures. Large areas of Greece are susceptible to drought, notablyeastern Greece and some Aegean islands. Catchments are often small and underlain by highlypermeable karstic formations. There was an extended drought in the Athens area from 1987 to1993, when rainfall was only 50% of normal, including two extremely dry years (1989/90 and1991/2) that were the most severe over the last century. Most of Spain, except the north-westcoast, was severely drought affected in the years 1990–1996. An analysis of seasonal rainfall(Institute of Hydrology and ISPRA 1999) indicates that the rainfall deficit was generally con-centrated in winter and spring. Autumn rainfall was normal or above average and summer rainfallfairly regular. Mean percentage departure from normal rainfall exceeded −20% in the southernpart of the country, which was worst affected. The drought reached its maximum coverage inSeptember 1994 and August 1995 when rainfall reached −25%, and over two-thirds of Spain wasaffected.

MEDALUS research by Goodess and Palutikof (Chapter 18) demonstrates the close coupling ofthe Atlantic Ocean pressure differences between the Azores High and the Iceland Low, on the one

The Evolving Context of Mediterranean Desertification 9

hand, and pressure fields over the Mediterranean that are linked to rainfall aberrations on the other.Earlier, Turkes (1996) showed, by the analysis of normalized rainfall patterns, that anticyclonicactivity affected Turkey more frequently over the period 1973–1993. The abrupt decrease in rainfallsince the early 1970s has been attributed to the northward shift of the Polar front, resulting from amore easterly extension of the drought-dominated subtropical anticyclone extending from the Azoresto the eastern Mediterranean.

According to the Institute of Hydrology/ISPRA report (1999), a study by Reynard et al. (1997)concluded, inter alia, that

• there is a general tendency for an increase in annual average runoff in northern Europe and adecrease in southern Europe of over 30% in some areas;

• the greatest sensitivity to change is in the drier parts of southern and eastern Europe;• before the 2050s there could be a substantial reduction in snowfall that would alter the current

temporal distribution of river flows by reducing or eliminating the spring peak and substantiallyincreasing winter flows in central and eastern Europe.

In addition to the impacts of meteorological drought, the public perception of desertification hasbeen heightened by water resource shortage arising from anthropologically induced water problems,including:

• the huge and continuing rise in demand for water to meet the needs of tourism growth, which haslocally caused salinization because aquifers have been drawn down, as in the case of Benidorm,Spain;

• a number of major floods, whose magnitude and time-to-rise have almost certainly been affectedby vegetation removal and soil erosion, but whose impact has resulted from the failure of planningmeasures to provide flood plain zoning;

• the heavy reliance in Mediterranean countries on irrigation for agricultural production: in Greece,80% of water is used for irrigation, in Italy 50%, in Spain 68% and in Portugal 52%;

• the continued rise in the demand for irrigation water, which has led to a reversion to engineering-type solutions.

An example of the latter is the National Hydrological Plan of Spain, which foresees the transferof water from the lower Ebro to both Catalonia (Barcelona) and Murcia. There has been a bitterdebate by the people of Aragon who claim that the water needs for the poorer areas of Aragon arealso exacerbating underdevelopment. There is a crisis of democracy because the central governmenthas had to try to balance out the needs of the wet north and the dry south. In 1998, in the severedrought, the existing transfer canal taking water from the River Tajo in Castilla la Mancha to theRiver Segura in Murcia failed to stave off the impacts of drought in Murcia, where large numbersof fruit trees were lost. The Tajo–Segura Trasvase (transfer canal) has a capacity for transferring6 × 108 m3 year−1 and the Spanish government ordered the diversion of a further 5.5 × 107 m3 to“save” Murcia. It is against this background that the current bitter row over transfer from the Ebroto Murcia is being waged. At a demonstration in the Aragon city of Zaragoza, two-thirds of thepopulation of Aragon turned out to protest against the projected transfer, instead of letting the waterflow to the Ebro delta and the irrigated lands around Tortosa. Meanwhile Barcelona is negotiatingwith France for water from the Rhône.

Water quality deterioration is adding to the environmental crisis that has been confused andcompounded with desertification and coupled to the issues of sustainability and the defence of ruralareas. Again, the effects of productionist agriculture are evidently the major causes and any actiontaken to mitigate desertification through regulatory measures in an integrated catchment context willhave to address the water quality problem (Foster 2000). The flux of fertilizer returns in water in thenorthern states is three times greater than in the southern states and contributes 73% of the total. Ofthe national amounts, the largest returns are of irrigation water (Egypt and Italy) and power stationcooling water (France).

10 Mediterranean Desertification

6 A MOSAIC AND A PALIMPSEST

One of the major difficulties facing this planning operation is the fact that the Mediterranean land-scape is one of the most complicated in the world. Over space, conditions rarely remain the samefor more than a kilometre or two because of local variations in topography, soils, land use, climateand surface water conditions. Another source of variety is that almost every municipality bears theimprint of national, regional and local constraints throughout history.

The challenge for those concerned with planning for environmental sustainability in a local Agenda21, including desertification and land degradation, is threefold:

• to identify the local-scale causes of desertification and its manifestations, and develop suitablesensitive indicators to do this;

• to understand the historical development of the problem, also at different time-scales;• to develop regulations that, far from being applicable to the whole of Europe, are sufficiently

flexible to accommodate the local variations in history and conditions in the hope that this willfacilitate implementation and contribute towards successful outcomes from the interventions.

Given the multiple pressures on national and regional governments from the International Conven-tion, from the European Community and from national and local pressure groups, rural planning hasshifted sharply into focus. With it has come the need for empowerment of local people in findingand negotiating optimal strategies to meet these legally binding requirements (Thornes 1998).

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