英文—土地退化控制及其全球环境效益

land degradation &development

Land Degrad.Develop.16:99–112(2005)

Published online in Wiley InterScience (4606e4f8941ea76e58fa04fa).DOI :10.1002/ldr.687

LAND DEGRADATION CONTROL AND ITS GLOBAL ENVIRONMENTAL BENEFITS

G.GISLADOTTIR 1AND M.STOCKING 2*

1Department of Geology and Geography,University of Iceland,Askja,Reykjavik,Iceland 2School of Development Studies,University of East Anglia,Norwich,UK

Received 18February 2004;Revised 12June 2004;Accepted 22December 2004

ABSTRACT

Acknowledged by world leaders as a global problem,land degradation has been taken seriously in three ways:its extent and the proportion of the global population affected;international environmental policy responses;and its inter-relation with other global environmental issues such as biopersity.Messages about land degradation have,however,suffered from abuses,which have rendered appropriate policy responses ineffective.For control to be effective,the paper argues that the synergies between land degradation and the two other main global environmental change components (biopersity and climate change)should be more fully exploited.A focus on the interlinkages,of which there are six possible permutations,is fully supported by empirical ?ndings that suggest that land degradation control would not only technically be better served by addressing aspects of biopersity and climate change but also that international ?nancing mechanisms and the major donors would ?nd this more acceptable.The DPSIR (Driving Force,Pressure,State,Impacts,Response)conceptual framework model is used to illustrate how land degradation control could be more effective,tackling not only the drivers of change but also major developmental issues such as poverty and food insecurity.Copyright #2005John Wiley &Sons,Ltd.

key words :land degradation;global environment;UN environmental conventions;synergies;biopersity;climate change

LAND DEGRADATION IN GLOBAL CONTEXT

Land degradation is widely recognized as a global problem associated with deserti?cation in arid,semiarid and dry sub-humid zones,commonly called the ‘drylands’.Yet,land degradation is a contested topic in its determinants,degree,distribution and effects.While long associated with drylands,which cover some 47per cent of the globe’s surface (UNEP,1997),land degradation is considered by many observers to be highly variable,discontinuous,arising from different causes and affecting people differentially according to their economic,social and political circumstances (e.g.Mortimore,1998).Uncertainty as to the extent and impact of land degradation is rife.Some sources routinely report that up to 70per cent of all drylands are ‘deserti?ed’;others suggest that the ?gure is no more than 17per cent (see Reynolds et al.,2003).Amidst such discrepancies,it is dif?cult to identify whether and how land degradation should be an issue of global concern.The overall aim of this paper,then,is to explore how the process of land degradation,which impacts upon people locally and differentially,can also be considered to be of global interest with global implications.

There are three principal ways that land degradation can be perceived to be global.First,it affects a large number of people over a signi?cant proportion of the earth’s surface.Adams and Eswaran (2000)estimate that it Copyright #2005John Wiley &Sons,Ltd.?Correspondence to:M.Stocking,School of Development Studies,University of East Anglia,Norwich NR47TJ,UK.

E-mail:m.stocking@4606e4f8941ea76e58fa04fa

Contract/grant sponsors:IGU Commission on Land Degradation;United Nations University,Tokyo;FAO–GEF Land degradation assessment in drylands project;United Nations Environment Programme,Nairobi.

100G.GISLADOTTIR AND M.STOCKING

impacts2á6billion people in more than a hundred countries,covering over33per cent of the earth’s land surface. Around73per cent of rangelands in drylands are currently being degraded,together with47per cent of marginal rainfed croplands and a signi?cant percentage of irrigated croplands.The science behind the actual extent of land degradation is open to debate,especially in dryland parts of Africa(Stocking,1996).However,even restrained estimates show that it affects the poor and most marginal rural people world-wide disproportionately.Taking only the world’s drylands,37per cent of the world’s total population live on land that is either potentially or actually 4606e4f8941ea76e58fa04fa,Africa and South America have the largest populations living in drylands,both in terms of numbers and percent:1á4billion,268million and87million people,or42,41and30per cent of each region’s population respectively.The drylands are the home of the world’s poorest and most marginalized people, economically and geographically.The number of poor rural people living in drylands is estimated to be close to one billion(Dobie,2001).

Second,land degradation has prompted a stream of national and international policy responses.The Dust Bowl era of the1930s United States prompted the?rst national research programme on soil erosion and its impact (Trimble,1985).Other countries and regions soon emulated this lead:e.g.Brazil(Lal,1977);Sri Lanka(Joachim and Pandithasekera,1930);and the Federation of Rhodesia and Nyasaland,now Zambia,Zimbabwe and Malawi (Jackson,1960).With major increases in funding for erosion research and surveys of soil degradation,a number of international projects were initiated:e.g.the Provisional Methodology for Soil Degradation Assessment(FAO, 1979).Other initiatives included the United Nations Conference on Deserti?cation(UNCOD)in1977and the United Nations Conference on Environment and Development(UNCED)in1992.The latter led to the adoption of the Convention to Combat Deserti?cation(UNCCD)4606e4f8941ea76e58fa04fand degradation was reaf?rmed at the World Summit on Sustainable Development(WSSD)in September2002as one of the major global environmental and sustainable development challenges of the21st century.The Summit(WSSD,2002)called on the Global Environmental Facility(GEF)to designate land degradation as a new focal area to support the implementation of the UNCCD.This proposal was embodied in the Beijing Declaration of the Second GEF Assembly in October 2002.As a follow up,the GEF launched a new Operational Program on Sustainable Land Management in July2003 to support the designation of land degradation as a focal area.Along with the new global policy came an immediate US$250million of?nancing for the incremental costs—that is,additional costs to meet global bene?ts—of land degradation control in developing countries.At the time of writing this paper that allocation had been fully committed and the GEF donors are under pressure to increase their contributions in the next phase of GEF. Third,land degradation negatively affects a number of important problems of global concern.Pagiola(1999) de?nes land degradation’s effects on global problems as direct,on the degradation processes themselves,and indirect,resulting from land users’responses to land degradation problems.In the?rst category are effects on climate change and loss of biopersity.Direct effects through biophysical processes include carbon reduction in soils and loss of below-ground biopersity.In the second category,involving arguably the greater impact on human society,are the reductions of productivity caused by climate change,deserti?cation and loss of biopersity. On rangelands,for example,Pagiola(1999)lists the disruption of migratory patterns of wild animals,the introduction and propagation of diseases,competition for available food and water,and changes in forage species composition.There are also effects on international waters,such as off-site pollution and sedimentation.These synergies between land degradation,biopersity and climate change have major implications for all the global environmental conventions.Global developmental initiatives are also involved,such as two of the most directly relevant Millennium Development Goals:No.1the eradication of extreme poverty and hunger,which is associated with declining status of natural resources,and No.7environmental sustainability,which is seen as a social responsibility(see The World Bank Group,2004).World leaders and the major multilateral development and environment institutions all subscribe to the importance of land degradation,development,food security and poverty linkages(see Table I).

There are,therefore,compelling reasons to see land degradation in global context.This paper addresses the developments and lessons in measures to control land degradation,and identi?es the linkages between actions at the local level and the consequent global environmental bene?ts.The objective is to justify that measures to control land degradation yield global bene?ts that are worth?nancing through international programmes such as Copyright#2005John Wiley&Sons,4606e4f8941ea76e58fa04faND DEGRADATION&DEVELOPMENT,16:99–112(2005)

LAND DEGRADATION CONTROL:GLOBAL BENEFITS101 Table I.Statements by world leaders and multilateral institutions on land degradation linkages with global development concerns

Statement Source

[We need to]address the causes of deserti?cation in World Summit on Sustainable Development,September2002 order to restore land and to address poverty resulting

from land degradation

Poor people care a lot about their environment UNDP2003:Human Development Report

Addressing land degradation[will]...contribute Operational Program15,Global Environment Facility,

signi?cantly to the Millennium Development Goals of December2003

reducing by half the proportion of people in poverty

by2015and ensuring environmental sustainability

Land degradation is equally cause and effect of poverty Klaus Topfer,Executive Director,UNEP

and it bears long-term environmental externalities...to(Foreword in UNEP2004)

which people in marginal lands are especially vulnerable

Deserti?cation...contributes to food insecurity,famine Ko?Anna,UN Secretary-General,17June2004

and poverty,and can give rise to social,economic and

political tensions that can cause con?icts,further poverty

and land degradation

Poverty and deserti?cation are closely linked.Two-thirds Secretariat,UN Convention to Combat Deserti?cation,

of the world’s hungry people live in rural areas1June2004

of developing countries

Source:DFID,2004.

the GEF.However,there are good ways and bad ways to promote land degradation control,and these need routinely to be re-examined in the light of the global environmental context.This paper therefore starts with a selective review of some of the lessons learned.This also sets the scene for further papers in this volume that examine how land degradation is being identi?ed and mitigated in a range countries varying from Iceland to South Africa

LESSONS LEARNED IN LAND DEGRADATION CONTROL

A principal theme of this paper is that land degradation control,whether promoted as soil conservation or reforestation or some other process,has been an international concern for well over70years.Yet there has been a tendency to see land degradation control as a purely technical exercise and self-evidently worthwhile for human society to 4606e4f8941ea76e58fa04fand degradation has been tackled by addressing the degradation itself,rather than its causes and symptoms.As this paper will argue,a large measure of the problems in?nancing and gaining active attention for land degradation control arises from a somewhat myopic and technocentric view of how to reverse such processes as soil erosion and deforestation.Simplistic messages have pervaded the subject,while actions to control land degradation have often been based on subjective choice of information.This section reviews three areas—land degradation data,ascribing cause,and use of information—where major lessons have been learned.From these,messages to inform current global efforts on land degradation control may be derived.

‘Health Warnings’Over the Data

Especially at global and regional levels,alarming statistics are regularly used to command attention with respect to the seriousness of land degradation.Often these are linked to what are determined to be the principal‘causes’(or ‘root causes’)and expressed in terms of hectares of land ruined.Table II gives a typical example,by no means at the most extreme end of the range of estimates,which identi?es great swathes of grazing,forest and agricultural land as degraded.What is rarely given are‘health warnings’as to the accuracy of the data,inherent problems in the techniques used to gather the information,and the assumptions made to extend the results to give a global picture. Copyright#2005John Wiley&Sons,4606e4f8941ea76e58fa04faND DEGRADATION&DEVELOPMENT,16:99–112(2005)

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Table II.Extent and immediate causes of land degradation

Degradation extent Immediate cause

(million ha)

680Overgrazing—about20per cent of the world’s pastures and rangeland have been damaged,especially recently in Africa and Asia

580Deforestation—large-scale logging;clearance for farm and urban use.More than220million ha of tropical forests were destroyed1975–90

550Agricultural damage—water erosion causes soil losses estimated at25000million tonnes annually.

Soil salinization and waterlogging affect about40million ha of land globally

137Fuelwood—about1730million m3of fuelwood are harvested annually from forests and plantations

19.5Industry and urbanization—urban growth,road construction,mining and industry.Mainly

a loss of agricultural land

Sources:FAO,1996;UNEP,2002.

Typical amongst the health warnings should be the use of conjecture as a substitute for evidence-based science. There has been debate as to the seriousness of global estimates of soil erosion over the last two decades.In a landmark publication from a leading environmental policy‘think-tank’institution in the United States,the Worldwatch Institute,Brown and Wolf(1984)estimated global erosion to be26billion tonnes per year over and above rates that might be considered allowable and which would not threaten agricultural production.This is a huge mass of soil,which,if true,would remodel whole landscapes within historical record.A critique by Pierre Crosson revealed the?imsy basis of the‘science’behind the estimate,an assertion by an eminent forest ecologist as to what might happen if tropical deforestation were to occur(Crosson,1995),and the extension of this conjecture to global proportions.As Dregne(1992)put it:‘little data and much informed opinion’(see also Crosson,2003).

The commonest problem is to take data of soil loss and runoff from small plots and to extrapolate the measured rates(in amounts of soil per unit area)to whole catchments,districts,countries and,even,sub-continents.Yet,it has long been known that estimates of soil loss derived from small plots do not match levels of river sedimentation, and the smaller the plot and the bigger the river basin,the greater is the discrepancy(Walling,1988).The lesson is that many measures of land degradation are scale-dependent.That means that the absolute rates to indicate its seriousness depend upon the area over which the measurements are taken.The smaller the area,the higher are the rates.This has led to selective use of statistics—see‘controlling the hyperbole’below.Where does the‘lost’soil go?It is redistributed within catchments,often to productive bene?t of downstream users.

The message for land degradation control in global context is that all data on rates of land degradation need to be treated 4606e4f8941ea76e58fa04fand degradation assessment needs itself to be reassessed in terms of its utility, components,presentation,attention to scale,and the use to which the information is put.Only very lately has the global environmental community recognized this critical need(FAO,2003)and instituted a new project‘Land Degradation Assessment in Drylands’funded by the Global Environment Facility with the speci?c task of examining assessment for the world’s drylands at a number of scales and with a variety of techniques. Controlling the Hyperbole

Closely related to problems of data are the use to which the data are put and how selection is made from an array of sometimes con?icting information as to the seriousness of degradation.It is natural to choose the data that make the fundamental point that land degradation is serious.However,this will then exaggerate the extent of the problem,creating scepticism amongst hearers,especially if such hyperbole has been used before and the dire predictions have failed to materialise.

Hyperbole,the literary device to express strong feeling,is sometimes used in the form of metaphors in natural science and post-modernist social science(Ley,2003).It is legitimized on the grounds that it enables attention to be drawn to high-pro?le but controversial topics believed to be important by the scientist(e.g.in entomology: Hunter,2000).Unfortunately,the understanding that hyperbole is not meant to be taken literally gets lost.Along Copyright#2005John Wiley&Sons,4606e4f8941ea76e58fa04faND DEGRADATION&DEVELOPMENT,16:99–112(2005)

LAND DEGRADATION CONTROL:GLOBAL BENEFITS103 with identifying the guilty,the debate on the challenges of land degradation has been beset by exaggeration, selective use of statistics and alarmist propaganda.Reij et al.(1996)have reviewed some of the‘facts’and the ‘?ctions’of soil loss data to explain the justi?cations for external interventions of soil and water conservation technologies.Alarm calls about the damaging environmental consequences have had an especially long history in Africa(Pretty and Shah,1994).Figures are routinely extrapolated,often by scientists,to give a global overview of soil loss:e.g.‘each year,75billion metric tons of soil are removed from the land’(Pimentel et al.,1995).They persist even today for the continuing debate on land degradation and deserti?cation.Take for example a recent pronouncement by the Director-General of the major international agricultural research centre for the arid tropics, ICARDA,based in Aleppo,Syria:

Today,about1á9billion hectares of land worldwide...are affected by land degradation.This year,as in previous years,about21million hectares of land will become so degraded that crop productivity becomes uneconomic and about6million hectares of land will be irreversibly lost for production.These?gures have serious implications for the future of humanity.The livelihoods of more than900million people in some100 countries are now directly and adversely affected by land degradation(El-Beltagy,2000).

Such views are reinforced by of?cial organizations responsible for overseeing global approaches to land degradation,such as the Secretariat of the UN Convention to Combat Deserti?cation(see below).The implications are clear:land degradation is leading inexorably to calamity;the global community must take urgent action. Identifying the Guilty

In calls to take action,attention is usually drawn to the cause of the problem so that control measures may be appropriately targeted.As in a court of justice,if you are the cause of a problem,then you are the guilty and will have to pay whatever penalty the court prescribes.The terms‘deserti?cation’and‘land degradation’are pejorative.They describe a process that is negative;they imply a perpetrator,the land 4606e4f8941ea76e58fa04fand degradation has routinely been used and abused to identify its so-called‘root causes’(Eskonheimo,2003)or‘immediate causes’(El-Beltagy,2000).The simplistic message is that the guilty have been identi?ed,and there is a person to blame.Searching for the guilty is a familiar occupation of all who seek to pert blame from themselves. Examples might include:scientists who can project themselves as independent arbiters of the state of the planet;decision-makers and politicians who can present themselves as merely reactive to needs;and local professionals who struggle with the dif?culties of working with poor and marginal farmers.Measures to control land degradation have,therefore,tended to focus at the most local of levels and with the practices of land 4606e4f8941ea76e58fa04fand degradation control projects were primarily designed to encourage land users to adopt speci?c conservation measures,selected by professionals and assumed invariably to be bene?cial to land users.As Pagiola(1999,p.23)admits,‘it is fair to say that this approach has failed...adoption of recommended practices was low...seldom did adoption spread spontaneously’.Even when the diagnosis of the cause of degradation is more sophisticated,the solutions designed may have unintended outcomes.Pagiola cites the identi?cation of lack of?nancial resources by farmers in El Salvador to implement soil conservation measures, leading to a subsidised rural credit scheme so that investments in conservation could be made.A follow-up study indicated that farmers were only undertaking conservation measures in order to access subsidised credit, so making conservation a cost of obtaining credit rather than a bene?t of doing so.Under such conditions land degradation control is unsustainable without continuous subsidy.

Only in the last ten to?fteen years has it been acknowledged that the primary drivers of degradation may occur at levels beyond the land user with,for example,the policies that drive land users to have to mine their soil resources in order to survive.This understanding of the political ecology of land degradation owes much to Piers Blaikie’s‘Chain of Explanation for Soil Erosion’(Blaikie,1989),which presents causes of erosion at levels from the practices of the land user,right through to the nature of the state and international relations.A typical example is a land user who is forced to farm steep slopes because his productive land is now taken by a hydro-electric power project?nanced by international donors.Who is to blame?The land user?Local and national government? Development aid donors?There is no simple answer.The message in global context is that land degradation has Copyright#2005John Wiley&Sons,4606e4f8941ea76e58fa04faND DEGRADATION&DEVELOPMENT,16:99–112(2005)

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become increasingly politicized and various‘actors’may play a game of blame(Stocking,1995).Usually it is the weakest—local land users—who get labelled as the perpetrators.A super?cial analysis of Table II is commonly used to denigrate pastoralists,forest dwellers and peasant farmers,for example.In global context,the lesson is that land degradation cannot just be seen as a local problem.Global–local linkages pervade,and without attention being paid to controlling the drivers of change—including those not directly related to land degradation—at multiple levels up to the global,there is no possibility that land users can or will alter their behaviour.

LAND DEGRADATION CONTROL AT GLOBAL LEVEL

The United Nations Convention to Combat Deserti?cation(UNCCD)is the main global agreement to address land degradation and the problems that it brings for poor developing countries,with an especial emphasis on Africa.Its origins can be traced back to the1977United Nations Conference on Deserti?cation,which adopted a Plan of Action to Combat Deserti?cation.The Plan was ineffective and largely ignored,having little backing from either developed or developing countries,and even less from potential donors.Therefore,the United Nations Environment Programme(UNEP)set in train a global consultation to ensure that land degradation would be included in the next major environmental conference along with mechanisms for?nancing

Originally launched at the Rio Earth Summit in1992,the UNCCD only became effective in December1996, once50signatory countries had rati?ed the convention.It was not only in formal rati?cation that UNCCD lagged, it was also in access to funds.A Global Mechanism(GM)was established,aimed at improving management, mobilization and coordination of funds for controlling land degradation.Developed-country parties to the Convention were to commit themselves to providing assistance to developing-country parties to implement National Action Plans,to provide?nancing,and to mobilize new resources(Pagiola,1999).But very little of this support materialized and the GM limped on,with the reputation in some quarters as an ineffective lobbiest and beggar among the environmental conventions.The UNCCD was,therefore,the laggard among the three global environmental conventions at Rio,and remained so until at least2002.Even since the Beijing Second GEF Assembly in October2002,when US$250million was immediately pledged to support the new focal area of land degradation in the GEF,the promised doubling of allocated funds has not materialized.Prejudice against the global institutions tasked with land degradation runs deep among the donor countries.

An analysis of why land degradation issues should have been so retarded is beyond the scope of this paper. However,any discussion would have to include a failure by the proposers of the convention to learn the lessons described earlier in this paper and the high degree of politicization of the deserti?cation debate by the main institutions responsible for its promotion(Thomas and Middleton,1994).Certainly,between1992and2002,there was considerable scepticism that the UNCCD was viable and committed to broad measures to combat land degradation,rather than political advantage of members of its secretariat and a grouping of mainly African countries seeking to use the Convention to leverage money from reluctant donors.Although that decade of suspicion has largely passed,the UNCCD is still the poor cousin alongside the UN Framework Convention for Climate Change(UNFCC)and the Convention on Biological Diversity(CBD).These last two,although not without their problems with inpidual countries,have been seen as far more effective in promoting their mandate to the international community.It is dif?cult to foresee the situation changing at a global level,until or unless the case is made strongly enough that land degradation control can bring global bene?ts.At the latest count,191 countries have either rati?ed the convention or agreed to its accession,the latest being the Democratic Republic of Korea in April2004.

Parties to the Convention commit themselves to adopting an integrated approach to addressing the physical, biological and socioeconomic aspects of land degradation,with countries obligating themselves to linking control measures to poverty eradication.Reinforced at the World Summit on Sustainable Development at Johannesburg in 2004,land degradation control is seen formally as part of the drive to achieving global development goals of eradicating poverty and achieving sustainable environments.For example,the United Kingdom states in its latest report to the UNCCD(DFID,2004,p.4)that,‘the means of addressing issues surrounding deserti?cation and land degradation are best assimilated within the broader contexts of development plans and 4606e4f8941ea76e58fa04fabating land Copyright#2005John Wiley&Sons,4606e4f8941ea76e58fa04faND DEGRADATION&DEVELOPMENT,16:99–112(2005)

LAND DEGRADATION CONTROL:GLOBAL BENEFITS105 deserti?cation is challenging and requires an interdisciplinary and crosscutting approach that is long-term and sustained’.In part,that is an implied criticism of the operation of the Convention by its secretariat,and in part it is the wish not to fund another institution tasked with bringing bene?ts to Africa through what appears to be purely technical solutions.

The emerging questions at global level that arise from this brief history of global interaction with land degradation control are:

*How can‘land degradation control’itself be rehabilitated as a topic,the funding of which will bring gains for both the global and local environments as well for local people?This is what is given as the task for the UNCCD,although it has singularly failed to attract a reputation for good and effective leadership within this responsibility.

*How far can synergies be explored between those topics with clear links to global environmental change—biopersity and climate change—and with land degradation control,which realistically in the end must rely on local actions by local people?There are some who argue(anecdotally)that land degradation is manifestly a global concern by itself.If not controlled it would lead not only to con?icts and wars over access to land resources,but also it would diminish the global stock of natural capital.

*How far is land degradation control a viable and useful way of proceeding with the major developmental goals, such as food security,eradication of poverty and promotion of livelihoods and well-being?Intuitively,the environmental and developmental goals are inseparable,but can they be grasped practically,or should attention merely revert to measures to promote development with the expectation that environmental problems will correct themselves?

A full exploration of these issues is beyond this paper.However,if it can be shown that land degradation is so interlinked with other global concerns,any failure to control it would almost certainly jeopardize less controversial issues(e.g.climate change),then a case could be made for land degradation control being a global bene?t and worth pursuing.In addition,if the interlinkages are all pervasive,a case could also be made that land degradation control should be tackled through biopersity and climate change goals to equal or better effect than tackling it directly.

EXPLORING THE SYNERGIES

Through the UNCCD and the GEF,it is now becoming increasingly understood that linkages exist between all three original global environmental change components determined back in1992at the Rio Earth Summit—biopersity,climate change and land degradation.If one component changes,the other two are also bound to change,usually in unison and in the same direction,positively or negatively.This is,of course,nothing new for ecology,which is the biological science of the relations between organisms.However,this understanding is a major step forward in justifying land degradation control as a legitimate global change topic rather than a solely local or domestic topic.It leads the way to justifying land degradation control as an entry point or lever to addressing practical issues of climate change control and protection of biopersity through local measures,such as soil conservation,restoration of land productivity and reafforestation.It leads also to a conclusion that land degradation control might be better pursued as part of poverty alleviation and food security programmes,or of biopersity conservation and climate change control projects,all of which have far better resonance in the international community and greater likelihood of funding and acceptance.

In the jargon of global environmental change,these linkages are called‘synergies’,suggesting that the combined global effect is greater than the sum of the inpidual global change effects.A focus on linkages is therefore essential.Interlinkages and the so-called‘drivers of change’are fundamental in understanding how approaches to land degradation control may be designed and implemented(Berry and Olson,2001).Again,taking the three original global environmental change components,there are six possible permutations of synergetic effects,all of which to one degree or another have been identi?ed as operative.The following are recently published examples to illustrate how synergies may occur and their degree of importance:

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(1)Land degradation on climate change

Land-surface properties and the way they change in response to land degradation are the primary means whereby climate change may occur.A study by Dirmeyer and Shukla(1996)used an atmospheric general circulation model to investigate the climatic effect of doubling the extent of the world’s deserts.Climatic response was not uniform, but parts of the globe especially affected include northern Africa with a far longer year-round drought.Soils subject to land degradation tend to become lighter in colour and more erodible.The driver of change appears to be the decrease in surface temperatures over most deserti?ed areas because of reduced absorption of short-wave radiation by the brighter surface.Additionally,carbon in soils is depleted,for which the links with climate change are well established(Schlesinger,1991).

(2)Land degradation on biopersity

Processes of land degradation not only make soils lighter in colour because of selective removal of organic matter and colloids,they also reduce the biological life,or soil biopersity.Soil erosion reduces productivity(Stocking,2003), and productivity is closely related to biological processes dependent on both the variety and number of above-ground and below-ground living organisms(Stocking,1987).Further,a degraded soil is less able to support vegetation biomass and the environmental conditions that would allow support of many sensitive and vulnerable species.So,the loss of habitat through land degradation in,for example,the conversion of forest lands to grassland results in the local extinction of plant and animal species(Sala et al.,2000).Conversely,sustainable land use and forestry are increasingly being?nanced as one legitimate way to enhance what is called‘collateral biopersity’(Koziell,2002)or the unplanned but deliberate increase in biopersity through actions other than those directly related to species. (3)Climate change on biopersity

Climate change is predicted to have a major impact on biopersity on a global scale(IPCC,2001).Some ecosystems could disappear,while others will be changed drastically,and the goods and services derived will be severely affected.Most work on this linkage comes from marine ecosystems and the study of changes in ocean temperatures that have occurred already.Coral reef bleaching may be a consequence of recent rises in global ocean temperatures(Goreau et al.,2000).Elsewhere,temperature decreases have been shown to cause physico-chemical changes,altering the abundance of nematodes and increasing deep sea biopersity(Danovaro et al.,2004).In terrestrial ecosystems,Midgley et al.(2003)estimate that in the Cape Floristic Region most species(17out of28 studied)will suffer contraction in their range with predicted climate change,while the remaining eleven will show range expansions.Speci?c impacts will be complex and not all will be negative.Nevertheless,most authors conclude that?ora and fauna are highly vulnerable to even very small changes in temperature and that the consequences of climate change will have potentially large-scale impacts that are almost impossible to predict.

(4)Climate change on land degradation

It is primarily through changes in rainfall patterns and in biomass production that climate change will affect land degradation.The erosivities of climates change with changes in total rainfall,such that raindrop sizes and the intensity of storms is generally greatest in the range500to750mm mean annual rainfall,this being the zone where rainfall is suf?cient to cause several severe thunderstorms but is insuf?cient to give a good vegetation cover. Sediment yields in single events in deserts can sometimes be huge(e.g.the Namib:Marker,1977),and in some climate-change scenarios such conditions are predicted to increase.A survey of the potential impact of future climate change in South Africa concludes that the currently most severely degraded parts of the country are likely to become even more susceptible(Meadows and Hoffman,2003).

(5)Biopersity on climate change

Land-use change is the principal way that biopersity is reduced,and this may impact regional and global climates through surface-energy budgets as well as through the carbon cycle(Pielke et al.,2002).Land change has an increasingly signi?cant role on climate change through such effects as El Nin?o events(Wu and Newell,1998) and the changing incidence of thunderstorms(Lyons,1999).Tropical deforestation is undoubtedly the major process translating loss in biopersity to effects on climate(O’Brien,2000).

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(6)Biopersity on land degradation

Changes in land use that alter biopersity similarly impact land degradation.Shifting cultivation is often identi?ed as a major driver in tropical forests that causes an overall diminution of the productive potential of the land.In the Chittagong Hills of Bangladesh,for example,Gafur et al.(2003)used paired catchments to examine the effect of clearing and cultivation with long-term fallow and mixed perennial vegetation.Each had signi?cantly different induced levels of biopersity consequent on change in land use.Soil losses in the year of cultivation were over six-times higher than in the other land stages and uses.Such empirical?ndings are well known in all climates:as vegetation cover diminishes,soil losses increase exponentially.The synergy here between biopersity and land degradation is,however,indirect—it is not the biopersity change that affects the land degradation,it is the consequence of a third factor,land-use change,that induces the degradation.

For the three Rio conventions,the many links between biopersity protection,mitigation of climate change and control of land degradation offer complementarities that are only now starting to be grasped in the implementation of the conventions(UNDP,2002).Inpidual assessments of biopersity(by UNEP,1995),climate change(by IPCC, 2001)and land degradation(by FAO,2003)have established the complexity of the links at global level.The linkages have also been recognized in the Millennium Ecosystem Assessment to be published in2005(see Figure1).One of

108G.GISLADOTTIR AND M.STOCKING

the most pervasive of the complex links is that derived from widespread deforestation.This converts forest into carbon dioxide,reduces the vegetative cover for CO2storage and reduces the water-holding capacity of the soil thereby inducing land degradation.This may,in turn,lead to changing weather patterns.So,it is argued by UNDP(2002),a programme for sustainable management of the land including forests and agriculture,as provided for in Operational Program15of the GEF(2003),will limit global warming and conserve some biopersity.

In turn,changes in weather patterns and climate affect natural forests,which are the most important sources of biological persity.They will change grasslands especially in semiarid zones,affecting wildlife and some of the most vulnerable human societies.Global warming will drive sea-level rise,and changing ocean currents will affect ?sh and marine life.On land the increased surface temperatures could result in reduced vegetation cover,which will affect soil biopersity through enhanced exposure to higher temperatures.Since soils are the main terrestrial pool of carbon,?xing of carbon(or sequestration)is the single best option for limiting atmospheric CO2 concentration and mitigating climate change(Watson et al.,2000).Again,sustainable management of land,or land degradation control,could be the primary buffer for society to utilize against the drivers of climate change and altered weather patterns.

Through synergistic effects,the case for land degradation control as the principal practical means of delivering global bene?ts in biopersity and climate change is compelling.Even though,as noted above,the UNCCD,is the weakest of the three conventions,the two other conventions,the CBD and UNFCC,recognize in their literature the importance of cooperation and the planning of programmes to exploit these linkages and synergies.The translation of the rhetoric into reality has,however,been slow.The GEF Land Degradation Linkage Study(Berry and Olson, 2001)found signi?cant barriers to building land degradation as a critical component of the global environmental change agenda and few GEF projects in the biopersity and even fewer in the climate change focal areas addressed land degradation unless it was speci?cally identi?ed at the outset.The study concluded that GEF projects with a strong land degradation component are fewer than previously thought.Not surprisingly,the UNCCD plays the joint programme approach more strongly than the other conventions,particularly in research, training,observation and information collection and exchange(UNDP,2002).However,its access to GEF funds only after2002and the imperfections of its other funding agency,the Global Mechanism,have meant that the linkages have rarely been exploited.Indeed,land degradation control has been primarily articulated as control of deserti?cation,which still continues today,and probably explains why the goals of the UNCCD are most unlikely to be met at global level.

CONCEPTUALIZING THE LINKAGES FOR LAND DEGRADATION CONTROL

To counter the pessimistic conclusion derived above that the global objective of land degradation control is unlikely to be achieved by the current focus solely on the processes of land degradation,two major initiatives have been instituted in order to conceptualize the linkages between global change components and introduce them as working models for land degradation assessment and then control.The?rst is the‘Feedback Loops’model developed by the Millennium Ecosystem Assessment(MA,2004).This is essentially a schematic way of presenting the linkages to highlight how the major components are linked.So,for example,biopersity loss, expressed in the loss of plant species persity reduces overall primary production,thus impairing the carbon sink function.Reduced carbon sequestration driven by biopersity loss,along with increased carbon dioxide emissions driven by soil erosion increases the atmospheric concentration of carbon dioxide,which then functions as a greenhouse gas causing global atmospheric temperatures to rise.Figure1presents a model of the main linkages and threats to ecosystem services driven by any change in one of the major global environmental components.It helps to demonstrate the multiple points of potential intervention for land degradation control.Soil conservation may be the most immediate,but equally effective could be measures to stem biopersity loss,such as increased water use ef?ciency,and maintenance of the soil carbon reserve.

The second model is more truly conceptual in embracing the process and factor linkages of environmental functions.The DPSIR(Driving Force,Pressure,State,Impact,Response)model,the prototype for which was Copyright#2005John Wiley&Sons,4606e4f8941ea76e58fa04faND DEGRADATION&DEVELOPMENT,16:99–112(2005)

developed for the OECD (1993),has been adopted as a policy tool to identify management options for a range of types of environmental problem.It captures the driving forces and pressures—largely controlled by human activity—and their effects on the environmental system and state of natural resources (Figure 2).For land degradation assessment and the identi?cation of ways of control,the impacts and societal responses are especially important,enabling the assessment process to feed directly into measures for control of land degradation.The model has been adopted by the new multi-national Land Degradation Assessment in Drylands project of the FAO,GEF and UNEP (FAO,2003)to identify suitable entry points for assessing the seriousness of degradation and for identifying potential points of intervention.

CONCLUSION

Concern for the extent and seriousness of land degradation is reassuming its rightful place within the international community since the Second Global Environment Facility Assembly in Beijing in 4606e4f8941ea76e58fa04fand degradation does,indeed,have serious consequences for the world’s drylands and for some of the most marginal and poverty-stricken societies globally.It is,however,largely a local problem,suggesting local solutions,such as better soil conservation and attention to local policies.It is not immediately a global concern,even though attention to it is mandated by the United Nations Convention to Combat Deserti?cation.A different approach to land degradation control might dwell on how it poses major threats for the other two main global environmental change components,biopersity and climate

change.

Figure 2.The DPSIR (Driving Force,Pressure,State,Impacts,Response)Conceptual Framework applied to potential land degradation control

interventions.

LAND DEGRADATION CONTROL:GLOBAL BENEFITS 109

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The legacy of hyperbole and misuse of messages as to the seriousness of land degradation is now thankfully being forgotten as a new generation of projects on the assessment of land degradation is being initiated and new models,such as the DPSIR framework,are being employed in place of the simplistic technical approaches of the past.The initial US$250million allocated to land degradation in Operational Program15of the GEF is being used to tackle land degradation in innovative ways often through primary attention to developmental constraints,such as poor governance,food insecurity and poverty,but also linked to protecting biopersity and controlling climate change.However,it remains a technical challenge as to how land degradation control might be addressed more directly and effectively.

In order to translate concern for land degradation into appropriate policy and technical responses,a new approach is needed that focuses on the synergies and interlinkages with the other global environmental change components.Not only is an approach to land degradation control through attention to biopersity and climate change likely to be more acceptable to the international donor community,but also it will provide a stronger,more ecologically sound way of addressing the complex linkages between issues that have acknowledged global importance.Additionally,the rhetoric of the biopersity and climate change lobbies that their measures will address land degradation and promote sustainable land management needs to be translated into real projects and programmes that utilize the synergies between all global environmental change 4606e4f8941ea76e58fa04fand degradation control has major global bene?ts,not just to counter land degradation but to initiate a new generation of projects that promote sustainable land management as the vehicle to a future with conservation of biopersity,control of climate change and prevention of land degradation simultaneously achieved.

acknowledgements

We acknowledge the following for their support for our work:the IGU Commission on Land Degradation,which hosted a conference in Iceland at which an early version of this paper was given in oral form;the United Nations University,which has sponsored some of our work through the project on People,Land Management and Environmental Change(PLEC),1996–2002;The United Nations Environment Programme,the UN Food and Agriculture Organization and the Global Environment Facility,through the project Land Degradation Assessment in Drylands;the University of Iceland.

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