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Do Humans Cause Deserts?J.F. REYNOLDS1 and D.M. STAFFORD SMITH2

1 Department of Biology and Division of Environmental Science and Policy,

Nicholas School of the Environment and Earth Sciences,Duke University, Durham, NC 27708, U.S.A.2CSIRO Sustainable Ecosystems, Alice Springs, NT 0871, Australia

ABSTRACT

Desertification the creation of a desert, perhaps by humans is a highly contentious issue.

Arguments surrounding this topic create confusion in policy and management programs intended to

help many of the worlds poorest people. While climate is obviously a controlling influence on deserts,which occur naturally in dry areas, it is equally certain that humans and their agriculture and ranching

practices have caused desertification in some places. However, there remains a great deal of

disagreement about the causes and extent of desertification and, consequently, about what part of itsimpact on human well-being is manageable and how. There is an urgent need fornew, interdisciplinary

approaches for addressing this global problem. We suggest that a new synthetic framework must bedevelopedbased on theuniqueandsimultaneousroles of themeteorological andecological dimensions

of desertification (the biophysical factors) and the human dimensions of desertification (the

socioeconomic factors). Previous failures to recognize and include the interdependencies of these

dimensions in decision-makinghave slowedprogress toward the syntheticapproaches needed to tackle

the enormous problem of dryland degradation.

INTRODUCTION

Desertification is a term that has long been associated with land degradation in drylands,

which cover 40% of the land surface of the globe (Table 1.1) and are home to about a fifth of

theworlds human population. Large areas of these drylands (inAsia, theMediterranean, Af-

rica, Oceania, and the Americas) are considered to be experiencing differing degrees of de-

sertification (Dean et al. 1995; Hoffman et al. 1995; Kassas 1995a; Le Hourou 1996;

Mortimore 1998;Mouat andMcGinty 1998). Desertificationis presumed to result in a reduc-

tion in the biological and, hence, economic potential of the land to support human popula-

tions, livestock, and wild herbivores. However, others vigorously contest such an

interpretation (e.g., see Leach and Mearns 1996). What are the roots of this controversy?

To answer this question, we must first define what is meant by land degradation. Whilethis is a term most often equated with soil degradation, it is a more general phenomenon that

Global Desertification: Do Humans Cause Deserts?Edited by J.F. Reynolds and D.M. Stafford Smith 2002 Dahlem University PressISBN 3-934504-10-8 To order book, contact: [email protected]


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involves wholeecosystems. TheUnited Nations (UN) Convention toCombatDesertification

(CCD) (UN 1994) defines it as the reduction or loss of the biological and economic produc-tivity and complexity of terrestrial ecosystems, including soils, vegetation, other biota, and

theecological, biogeochemical, and hydrological processes that operate therein. In drylands,this includessoil erosion andsedimentation byboth water andwind, often resulting in a redis-

tribution of topsoil, soil compaction, dune formation, and gully formation. However, there

may also be shifts in natural fire cycles, disruption of biogeochemical cycling, including the

redistribution of essential nutrients, decreased efficiency of nutrient cycling, and increased

nutrient losses from the system. Native perennialplants (coverandbiomass), andmany asso-

ciatedmicrobialandanimalpopulations, maybe reduced whileexotic, andusually less desir-

able, plant species may increase in dominance.

The controversy centers on the causes and consequencesof land degradation. The prob-

lem is twofold:

First, whereas desertification is most often attributed to a myriad of human activities,

particularly overgrazing, it may be triggered or exacerbated by climate variability,

mainly drought, so that the causes are not necessarily or solely anthropogenic (at least

at the local land-use level); and,

Second, not all such ecological, biogeochemical, and hydrological changes have an

immediate or direct economic impact on human activities.

In spiteofmuch international effort toaddress this problem (UNEP1991,1994),many uncer-

tainties and misconceptions exist.

The extensive literature on what constitutes desertification and land degradation, and its

causes and consequences has developed many well-meaning but conflicting definitionsthat only serve to confuse. The most authoritative definition of desertification at present is

that applied by the CCD: land degradation in arid, semi-arid and dry subhumid areas result-

ing from various factors, including climatic variations and human activities. This explicitly

focuses desertification on the linkages between humans and their environments that affect

human welfare in arid and semi-arid regions. However, this definition does not lend itself to

easy quantification andrequires elaboration to elucidate thediscussion that weaimto synthe-

size here. The problem is that humans are often concerned only with that subset of this broad

definition of desertification that impacts on human activity whether at the local land-use

level or through feedbacks at a wider scale. Further, it is important to identify another subset

that is causedby human activity, since this often requires different forms of intervention. Forexample, farmers inmany regions of the world are generally onlyprepared to accept that they

may need to change their management if land degradation is a direct consequence of their ac-

tivities and/or it directly impacts them (or other members of society).

The meanings and interpretations of all issues in desertification are affected by the scale

and purpose of concern. Additionally, the causal factors involved in land degradation have

differing levels of influence in different regions of the world and at different times (Stafford

Smith and Pickup1993).Afailure to recognize thishas led tomanydisagreements about a va-

riety of issues that include the causes and processes of land degradation and its importance,

theextent to which land changes are natural (climate-driven) vs. anthropogenic, the role of

abatementefforts aimed at socialandinstitutional vs.scientific andtechnological issues, how

Do Humans Cause Deserts? 3


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4 J.F. Reynolds and D.M. Stafford Smith

General Issues

Is desertificationa process (i.e., a phenomenon characterized by recognizablechanges that eventu-

ally lead toward some final end point)? Or, is desertification a state (i.e., the condition of the land

produced as a result of land degradation)?

What precisely is land degradation (decline in vegetation, soil erosion, loss of economic value,

etc.)? Are there consistent, unambiguous methods to quantify land degradation? Does land degra-

dation in Botwana have the same meaning as in Argentina? Is land degradation reversible?

Under what circumstances does land degradation reallymatter? Howdo different stakeholders de-

termine when land degradation matters to them?

What are the underlying causes of land degradation in drylands? For example, what is the relativeimportance of natural (e.g., climate-driven) vs. human-made (e.g., overgrazing by domestic ani-

mals, land practices) processes?

Globally, what is the amount of dryland affected or at risk? How can this be determined? Are there

indicators of land degradation? If so, are these indices functionally relevant at one scale, while los-

ing their meaning when extrapolated to larger spatial areas?

Meteorological Dimensions

Will changes in surface energy and water balance caused by changes in land cover significantly af-

fect vegetation?

Can changes in near surface climate caused by land degradation be translated into a recognizable

contribution to global scale changes, that is, a desertification warming signal? Do biogeophysical feedback-based climate models contain sufficient mechanisms to predict

droughts accurately? What is the relationship between the loss of vegetation, albedo, surfaceroughness, and drought?

Willglobalclimate changeexacerbate the high natural variability of precipitation and temperature

in drylands?

Ecological Dimensions

Areshort-term ecosystemdynamics(e.g.,decreasesinplantcover) indicative ofdesertification?

Dolong-termchanges indryland ecosystems alter theresource base of theentiresystemsuch that it

moves beyonda thresholdwhereby degradationaccelerates andbecomes irreversible?Domultiplethresholds exist?

How do the key physical drivers influence other factors such as animal disease carriers, e.g., how

do temperature and drought affect insect behavior? When is animal production a function of rain-

fall (plant production) and when is it decoupled?

If global climate change further exacerbates the already high natural variability of precipitation in

dryland ecosystems, will this lead to permanent degradation of their productive potential, particu-

larly since there is a lack of buffering by large reserves of organic matter in the soils or in woody

vegetation?

Can early warning functional indices (based on soils, vegetation, biota, and ecological,

biogeochemical, and hydrological processes) be developed to indicate major physical restructur-ing of a system symptomatic of land degradation?

Table 1.2 Historically, desertificationhas been a contentious issue involvingecological, meteoro-logical, and the human dimensions of the problem but usually in isolation from each other. Some ofthe major issues of the debate are summarized here.


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to determine the amount of land affected or at risk, and whether or not desertification is re-

versible (Table 1.2).

We believe that there is a pressing need for new and creative interdisciplinary approaches

for addressing the global problem of desertification, as well as for new thinking beyond re-

gional and disciplinary concerns. We suggest that the only way to resolve the labyrinth of is-

sues, disagreements, and misinterpretations surrounding desertification is to create a new

synthetic framework. In the absence of a framework, the answers to most questions are: It

depends! This leads to endless and unproductive debates, which have been one of the lega-

cies of desertification research, resulting in undesirable impacts on policy and on the pro-

grams intendedtohelp people livingin these lands.In this chapter, weprovide backgroundon

why desertification is considered a contentious issue, identify some key questions that must

be resolved, and suggest some initial ideas for developing a new, synthetic paradigm for this

important global problem.

BACKGROUND

Thealarmist tone connoted by theword desertificationcreates thepicture of deserts mov-

ing across the landscape, engulfing fertile lands and leaving starving people in their wake.Such images have their roots in a series of papers written by Stebbing in the 1930s, who used


Human Dimensions

How do human populations in the various natural, semi-natural, and intensively managed drylandecosystems of the globe affect those ecosystem goods and services considered vital to the

sustainability of human populations? Should land degradation be defined in terms of loss of key

ecosystem goods and services?

What are the key socioeconomic drivers of land use that lead to desertification? For example, is

there a relationship between how land is used (accountability) and ownership (which tends to be

low in poor countries and high in rich ones)?

Are regional and national programs to combat desertification based on economic integration and

sustainability of local people who are most directly affected? How can local people be integratedinto the decision-making process? Is the stakeholder concept a feasible one at all scales of inter-

est? Is it possible to reconcile thedifferentviewpoints of different stakeholders in relation to deser-

tification issues?

What are the respective roles of government, local communities, and land users in maintaining

sustainability of drylands? Do ecologically sound land-use practices lie at the level of recognizingthe rights and environmental knowledge of local communities? What resources are needed to ac-

complish this?

What is theresponse of human activities to different stagesof land degradation?Arethere adaptive

adjustments?

What is the role of technology in providing new opportunities for ecological sustainability indrylands of the globe?

Table 1.2 continued


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DIMENSIONS OF DESERTIFICATION

The first step in developing a synthetic framework is to recognize that the nature and struc-

ture of such a framework can be best explored via the recognition and the simultaneous

consideration of the unique roles of the meteorological and ecological dimensions of de-sertification (collectively, the biophysical factors) and the human dimensions of


HEADLINE SOURCE DATE

Droughts, Deserts and Death Nassau Guardian May 13, 1985

Threat of Encroaching Deserts May Be More

Myth than Fact

New York Times Jan.18, 1994

Orchard of Spain Crumbles into Dust: Drought,

tourism and intensive cultivation all helped to

transform lush farmland into a desert in

just 20 years

Guardian of London May 25, 2000

Desertification Threatens Half of TanzaniasLand

Africa Newswire Network July12, 2000

Beijings Desert Storm: The desert is sweeping

into Chinas valleys, choking rivers and

consuming precious farm land

Asiaweek Oct. 13, 2000

FarmingPasturing Area Faces Rapid

Desertification

Xinhua News Agency

(China)

Aug. 22, 2000

Sahara Jumps Mediterranean into Europe Guardian of London Dec. 20, 2000

The Arid Expansion Guardian of London Jan. 11, 2001

Expanding Desert An Urgent Problem China Daily June 30, 2001

A Harvest of Bounty and Woe: Experts estimate

that 20 percent of Spain is turning into a desert

The Christian Science

Monitor

Aug. 22, 2001

30 Per Cent of the Land Surface Is Threatened

by Desertification

Narodnoye Slovo

(Uzbekistan)

June 16, 2001

Boom in Hothouse Farming Yields More

Desert in Spain

International Herald

Tribune

Apr. 4, 2002

Human Activity Turns China into Desert Australian Broadcasting

Corporation Online

Jan. 29, 2002

Dust Storms May Add to U.S. Pollution:Increasing desertification that began in Africa

in the early 1970s, and more recently in parts

of China, is intensifying the giant dust storms

The Herald-Sun(Durham, NC)

Apr. 6, 2002

Table 1.3 Droughts, Deserts and Death: Headlines in the popular press illustrate the high visibility(and often melodramatic) interest in desertification.


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desertification (thesocioeconomic factors) (Figure 1.1). This will not be easy: these dimen-

sions arecomplex, multi-scaled, difficult to predict, and highly interdependent. Anewdeser-

tification paradigm should identify when and how the different dimensions of desertification

matter, to enablescientists andpolicymakers to extrapolate results from studies in onearea to

other regions, as well as to provide a basis for a global classification of drivers and responses,

and their consequent geographic distributions. Importantly, we believe that previous failures

to recognize and include the interdependencies of these dimensions in decision-makinghave

slowed progress in developing thesynthetic approaches needed to tackle theenormous prob-

lem of dryland degradation. In this section, we briefly review each of these dimensions,building on some of the questions raised in Table 1.2.


Figure 1.1 Land degradation in drylands involves complex interactions between biophysicalfactors(the meteorological and ecological dimensions of desertification) andsocioeconomic factors (the hu-mandimensions ofdesertification. Past failures to recognizetheuniquerole ofeach of these dimensionsand their interactions across various spatial and temporal scales ranging from thehousehold to inter-

national hasledto misconceptions andcontroversies about theconcept. BasedonReynolds (2001).


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Meteorological Dimensions

Drylands are particularly vulnerable to climate variability, of which precipitation is the most

important component; temperature, humidity, or wind can, however, be important in some

places. For example, a slight shift in seasonal precipitation and/or frequency of extreme rainevents can lead to the overexploitation of the meager natural resources of drylands and con-

tribute to thefurther degradation of thevery resourcebase on whichhumanpopulations areso

dependent. Recently, communally owned Mexican rangelands were authorized to begin pri-

vatization in hopes of improving resource conditions and productivity; yet, a subsequent fol-

low-up analysis showed no differences between private and communal tenure systems:

annualprecipitation wasthemost important factor related to rangelandconditions (Coronado

1998). As Williams andBalling (1996)report, in recentyears substantial improvementshave

been made in our understanding of the causes of interannual variability in drylands climates,

including the natural causes of droughts. Variations in annual precipitation levels are interre-

lated with the natural variations within global-scale climate systems. However, great uncer-

tainties remain and the relationship between desertification and climate resembles the

proverbial chicken and eggproblem. The array of impacts of climate on land and the impli-

cations of degraded land surface forthe climate systemarevariedandcomplex.Human activ-

ities impact surface characteristics and atmospheric composition of various dryland regions,

including the breakdown of soil structure, reduction in soil moisture retention, increased sur-

face runoff, reduction in species diversity, increase in aerosol and trace gas emissions from

burning, etc.

Ecological Dimensions

Drylands areusually subdivided into threedominant typesof human land-use categories: irri-

gated agricultural cropland, rainfed agricultural cropland, and rangelands. Hence, from the

point of view of agricultural land use, the overwhelming majority of drylands are rangelands

(88%) and only 3% are irrigated croplands and 9% rainfed cropland (UNEP 1997). The natu-

ral vegetation of rangelands is usually composed of various mixtures of grasslands,

shrublands, and savannas, with trees either scattered or concentrated along watercourses.

Sincevegetation cover is usually relatively sparse, much of the soil is exposed directly to rain,

overland flow, sunlight,andwind. Drylands have a numberofdistinguishingecological char-

acteristics that contribute to their susceptibility to disturbance and, ultimately, to desertifica-tion (OIES 1991). Many soils are sensitive to disturbances because they contain only small

amounts of organic matter and have low aggregate strength. Both tillage and grazing by do-

mesticated animals can have profound effects in a very short period of time on these

soils, including lowering their permeability to water (thus decreasing infiltration), disturbing

their surface integrity (thus increasing susceptibility to erosion and sedimentation), and de-

creasing their quality (decreased nutrient status) for plant growth.

Since nearly all drylands are characterized by extreme year-to-year weather fluctuations,

it is often difficult to distinguish between short-term variability and long-term changes in

ecosystem appearance, as well as between temporary and permanent changes. Short-term

variability in precipitation tends to affect the range and frequency of shocks, whereaslong-term change alters the resource base, that is, the entire system moves beyond some



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threshold. Once this threshold has been exceeded, the vegetation changes may or may not be

reversible, depending on the interactions of numerous climatic, edaphic, and biological fac-

tors in combination with the economic feasibility of rehabilitation.

Human Dimensions

Rapidly changing social and economic conditions along with the potential for climate

change pose serious challenges to many drylands regions of the world. Globally, there are

differences in socioeconomic factors (e.g., human population growth rates) and

biogeography (e.g.,natural vegetation) that play a large role of thetype of major human activ-

ities in any given area (Kassas 1995b; Mainguet 1991; Mainguet and Letolle 1998). More-

over, therearedifferences in howhuman interference is affecting biodiversityandecosystem

functioning in poor andricher countries (Lopez-Ocaa 1996). Key ecosystemgoods and ser-

vices (e.g., food, construction materials, water purification, flood control, climate regula-tions, soil maintenance, carbon sequestration, nutrient recycling, wildlife habitat, erosion

control, tourism/ recreation) are being seriously affected (Hutchinson 1996; Sherbrooke and

Paylore 1973).

To understand the human dimensions of desertification, it is important to compare and

contrast different regions of the world to seek generalities (Stafford Smith and Pickup 1993;

Thomas 1997). As new economic policies are adopted, many pastoral and drylands farmers

are marginalized and end up moving to urban areas; social and economic conditions are rap-

idly changing, e.g., the rise of tourism, intensification of high-tech agriculture, and the shift-

ing of populations to urban environments (Thornes 1995). Often, such changes result in the

abandonment of land for traditional agriculture and the rise in demand for water for urban ex-pansion, tourism, and irrigation, resulting in increased land-use conflicts.

CONCEPTUAL MODEL OF DESERTIFICATION

Over a hundred formal definitions of desertification have been proposed. Not surprisingly,

these cover a breadth of topics, many spatial and temporal scales of interest, and represent

disparateviewpoints. Ingeneral, the various definitions differ in their emphasis on the meteo-

rological, ecological, and human dimensions of the problem (Table 1.4).

Rather than propose yet another definition, here we attempt to tackle the misunderstand-ings and/or differing interpretations of (a) what is actually meantby land degradation and (b)

the differing reasons why people or organizations may or may not be concerned with it. As a

starting point fordiscussion,were-emphasize, as notedabove, that most debates about deser-

tification revolve vaguely around changes in the structure and functioning of local or re-

gional agro-ecosystems that:

1. may or may not be causedby human activity,

2. when in fact are caused by human activity, have causes that may be eitherlocal(e.g.,

clearing of land) orglobal(e.g., institutional causes like tradeagreements, or biophys-

ical causes like climate change), and,

3. regardless of the cause, may or may not have an impact on human activities at thesedifferent scales.



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Human Dimensions

Meteorological Aspects

Definition Ecological Aspects Reference

... the spread of desert-like conditions in arid or semi-arid areas due to

mans influence or to climate change Rapp

(1974)

... diminution or destruction of the biological potential of the land

(that) can lead ultimately to desert-like conditions. It is an aspect of

the widespread deterioration of ecosystems, and has diminished ordestroyed the biological potential, i.e., plant and animal production,

for multiple use purposes at a time when increased productivity isneeded to support growing populations in quest of development

UNEP

(1977)

... an aspect of the widespread deterioration of ecosystems under the

combined pressure of adverse and fluctuating climate and excessiveexploitation

UNCOD

(1978)

... the process of environmental degradation in non-sandy areas where

the fragile ecology is disturbed by excessive human activities Zha and

Gao (1997)

... the impoverishment of terrestrial ecosystems under the impact of

man...the process of deterioration ... that can be measured by reducedproductivity of desirable plants, undesirable alterations in the biomass

and the diversity of the micro and macro fauna and flora, acceleratedsoil deterioration and increased hazards for human occupancy

Dregne

(1985)

... the irreversible, sustained decline of the biological productivity of

arid and semiarid land resulting from pressures caused both by people(e.g., increased population) and by abiotic factors (e.g., variable rain -

fall and long-term climate changes)

Gorse and

Steeds(1987)

Desertification ... is the spread of desert-like conditions of low biolog-

ical productivity due to human impact under climatic variations Helldn

(1991)

lower useful productivity (for humans) Johnson(1977)

... the expansion of desert-like conditions and landscapes to areaswhere they should not occur climatically

Graetz(1991)

... land degradation ... resulting from adverse human impact UNEP

(1997)

Desertification, revealed by drought, is caused by human activities in

which the carrying capacity of land is exceeded; it proceeds by exacer-

bated natural or man-induced mechanisms, and is made manifest by

intricate steps of vegetation and soil deterioration which results, in hu-

man terms, in an irreversible decrease or destruction of the biologicalpotential of the land and its ability to support population

Mainguet

(1991)

... land degradation in arid, semi-arid, and dry subhumid areas result-

ing from various factors, including climatic variations and human

activities

UN (1994)

Table 1.4 Over a hundred definitions ofdesertificationhave been proposed,each emphasizinguniqueissues and (often) particular spatial and temporal scales of interest. Select examples are classified herein terms of the emphasis on the ecological, meteorological, and/or human dimensions of the problem.Modified from Reynolds (2001).


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Land Degradation: A Stakeholders Perspective

We begin with a simple example of desertification or humans creating a desert. Imagine

that we visit a large cattle ranch in central Mexico where herds of cattle are grazing in range-

land that has a large number of erosion gullies. It is tempting to deduce that these gullies arethe result of overgrazing by cattle, which removes the protective vegetative cover, leading to

soil erosion and lost beef productivity. As logical as this may seem and as true as itmay be

in some instances alternative views are possible (Figure 1.2):

1. Some erosion gullies are the result ofnatural phenomena (wind and water).

2. In some landscapes, a modest number of gullies, whether natural or induced by over-

grazing, may have no effecton things that matter for human values (i.e., secondary

productivity or meat production by cattle in this case).

3. Although the erosion gullies may not cause a loss in meat production on this ranch per

se, they may well be creating major salinity problems and production losses down-stream from the ranch.

4. Even if the gullies are the direct result of overgrazing, there is room for debate as to

whether the root cause is deliberate (or unintentional) overstocking by the local ranch

manager, or a fault of the land tenure system, or an indication of a broader institutional

problem (or indeed any combination of these).


Pastoralist = Ive got a load ofgullies forming, but I cant help it as

long as interest rates force me tostock-up!

Farmer downstream = Without thisgully I wouldnt be getting enough

run-off for my millet plot!

Dam manager downstream = Thisgully is part of whats silting up the

citys water supply!

Film-maker = These badlands are

perfect for my next movie set!

Soil scientist = The landscape is

losing water and soil down this gully,which is negatively affecting local

nutrient cycles

Eco-tourist = These gullies

look terrible and Im not coming

here again!

Conservationist = This gully is

symptomatic of the loss ofbiodiversity in this region!

Pastoralist = This gully is naturaland doesnt affect my animals

anyway!

???

Figure 1.2 Vastly different perceptions by stakeholders arising from concerns over erosion gullies.This illustrates how land degradation is a concept truly in the eye of the beholder.


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Obviously, different segments of society will see this problem with differing degrees of

concern and interest. For example, an ecologist would view the erosion gullies on the Mexi-

canranch as an immediate breakdown in ecosystem function, e.g., the ability of the soil to re-

tain water, nutrient cycling, long-term soil stability, and forage production. However, asnoted, such ecosystem breakdowns will resonate with a farmer only if they have a demon-

strable, local impact on animal performance (or perhaps even as a local traffic hazard!). Of

course, broader concerns for appearances or genuine environmentalism may also arise, but a

rational decision maker would not invest in gully control on these grounds alone unless, for

example, they were linked to an environmental accreditation scheme for the ranch. Gullies

could also matter to a local tourist operator who finds that eco-tourists are put off by the ap-

pearance of environmental damage.

Reasons for Caring: Who and Why and at What Scale?

These issues are no mere disputation whether the erosion gullies are considered natural or

not will affect the management response. If there is no local loss of meat production, what is

the incentive for a local manager to view this as a problem, especially in the short term? On

the other hand, if the gullies are causing an off-site impact (downstream), this may generate

conflicts between local management objectives and regional ones. Of course, even under cir-

cumstances where the existence of an erosion gully might elicit little or no localconcern, it

may matter a great deal regionally if there is a threat of salinity impacts on a downstream

catchment, or even nationally orinternationally if conservationists view this as a perceived

threat to biodiversity.

Whether the ultimate cause is local or broader will ultimately determine the policy re -sponse. Thus scale enters into the equation in terms of the relevance and importance of im-

pacts (Table 1.5). Further, there is the question of whether the gullies can be economically

rehabilitatedor have been permanentlychanged a question that hasboth biophysical and

socioeconomic elements to it.

Scale also enters into the question of causes. Even where there is agreement that certain

impacts constitute genuine loss of productivity, there is a great deal of debate over the degree

to which causes are local or remote and whether they lie in the biophysical or socioeconomic

spheres. In most cases it is likely that the biophysical backdrop sets the stage for the ease with

which institutional failure causes problems, and the two cannot be divorced. In Table 1.6 we

present the beginnings of a generic scheme to link the various types of causes and impacts ofland degradation, through to the policy and management implications that could emerge.

While this preliminary scheme separates biophysical and institutional causes thus mask-

ing their interrelated nature it suggests the need for a more comprehensive framework that

is able to identify when different systems are at risk of desertification, and what policy and

management implications must be implemented.

Fundamental Tenets of a New Synthetic Framework

While overly simplistic, the erosion gully example in Figure 1.2 captures many of the ele -

ments that give rise tocontroversies withdesertification and points the way tosome of the es-sential elements of our new synthetic framework for desertification. It is essential:



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to be unambiguous when referring to system change defining whether it is

biophysical, social, or economic; to specify whether such change affects human use values or not;

to specify whether thechangeiscaused(direct or indirectly)by human activities;and

to specify the explicitscale of concern (e.g., local, regional, international).

We must also be prepared to be explicit about what human use value forms the basis for con-

cern (e.g., local or regional livestock production, local soil conservation, international

biodiversity conservation, etc.), and whether a causative human use or institution is local or

regional-global. A start towards a classification of these factors and of their implications is

given in Tables 1.5 and 1.6.

Links between Biophysical and Socioeconomic Factors

In this section, we target areas of disciplinary effort that must be integrated to provide the

foundation for a comprehensive framework for desertification. While we use subsistence

pastoral systems in Africa as the basic model for this conceptual framework, and accentuate

smaller spatial and temporal scales, we believe the ideas are sufficiently general to be readily

extended to most dryland systems and broader scales.

The core of the biophysical system is the state of the ecosystem whereas the core of the

socioeconomic system is rural livelihood. The socioeconomic and biophysical factors in-

volved in dryland degradation are closely linked and constantly changing, both in the

short-term (e.g., climaticvariability, interest rates, cropyield, changes in markets, populationmigration) and in the long-term (e.g., global change, including increasing population,


Table 1.5 A simple taxonomy of types of system change in terms of causes and effects, and scale ofconcern, illustrating the diversity of combinations that are possible even for a single type of change.Each combination has different implications for the attribution of the cause of the change and the man-agement response that might be made to it. Debates on desertification are often conducted at cross pur-

poses by protagonists who fail to clarify that their experiences are based on different types of changes,so it is important to specify these combinationsclearly. Taxonomy couldbemade more comprehensive.

Scale of Effect

Type of Change Scale of Cause Local (e.g., local

productivity)

Regional (e.g., on

biodiversity or down-

stream salinity

Local landscape

change

(e.g., shrub

invasion, soil loss)

Local(e.g., overgrazing,

debt, overcultivation)

YesYes

No

No YesNo

Regional-global

(e.g., climate change,

trade systems)

YesYes

No

NoYes

No


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Table 1.6 Examples of how a (partial) systematic classification might lead to well-targeted alterna-tive approaches to different categories of desertification problems (see text).

Impact Scale and Type of Cause Possible Types of Implications

Local

landscape

change, withlocal impacts

Caused

by local

drivers

With immediate, manageable feedbackon productivity (e.g., reduction in soil

fertility due to lack of manuring)

Market forces should rule

Feedback swamped by discount rates

(e.g., slow increase in shrubs because of

reduced burning, not affecting produc-

tion for many years but then doing so

irreversibly)

Market failure likely possible

conflict between current and future

generations or between local and re-

gional effect requires resolution by

policy institutions

Caused by

regional-

global

drivers

Biophysical and intrinsic to Earth

system (e.g., natural climate variability

triggering a long drought)

Recognize and manage for effects

locally and, if necessary, regionally

Biophysical but anthropogenic in nature(e.g., climatic change intensifying local

droughts)

Manage for effects locally and, ifnecessary, regionally; argue for/

contribute to collective action at

regional-global scale (dependingon scale)

Based in human sociopolitical system(e.g., trade agreements promoting over-

stocking and eventual lost productivity)

Seek changes in institutions, orcompensate local/regional impact if

incidental fallout from a broadergood

Local

landscape

change, with

no localimpacts

Causedby local

drivers

With no apparent regional effects (e.g.,minor gullying enhanced by grazing

and looking bad locally but with negli-gible effects on local production or

regional runoff)

Conflict between scientist andmanager perceptions; scientists

probably wrong!

Regional/offsite effects (e.g., tree clear-

ing in a catchment for extra forage

causing downstream salinity or cumula-

tive effects on regional climate)

Conflicts between local managers

and regional interests; policy

institutions must resolve these

Caused by

regional-

globaldrivers

and with

regional

effects

Biophysical and intrinsic to Earth sys-

tem (e.g., natural climate variability

triggering extinction of species region-

ally that do not matter for local produc-tion)

Recognize and manage for effects(if needed for regional impacts,

locals may need compensation)

Biophysical but anthropogenic in nature

(e.g., climatic change, again triggering

regional extinctions)

Manage for effects locally, argue

for/contribute to collective action at

regional-global scale (depending onscale); compensation may be needed

Based in human sociopolitical system(e.g., free trade movement causing pest

and weed introductions with regionalimplications)

Seek changes in institutions


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land-use change, climatic change). Note that some of theseprocessesarefast relative to the

time frame of interest whereas others are slow (Carpenter and Turner 2000). The resulting

institutional and political systems, which also vary over time and space, are partly driven bythese factors. While all of these linkages are fundamental components of the desertification

problem, it is not possible to research most of them directly. The way in which these linkages

respond is dependent upon the underlying human and biophysical processes, which are sum-

marized in a very simplified way in Figure 1.3, and in more mechanistic detail in Figure 1.4,

which identifies some explicit processes that might be amenable to research in subsistence

pastoral systems.It is essential that rural people are not seen as either the problem (some-

times an implicit biophysical view) or as victims (sometimes an implicit socioeconomic

view), but instead simply as part of an integrated system.

As previously emphasized, themeaning of all statements pertaining to thecausesandcon-

sequences of desertification is affected by the scale andpurpose of the interpretation. Weidentify four essential scales of interest: (a) farm/household, (b) village/community, (c) na-

tional, and (d) international.Manyof the linkagesshown inFigures 1.3 and 1.4 can beconsid-

ered at each of these scales, often with different issues being important at different scales

(Table 1.7). In fact, some of the most important issues arise fromconflicts betweenscales, for

example, when expectations or structures at provincial levels fail to provide suitable incen-

tives at village level, or when tenure systems instituted by national governments do not allow

for appropriate local management. Another challenge is for researchers to link biophysical

factors with social factors at the same level ofresolution: it isnot sensible tostudy the linkbe-

tween land tenureandplant species composition, norbetween milk production andrural live-

lihoods. Hypotheses must be structured in terms of equivalent andmeasurable variables, e.g.,

milk production and income from trading surplus farm production.


Figure 1.3 Social and biophysical factors in global drylands are closely linked, difficult to predict,and involve a mixture of fast and slow variables. The core of the biophysical system is the state ofthe ecosystem whereas the core of the socioeconomic system is rural livelihood.


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Land Degradation as an Integrated Concept

Asnoted earlier, the coreof the biophysical systemis the state of the ecosystemwhereas the

core of the socioeconomic system is rural livelihood (seeFigure1.3). The state of the eco-

system expression is used to encompass those important characteristics that determine how

the biophysical system will respond to land-use practices and the driving forces of climate.

This includesthecomposition of the vegetation, soil fertility, soil structure(such as theability

of water to infiltrate), and the patchiness of the landscape (Ludwig and Tongway 1996)

factors that determine both thepotential quantityandquality of ecosystemgoods andservicesthat can be obtained by humans from an area, including meat production, crop yield, re -

sources forhunting andgathering, andopportunities for tourismandcottage industries. Many

elements may be part of rural livelihoods, including needs for food, water, fuel, medicinal

plants, construction materials, clothing, and cash the supply of which results in different

levels of health, shelter, happiness, the ability to trade externally to the household, and accu-

mulated wealth invarious forms.Appropriatemeasures of theseelementsmaydifferbetween

cultures and scales, but must be explicitly defined to permit a mechanistic understanding of

linkages with the productivity of the biophysical system.

The socioeconomic system also incorporates a variety of institutional structures and poli-

cies that influence the way in which individuals obtain and use their rural livelihoods, and

consequently affect the biophysical system. These include tenure systems, markets (driven


Figure 1.4 Example of a preliminary mechanistic model for the processes shown in Figures 1.1 and1.3 for rangelands/human interactions in subsistence pastoral systems of Africa. Note that this modelcan be applied at various scales. Solid lines indicate driving processes, dashed lines controlling feed-backs, and the heavier arrows (and their feedbacks) indicate where there is a close integration of socialand biophysical factors.


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by demand), and subsidies, in a fashion loosely comparable to the way in which the state ofthe ecosystem affects the productivity of the biophysical system.


Table 1.7 Examples of socioeconomic issuesand their potential impacts on ecosystems as viewedbydifferent scales of concern. Based on Odada et al. (1996).

Level Socioeconomic Issues Impacts on Ecosystems

Farm/household

Household size

Labor shortage

Food security

Poverty

Overexploitation of key resources (water,

land)

Land abandonment

Overgrazing

Overcultivation

Community or

village

Land tenure, ownership, control

Conflict resolution

Population size

Local land planning

Expanding hinterlands

Differential impacts and vulnerability of

different ecosystems

Natural resources (water, wildlife)

District/

Provincial

District land planning

Decentralization of planning for

communal land

Damaging if carried out at wrong level or

with inadequate information or under-

standing of ecosystems

Land reform Can alleviate or increase land-use pressures

Ethnic and interest group

conflicts

Replacement of management systems

Pressure on marginal levels by displaced

people

Financial constraints (subsidies)

Macro-economic enablingtrends

Economic opportunities

Investment constraints/subsidies leading to

dominance by one economic activity,e.g., grazing or mining

Demand for natural goods and services

Trade in goods

Natural disasters (e.g., floods,

drought, fire, pests, diseases)

May be positive (e.g., fire is an important

factor in species regeneration, competi-

tion, etc.) or negative (loss of species,

soil erosion, etc.)

Loss of local knowledge

following transmigration

Overexploitation of resources may lead to

need to migrate and hence loss of localknowledge

National/

International

Human population growth

Macro-economics/trends

National policies (e.g., resettle-

ment programs, economic)

War

Encroachment into undisturbed ecological

systems

Overexploitation of key resources (water,

land)

Contamination of soil, water


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The traditional approach to determine whether a particular landscape is degraded has

been solely on the basis of either its state of the ecosystem orthe status of its local rural

livelihoods, which causes great confusion and argument. Rather than a precise definition of

land degradation per se, our synthetic framework (as summarized in Figures 1.11.4) re-quires that researchers simultaneously focus on both biophysical and socioeconomic factors

within the context of fundamental tenetsof the framework described above and specifi-

cally on measuring the capability andsustainable natureof thebiophysical systemto produce

the goods and services relevant to rural livelihoods (socioeconomic system).

CONCLUSIONS

Do humans create deserts? For a given location, one stakeholder group may emphatically

conclude that the answer is yes!, while another group may conclude (and with equal con-

viction) that theansweris obviouslyno!We havearguedthat the answer to thisquestionde-

pends on the context of the question: specifically, the type of land involved (soil types,

vegetation,soil fertility, etc.), itsusehistory, a consideration of theviews of thevarious stake-

holders involved, and the spatial and temporal scales of concerns. To make serious progress

beyond the It just depends!mode, we must develop a synthetic frameworkthat comprehen-

sively identifies when different systems are at different risk of desertification, and what pol-

icy and management implications flow from these particular conditions.

The preliminary desertification framework presented here recognizes the simultaneous

roles of andcomplex feedbacks between the meteorological, ecological, andhuman di-

mensions of the problem. It is able to incorporate our state-of-the-art knowledge about risks,

detection, processes, and consequences of desertification, and is able to capture emerging

ideas, data, and conceptual schemes for exploring quantitative, as well as qualitative interac-

tions, between the various dimensions of desertification. However, this framework must be

refined to represent the degree of uncertainty in our knowledge of the desertification puzzle

andtopropagatetheseuncertainties in theanalyses, thus reflecting themin theconclusions.

There is an immediate need at all levels (local, regional, national, international) for policy

decisions on how to identify, prevent and/or adapt to desertification and land degradation in

general. It is essential to move beyond isolated studies of various parts of the desertification

problem, which has been the traditional approach. It is crucial to work through the causal

links of dryland land degradation, from climate dynamics to ecological impacts to policy re-sponse strategies, and to span a wide range of temporal and spatial scales, from small geo-

graphical units to larger regions.

The remainder of this volume (Reynolds and Stafford Smith 2002) seeks to address these

questions by providing a series of examples relevant to our preliminary framework. In Chap-

ter 21 (Stafford Smith and Reynolds 2002), we return to a synthesis that emerges from this

discourse.

ACKNOWLEDGMENTS

The authors thank the entire staff of theDahlem Konferenzen der Freien Universitt Berlin,especially Wedigo de Vivanco and Julia Lupp, for their support and encouragement in



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organizingandconducting the workshopwhich ledto the developmentof these ideas.JFRac-

knowledges the Alexander von Humboldt-Stiftung, NSF INT0107875, and the Center for

Integrated Study of the Human Dimensions of Global Change, created through a cooperative

agreement between the National Science Foundation (SBR9521914) and Carnegie MellonUniversity. MSS acknowledges the support of CSIRO in allowing time to explore these

issues.

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Coronado, J.A. 1998. Relationship between Range Condition and the Land Tenure System in Sonora(Mexico, Ejidos, Cattle Management). Ph.D. diss, Univ. of Arizona, Tucson.

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37:419432.



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SI - Chap 1

A

accountability

= how land is used 5aridity zones of the globe 2

B

biophysical factors 8

= meteorilogical/ecological dimensions 1

links with socioeconomic factors 16

biophysical factors

links to social factors 17

biophysical system

core of 18

Cclimate variability

interannual 9

D

definition of desertification 3

problems surrounding 3

definitions of desertification 11


definitions of desertificfation


Eecological dimensions 5, 8, 9

economic policies

effects of 10

F

Figure 8

H

human dimensions 5,8, 10, 12

I

institutions 16

irrigated agricultural cropland 9L

land degradation

definition orf 3

landscape patchiness 18

land-use categories

rangelands 9

M

markets 18

media coverage 7

meteorological dimensions 4, 8, 9O



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overgrazing 13

P

political systems 16

Rrainfed agricultural cropland 9

rangelands 9

vegetation of 9

rural livelihood 16, 18

S

scales of interest 17

social factors

link to biophysical factors 17

socio-economic drivers

ownership 5socioeconomic factors

links with biophysical factors 16

socio-economic factors

= human dimensions 1

socioeconomic system

core of 18

soil fertility 18

soil structure 18

spatial scales 8

stakeholders 5, 12, 13state of the ecosystem 16, 18

subsidies 18

synthetic framework1, 4, 14, 18

development of 8

T

taxonomy of types of system change 14

temporal scales 8

tenure systems 18

U

UN Convention to Combat Desertification 3



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