Geography Reference
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differential gender, poverty and health impacts;
and famine, malnutrition and starvation).
concept of carrying capacity; a shift in the research
paradigm now suggests that range potential is a
mainly rainfall-driven parameter. Moreover, issues
surrounding stock numbers and land degradation
are complicated because of degradation by stock
concentrations around watering points and the use
of feed supplements, e.g. in eastern Jordan
(Campbell and Roe 1998). However, high
population density does not always lead to
degradation. Boserup's argument that high
population densities lead to agricultural
innovation can be seen in the development of
indigenous soil and water conservation systems in
drylands (Reij 1991) and in the management of
trees in areas of intense pressure from fuelwood
collection.
Large-scale population movements are another
aspect of demographic change that affect
desertification. These movements occur because of
land shortages, land alienation and warfare.
Movements can be rural-to-urban or rural-to-
rural. The first type of migration is known to
increase pressure on rural production systems,
particularly biofuel production systems, which
have a dominant rural-to-urban flow in drylands
(Floor and Gorse 1988; see Plate 13.1). In Kenya,
people have moved from the fertile Kenyan
highlands to the drier, northern regions because
of land alienation, while in Jordan, the limited
amount of highly productive land (in the Jordan
valley and the western highlands) combined with
the large numbers of Palestinian refugees has
shifted the frontier of cultivation eastwards into
desert regions with mean annual rainfall totals of
less than 250 mm. In the West African Sahel,
pastoralists have moved southwards due to
drought, while cultivaters have moved north due
to lack of land, thereby causing an uneasy mix of
pastoralism and cultivation in a zone that is
economically marginal in terms of cultivation
(Warren and Khogali 1992). Population
concentrations around refugee camps leads to
pressure on natural resources (e.g. biofuels) in their
immediate environs (Munslow et al . 1989).
Areas of outmigration also suffer from
desertification because the labour shortages
created lead to a lack of maintenance of
It is evident from studies of desertification that
many of the processes listed above are not only
effects of a wide range of processes but that they
also act as causes. There are no simple cause-and-
effect relationships in desertification, only a
complex web of interrelated processes that act as
both cause and effect. These causes and effects
overlap on the ground; nonetheless, it is important
to try to discriminate between causes to enable
policies and interventions to be developed that
address the issues (Warren and Khogali 1992). The
main demographic change and policy issues are
population growth, population movements,
agricultural change and modernisation, warfare,
and political change. In terms of climatic forcing
there are two main areas: first, unpredictable, short-
term fluctuations in climate— droughts and
floods—and, second, longer-term climatic
desiccation. However, it is not adequate to ascribe
the main cause of desertification in an area to
either climate forcing or demographic and policy
issues. For example, Livermann (1990), working
in northern Mexico, argues that drought impacts
are not simply a function of drought severity but
are also influenced by the political, economic and
technical characteristics of the region affected; and
Glantz (1994) provides a number of detailed case
studies in this area.
Demographic change, policy issues and
desertification
The interactions between human activities and
natural resources in the context of desertification
are a complicated area. In some cases, high rates of
population directly increase pressure on the
natural resource base. This may lead to high
cultivation densities, which reduce fallow periods
and lead to soil nutrient depletion (Warren and
Khogali 1992). Alternatively, it may lead to
rangeland overstocking. In this area though, ideas
have changed. In the 1960s and 1970s, the
prevalent paradigm in range science was to match
stock numbers to range resources using the
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