Environmental Engineering Reference
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a particular rangeland lies. Briske et al. (2003) argue that in drier regions
where the intra-annual variation in rainfall is greatest then rangelands are
likely to exhibit non-equilibrium dynamics, however in wetter areas where
variation in rainfall is less then equilibrium theory is more appropriate.
Following this argument in Tanzania would lead to the Somalia-Maasai
region being considered a non-equilibrium system since rainfall is highly
variable. In contrast the Zambezian region would be subject to equilibrium
dynamics since rainfall averages are higher and more consistent. However,
even in the Zambezian region rainfall is highly seasonal and intra-annual
variation is still high, although total rainfall is generally greater than in the
Somalia-Maasai region. As a result non-equilibrium dynamics cannot be
discounted as important for at least some parts of this system.
Social paradigms
The two dif erent ecological paradigms outlined above are central in
determining which social paradigm inl uences policy, because each focuses
on a dif erent cause of environmental degradation. In equilibrium theory
overstocking and overpopulation are seen as the primary causes of deg-
radation of rangelands and management regimes should seek to control
stocking rates and change land tenure so as to maintain rangelands in
an optimal condition. Equilibrium theory leads to the pastoral paradigm
being the dominant theory that frames understanding of communities.
In the pastoral paradigm pastoral communities are seen as unable to
adequately manage rangeland resources, leading to degradation (Warren,
1995). Population increases accompanied by inappropriate management
are therefore considered to be key problems that require intervention in
order to prevent over-use and protect natural resources and wildlife. In
Tanzania the predominance of the equilibrium paradigm in understand-
ing rangeland ecology has helped support the view that pastoral ways of
life are primitive and economically unproductive (Armitage, 1996). Early
successional stages in rangeland composition are given as evidence that
pastoral communities overstock the rangelands leading to degradation.
Interventions that de-stock and change land tenure are therefore seen as
necessary to prevent degradation and ultimately soil erosion and desertii -
cation (Ellis and Swift, 1988; Warren, 1995).
In contrast, abiotic factors, particularly rainfall, are attributed the key
role in determining range condition in non-equilibrium theory. As a result,
managing stocking rates would not necessarily lead to improvements in
range condition. In addition, it is now recognized that most development
ef orts based on equilibrium theory and the pastoral paradigm have ulti-
mately ended in failure (Oba et al., 2000). While it could be argued that
failures have been due to resistance of pastoral communities to accept
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