Environmental Engineering Reference
In-Depth Information
24
Stability and Instability in the
Management of Mediterranean
Desertification
John B. Thornes
Formerly of Department of Geography, King's College London, UK
of the culture/nature dichotomy so carefully exposed
and discussed by van der Leeuw (1998) following Evern-
den (1992). Hudson (1992) also identifies the contrast
between the technical and land-husbandry approaches to
land degradation. The problem is not simply to identify
and apply technical fixes to solve soil erosion. Rather it
is to develop a deeper consciousness of the problem and
cultivate the notion of social responsibility to the land, so
well encapsulated in the term 'land husbandry'.
Nevertheless, at the end of the day, efforts have to be
focused in the right direction on a common basis, espe-
cially in a multidisciplinary context, to avoid repetition,
replication and poor return for the effort applied. To
this end, 'desertification' is understood here to be: 'land
degradation in arid, semi-arid and dry sub-humid areas,
resulting from various factors, including climatic varia-
tions and human activities.' 'Land' means the terrestrial
bio-productive system that comprises soil, vegetation,
other biota and the ecological and hydrological processes
that operate within the system. 'Land degradation' means
reduction and loss of the biological or economic produc-
tivity caused by land-use change, from a physical process,
which include processes arising from human activities
and habitation patterns such as soil erosion, deteriora-
tion of the physical, chemical and biological or economic
properties of the soil and long-term loss of vegetation.
In this chapter, the priority is to engage with the
physical processes that involve the interaction between
24.1 Introduction
In this chapter, the primary objective is to introduce
the problems of desertification and to develop some
ideas based on the complexity of response, as a basis
for a fresh theoretical approach to understanding and
managing desertification. The emphasis will be on the
stability of soil and vegetation, the relationships between
them and the behaviour of this relationship in the light
of varying climatic conditions. Surprisingly, in the early
1990s there were some who believed that the issue of
desertification in the Mediterranean required not much
more than the solution of the differential equations of
atmospheric motion over flat regions, provided that the
boundary conditions and the model parameters could be
properly identified and satisfied.
The approach here is heuristic reasoning, revitalized
by P olya (1964). Heuristic reasoning is not regarded as
final and strict, but as provisional and plausible only,
whose purpose is to discover the solution of the present
problem. Before obtaining certainty, we must be satisfied
with a more or less plausible guess. We may need the
provisional before we obtain the final (P olya, 1964: 113).
This approach is not intended to provide an excuse for
lack of rigour but rather to admit the possibility of a cre-
ative approach to the problem, where 'technical fixes'
(solutions) have largely failed. The creative-technical
dichotomy of approaches is an alternative expression
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