Geoscience Reference
In-Depth Information
3. Likewise, a second deduction is that we should not
systematically
add materials to a natural
or humanly modified system at a rate faster than that at which the system can absorb
and recycle those materials. (Excessive use of pesticides, herbicides and fertilizers is one
example of breaching this precondition, as is the general problem of chemical pollution of
soils, water and air.)
4. The final prerequisite, based on simple human justice, is that there should be fair and
effective access to natural resources by all people of the globe. (Access to clean, safe
drinking water is an obvious and pressing example). We will now consider how each of
these four conditions, or prerequisites, can be put into practice in order to achieve sustainable
use of the natural resources of the desert world.
26.3 Safeguarding desert ecosystems and retaining plant cover
The Greek philosopher Empedocles (ca. 495-435 BC) believed that life on earth was
made up of four ultimate elements, namely, earth, air, fire and water, an idea that
reflected far older Babylonian concepts. Thinkers from every great civilization and
religion have speculated about the origin and nature of life on earth (Glacken,
1973
),
and these ideas have been greatly refined over the last few centuries. However, it is
only comparatively recently that we have come to realise the crucial importance of
biological diversity (or biodiversity) for maintaining the health of soil, air and water
on this planet. The seasonal fluctuations in the global atmospheric concentration of
carbon dioxide are a direct reflection of reduced photosynthesis in northern mid- and
high latitudes in winter and the renewal of plant growth in the boreal (northern) spring
and summer. The removal of forest and burning of the savannas means less oxygen
input to the atmosphere and an increase in emissions of carbon dioxide and carbon
particles. Biomass burning can also lead to increased run-off and erosion (Dube,
2009
). Common sense therefore tells us that any removal of the plant cover in one
place should be balanced by its replenishment in another. Failure to achieve such
a balance means a reduction in global biomass and a change in atmospheric com-
position. Consequences that are more obvious because they are more visible include
the dust storms and mobile dunes that are engendered by the stripping of the former
stabilising plant cover. Soil nutrients are generally concentrated in the organic rich
top-soil. The presence of soil humus also promotes soil structural stability and higher
rates of infiltration, thereby minimising erosion from surface run-off or overland
flow.
People who have spent their lives in deserts are well aware of the importance
of maintaining an appropriate plant cover. The Kababish camel herders of northern
Sudan may not be aware that the earth is an oblate spheroid, but they are certainly
aware that their survival depends on only taking what is needed for their animals, and
being selective at that. Charles Doughty in his wanderings through 'Arabia Deserta'
in the late 1870s mentions the scorn exhibited by the Bedouin nomad children when
he collected shrubs valued as camel fodder to put on the fire (Doughty,
1956
, p. 79).
