Land degradation is a social concept. It involves value judgements about an area's long-term potential for contributing to human welfare - and about the sacrifices, efforts and other costs implied in realising it. Such judgements are influenced both by the social context and by the position of different actors within their societies.

Members of hunter-gatherer societies have perceptions of land productivity and its degradation that are different from those of shifting cultivators and semi-nomadic pastoralists in similar dryland areas. The former may view an abundance of wild game as welcome food reserves while the latter are likely to see them as a threat to crops and livestock. Both may have sharply different perceptions from commercial farmers with access to chemical fertilisers and other modern inputs.

Even within the same society, different social groups, and different genders, may view land degradation in very divergent ways. Landlord moneylenders in clientelistic rural societies, for example, may sometimes welcome droughts as an opportunity to increase their holdings at the expense of indebted small cultivators. Near Lake Titicaca in highland semi-arid Peru, male peasants were easily persuaded by a rural development programme to plant degraded 'idle' village brushlands with trees for a community woodland - but the seedlings were promptly ripped up by village women who saw the same land as part of their long-fallow potato rotation.

Volcanic soils eroded by heavy rains from upland communities' pastures and cultivated plots in semi-arid northwestern Mexico wash down gullies to be deposited in arroyos - replenishing the lands of other peasant villages with badly needed nutrients. Some is washed even further down to fertilise floodplains controlled by commercial farmers. As often happens, one group's land degradation contributes to the renewal of productivity for others. On the other hand, deforestation, overcultivation and excessive grazing of large semi-arid regions may leave them so eroded, so depleted of native species and with such altered local rainfall patterns and water reserves, that it may take decades or centuries before they recover former levels of productivity.

Historical Perspectives

The issues become increasingly complex the larger the regions and the more diverse the social groups included in the analysis. When taking a global view, the issues tend to appear different for national and transnational authorities and for farmers, peasants and pastoralists.

These issues of conflicting perceptions and interests cannot be resolved 'scientifically' by reducing them to a calculus of monetary costs and benefits as indicated by price relationships in national and world markets. This subsumes the livelihood concerns and the values of weaker social groups to those of the stronger ones now dominating the world system. It pretends to offer an attractive technocratic solution to what are essentially political issues about the distribution of resources and power.

Dryland degradation has been recurrent in human history. In the distant past it tended to be sporadic and limited to certain areas in response to particular combinations of natural and social factors. Since the present world system of production, finance, trade and consumption began its rapid expansion from western Europe in the 16th century, land degradation has increasingly spread throughout dryland regions nearly everywhere. This cannot be convincingly explained by recent climatic changes. It suggests that global socio-economic processes as well as local ones are driving desertification.

The Akkadian empire which prospered in Syrio-Mesopotamia between 2600 and 2200 BC apparently collapsed during a long dry spell induced by warming ocean currents. Its highly stratified social structure and centralised economic system made it particularly vulnerable to drought. Land degradation accelerated rapidly in dry areas of the Mediterranean basin under the Roman Empire as increasing supplies of timber and food were extracted to sustain Rome and its armies. Desertification may have triggered the collapse of the Mayan city states in the 10th century when decreasing agricultural production from overcultivated soils eliminated the surplus customarily delivered to their theocratic rulers: once relieved of this burden, Mayan peasants reverted to their age-old sustainable farming practices.

Rural societies with secure control of their natural resources can adapt sustainably. Nomadic peoples in the vast Algerian steppe developed opportunistic grazing strategies, relatively egalitarian social institutions and complementary trading and land-use relations with sedentary agriculturists to the north and south of their territories. This shielded them from the worst social consequences of recurrent droughts. But this sustainable land management system collapsed after European conquest in the 19th century when colonists cut their access to the agricultural lands to the north and attempted to impose 'development'. The pastoralists' plight did not improve following independence, when the state continued a similar development strategy but with more emphasis on national industrialisation.

The legacy of colonialism

Colonial penetration through trade or conquest led to accelerating land degradation in the dry regions of the Americas, Africa and Asia. This cannot be explained merely by rapid population growth as this is a recent phenomenon. Indeed population collapsed in the Americas following European conquest: in most of Latin America it did not reach pre-conquest levels again until the late 19th century in spite of massive immigration of settlers and slaves. In the depopulated Andean highlands after the Spanish conquest, the disruption of indigenous social systems, the scarcity of labour and land alienation by Europeans all contributed to the decay of traditional intensive, but sustainable, farming systems. In much of Africa, populations were relatively stable until well into the 20th century, but massive desertification accelerated in its dryland areas almost immediately after European commercial penetration or conquest.

Over 200,000 people and millions of their animals died in the Sahelian famine of 1968-1974 and there were massive politically destabilising migrations from drought-stricken areas. The famine was triggered by drought, but social factors bore a much greater responsibility for the tragedy. Throughout this period about half the affected countries' cultivated areas continued to be dedicated to export crops such as groundnuts and cotton - and the level of these exports decreased only modestly. Such land alienation for export crops, together with market forces and social relations and policies, shifted the burden of the drought to subsistence-oriented peasants, pastoralists and rural workers.

Source: Our Planet, Journal of the United Nations Environmental Programme, Vol. 6 No. 5.