Drylands conventionally are defined in terms of water stress: as terrestrial areas where the mean annual rainfall (including snow, fog, hail, etc) is lower than the total amount of water evaporated to the atmosphere. This definition usually excludes the Polar Regions and high mountain areas, which on account of their low average rainfall can also be classified as drylands. Drylands can be found on every continent and cover extensive areas of land – they stretch over 41% of Earth’s land surface.
One over-riding feature of drylands is their low, but highly variable, precipitation and it is this variability, as much as the low quantity, which gives drylands their special features. Dryland ecosystems are constantly in flux, making it difficult, if not impossible, to define an “average” condition for rangelands. Drylands are particularly sensitive to land degradation, with 10-20% of drylands already degraded (Millenium Ecosystem Assessment, 2005).
At various times in the past, policy makers have tried to lay the blame for this degradation with the local communities that use drylands resources: namely the pastoralists. Negative perceptions of pastoralism are strongly influenced by images of overgrazing and soil erosion around water sources, or by livestock death and food insecurity during some droughts. This extensive production strategy seldom fits with a government’s concept of the nation-state or its vision of development and pastoralism is usually portrayed as a national problem and an archaic form of land use.
However, pastoralism is an adaptation to an unpredictable environment and pastoralists have learnt to harness the erratic changes in rangeland condition through a mobile livestock production system. Pastoralists accept the variability of productive inputs (such as pasture and rainfall) as a given and adapt their social and herding systems accordingly. Mobility is a highly efficient way of managing the sparse vegetation and relatively low fertility of dryland soils. In fact, dryland ecosystems may be more ecologically resilient than has previously been accepted, as long as some degree of livestock mobility or general resource-use rotation is retained in their management.
“Overgrazing” is usually a convenient and more palatable scapegoat for many other causes of land degradation and although land degradation may be evident around permanent settlements and water points, where livestock mobility is reduced, it is much less in open rangelands where mobility is unrestricted. Where mobility continues unhampered, it has resulted in biodiversity conservation and sustainable land management. Where it is constrained it has led to serious over-grazing and land degradation.
Nevertheless, policies of sedenterisation have been widely pursued in the past, with dire environmental consequences. Such policies were based on a profound misunderstanding of the logic behind pastoral production, favouring production systems imported from developed countries and supported inappropriately by the theory of the ‘tragedy of the commons’. Movement was restricted by providing stationary settlements, replete with services and resources, especially water, ignoring the wider ecological necessity behind mobility in this ecological setting.
Not surprisingly, the imposition of sedentary life failed miserably and was resisted by herders who needed grass and water for their animals and had to move to find it. Services were not delivered or maintained and pastoralists were accused of being anti-development. Eventually, the big pastoral livestock projects of the 1970s and early 1980s were halted as donors abandoned the sector, but not before large swathes of drylands were degraded as a result of the experiment. Simultaneously, the small but resource-rich buffer zones that enable pastoralism were expropriated and converted into irrigation schemes for settled agriculture, or fenced off for wildlife and forest reserves. This combination of bad policy and resource loss has profoundly compromised pastoralism and dryland environments.