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Wildlife and desertification

1. Impact of desertification on wildlife

Desertification impoverishes habitats and biodiversity.

The natural causes of desertification could be accepted by wildlife without too much upheaval in a natural ecosystem (without man's interference). Most animal species in arid and semi-arid areas migrate according to season and would only migrate a little further for a temporary period. Unfortunately, however, these natural causes are compounded by man-made causes which restrict the ability of wildlife to adjust. Competition with man, livestock and crops produces a fragile equilibrium which is immediately destroyed to the detriment of wildlife when the pressure of desertification increases.

Certain activities to stop desertification can also have a negative impact on resident populations by modifying the natural environment (planting of exotic species, changes to natural watering points, horizontal expansion of cropland, etc.).

2. The role of wildlife in combating desertification

The role of wildlife in the conservation and regeneration of grassland and in the control of desertification is often neglected, though several studies have shown how wildlife can rehabilitate degraded and overgrazed zones and areas unsuited to traditional livestock production (excessive salinity, for example), while conserving their economic potential.

The essential factor to consider is the dietary behaviour of most herbivorous forms of wildlife. Each species uses a small section of the herbaceous or woody plant very selectively, whereas cattle, sheep and goats are far less selective and consume indifferently most of the vegetation. Another important factor is the very precise ecological niche of each species, making it possible for numerous species to coexist and indeed benefit from such co-existence. The pasture sequence is a good example: the tall dry grasses are consumed by buffaloes and zebra; the medium-size grass is then consumed by gnus and hartebeests; finally, the regrowth is consumed by small species needing a more "concentrated" diet.

The value of wildlife lies in the fact that a group of wildlife species will have a lower impact on a given volume of biomass than domestic livestock, and that, for a given supply of forage, the potential wildlife biomass will be greater than the potential cattle biomass.

In degraded areas, measures for the rehabilitation of wildlife populations can help to gradually restore plant cover and permit a certain number of economic activities, such as photo-tourism and even regulated hunting.

National parks and wildlife reserves are much more resistant to drought, such as that of 1992/93 in southern Africa, and game losses are far lower than cattle losses. There is still considerable plant cover within the national parks though wildlife population densities remain high. In contrast, the same conditions devastate cattle ranches and much of the herd often has to be slaughtered. Finally, the ranches lose all their immediate economic value, while tourism or hunting are still possible in the wildlife reserves.

An excessive concentration of animals produces soil trampling. This, however, is far more limited in the case of wildlife species which are less gregarious and occupy the available land area better.

Many wildlife species in arid zones are not excessively water dependent and visit the watering points far less frequently than cattle, producing less trampling and overgrazing in these areas.

The seasonal migration of many wildlife species enables the vegetation to regenerate, particularly during the dry season. The obstructing of such migration (fencing, canals, agricultural land, etc.) generally causes serious disruption to these animal populations.

Some species, however, can be detrimental to the environment, at least locally. Impalas are extremely adaptable and consume available vegetation indiscriminately, in the form of grass leaves much like cattle. Sizeable warthog or elephant populations can have a negative impact, particularly when restricted to certain areas. These types of degradation are, however, usually natural phenomena which man has exacerbated by cordoning the species off in protected areas.

The rational management of wildlife can therefore play a role in controlling desertification:

- Highly degraded areas without agricultural economic value can be rehabilitated through land use measures that include the reintroduction of wildlife, for the rapid recovery of some of the land's economic potential.

- Under certain conditions, wildlife can provide an alternative to traditional livestock raising as it has a lower impact on vegetation and can use limited plant biomass more effectively.

- A careful balancing of wildlife species or groups, particularly between browsers and grazers, can facilitate certain specific measures to rehabilitate the habitat (control of brushwood growth or, on the contrary, establishment of woody cover) without reducing ecosystem productivity.

February 1993

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