Land degradation vs. overgrazing

In considering the ecological explanation of land degradation,” we need a definitive understanding of the differences between degradation and over- grazing. Perevolotsky and Seligman36 define land degradation as negative changes based on the use of subjective vegetation indicators (cover, species composition, and biomass and species richness); while overgrazing is an operative word that refers to the overuse of plants by herbivores. The same authors state: ‘We suggest that traditional heavy grazing, often incorrectly termed “overgrazing” and blamed for many of the landscape ills of the Mediterranean region, is in fact not only an efficient form of land use but one that is ecologically sound.’ Although the impression created in the historical literature is that overgrazing would permanently alter the biotic and abiotic components of rangeland ecosystems, this does not in fact happen—and if it does, it occurs only at the scale of landscape patches, as opposed to geographical scales.

We now examine the voice of a proponent of the overgrazing view, Henri-Noel Le Houerou, who spent much of his professional career working on issues of rangeland degradation in the Mediterranean ecosystems of North Africa. He believed that a century’s evidence from interdisciplinary teams of scientists confirmed that there was general deterioration of the ecology, and that this was attributable to human actions and livestock grazing. This claim was challenged by the findings of colonial and post- colonial researchers (see Chapters 5 and 10). Le Houerou’s sarcasm can be gauged from a statement such as ‘livestock consume more feed than the pasture produces.’3. However, this doesn’t sound like a logical preposition, given that supplementary feeding is rarely practiced on a large scale in Sahelian Africa.

Returning to the work of Perevolotsky and Seligmanif> in the Mediterranean rangelands—they provide an alternative opinion based on their knowledge of meta-analysis (500 years) of Mediterranean rangelands and grazing systems. They arrive at the following conclusion:

Herbivores rarely denude plants completely, nor are herbivores completely excluded from the community; ... instead, there is ... an intermediate level of dynamic coexistence.... The high resilience of the Old-World Mediterranean rangelands and the persistence of grazing by small ruminants ... over thousands of years is an example of such dynamic coexistence.

Le Houerou and Host39 (in another publication) acknowledge the interdependence between rainfall and rangeland production. Other researchers have supported this view, implying that the dynamic interactions between climate variability and vegetation productivity need to be separated from grazing impacts—and this can be achieved only under experimental conditions.40 The differences of opinions were even more acute regarding African systems of livestock grazing, which the colonial government blamed for land degradation.

The officials appeared to be ignorant of the fact that indigenous land-use systems adeptly set land aside for grazing during different seasons of the year.41 Another colonial misunderstanding was the use of carrying capacity as a measure for controlling stocking of the rangelands, and that this could be a fixed quantity for any particular landscape. In reality, different rangeland landscapes have different carrying capacities, which depend on several variables and refer to specific conditions, including the amount of forage produced, rainfall, soil type and moisture, grazing history, and the daily food intake required by specific species of livestock.42 Accordingly, in a drought year when there is no forage production, the so-called carrying capacity can refer only to residue vegetation from previous seasons, which would be insufficient to sustain livestock. Consequently, the order by colonial officials requiring herders to reduce their herds to correspond with carrying capacity was not a practical solution. Archer4’ is even more blunt when he states, ‘the concept is discussed without evidential support backed by controlled and pre-grazing trials—[and cannot] be applied in a historical study.’

Consequently, the argument by colonial officials for maintaining stocking rates according to carrying capacity was nothing but a myth, considering that there was no livestock census, neither was any rangeland productivity data available. The reality is that the best utilization strategy for such variable rangelands is according to traditional methods employed by African pastoralists. Therefore, if applied to African rangelands, a statement such as ‘when a population is above a system’s carrying capacity, environmental degradation occurs’44 is not factual, since carrying capacities and herd population numbers remained unknown. Thus, it is not an understatement that colonial land-use policies had huge influence on environment impact directly or indirectly.

 
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