Rangeland rehabilitation has multiple, sometimes conflicting goals, such as the reestablishment of the predisturbance vegetation, soil protection, and forage production. The rehabilitation techniques should be also cost-effective and practicable. Given the difficulties and high costs of restoring Succulent Karoo rangelands and the continuously high grazing pressure in the communal lands, tradeoffs should be accepted in the achievement of these goals. We tested the capability of paddock manure redistribution to reverse degradation trends in a heavily grazed Succulent Karoo rangeland in South Africa. Over 3years, the effects of the manure application were compared with areas planted with mature shrubs as a benchmark for a predisturbance vegetation structure and with four popular rehabilitation techniques: (1) livestock exclusion; (2) brushpacking (coverage of dead shrubs); (3) mineral fertilizing; and (4) microcatchment construction. Manure was, besides planting, the only treatment that resulted in a significant increase in drought-resistant vegetation cover, but it compromised the dominance of native vegetation. In the manure plots, a pasture-like vegetation of non-native forage plants (which germinated mainly from seeds in the dung), developed (foremost Atriplex semibaccata). Manure application counteracted erosion as effectively as the planted shrubs and brushpacks. Expected negative side effects such as a decrease in plant species richness or salinization of topsoil were not detected. We also checked the potential of topsoil salinization by the halophytic A. semibaccata and found it to be low. For sites where a decrease in grazing pressure is unrealistic under current land tenure, redistribution of manure should be further explored to mitigate acute symptoms of degradation.
Field experiment - Twenty mature individuals of B. pseudoschlichtianus were transplanted from the surrounding areas to the designated plots and watered for 2 weeks. The transplants were rranged in a regular fashion with at least 2 m between them. Three years after planting, 65% of the transplanted individuals had survived. Transplanting served as a benchmark for the optimum outcome – a vegetation of long-lived shrubs similar to that of nondegraded rangelands.
|Climate change impacts
|Effect of Nbs on CCI
|Loss of food production
|plant cover (%) of palatable species
|Soil erosion (or soil deposition) was measured by metal pins driven into the ground during treatment establishment. One year later, in 2008, after the disturbance of the soil surface, caused by treatment establishment and pin installation, had abated the pin height above soil surface was recorded. The height was remeasured in 2009 and the difference taken as a measure of soil erosion (or deposition) in that year.
Nforthern Succulent Karoo, in the Richtersveld, near the village of Ekst