Tradeoffs in the Rehabilitation of a Succulent Karoo Rangeland

Hanke, W., et al., 2015. Land Degradation and Development

Original research (primary data)
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Abstract

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.

Case studies

Basic information

  • Case ID: INT-044-1
  • Intervention type: Restoration
  • Intervention description:

    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.

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Loss of food production  Positive plant cover (%) of palatable species
    Soil erosion  Positive 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.
  • Approach implemented in the field: Yes
  • Specific location:

    Nforthern Succulent Karoo, in the Richtersveld, near the village of Ekst

  • Country: South Africa
  • Habitat/Biome type: Deserts and xeric shrublands |
  • Issue specific term: Not applicable

Evidence

  • Notes on intervention effectivness: effectiveness determined by comparing to control experimental plots
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Other non-NbS approach(s)
  • Compare effectivness?: Yes
  • Compared to the non-NBS approach: Mixed
  • Report greenhouse gas mitigation?: No
  • Impacts on GHG: Not applicable
  • Assess outcomes of the intervention on natural ecosystems: Yes
  • Impacts for the ecosystem: Positive
  • Ecosystem measures: Total plant cover, species richness The impact of the treatment on the cover of functional plant groups
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures:
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: Yes
  • Experimental evalution done: In-situ/field
  • Non-experimental evalution done: Not applicable
  • Study is systematic: