mentioned above, carbon storage in the grassland occurs mostly
below ground and no quantitative data on above-ground biomass
were available for the entire study area.
2.2.1.4. Soil retention. Soil retention is the ability of vegetation
cover to retain soils in order to prevent erosion. Natural vegetation
cover needs to be maintained in areas with high erodibility to
ensure the continuous delivery of the services of land productivity
and to prevent erosion and its consequences such as sedimentation
and eutrophication of nearby rivers. Soil retention is an important
service in the grasslands where cultivation and grazing are major
land uses. Soil retention was mapped as a function of vegetation
cover and soil erosion potential (Egoh et al., 2008). The service of
soil retention is localised and the hotspots are most vulnerable.
Therefore only the soil retention hotspots for the grassland were
considered in this study and extracted from the national dataset
and summarised in ha of soil retention hotspot per quaternary
catchment.
2.2.1.5. Soil accumulation. The accumulation of soil organic matter
is an important process of soil formation which can be negatively
affected by habitat degradation and transformation (de Groot et al.,
2002). Egoh et al. (2008) mapped soil accumulation as a function of
soil depth and litter accumulation for the whole country using data
from Schoeman et al. (2002) and Schulze (2004) respectively. Such
areas, especially the hotspots are key nutrient sinks and needs to be
kept in natural condition. Hotspots of soil accumulation were
extracted from Egoh et al. (2008) for this study and summarised per
quaternary catchment.