A systematic conservation assessment of habitat transformation and degradation in the Little Karoo, South Africa

Master Thesis


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University of Cape Town

This study focuses on the state of the environment of the Little Karoo and is comprised of three main analyses. In the first analysis, a fine-scale vegetation map of the Little Karoo (Vlok et aI., 2005) comprised of 369 vegetation units and 56 habitats within 6 biomes (or sub-units of a biome) was linked to a degradation map (Thompson et al., 2005) of the region. Using these data sets the extent of transformation and degradation with the major biomes, habitat units and vegetation units in the Little Karoo was quantified. The results were then compared with previous assessments of degradation in the area. In the second analysis, the output from the quantification of degradation was used to develop a map of the ecosystem status of the Little Karoo within four classes (Critically Endangered, Endangered, Vulnerable and Least Threatened). Conservation targets were modified according to the number of species and degree of endemism within each vegetation unit. Finally, using long-term climate and agricultural census records, the historic causes of degradation in the region were also investigated. The results indicate that 53.4% of the habitat units are moderately degraded with 14.1 % considered severely degraded. The Succulent Karoo biome, Azonal habitats and Thicket biome are particularly affected by degradation. When comparing the results of this study to those of the South African National Land cover assessment, it appears that the extent of degradation in the Little Karoo has been substantially under-estimated in the past. In terms of ecosystem status it was found that of the 369 vegetation units mapped 26 (7.1 %) were classified as Critically Endangered 58 (15.7 %) Endangered, 67 (18.2 %) Vulnerable and 218 (59.1 %) Least Threatened. The Succulent Karoo has the highest number (13) of Critically Endangered vegetation units in the study area. An analysis of climate data of the study area did not show any statistically significant long-term changes in rainfall and temperature except for Ladismith which has experienced a decline in rainfall and increase in mean annual minimum temperature over the last fifty years. Lucerne is the dominant crop in the region and its production has increased. There has been a general decline in goat numbers but an increase in sheep and ostriches over the last 100 years. It is concluded that anthropogenic forces underline the changes that have taken place in the Little Karoo especially, grazing by domestic livestock, ostrich farming and lucerne cultivation.

Includes abstract.

Includes bibliographical references (leaves 71-81).