Quantifying the effectiveness of private land conservation areas in preventing losses of natural land cover and biodiversity intactness across South Africa

Author(s): Tafadzwa Shumba
Link to CST author(s): Tafadzwa Shumba
Publication: Stellenbosch University
Year: 2019
Full reference: Shumba, T. 2019. Quantifying the effectiveness of private land conservation areas in preventing losses of natural land cover and biodiversity intactness across South Africa. Stellenbosch University
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Global biodiversity conservation targets cannot be achieved by relying on state-owned protected areas (PAs) alone. Private land conservation areas (PLCAs) are one potential complementary conservation strategy. However, despite their increasing extent and recognition, little is known about their effectiveness in conserving biodiversity, or how different environmental and social-ecological factors influence their effectiveness. In South Africa, a long history of conservation on PLCAs and the diverse PLCA models provide an interesting case study to address this knowledge gap. The effectiveness of PLCAs across South Africa, and factors influencing their effectiveness, were thus quantified using losses in natural land cover (NLC) and the biodiversity intactness index (BII) as proxies. NLC was based on 1990 and 2013 national land cover maps, while BII represented a measure of the percentage of major taxa that can persist in an area given different land use scenarios. Points within PLCAs were matched with unprotected control points to test the prediction that if PLCAs offer effective protection, losses in NLC and BII would be significantly lower within their boundaries in comparison to unprotected controls exposed to similar conditions. NLC and BII losses were then compared across different types of PLCAs, with the hypothesis that legally protected PLCAs would be more effective than the informal ones. Of particular interest was also how different factors influenced the effectiveness of PLCAs in preventing losses of NLC and BII. In that regard accessibility (distance to road, distance to town, elevation and slope), rainfall, age and size of PLCAs were considered as explanatory variables. There were significant differences in losses in NLC and BII between PLCAs and matched unprotected areas. PLCAs lost 3% NLC and 2% BII between 1990 and 2013, while unprotected areas lost 6% NLC and 4% BII. These findings indicate the relative effectiveness of PLCAs, and provide insight into the implications of NLC loss on biodiversity intactness, thus advancing standard approaches for quantifying PA effectiveness. There were also significant differences in losses of NLC and BII between different types of PLCAs. However, contrary to the hypothesis, effectiveness did not depend on legal protection, as informal PLCAs were relatively more effective than some of the formally protected ones. NLC and BII losses were likely to occur at points within PLCAs that were closer to towns, further from roads, with low elevation, gentle slopes, within small and old PLCAs, and with low rainfall. This supports research on state-owned PAs, in which highly accessible areas were shown to be less effective due to higher human pressure. This study provides evidence that PLCAs are relatively effective, which is highly relevant given current discussions around their inclusion towards biodiversity targets. The study also highlights how different factors influence the effectiveness of PLCAs, which has important implications on where best to establish future PLCAs and how different management strategies and policies can be better placed to facilitate biodiversity conservation within PLCAs. The study contributes to the growing body of knowledge about PLCAs as a complementary biodiversity conservation strategy worth considering, which future studies can build upon.