Vegetation Changes Following Large-scale Fence Removal Across a Protected Area Network Within the Kruger to Canyons Biosphere Reserve, South Africa

Abstract

In the early 1990’s, reserves adjacent to Kruger National Park (KNP) removed their fences to create a continuous landscape within the Kruger to Canyons Biosphere Reserve. Understanding how these interconnected multi-management systems responded to changes in environmental factors and management regimes can help to maintain natural large-scale landscape heterogeneity and ecological resilience. Our objective was to analyze remote sensing-derived vegetation metric changes between the different management types pre- and post-fence removal. The study area included fourteen reserves and the central section of KNP. We calculated the residuals between TIMESAT-derived metrics (from AVHRR NDVI time series) and rainfall to analyze changes in vegetation from 1985 to 2006. We then compared vegetation-rainfall residuals between different management types pre- and post-fence removal using mean–variance plots, nonmetric multidimensional scaling plots, and permutational multivariate analysis of variance to statistically identify and analyze changes. All management types experienced increased greenness. Reserves that removed their fences had greater changes in vegetation post-fence removal compared to reserves that remained fenced and KNP. Our findings suggest managers may need to address landscape changes by implementing management regimes such as reducing artificial surface water to counterbalance increased grazing pressure as a result of increased animal mobility across artificially created resource gradients. Habitat connectivity within and between protected area networks can be achieved by removing fences across adjacent conservation areas thus potentially increasing ecological resilience, which is vital to effective long-term conservation.