Doctoral Dissertation Research: Characterizing Land-Management Impacts on Ecosystem Structure in the Botswana Central Kalahari

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Arid and semi-arid savanna ecosystems are globally significant and are an important element of the Earth system due to their major role in land-atmosphere energy balance as well as carbon and nutrient cycles. They are essential contributors to both productivity and biodiversity, especially in southern Africa, where they support high populations of economically critical domesticated livestock, some of the largest expanses of protected wildlife habitats, and wildlife-based tourism. Recent changes in land-use pressure, altered fire regimes, and climatic shifts have led to large-scale changes in the vegetation structural and functional attributes of xeric systems, which have important implications for both biogeochemical processes and the availability of habitat-related key structural resources, such as solitary nesting trees, foraging grounds, breeding zones, hiding places, and safe migration routes. This doctoral dissertation research project will focus on the semi-arid savanna system in the central Kalahari, Botswana, in order to examine the differential impacts of three dominant land-management strategies (protected areas, game ranching, and open access/cattle ranching) on ecosystem structure and function. The doctoral student will build on field-based data collection and subsequent analysis of areas within the Central Kalahari Game Reserve (CKGR) to extend sampling to neighboring and similar systems outside the reserve. He will use a bottom-up hierarchical approach to integrate field-derived vegetation measurements with spatio-temporally coincident data from high- and medium-resolution satellite imagery to quantify the vegetation and soil characteristics. Estimates derived from analysis of high-resolution imagery will be used to validate the estimates derived from spectral mixture analysis of medium-resolution imagery across the central Kalahari. To better understand the spatial heterogeneity of savanna systems, fractional estimates will be combined with other topographic and spectral variables representing slope, aspect, elevation, soil moisture and vegetative productivity) to map physiographic-physiognomic landscape units. Fractional cover and landscape units will be integrated and then parsed into the three land management designations to comparatively assess their impacts on savanna ecosystem structure in the central Kalahari.The results of this project will help to fill a void in the scholarly literature of savanna ecology, where structure assessments typically are conducted either remotely or in the field but rarely are integrated into a cohesive multi-scale sampling strategy. The project will generate both field- and satellite-derived ecosystem variables and test new research methodologies in an understudied and remote area that is functionally similar to savanna systems globally. Project results will be provided to wildlife, park, and agriculture government authorities, local researchers, ranching associations, and rural administrative district officers, thus facilitating the integration of lessons learned at this locale into the practice of rangeland ecology and conservation management. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.