Long term vegetation monitoring in the arid Kalahari Gemsbok National Park

In drylands, the detection of trends in vegetation cover and composition is especially challenging. Long-term research and monitoring are crucial to provide important ecological insights and improved management of natural resources. One of the ways of early detection of pattern and rate of directional change is to use pre-existing datasets rather than establishing new monitoring efforts. By using such datasets, results can be produced relatively quickly and at minimal expense.

In the late 1970s the University of Pretoria (UP) began vegetation surveys in the Kalahari Gemsbok National Park. Various study sites were established in the park primarily to monitor vegetation change over time. The study sites were surveyed intermittently over the years as a joint effort between the University of Pretoria and SANParks until 2008. In 2016, SAEON joined this partnership and eight of the original study sites were re-surveyed.

One of the main study focusses was to quantify the effect of artificial watering points on the landscape. Artificial watering points have been provided in the park since the 1930s. The provision of such watering points generally promotes heavy concentrations of animals around the watering point resulting in the degradation of herbaceous vegetation and bush encroachment. This part of the study was aimed at establishing whether encroachment has occurred at and away from artificial watering points over time. A second main area of study was the growth and population dynamics of Vachellia erioloba (Camel thorn), a keystone tree species in the southern Kalahari. This long-term study over nearly four decades tracks two populations in different landscapes i.e. interior sandy dune field versus clayey Nossob riverbed.

The SAEON mandate is to develop and sustain a dynamic South African observation and research network that provides the understanding, based on long-term information, needed to address environmental issues. SANParks primary mandate is the conservation of South Africa’s biodiversity, landscapes and associated heritage assets through a system of national parks. Both these mandates require research to distinguish natural variability from human-induced directional change as well as understand how ecosystems are affected. The synergies between these two organisations are obvious and collaboration enables both parties to efficiently and effectively meet their mandates. This is illustrated by the partnership in the Kalahari between the SANParks and SAEON’s Arid Lands Node.

Picture, from left to right: Drs Hugo Bezuidenhout (SANParks), Helga van der Merwe (SAEON) and Charlene Bissett (SANParks) during resurveying of a belt transect in 2016.