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Vaalbos monitoring reinforced the long-term partnership between SAEON’s Arid Lands Node and SANParks
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Semi-arid rangelands of southern Africa support a vast array of wildlife and are particularly important for livestock production.
Therefore, understanding the long-term dynamics of semi-arid savanna is essential in developing and implementing successful management practices.
In order to assess the primary determinants of arid savanna ecosystems, consistent long-term data on rainfall patterns, fire regime and grazing pressure will help us to model and describe how changes occur, and what drives such fluctuations.
It has been well documented that vegetation changes in the savanna are mainly influenced by rainfall. Rainfall intensity and timing affect species abundance and diversity that often result in shifts in composition of palatable and unpalatable species. Secondary elements that can also transform the structure of arid rangelands include the combination of nutrient availability, fire and herbivory.
SAEON/SANParks partnership
The partnership between SAEON’s Arid Lands Node and SANParks Scientific Services goes back nearly a decade to when the node first established an office in Kimberley. The initial aim of the partnership was to continue monitoring existing sites, establish new projects and promote the use and incorporation of data output generated from collaborative research projects.
The benefits of this partnership include sharing a laboratory and research equipment, open access to the herbarium and the exchange of scientific ideas. The relationship was reinforced in 2011 when the two institutions collaborated on a project to resurvey the de-proclaimed Vaalbos National Park .
The park was named after the dominant Camphor Bush (Tarchonanthus camphoratus) or regional Afrikaans name “vaalbos” in the area.
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Two decades of vegetation monitoring
SANParks initiated vegetation monitoring at Vaalbos in April 1993. Surveys were interrupted due to a land claim and the subsequent deproclamation of the park, resulting in gaps between surveys. Upon opening its doors, SAEON’s Arid Lands Node continued the monitoring in collaboration with SANParks until 2017, after which mining operations prevented further research activities at the site.
The monitoring team used the wheelpoint technique for herbaceous species and the belt transects method for woody species across 11 vegetation communities. The results show that over the 20-year study period, no change was detected in the density of woody species. This was also supported by repeated photographs.
The team’s analyses indicated that the amount of rainfall experienced during early or late summer of the current or preceding season was the most important determinant of change for most of the perennial grasses, with details of responses depending on soil-water storage capacity and the phenological characteristics of the species.
Not only does the Vaalbos experience demonstrate the good collaboration between SAEON and SANParks, but also entailed excellent collaboration within SAEON, starting with Yolandi Els and field technicians Iain Olivier and Tshililo Ramaswiela at the outset, continuing with Tshililo, field technician Marco Pauw and node manager Joh Henschel, and finally also involving SAEON’s observation science specialist Tim O’Connor in the analyses, working closely with the SANParks team, Hugo Bezuidenhout and Judith Botha, who represented the continuity over the 22-year study period.
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