Mapungubwe Riparian Trees
We have been very forgunate to work with Dr. Tony Swemmer on a project in Mapungubwe National Park since 2012. Mapungubwe is an UNESCO World Heritage site located at the former kingdom of Zimbabwe during the 13th century. Mapungubwe sits at the confluence of the Shashe and Limpopo Rivers bordering South Africa, Botswana, and Zimbabwe.
Map of Mapungubwe. Botswana is west of the Shashe river, Zim to the east, and South Africa is south of the Limpopo. Our sampled trees lie to the east of the confluence
In Mapungubwe National Park, riparian forests along the Limpopo River have contracted, and extensive stands of closed-canopy forest once dominated by Acacia xanthophloea, Faidherbia albida, Ficus sycomorus have been replaced by savanna. Water availability for these forests has changed over time, with altered flow in the Limpopo River. The goal of this research is to understand the spatial and temporal patterns of water-use among these trees.
Source water use using natural abundance stable isotope analysis for determination. R refers to river water, and D refers to soil water beyond 2 m depth.
Our results to date show that the species most suseptible to mortality have a greater reliance on water from unsaturated soils and /or are more suseptible to elephant damage. In addition, we have preliminary data that suggests that expansion of the sub-canopy / small tree Croton megalobotrys (feverberry) may have a novel source-water strategy compared to coexisting tree species. Thus, multiple interacting factors are having species-specific impacts in the Mapungubwe riparian forests, with consequences for habitat availability, hydrology, and biodiversity in this system.
A lone Sycamore Fig on the Limpopo River during the dry season.
Project supported by SAEON-Ndlovu Node
Project PI's:
Dr. Tony Swemmer (SAEON Ndlovu Node)
Dr. Jesse Nippert (Kansas State University)
Our dear friends Louise and Tony Swemmer