Abstract
Savanna is a species-rich biome, that includes many modern mammal lineages and C4 grass (Poaceae) species. The greater productivity and grazing pressure associated with savannas is likely attributable to the foliar traits of the grasses they support. Thus, it is important to understand the complex relationships between the abiotic environment, foliar attributes and the floristic composition of savanna grasses, and the supported grazer densities. We sampled 37 grass communities in the Kruger National Park (South Africa) across three soil types and along a rainfall gradient and found that these communities lack strong phylogenetic structure. We then measured specific leaf area and leaf tensile strength for 384 individuals representing 66 species and found that both traits were strongly phylogenetically structured and associated with both rainfall and soil type. Finally, we found that grazer densities in the Park are correlated with the foliar traits of the associated grass communities, but the resolution of our data do not allow for a thorough analysis of this association. Our results demonstrate the complex interactions between climate, soils and grazer densities relative to C4 grass functional traits.
Highlights
Savanna ecosystems cover around 20% of the global land area and are characterized by both a high diversity of ungulates and C4 grasses (Turpie and Crow 1994; Lehmann and Parr 2016)
At our study site in the Kruger National Park (South Africa), the highest rainfall is around 750 mm in the south of the Park (Holdo et al 2018) and as a result we would expect herbivore biomass to increase as rainfall increases
Our results show that leaf functional traits of 66 grass species from 37 communities distributed across the KNP are associated with both soil type and mean annual precipitation (MAP)
Summary
Savanna ecosystems cover around 20% of the global land area and are characterized by both a high diversity of ungulates and C4 grasses (Turpie and Crow 1994; Lehmann and Parr 2016). These ecosystems are of socioeconomic importance because they support a substantial portion of the world’s population and most of its rangeland and herbivore biomass (Sankaran et al 2005; Scholes and Archer 1997). A potential increase in vegetation biomass is, controlled by a combination of both herbivory and fire to around 700 mm MAP after which fire takes over as the dominant determinant (Sankaran et al 2005; Archibald and Hempson 2016). Presumably because of high precipitation fosters, high grass productivity, and standing biomass (February et al 2013), these conditions promote high fire frequencies (Archibald and Hempson 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
