Experimental plot design
Data were collected within the MOSAIK (Monitoring Savanna Biodiversity
in Kruger National Park) project, which explores the patterns and
interactions among plant, insect, bird, and mammal communities (see
Hejda et al. 2022). Data were collected along a gradient of water
availability and on two types of bedrock. Water supply was accounted for
by locating the plots in three habitats: (i) near a perennial river or
another permanent water source, such as artificial water points or dams,
(ii) near a seasonal river with a lack of water during dry periods, and
(iii) on dry crests, at least 5 km from any source of water (Fig. 1).
These habitats types affect
groundwater availability for
animals as well as soil moisture for deep-rooting perennial species. The
plots were grouped into triplets by habitats, with plots within the
triplet being closer to each other (~ 7–13 km apart)
than to other plots outside the triplet. The plots were located on two
contrasting bedrocks, basalt and granite, which weather into soils that
differ in nutrients, water retention capacity, and texture (Venter et
al. 2003, Mucina and Rutherford 2006). We established 60 permanent plots
50 × 50 meters that were equally distributed among the three habitats
(20 in each) and two bedrocks (30 in each) (Fig. 2). As we focused on
the shrubby savanna, we placed our plots outside the riparian gallery
forests, and the presence of trees in the plots was generally very low
if any.