Herbivore browse utilisation and selection in the Kazuma Forest Reserve, Northern Botswana

Herbivore browsing can influence the structure, composition, and processes of an ecosystem, and its effects can cascade to other functional components, especially when coupled with other disturbances. Ungulate browsing is not random, as it can be influenced by various biophysical factors. This study assessed overall herbivore browse utilisation in the Kazuma Forest Reserve (KFR) in the Chobe District of Northern Botswana at two scales of aggregation: vegetation class and study area. Vegetation of the KFR can be divided into three broad classes: shrubland vegetation, grassland vegetation, and woodland vegetation from which 23 sampling plots were selected. In each sampling plot, browsed and unbrowsed terminal shoots of all woody species were counted, from which browse utilisation and selection were determined. In total, 46 woody species were recorded in the KFR. The Sorenson Similarity Index reveals a weak overlap in species composition across the three vegetation classes of the KFR. Overall proportionate browse utilisation by the herbivore community of the KFR was influenced by vegetation type, whereas selection was not. Utilisation of most woody species was low, and few species were preferentially browsed by the KFR herbivore community. Both woody species utilisation and selection were not consistent across the two scales of aggregation. Woodland vegetation, on nutrient-poor Kalahari Sands, was associated with the least and highest proportion of browsed and unbrowsed woody species, respectively. However, even low browsing pressure can effect notable changes in ecosystem structure, composition, and hence function. The results of this study did not find any effect of predation risk on browse utilisation or selection across the three vegetation classes of the KFR. In conclusion, this study has laid a benchmark for future monitoring of browsing pressure and changes in wood species community structure in the KFR. It recommends further research to assess the effect of environmental and biological factors on browse utilisation and selection in the KFR.