Influence of abandoned cattle enclosures on plant assemblages and herbivory in a semi-arid savanna

In semi-arid savannas, abandoned cattle (Bos taurus) enclosures or kraals have been demonstrated to be nutrient-hotspots for large herbivores. In this study, we examined the interaction between herbivory and forage quality, structure and diversity at 12 kraals (abandoned for 22 years) paired with savanna control plots in Save Valley Conservancy, Zimbabwe. Plant diversity was not different between sites. Herbaceous cover was higher and woody species density lower on abandoned kraals than control plots. Furthermore, abandoned kraals had higher herbaceous productivity and foliar nutrient concentration for grasses than forbs. The abandoned kraals had higher concentration of soil nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), organic carbon (C) compared with control plots and a slightly acidic pH. Grasses were grazed more than forbs on nutrient-rich abandoned kraals. Only herbaceous biomass for grasses had a significant influence on the interaction between plants and herbivory. No clear relationships were observed between forage quality and herbivory and plant species diversity. Abandoned kraals provide patches of nutrient-rich forage, increasing savanna heterogeneity and in turn influence grazing patterns of large herbivores, and therefore influence ecosystem functioning. A conservation monitoring programme is recommended on such nutrient-rich patches as they serve as foraging-hotspots for herbivores in a dystrophic African semi-arid savanna.