Abstract:Our study investigated the influence of termitaria on vegetation utilization by elephants in Chewore North, Zimbabwe. Ten termite mounds and ten similar sized control plots were surveyed for soil nutrients, tree species diversity and plant biomass removal by elephants. Termite mounds had higher mean (± SE) concentrations of P, Ca, Mg and Na (0.15 ± 0.01, 48.8 ± 9.32, 5.78 ± 1.59 and 0.47 ± 0.12 meq per 100 g respectively) than control plots (0.05 ± 0.01, 3.33 ± 0.56, 1.53 ± 0.22 and 0.19 ± 0.02 meq per 100 g). However, Shannon Wiener index of tree diversity did not vary significantly between termite mounds (1.13 ± 0.280) and their control plots (0.827 ± 0.469). Contrary to most studies investigating patterns of vegetation utilization by large mammalian herbivores on termitaria, biomass removal was five times more on control plots than termite mounds. No difference in biomass removal was noted for Colophospermum mopane which had enough replicates for statistical analysis both on termite mounds and control plots. Our study negates the hypothesis that nutrient-rich soil patches will act as feeding hotspots for large mammalian herbivores. We concluded that vegetation utilization by elephants may be tree species specific, particularly in nutrient-rich environments.
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.
Zimbabwe is experiencing a shift in land‐use, away from livestock farming and towards wildlife conservation. The abandonment of livestock farming may have unforeseen consequences on biodiversity and ecosystem functioning, as cattle kraals create valuable nutrient‐rich patches across the semi‐arid savannah. It is unclear how macroinvertebrates functionally respond to such nutrient‐rich patches in semi‐arid savannahs. We analysed functional diversity of both aboveground and belowground taxa on abandoned cattle kraals and savannah control plots in Save valley Conservancy (SVC). We used distance‐based multivariate techniques to estimate indices of functional diversity. Our results indicated that after two decades of abandonment, kraals had higher functional richness (FRic), functional divergence (FDiv) and functional dispersion (FDis) of macroinvertebrates when both aboveground and belowground species are combined. When aboveground macroinvertebrates were considered alone, no difference was observed for all the considered functional indices. However, only FRic was higher on kraals when belowground macroinvertebrates were separately considered. Our results suggest that two‐decade‐old abandoned kraals may have recovered enough for aboveground species to match the surrounding savannah plot and even surpassed the savannah control for belowground species functional diversity.
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