Influence of Impala (Aepyceros melampus) Dung Midden on Grass Species Composition and Soil Chemical Properties in Nyakasanga Hunting Area, Zimbabwe

Herbivory and nutrients are major ecosystem drivers in African tropical savanna. We studied the effects of Impala (Aepyceros melampus) dung midden on some selected soil properties and grass species diversity in Nyakasanga Hunting Area. The main objective of the study was to measure nutrient concentrations and grass species diversity on impala dung midden and nondung midden. A purposive sampling technique was used to select grass and soil sampling points. Ten (10) sample sites in mopane woodland (wet season) and eight (8) from the floodplain (dry season) were sampled for vegetation and soil attributes. The titrimetric method using ferrous sulphate was used to test soil organic carbon and other chemical properties were determined by the atomic absorption spectrophotometer.
Differences in soil chemical properties and vegetation diversity between two strata were tested using a student’s t-test. There were significant differences (t(10)=2.291, p=0.002, F=10.20) between the soil pH, ExCa, ExMg, ExK, TEB, CEC, ESP and Organic carbon of non-dung and dung sites samples in both wet and dry seasons. We recorded higher concentration of soil nutrients on dung middens sites as compared to non-dung sites and marked differences were statistically tested. We used the bottom-up approach to explain our findings.
Our Canonical Correspondence Analysis (CCA) output showed associations between some grass species and soil chemical properties. Dung middens are important patches in savanna ecosystems they help to recharge and improve soil fertility and are hotspots of diverse grass species.