Effect of scattered tree species on the diversity, abundance and biomass of pastures in a sedentary grazing system in South-western Uganda

Abstract

Tree species play a significant role in sustaining the productivity of grazing lands. However, information on appropriate species to use in restoring degraded grazing areas is limited. This study used 120 trees to assess the effect of 8 tree species on pasture diversity, abundance and biomass. This was done in a total of 960 quadrats of 1 m 2 established under tree canopies and 5 m away from the edge of tree canopies. In each quadrat, the different pasture species and their ground cover were recorded. The pastures were harvested, weighed and their biomass recorded. Results of analysis by Shannon-Wiener's index indicated that pasture diversity was almost the same under and outside tree canopies (H = 1.8 and H = 1.78 respectively), but pasture abundance was significantly higher under tree canopies (p < 0.05). Ficus natalensis and Albizia coriaria had the highest pasture abundance under their canopies. Pasture biomass never varied significantly under and outside tree canopies but between tree species, F. natalensis had a significantly higher positive influence on pasture biomass than other species. It was discovered that F. natalensis and A. coriaria have a higher potential for restoring degraded grazing areas in Southwestern Uganda.