Influence of hydrological fluctuations on vegetation and Avifauna species composition, abundance and diversity in the Bahi Swamp wetlands Central Tanzania

Abstract

This study was conducted in Bahi wetlands to assess the influence of  hydrological fluctuations on the vegetation and avifauna species  composition, abundance and diversity. A total of 80 rectangular vegetation plots measuring 2m x 5m were established along transect lines radiating from the core wetland, along eight cardinal directions each transect having a length of 1200m and accommodating 10 sampling points. Avifauna  species were inventoried in 3 points along each transect making a total of 24 sampling points for birds. One-way ANOVA was performed to  test for significant differences in the avifauna species diversity along the  hydrological gradient. A total of 40 avifauna species and 56 plant species belonging to 18 and 7 families respectively were recorded. There were  significant differences (p<0.05) in avifauna and plant species composition, abundance and diversity between distances from the centre of the wetland. Avifauna species abundance and diversity decreased with increasing   distance from centre of the wetland. Likewise, the abundance of plant species decreased with increasing distance from the centre of the wetland. The flora and avifauna species composition, abundance and diversity in the
Bahi wetlands are influenced by hydrological fluctuations, whereby the  composition, abundance and diversity are higher closer to the wetland than away from the edge of the wetland. The vegetation of wetland is  dominated by Leersia hexandra and other members of the Graminae  family. Bahi wetland is a refuge for migratory avifauna species. It was observed that both distant and African migrants visit the wetland for wintering. The most abundant species were Greater Flamingoes and Red Knobbed Coot. Awareness and education on the biodiversity values of the wetland is needed to influence conservation and sustainable utilization of  the wetland resources.