Comparison of tree species diversity in highly degraded and moderately exploited parts of west Bugwe central forest reserve Uganda.

Abstract

West Bugwe CFR was heavily degraded through uncontrolled harvesting of timber, firewood, poles, charcoal burning, grazing and agricultural encroachment. There is natural regeneration in the CFR under NFA. However, the CFR continue to provide the function of protection of watersheds, biodiversity and soils and the local communities continue to harvest firewood and poles for domestic use. The aim of this research is to assess the impact of deforestation on diversity and distribution of tree species in West Bugwe central Forest reserve, identify the dominant tree species in West Bugwe central Forest Reserve, determine tree species evenness in WBCFR, using Diversity index, Shannon Weiner diversity index, field measurements to determine Woody species composition in the forest reserve and Shannon equitability for evenness distribution of tree species. Trees species diversity, richness, and evenness were studied in fourteen plots of West Bugwe CFR, based on trees inventories conducted on fourteen plots of 0.09 ha installed in two zones of the forest that were highly degraded zone and the moderately degraded forest zone. In all of the plots installed, all trees with diameter at breast height, DBH ≥ 5 cm (Ifo et al., 2016) were measured. The Shannon diversity index, Simpson diversity index and equitability index were computed to see the variation in tree species among plots but also between the highly degraded forest area and the moderately exploited forest area. A total of 847 trees and 711 saplings representing 32 tree species were identified from the total area of 1.26 ha. A total of 576 trees were identified from moderately exploited area while 271 trees were recorded from the 7 plots of highly degraded area of West Bugwe CFR. In terms of the number of trees, Broussonetia papyrifera was the most abundant with 294 trees encountered followed by Trema orientalis with 179 individuals each. The least abundant species were Ficus sycomorus (11). A low Shannon diversity index value was obtained in plot 1 while the highest value was obtained from sample plot 6. The evenness index values varied between 0.728(sample 1) and 0.943 (sample 6). The value of equitability varied from 0 to 1. It’s equal to 1 when all the species have the same abundance and tend towards 0 when the near total of flora is concentrated on only one species. The value in sample plot 1 and 2 confirms a well conducted survey in the plot as they are dominated by two species of Trema orientalis and Broussonentia papyrifera (Boniface & Yamungu, 2020). Species diversity was higher in the moderately exploited forest area and least in the heavily degraded forest area. Knowledge of how deforestation influences tree species composition and diversity and the impact of deforestation on the environment is very important for designing the appropriate restoration and other management strategies of WBCFR by the policy makers and locals’ in conservation of tree species biodiversity of the forest reserve.