The effects of illegal anthropogenic activities on the vegetation community structure in the western Rungwe mountain forest reserve, Tanzania

It was assessed the effects of illegal anthropogenic activities on the vegetation community structure in western Rungwe Mountain Forest Reserve. Nested sampling technique was used to collect data in the field. A total of 99 plant species distributed among 47 families were identified where the dominant families were Rubiaceae, Poaceae, Euphorbiaceae, Asteraceae and Leguminosae. The moderately disturbed site had significantly higher species richness, diversity and evenness than the least and highly disturbed sites and hence concurs with the intermediate disturbance hypothesis. TWINSPAN, two vegetation communities were identified based on anthropogenic disturbance. Community A included samples from least to moderately disturbed area and B was from the highly disturbed area. The difference in density of trees among disturbance levels was obvious that a total of 567 stems/ha was recorded in the least disturbed, 810 stems /ha in the moderate disturbed site and 83 stems/ha in the highly disturbed sites. The diameter size class distribution pattern displayed an inverted J shape which indicates an active regeneration. The least disturbed site had many individuals with DBH ranging from 19 to 57 cm, moderately disturbed sites from 10-47 cm and highly disturbed site had 11-14 cm. It can be concluded from this study that charcoal cutting, firewood cutting, clearance for cultivation, pole cutting and burning were anthropogenic activities that have significant effects on forest structure and plant species composition.