Abstract

Forest cover loss is one of the major challenges facing Kenya; and there is insufficient data to guide sustainable biodiversity conservation stratagems. We determined the floristic and growth characteristics, plant species diversity, evenness, relative density, frequency, dominance, important value index, and indicators of biodiversity disturbance. From the 52 plots sampled in Kiang'ombe and Kianjiru hills, we recorded 472 plant species belonging to 90 families. Plants of the Poaceae family were the most abundant and the most diverse, contributing to 90% of all plant species in the study sites. In terms of growth forms, trees were the commonest, followed by herbs and shrubs, while climbers were the least common in both hills. Besides, Kiang'ombe hill had a higher population of herbs than Kianjiru hill. Besides, the Kiang'ombe hill had a higher species diversity (230 plant species; H’= 5.12) than Kianjiru hill (162 plant species; H’= 4.7). Notably, Vepris glandulosa and Euphorbia friesorum were endangered and vulnerable, respectively. Human activities, especially grazing, threatening plant existence and diversity were observed in the two studied hills. Therefore, the two hills are richly endowed with diverse plant species and are refugia for endemic and vulnerable species which should be conserved.

Key words: Belt transect, Shannon-Wiener diversity index, plant growth form, diversity threats, species diversity, species evenness, relative density, species dominance.