Ecological and ethnobotanical analyses for forest restoration in the Taita Hills, Kenya.

摘要

The Taita Hills in southeast Kenya form the most northern part of the Eastern Arc Mountains, which is one of 25 globally recognized biodiversity ‘hotspots’ because of its high species richness, number of endemics and potentially threatened status by human activities. The underlying causes of deforestation in Taita Hills are complex, being a net result of external and local factors. Realizing the need to address forest biodiversity conservation in a manner sensitive to the historical context, environmental conditions, and the resource needs of the Taita people, I carried out an ecological and ethnobotanical study in two closed canopy forests, Ngangao (92 ha) and Mbololo (200 ha). The three objectives of the research were: (1) undertake plant community analyses and determine vegetation relationships with environmental conditions; (2) describe and quantify the value of forest resources to the local communities through participatory ethnobotanical research and examine the size class abundances of valued resources; and (3) identify adaptive management options for forest restoration across the Taita Hills landscape.; During June–November 1999 and June–August 2000, I established 57, 0.1 ha plots in the study forests to describe the plant communities. Sorensen's community coefficients indicate over 68% compositional similarities within and across the forests. Species composition of the forests is highly modified from early resource extraction, the dominant species being fast growing, broadly distributed pioneer species. Plant community analyses using Detrended Correspondence Analysis (DCA) and Two Way Indicator Species Analysis (TWINSPAN) based on relative importance values of species failed to identify distinguishable plant communities. In both forests, weak vegetation and environmental relationships were identified using Canonical Correspondence analysis (CCA). The ethnobotanical study documented that the forest provides firewood, construction materials, medicines, crafts and food.; By synthesizing data from multiple perspectives that include historical, ecological and ethnobotanical, I propose a forest restoration program for the Taita Hills landscape. I identify sites and thirteen species for forest restoration based on the spatial distribution of endemic, rare and locally important forest resources, their relationships with environmental conditions, and their regeneration status. The enrichment of aging exotic plantations within forest reserves presents the most significant mechanism of increasing overall indigenous forest cover in the Taita Hills landscape. Agroforestry practices that incorporate indigenous species outside of forest reserves presents a mechanism of conserving elements of forest biodiversity within individually owned land parcels.