TAXONOMY, DIVERSITY, STRUCTURE, USES AND THREATS OF PLANT SPECIES IN CHERANGANI FOREST OF ELGEYO MARAKWET, KENYA

Abstract

The pursuit for a local floristic database amidst, uncontrolled resource uses, an alarming rate of forest destruction and loss of species informed the need for a botanical inventory in five blocks of Cherangani forest. Fieldwork was conducted between May 2017 and March 2018 using exploratory surveys guided by transects (20m×20m) located in different plant communities. The purpose was to obtain data on species richness, forest structure, plant uses, and forest disturbance. Botanical work was carried out using standard botanical references and herbarium procedures. Forest structure was categorized by cover % and height of key species found in 50 plots (30m×30m). Ethnobotanical and forest disturbance data was collected using semi-structured questionnaires administered to 100 respondents purposefully selected. Statistical packages for social scientists (SPSS version 2.0), Microsoft Excel and ArcGIS software version 10.2.2 were used to analyse botanical, ethnobotanical, and geospatial data. Sorensen’s similarity coefficient was used to compute beta diversity. Species importance was assessed using relative cultural indices (RCI). Plant families were listed phylogenetically using molecular-based current classification schemes with species listed alphabetically. The report presented the first identification key of the local flora including all plant life forms across families. They included 815 species in 128 and 450 taxonomic families and genera respectively. The study area being the fifth richest in species countrywide was represented by 11% species, 23% families, and 12% genera of Kenyan flora. The novelties included Calceolaria tripartita, Nothoscordum bobornicum and Petunia species as new records for Cherangani, Kenya and probably East Africa. There were 45 species of economic importance and 35 species listed under CITES. Afrocarpus gracillior was the most useful species locally, with encroachment and charcoal burning as the most rampant forms of forest disturbance. The local people recommended alternative income and sources of wood to save the forest. Fourteen vertical forest structures were discerned with blocks reporting a beta similarity of 47.9% in species composition. The study recommended that disturbance levels be checked especially in blocks with species protected under CITES. In addition, species with high RCI should be considered for further analysis to validate local claims and to explore possibilities of commercial exploitation. These findings are expected to reinforce the existing knowledge base, conservation and management of important resources in Cherangani forest.