Floristic And Ethnobotanical Study Of Tharaka-Nithi County,Kenya

Tharaka-Nithi County is located in the central and eastern part of Kenya.The county has great attitudinal ranges of 600 m to 5200 m a.s.l.and hosts a wide range of ecosystems and biomes spanning from montane forest to vast deciduous dryland forests characterized by scrub and wooded bushlands and grasslands.Despite the natural biodiversity in this region being diverse,it is threatened by climate change and anthropogenic activities.Additionally,the background floristic knowledge for Tharaka-Nithi County is lacking:threatened status for most species has been not assessed,and the vast ethnobotanical knowledge has also not been systematically investigated and documented.Based on the literature,specimens,online databases,and extensive field investigations,this study provides the first vascular plant checklist of Tharaka-Nithi County.The field investigation was conducted in both dry and rainy season from May 2018 to February 2019,covering all the forests of Tharaka-Nithi.This study analyzed the diversity of families,genera and life forms according to the latest checklist.It also used Vegan and Picante packages in the statistical software R to analyze altitude affinities.According to all data available,there are currently 820 known vascular plant species in a total of 487 genera and 134 families in Tharaka-Nithi County,including 26 species endemic to Kenya and 10 species endemic to the county.In addition,Sauromatum venosum(Dryand.ex Aiton)Kunth,Zehneria longiflora G.W.Hu&Q.F.Wang,and Alectra parasitica A.Rich.are new records for the county recorded during the field investigation.Statistics of life forms showed that the herbaceous plants are the most abundant(33%),followed by trees(29%)and shrubs(25%).For the distribution patterns of plant diversity,species affinity analysis showed the highest species richness at 1000-2000 m a.s.l.According to the current progress of IUCN assessment,most species in this region have not been assessed(80%),and 1.6%of the assessed species are worrisome,most are endemic to the region,including four(4)endangered(EU)and nine(9)vulnerable(VU)species.Based on the distribution characteristics of endangered species,this study proposed two localities with the highest concentration of endemic species in Tharaka Nithi County,whose priority for protection is also the highest.The two localities are the Chogoria montane forest in Mount Kenya and the Kijege hills on the drylands.A systematic ethnobotany investigation was also carried out in Tharaka-Nithi County.Through semi-structured interviews with key informants and targeted field collection in local forests and hills,this study obtained a total of 214 species with 616 indications of utilization,of which trees are the main type of plant life,and species from Leguminosae are the most abundant and widely distributed.This study provides the first systematic vascular plant checklist and comprehensive ethnobotanical study for Tharaka-Nithi County and lays a foundation for further floristic investigation,use,and conservation of plant resources in the future,as well as contributing to the ongoing Flora of Kenya project.