Assessment of Vegetation Changes in Kilombe Caldera, Baringo County Kenya; Inferences From Micro-botanical Remains and Current Vegetation

Abstract

Human and climate changes have played a great role in shaping the present vegetation and impacting the paleo environments. This study explored the effects of climate change and anthropogenic activities in Kilombe caldera, Baringo County, Kenya. The specific objectives of this study were to; determine the past vegetation in the caldera, determine the current vegetation composition and distribution within the caldera, and third to infer the impacts of climates and human activities on vegetation. A multiproxy analysis using plants micro-botanical remains (pollen, phytoliths, and charcoal) was adopted to reconstruct the past vegetation. A total of 42 sediments samples, collected from a pit suitably selected on a flood plain within the caldera, were processed using specific acids /alkali for clear visualization on the microscope. The paleo data analysis was done using Tilia program and Cluster analysis. Current vegetation was sampled using stratified random sampling method in 9 transects from 25 plots within the caldera. All plants species were identified, tallied, and recorded. Species diversity were analysed as well as species spatial distribution. Species distribution along environmental gradient within the 9 transects was determined at different elevations taken at the beginning and at the end of each transect was. The paleo data results indicate past existence of a dry montane forest, comprising of montane tree taxa such as Juniperus, Morella, Podocarpus, among others. Shrubs and herbaceous taxa were represented by species such as Amaranthaceae, and Brassicaceae while aquatics were represented by species such as Hygrophilia, Sedges, and Typha. In contrast, the current vegetation data showed a gradual succession from primary to secondary vegetation where a total of 127 plant species were documented from 50 families. A few plant species that were documented in the paleo data were not found in the current vegetation e.g. Morella. Similarly, some plant species that were represented in the current vegetation were not represented in the paleo data for example Diospyros abyssinica and Flacourtia indica. Consequently, some species were over represented in the current vegetation for example Dodonaeae viscosa and Tarchonanthus camphrotus. Analysis of the phytoliths and pollen indicated that prior to the advent of human settlements, there existed in the past a relatively open woodland with forest trees species. The abundant assemblages of grass phytoliths of Pooideae, Panicoideae and Chloridoideae encountered in the sediment samples indicated the existence of a cool /warm temperate past environment in that part of Baringo County. The main drivers of land cover changes in the caldera were past patterns of climate variability, past incidences of fire and human activities, especially livestock keeping, crop cultivation and utilization of woody plant biomass. Human activities were reflected in the paleodata by the presence of the cereals evidenced in phytoliths data, and pollen grains such as Amaranthaceae, Asteraceae, and Zea mays. This research demonstrated the existence of a long-term climate driven changes as well as human-mediated changes through use of rapid fire that have shaped the existing vegetation in the Kilombe caldera. However, a more detailed study is still required to establish the full impacts of anthropogenic activities on ecologically and economically important plant families and species that may have disappeared from the caldera.