Assessing distribution changes of selected native and alien invasive plant species under changing climatic conditions in Nyeri County, Kenya

Abstract

Changes in climatic conditions increases the risks of native and alien taxa expanding in geographical range and causing habitat transformations. The role of climate change in enhancing bio-invasions in local natural environments need to be assessed to guide on effective species management policy formulations. In this present study, we used species presence records, predictor variables and an ensemble of General Circulation Models data to predict suitable ecological niches for five of the selected invasive plant species within Nyeri County, Kenya. We predicted species distributions under RCP2.6, RCP4.5, and RCP8.5 emission scenarios for the years 2050 and 2070. We analysed species distribution changes to identify invasive species requiring immediate management action. Our analysis indicated that three of the five study species were suitable in ~50% of the study area while the other two were suitable in ~30% under the current climate. Lantana camara L. and Solanum campylacanthum Hochst. ex A. Rich species would experience the largest range shift distance of ~6 – 10km and the largest habitat gain of ~12 – 33% in the future. Caesalpinia decapetala (Roth) Alston, Opuntia stricta (Haw.) Haw. and Senna didymobotrya (Fresen.) H.S. Irwin & Barneby species on the other hand would have a decline in habitat range under future climate change scenarios. Although, S. didymobotrya is considered a native species, it would lose half of its current suitable habitat in the future. Range shift analysis showed all study species would generally shift to the north west direction or towards the Aberdare ranges. From this study we conclude that invasive species management programs for smaller geographical areas ought to consider projecting species distributions under climate change scenarios to identify areas with high possible biodiversity changes. This would be important to conservationists when prioritizing management actions of invasive species in the region where data on invasive species is still limited.