Addressing risks to biodiversity arising from a changing climate: The need for ecosystem restoration in the Tana River Basin, Kenya

refugia are concentrated within and around Mount Kenya and Aberdare National Parks in the north of the basin and around some PAs in the delta region. For amphibians, a large area in the east of the basin is also projected to be refugia with these high levels of global temperature rise (S1 Fig). Less than 1% of the basin is projected to act as refugia for all five taxa (S6 Fig). Agriculture is present to some extent in all of the protected areas examined in this research. Over 20% of the land in Imenti or Upper Imenti Forest Reserve, the Tana River Primate Reserve, Kora National Park, Kikuyu Escarpment, Mwea National Reserve, South Kitui National Reserve, Ishaqbini-Hirola Community Conservancy, the Lower Tana Delta Conser- vation Trust and Hanshak-Nyongoro Community Conservancy is identified by remote sens- ing as agricultural land. Proposed land use changes detailed in the GoK’s National Spatial Plan [52] (S8 Fig) will have implications for wildlife and plants, both in terms of current PA management and poten- tial climate refugia. The area in the north of the basin contains most of the high and medium potential agricultural land, as well as large, proposed irrigation areas and a proposed economic growth area. Another area of proposed irrigation land runs next to the river in the lower part of the basin. In total, these activities cover over 36,000 km2 (38% of the basin). Proposed hydropower stations will be situated along the main river, further downstream than the exist- ing hydropower stations. The proposed irrigation area in the upper basin appears to coincide

with these hydropower stations and dams. The Lamu Port-South Sudan-Ethiopia-Transport (LAPSSET) corridor transport and infrastructure project runs along the eastern edge of the Fig 3. Percentage of the Tana River Basin projected to contain refugia with different warming levels. Refugia are areas where at least 75% of the current species richness is able to persist in a changing climate by 11+ GCMs for the five taxa (amphibians, birds, mammals, plants and reptiles) with different global temperature increases. https://doi.org/10.1371/journal.pone.0254879.g003 PLOS ONE Risks to Kenya’s biodiversity from climate change PLOS ONE | https://doi.org/10.1371/journal.pone.0254879 July 21, 2021 8 / 25