Modeling of the Impact of Climate Change on Herbivores Distribution in the Savanna Ecosystems, a Case Study of Amboseli Ecosystem, Kajiado County, Kenya

Abstract

For years, conservationists have been captivated by the existence of many species of large herbivores in grasslands and savannas. However, climate changes manifested through increasing land temperatures and changing rainfall regimes increasingly threaten the distribution of large herbivores. There is a developing understanding of the significance of including environmental change scenarios in management planning and actions, yet this is lacking in numerous frameworks. The main objective of this study was to investigate the potential impact of climate change and variability on herbivore distribution in the Amboseli ecosystem. Trends of rainfall and temperature were examined based on historical Climate Hazards Group InfraRed Precipitation with Station (CHIRPs) and Climate Hazards Group Infrared Temperature with Station (CHIRTs) data for 1960 - 2014 and the period 2006-2100 for the projections. The projections data were from the regional climate models from the Coordinated Regional Downscaling Experiment (CORDEX). Analysis of long-term annual and seasonal rainfall trends and temperature were done using quadratic and linear trend analysis. The range maps of herbivores were developed from aerial censuses conducted in the study area from 1977 to 2014. Future distributions were done based on temperature thresholds for each of the fifteen species for the 2030s, 2050s, and 2070s. The results show that the annual and seasonal rainfall declined slightly between 1960 and 2014. On the contrary, the annual minimum temperatures increased by 1.23 °C and the maximum by 0.79 °C. There was a variation in projected rainfall with RCP 2.6, indicating a decline for the four seasons and a marginal increase in annual and October-November-December (OND) with decreases in the March-April-May (MAM) and June-July-August-September (JJAS) for RCP 4.5 and 8.5. Projected maximum and minimum temperature for RCP 2.6 show increments of less than 1°C, while for RCP 4.5, the maximum range is between 0.57 °C and 1.85 °C, and the minimum is between 0.51 °C to 1.98 °C. RCP 8.5 indicated the most significant increment in maximum temperature between 1.11°C and 4.34 °C and a minimum temperature between 1.34 °C and 5.26 °C for the 2030s, 2050s, and 2070s. Range analysis showed that the increasing temperatures would lead to a contraction in the range size of most herbivores. According to the findings, 3 out of 15 species will lose more than half of their range by the 2030s, 5 out of 15 by the 2050s, and 4 out of 15 by the 2070s under RCP 2.6. According to the RCP 4.5 climate change scenario, three species would lose more than half of their range by 2030, and five will lose more than half by 2050 and 2070. Finally, based on the RCP 8.5 scenario, five species will lose 50% of their range in the 2030s, seven species in the 2050s, and xi ten species in the 2070s. The level of range loss varied by species, but it was most severe for water-dependent species such as buffalo, Thomson's gazelle, waterbuck, and wildebeest. The elephant, gerenuk, hartebeest, lesser kudu, and oryx, on the other hand, are anticipated to maintain the majority of their range in all RCP scenarios. Further investigation into the relationship between elephant population and rainfall revealed a robust linear relationship between the elephant population and OND's historical seasonal rainfall over 13 years. Under RCP 2.6 and 4.5, annual rainfall increased marginally, but RCP 8.5 indicated a significant rise. The Amboseli ecosystem's anticipated elephant population was influenced by rainfall fluctuation. The elephant population increased by 2455 and 2814 elephants in RCPs 2.6 and 4.5, respectively, whereas RCP 8.5 recorded an average of 3348 elephants. The community's perspectives were determined through a survey, key informant interviews, and stakeholder’s forums. The results show that there is a relationship between the modelled climate and the observations from the locals. Through participatory mapping, it is evident that changes in community livelihoods and human activities are blocking the corridors used by herbivores, further affecting their adaptation to the changing climate. Coupled with the projected range contractions, this scenario raises severe worries about the future of wildlife in Kenya's savannah. As a result, the wildlife sector must adopt climate policies and strategies that consider future climatic scenarios.