Biotic Effects of Climate Change in the Tropical Alpine Moorlands of Mount Kenya and Mount Elgon, and Its Impact on Dependent Local Communities

Abstract

Tropical alpine areas are extraordinary ecosystems that provide valuable services including water, biodiversity, and food. These areas are uniquely threatened by climate change as they are predicted to warm more over the next century than other areas of the globe, and may be more sensitive to that change as the biotic communities have narrow thermal niches. While the threat to climate change on tropical mountains is widely appreciated, there have been remarkably few studies documenting the impacts and effects on the wider socio-ecological system. This is particularly true in East Africa where these mountains support large vulnerable populations. This study examined the impacts of climate change in two alpine areas of Kenya - Mount Kenya and Mount Elgon. It examined patterns and trends in the climate, ecology, and socio-economic setting of these two mountains. Climate trends were investigated using reanalysis datasets, meteorological station data, and in-situ data loggers. Ecological trends were examined through a resurvey of a historical vegetation study from 1980 in the Teleki Valley of Mount Kenya. Socioeconomic patterns were explored through household questionnaires, focus group discussions, and key informant interviews. The data was analysed with descriptive statistics to demonstrate patterns and changes in those patterns. Results indicated that temperature has warmed consistently in the alpine zones of both mountains - warming at a rate of 0.2-0.3° C/decade. Precipitation has not changed appreciably up on the two mountains, but down by the base there have been changes in seasonal patterns and streamflow. Vegetation patterns have not changed much over the 40 year period, with most of the dominant species existing in similar densities and distributions as in 1980. The biggest changes were a decline in species diversity, and shifts in the distribution and demography of the characteristic Dendrosenecion keniodendron species. Communities surrounding the two mountains rely heavily on mountain ecosystem services for their livelihoods, and most particularly water provision. These communities have noticed changes in ecosystems service delivery over their lifetimes, but few considered climate change as the primary challenge they face. The afroalpine socio-ecological systems of Kenya are changing in response to climate change, but there are also indications of resilience and inertia in these systems: the changes have not been as pronounced as expected. More ecological research and monitoring is needed to better understand these unique and important ecosystems in order to prepare for future changes. The possible existence of ecological tipping points present a particular concern.