Das Projekt "Fire, climate change and human impact in tropical ecosystems: long-term biodiversity and stand dynamics of tropical vegetation" wird vom Umweltbundesamt gefördert und von Universität Bern, Departement Biologie, Institut für Pflanzenwissenschaften durchgeführt. Forecasted change in precipitation may lead to an increase of biomass in area covered by savannah and to a consequent increase in biomass burning, affecting the carbon emissions at global scale. Understanding how tropical ecosystems will react to those changes is relevant particularly for East Africa, where population density is the highest of the continent. We generated high-resolution sediment charcoal data spanning the last 2000 years across a climatic gradient (wet to dry savannah) to assess the long-term impact of fire, climate and land use on tropical savannah ecosystems. Records of biomass burnings show contrasting fire pattern among the two regions. In wet savannah ecosystems, fire was limited by wetter periods until the colonial period (AD 1800), when biomass removal led to a decrease in burning. In contrast, in the dry setting of Kenya, fire conditions during the last 2k years peaked at intermediate rainfall, and increased in recent times following land use intensification. On the basis of our data we hypothesize that under a future scenario with increased rainfall fire will increase in the wet savannah and decrease in the (eastern) dry savannah, unless fuel will be limited by agriculture practices. Yet, it is not understood how important vegetation properties and ecosystem services such as plant biomass and diversity will respond to inter-annual to seasonal variation in the moisture balance, and how tropical species will cope with extreme events, such as droughts. The following proposal addresses highly relevant questions for todays key issues of biodiversity and the adaptation of vulnerable communities to global change. Additionally, it will contribute to ongoing multi-proxy research concerning the magnitude, frequency, and rates of past climate change in equatorial East Africa. Finally, the project will improve our understanding of tropical ecosystem functioning and its interaction with cultural and economic systems at local to regional scales.