The enormous diversity of plants and animals in tropical ecosystems has stunned many researchers since the 19th century. Biodiversity of tropical microbes, including fungi, has received little attention, although these organisms contribute to much of the nutrient cycling (plant nutrition and decomposition). The ecologically and economically important plant families Caesalpiniaceae, Dipterocarpaceae and Uapacaceae that form ectomycorrhizal symbiosis are particularly speciose and abundant in the Central African rain forest belt (forming monodominant stands among the more diverse matrix of arbuscular mycorrhizal vegetation) and the surrounding seasonal ‘miombo’ savanna ecosystems, but the diversity and ecology of their fungal symbionts has been virtually overlooked. Many taxa of the relatively well-studied plants and animals have evolved in tropical ecosystems, particularly Africa. Similarly, we hypothesize that many of the symbiotic fungal taxa originate in African rain forests, followed by dispersal to the Northern Hemisphere, South America and South-East Asia as well as to seasonal savanna woodlands after climate change. The main aims of this project include documenting i) the biodiversity of African ectomycorrhizal fungi and the importance of host and edaphic factors in structuring the fungal communities; ii) their origin and biogeographic relationships; iii) undescribed lineages of ectomycorrhizal fungi, improving the understanding of the magnitude and evolutionary (in)stability of this symbiosis; iv) radiation patterns of ectomycorrhizal fungi in savanna compared to the more ancient rain forest ecosystems; v) the role of ectomycorrhizal fungi in tropical monodominance via host specificity and/or positive soil and litter feedback. Through field expeditions and employing molecular DNA sequence data, the project will contribute to the understanding of coevolution of plants and fungi, fungal biogeography and potentially explaining tropical monodominance.