Prozesse der Strukturierung von Termitengemeinschaften in West Afrika
Zusammenfassung der Projektergebnisse
Tropical ecosystems harbour the world’s highest species richness. Yet we still do not understand how so many species can co-exist. According to classical niche models interspecific competition is predicted to limit the number of similar co-existing species. Using termites as models we studied community assembly processes in the two major West African terrestrial ecosystems, savannas and forests. Termites are important ecosystem engineer that enhance soil functioning and increase biodiversity. Despite their ecological similarity as detritivores, many termite species co-exist. In total, we identified 35 termite species using morphological and molecular means. We revealed cryptic species diversity but also had to lump species as molecular means did not support species status. This showed that morphological species identification in termites is unreliable. Our data will serve as a basis for all upcoming termite studies in West Africa. Community assembly processes seem to differ between the savanna and the forest and between protected (national parks) and anthropogenic, disturbed areas (fallows, teak plantations). In the protected savanna, random processes together with environmental filtering seem to structure termite communities. In fallows, the importance of environmental filters increases. Especially temperature and rainfall - probably through their influence on vegetation density - affect the occurrence of species and select for species that are common pests. In the protected forest, environmental filtering also seems to be important but here rainfall appears to be more crucial than temperatures. In contrast, in teak plantation interspecific competition occurs, probably due to the reduced availability of dead plant material. It seems to reduce termite diversity to a few pest species. Our study shows that the mechanisms that structure communities differ but that disturbance seem to select for specific species which are common pests. In contrast to former expectations for termites, interspecific competition is of low importance for community assembly under natural conditions.
