The consequences of tropical forest disturbances at the community and the ecosystem level

Abstract

Tropical forests are the most biodiverse biome on Earth and play important roles in global water and carbon cycles. Despite the importance of tropical forest in providing ecosystem services to all humans, anthropogenic activities are imposing significant changes upon this biome. In the Anthropocene, tropical forests suffer impacts from conversion to non-forested land-uses, degradation of remaining forests through logging, fire, hunting and fragmentation, and regeneration of secondary forests. Although scientists have been investigating these disturbances for a long time, there are still some knowledge gaps. In this thesis, I addressed knowledge gaps at both the community and the ecosystem level. In chapter 1, I investigated the effects of tropical forest degradation through rare species loss on functional diversity using dung beetles as focal group. In the second chapter, I focused on the ecosystem-level responses to different types of forest disturbance to question which ecosystem component was more vulnerable to tropical forest disturbance. In both chapters I used data collected in hundreds of sites in the biggest tropical forest on Earth, the Amazon. The results of chapter 1 showed that dung beetle local communities were resistant to tropical forest disturbance due to functional redundancyof the regional pool of species, which in turn is maintained in the forest matrix in the landscape. In the chapter 2, I found that biodiversity was the ecosystem component of tropical forests that was most sensitive to the occurrence of multiple types of disturbance. Taken together the results from both chapters not only demonstrate the vulnerability of tropical forest biodiversity, but also support current initiatives to conserve substantial areas of intact forest to serve as refugees for species and sources of tropical diversity. At the end of the thesis, I discuss the implications of my findings in the context of global conservation of tropical forests.