Ant community structure and biological control in Indonesian cacao agroforestry: long-term changes, land-use management and precipitation gradients

Land-use and climate change are the most important driver of biodiversity loss in terrestrial ecosystems. In agricultural habitats, intensification of agricultural management through the conversion to monocultures and pesticide application have further negative impact on diversity. However, some agricultural land-use types, such as tropical agroforests, are able to conserve biodiversity. In the present thesis, I studied ant community structure and biological control in cacao agroforestry with emphasized on the effect of long-term changes, land-use management and precipitation gradients. The research was conducted in cacao agroforestry located around Lore Lindu National Park (LLNP), Central Sulawesi, Indonesia. Our results showed that decreasing numbers of shade trees have no effect on ant diversity in cacao agroforestry on a regional scale. In contrast, precipitation strongly influences ant community similarity in cacao agroforestry. The long-term change in ant communities differed greatly between rainforest-poor (Palolo region) and rainforest-rich (Kulawi region). Temporal changes in ant communities in agroforestry appeared to be more difficult to predict than expected, highlighting the importance of long-term studies for better understanding of the processes underlying the patterns. Finally, ant species richness had no significant effect on pest incidence or in improving detection of prey in the predation experiment, and was not associated with a reduction in the incidence of a minor pest. Both ant species richness and identity are associated with ecosystem services and disservices delivered by the ant community.