Temperature and a dominant dolichoderine ant species affect ant diversity in Indonesian cacao plantations

Agricultural land conversion and climate change play a major role in shaping tropical landscapes, but thedirect and indirect links to biodiversity and species community composition remain little understood.We tested how landscape and environmental factors and management techniques, affect the diversity ofground and tree living ants in cacao plantations in Sulawesi (Indonesia). In addition, we investigated theoccurrence of an aggressive, numerically dominant dolichoderine ant species (genusPhilidris). Half of the43 study plots, which differed in canopy cover, shade tree diversity, cacao tree age and their distance tothe nearest rainforest, were weeded manually every 3 month, the others biannually. Each plot wasdivided into two subplots, one was fertilized twice a year whereas the other remained unfertilized. Usingprotein and sugar-solution baits, we examined species richness, abundances and interspecificinteractions of ants on the ground and in cacao trees. In total we collected 160 ant morphospecies.Reduced ant species richness on the ground and in the trees was significantly correlated with highermean temperatures while the other factors, including number of shade trees did not have any significantinfluence. The abundant and aggressivePhilidrisspecies, reduced arboreal ant species richness. Itoccurred more frequently in warmer, less shaded plots and on older cacao trees, which offer morenesting sites. In our study we show, that micro-climatic conditions and the occurrence of singleecologically dominant species are the major factors predicting species diversity in tropical agriculturalecosystems.