Complexity of cacao production systems affects terrestrial ant assemblages

Summary

Given the rapid changes in tropical agricultural production, the evaluation of different management practices has gained interest to determine the effects of land-use change on biodiversity. The conversion of forests into agricultural land is one of the main drivers of diversity loss. Agroforestry systems have been shown as a promising option to provide suitable yields in addition to conserving biodiversity. In this study we compared species richness and community composition of terrestrial ants in six different systems in a long-term experimental site established in 2009 in Bolivia: a full-sun monoculture and an agroforestry system under conventional management, a full-sun monoculture and an agroforestry system under organic management, a highly diverse and dense agroforestry system without external inputs and a secondary forest. Using pitfall traps, we sampled ants four times during a seven-year period (2015-2021). We collected a total of 85 ant species belonging to 6 sub-families and 41 genera. More than 80% of the species were recorded in less than 10% of the traps. Species richness did not significantly differ between the systems. However, species composition mainly differed between the fallow and the production systems, and within the latter, it followed the management intensity gradient, i.e., complex agroforestry, agroforestry and monocultures. The indicator species analysis clearly showed species exclusively associated with one or more production systems, whereas others were only associated with the secondary forest. Species with specialised trophic roles were more frequent in forest and agroforestry systems. Our results showed that the disturbance generated by cultivation was the main driver differentiating ant communities, but also reinforced the importance of the complexity and management intensity of the production system. These results have strong implications for landscape management and highlights the importance of preserving natural patches of forest but also diverse and complex agroforestry systems within the agricultural matrix for ant diversity conservation.