Effect of tropical forest disturbance on the competitive interactions within ant communities

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Citation:
Gray 2016


Ross Gray of Imperial College London investigated what effects habitat disturbance has on competitive interactions between ant genera in tropical forests. In order to understand the effects of anthropogenic alteration to tropical forests it is necessary to understand how this disturbance influences patterns of community composition and the reinforcing interactive processes that structure communities. He found that both community composition and the competitive interactions between genera changed with forest disturbance, with a shift in the dominance of several genera. He observed that there was lower species richness and diversity in disturbed forests as well as 22.7% and 15.9% of genera being endemic to primary and logged forest respectively. The changes in the community composition, along with genera exhibiting changes in dominance, indicate that there has been an alteration in the ecological network of the logged forest. Ants are considered ecosystem engineers and these shifts in dominance between genera that Ross observed in the different forest types implies an alteration in community which is likely to have repercussions felt throughout the ecosystem.

How anthropogenic disturbance affects the processes that structure patterns of biodiversity remains unresolved. Here, I examine how the disturbance of tropical forests in Borneo may alter competitive interactions within functionally important ant communities. I assess whether forest disturbance reflects changes in ant community composition, competitive traits (body size, cumulative occupancy, average arrival time) and competitive interactions among genera. I used a camera to film bait cards to examine the variation of competitive traits in the community and interactions among genera. Winkler bags were used to sample the leaf litter; providing a baseline community data set for comparison between forest types. Genera richness and diversity was lower in logged forest in comparison to primary forest. There was a change in composition with 22.7% and 15.9% of genera being endemic to primary and logged forest respectively. The size distribution of genera, cumulative occupancy and average arrival time, along with the proportion of competitive interactions, did not differ between primary and logged forest. However, inter-genera competition did change between forest type, with Acanthomyrmex and Odontoponera becoming more dominant and Lophomyrmex becoming more submissive. Competitive changes matched variations in community metrics between forest types suggesting that disturbance can not only affect competitive processes within ant communities but this can also have knock-on effects for future composition. This study indicates a need to focus on how disturbance affects the interactions between taxa that underlie community patterns as well as the patterns themselves.