Predators have a strong negative effect on decomposition

Alice Walker, Mark Robertson, Paul Eggleton, Katherine Bunney, Candice Lamb, Adam Fisher, Catherine Parr

This is a plain language summary of a Functional Ecology research article which can be found here.

Decomposition is the process of dead animal or plant tissue being broken down, and is carried out by decomposer organisms. It is an important ecosystem process that is vital for facilitating nutrient, energy and carbon flow through ecosystems. It is possible that predatory animals may control decomposition via their effect on decomposers, but predator populations are likely to change in future due to climate and land-use changes. Therefore, an understanding of how predators affect decomposition is needed to predict how ecosystems might change in the future.

Opthalmopone, an ant genus specialised in preying on termites, attacking a termite worker (photo: Alice Walker).

In tropical and subtropical ecosystems termites are particularly prolific decomposers, and are frequently preyed on by ants. In this study, we manipulated ant abundance in an African savanna to explore the effect of ant predation on termite activity, and on termite-mediated decomposition rates of three common organic substrates.

We found that ants inhibit termite abundance and activity, resulting in lower decomposition rates. We conclude that ants indirectly influence decomposition by preying on termites.

Our results suggest that predator abundance can play a significant role in determining decomposition rates. As ants and other predators of decomposers are threatened by a suite of anthropogenic pressures, our results imply that disruptions to these predator-prey relationships could affect the decomposition process. We therefore highlight the critical importance of assessing the indirect effects of changes in predator abundance on key ecosystem processes.


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