Restoration ecology: are we forgetting top-down control?

Posted on June 1, 2016


Authors of a recent review article argue that restoration ecologists rely heavily on the assumption that natural communities are controlled by bottom-up processes (i.e., the upward transfer of nutrients and energy from plants to animals), but tend to ignore the complementary effects of top-down control by animals on nutrient cycling and the abundance and diversity of plants. They urge practitioners to try to re-establish both top-down and bottom-up controls by targeting the species composition of food webs more explicitly. They suggest that food web theory can be applied to restoration by methods such as: increasing variation in habitat types to foster trophic structure; increasing plant diversity and complexity to encourage total biodiversity and ecosystem stability; adding plant litter (e.g., by planting trees) to assist decomposition and nutrient cycling; introducing top predators to trigger trophic cascades; and removing non-native top predators, especially invasive species. As an aquatic example of the removal of non-native species, the authors cite the rapid recovery in the trophic position of a native apex predator (lake trout) following the elimination of a non-native apex predator (smallmouth bass).

References:

Fraser, L.A. et al. 2015. A call for applying trophic structure in ecological restoration. Restoration Ecology 23(5), 503–507. http://biodiversitygenomics.net/site/wp-content/uploads/2016/01/2015%20-%20Fraser%20-%20A%20call%20for%20applying%20trophic%20st.pdf

Lepak J.M. et al. 2006. Rapid food web recovery in response to removal of an introduced apex predator. Canadian Journal of Fisheries and Aquatic Sciences 63, 569–575. http://www2.dnr.cornell.edu/cek7/Publications/Lepak_et_al_2006.pdf

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