Defaunation, rewilding and ecosystem sustainability

Credit: Jan Graf

Our planet is currently facing a dramatic and rapid loss of the world’s last wild megafauna (mammalian herbivores and carnivores > 40kgs) due to land use change and overhunting. If current trends continue, near future mammal communities will consist of few species of smaller body size.  This so-called defaunation may have huge consequences for the sustainable functioning of ecosystems. We investigate the patterns and processes of defaunation, its functional consequences, and the process of rewilding as the reversal of defaunation.

Defaunation & Ecosystem Sustainability

We study the effects of so-called megaherbivores, such as white rhino and elephant, on the functioning of South African ecosystems. Megaherbivores (> 1,000 kgs as adult) are said to have disproportionate effects on ecosystems because their populations are not controlled by predation. Current rampant poaching of rhino and elephant is threatening the survival of these last remaining megaherbivores. We explore a broad diversity of the consequences of their loss ranging from biogeochemistry, to fire regimes, and climate-vegetation feedbacks.

Credit: Leo Linnartz

Rewilding & Ecosystem Sustainability

In contrast to large parts of the world, Europe is experiencing a revival of several larger mammal species, including large carnivore such as wolf, ungulates, and larger bird species. This rewilding occurs passively or through active (re)introductions of large mammals. The aim of active rewilding is to mitigate effects of global change (such as biodiversity loss) and restore top-down trophic interactions and associated ecosystem structure and functioning. In a variety of projects across Europe, we study the consequences of rewilding, including the effects of introductions of European bison and red deer in the Netherlands and the consequences of the large carnivore comeback in Europe.

Publications

Cromsigt, J. P., Te Beest, M., Kerley, G. I., Landman, M., le Roux, E., & Smith, F. A. (2018). Trophic rewilding as a climate change mitigation strategy? Philosophical transactions of the Royal Society of London. Series B, Biological Sciences, 373(1761). 

Le Roux, E., Kerley, G. I., & Cromsigt, J. P. (2018). Megaherbivores modify trophic cascades triggered by fear of predation in an African savanna ecosystem. Current Biology, 28(15), 2493-2499. 

Owen-Smith, N., Cromsigt, J. P., & Le Roux, E. (2017). Smaller ungulates are first to incur imminent extirpation from an African protected area. Biological Conservation, 216, 108-114. 

Cromsigt, J. P., Kemp, Y. J., Rodriguez, E., & Kivit, H. (2018). Rewilding Europe's large grazer community: how functionally diverse are the diets of European bison, cattle, and horses? Restoration Ecology, 26(5), 891-899. 

Valdés-Correcher, E., Rodriguez, E., Kemp, Y. J., Wassen, M. J., & Cromsigt, J. P. (2018). Comparing the impact of a grazing regime with European bison versus one with free-ranging cattle on coastal dune vegetation in the Netherlands. Mammal Research, 1-12.

Kuijper, D. P. J., Sahlén, E., Elmhagen, B., Chamaillé-Jammes, S., Sand, H., Lone, K., & Cromsigt, J. P. G. M. (2016). Paws without claws? Ecological effects of large carnivores in anthropogenic landscapes. Proceedings of the Royal Society B: Biological Sciences, 283(1841), 20161625.