Anne M.G. Kwak Return of the wolves Implications of the role of top predators in terrestrial ecosystems for the return of Eurasian wolf Canis lupus lupus to Western Europe Author Anne M.G. Kwak Radboud University Nijmegen E-mail:
[email protected] Education Master Biology, track Communities & Ecosystems Radboud University Nijmegen Faculty of Science Heyendaalseweg 135 6525 AJ Nijmegen Phone: 024-365 26 61 Fax: 024-355 34 50 Website: www.ru.nl/fnwi Supervisor Prof. dr. H. (Hans) de Kroon Institute for Water and Wetland Research Radboud University Nijmegen Date October 2013 SUMMARY In many terrestrial ecosystems in Western Europe today, top predators are absent (Terborgh et al., 1999). Since top predators are considered to be important for the structure of ecosystems and their biodiversity, the absence of such species might have large impacts on these systems. In this thesis I want to investigate how the absence of top predators has affected terrestrial ecosystem trophic structure and biodiversity. The focus on terrestrial ecosystems comes forth from the fact that the Eurasian wolf Canis lupus lupus is currently expanding its range throughout Western Europe (Chapron et al., 2003; Randi, 2011). Here, I investigate how species like the Eurasian wolf might affect our ecosystems when they spread further, and what the implications of these effects are for the management of our ecosystems and of the Eurasian wolf. Carnivores can be assigned the role of keystone species, where they create ecological boundaries that protect lesser competitors from exclusion (Miller et al., 2001). In this role of keystone species, carnivores are also capable of increasing plant biomass through their limiting effect on herbivore numbers, causing both plants and carnivores to flourish (Miller et al., 2001).