Rewilding: definitions, success factors and policy, a European perspective Ashleigh Campbell Supervisors: 12910708 Kenneth Rijsdijk Date submitted: 01/12/20 and Carina Hoorn 1 2 Contents Abstract............................................................................................................................................................................. 4 1. Introduction .............................................................................................................................................................. 5 2. Oostvaardersplassen, the Netherlands: Grazer-managed grasslands in a man-made nature reserve ................. 6 3. What is rewilding? .................................................................................................................................................... 8 4. Why rewild? ............................................................................................................................................................ 10 5. Policy and socio-economic implications ................................................................................................................ 11 6. Ecological success factors and progress in rewilding ............................................................................................ 13 7. Trophic rewilding and the landscape of fear ......................................................................................................... 16 8. What factors are essential for success in a rewilding project? ............................................................................. 19 6. Conclusion .............................................................................................................................................................. 21 References ...................................................................................................................................................................... 22 3 Abstract European landscapes are highly urbanised and densely populated, this high level of human pressure has resulted in a fragmented landscape with low habitat heterogeneity. The demand for biodiversity continues to grow as both the quantity and quality of natural ecosystems declines. Rewilding offers an opportunity for degraded landscapes to be restored through natural processes to a state that supports a higher species richness and allows for reintroduction of keystone species. In this review, I look at the varying and disputed definitions of rewilding in literature to determine a common definition. I address and evaluate the ecological success factors of rewilding and assess the relative influence that socio-economic factors and policy can have on rewilding schemes. Through the findings of the review I determine why rewilding is a long-term option for conservation management, in comparison to other strategies. There is no clear consensus on the definition of rewilding in literature, however the continuous theme I found is that, even with initial human intervention through species introductions or ecosystem engineering, the ecosystem should ultimately be left to develop on its own with minimal future human intervention. Reintroduction of megafauna must occur to restore trophic complexity for a rewilding project to be effective. This, alongside increasing habitat connectivity and restoring natural disturbance regimes are essential features to achieve many of the ecological factors that result in rewilding success. Socio-economic aspects of rewilding such as policy, human-wildlife conflict and social conflicts must be considered and mitigated to secure the success of a rewilding project. Rewilding can restore ecosystem processes, provide vital ecosystem services and subsequent economic benefits. Through mitigation of current and future climate change impacts and the sustainable usage of terrestrial ecosystems, rewilding brings us closer to achieving the UN sustainable development goals. 4 1. Introduction Urbanisation and population increase are driving a global reduction in biodiversity through the rising demand for both space and natural resources (Seto et al., 2012). Biodiversity is often used as an indicator for the success or health of an ecosystem, the greater the level of biodiversity present, the healthier the system (Spash and Hanley, 1995). Creation and expansions of urban environments for humans and the increased use Biodiversity: a shortened form of ‘biological diversity’, is used to describe the number, of land for agriculture to support a growing global population has led to variety and variability of living organisms in a decrease in the quantity and quality of many natural systems each location (Spash and Hanley, 1995). (Bonebrake et al., 2019; Seto et al., 2012). This is either through direct impacts such as habitat fragmentation and destruction or indirect impacts occurring through anthropogenic climate change, sensory pollution (chemical, sound and light), changes in gene flow within populations, or invasive species introduction (Bonebrake et al., 2019). European landscapes are characteristically smaller in size, lower in landscape heterogeneity, more fragmented with a higher human pressure than those generally found in, for example, America (Kuijper et al., 2013). Subsequently, the loss of many ecological processes within an ecosystem can occur, reducing its resilience, complexity and consequently its ability to recover from perturbations (Perino et al., 2019). With the constant demand for increases in biodiversity, rewilding offers an opportunity for degraded landscapes to be restored through natural processes to a state that can support a higher species richness and allows for the reintroduction of keystone species (Pereira and Navarro, 2015; Torres et al., 2018). Naturally functioning ecosystems are also beneficial for humans in creating income through nature-based tourism, reducing flood impacts and increasing carbon storage, which in turn helps to mitigate the impacts of climate change (Martin and Watson, 2016; Pereira and Navarro, 2015). Implementation and management of new rewilding schemes requires great amounts of research, planning and funding to ensure the project outcomes are a success (Pettorelli et al., 2018). This review will evaluate the current rewilding schemes and policies, particularly across Europe, and give an insight into the factors that have resulted in rewilding success in these projects and regions. The results of this review can help advise governments on how to improve current rewilding schemes and better implement future rewilding plans. The main research questions addressed will be: - What is the definition of rewilding? - What ecological factors are essential for the success of rewilding schemes? o How do socio-economic factors influence the relative success of schemes? It will also discuss whether rewilding is a viable long-term conservation approach or if a variety of approaches are necessary in order to maximise biodiversity in a fragmented landscape. This will be a systematic/meta-synthesis review, where I interpret and integrate the findings of multiple studies in order to answer the research questions laid out above. Research for this review was carried out between March and April and then continued from the middle of June until September. I searched for literature using key words such as ‘rewilding’, ‘Europe’, ‘landscape of fear’, ‘biodiversity’, ‘Oostvaardersplassen’, or a combination of these key words with additions such as ‘success’ and ‘progress’, and sought to find the most reliable and up-to-date research. This 5 meant selecting papers with high numbers of citations (100+) where possible. As many of the relevant papers I came across were published in the last 3 years and rewilding is a relatively new topic in literature, this was not always feasible. In some instances, grey literature sources were used. In these cases, the most recent sources were selected to provide a more up-to date knowledge and insight or sources from the discussed date for the most accurate context (e.g. newspaper articles). All literature and sources were found through google scholar and the google search engine and stored on free, open-source reference management software, Zotero. I used the referencing style Elsevier – Harvard (with titles) for all sources referred to in this review. In total, I have referenced 50 different sources for this review. 2. Oostvaardersplassen, the Netherlands: Grazer-managed grasslands in a man-made nature reserve The Oostvaardersplassen in the Netherlands (Figure 1) is well known for being an extensive man-made wetland, created as a nature reserve that now supports a wealth of breeding and migratory bird species. The management of this reserve, however, has been subject to criticism. Many papers refer to the Oostvaardersplassen as the basis or inspiration behind current rewilding projects (Jepson, 2016) and, as such, I have referenced it as the starting point for this review. Figure 1: Map showing the location of the Oostvaardersplassen in the Netherlands (Lorimer and Driessen, 2014, fig.1) The Oostvaardersplassen is a well-established marshland, managed by Staatsbosbeheer (the Dutch State Forestry Service) since 1996, and is of international significance due to the presence of rare breeding and migratory birds. Since 2010, it has been a part of the Natura 2000 making it one of the top ranked European nature reserves that should be protected, as well as being one of the largest nature reserves in the