Rewilding and restoring nature in a changing world

Overview of the PLoS ONE collection 'Rewilding and Restoration'

Rewilding complex ecosystems

BACKGROUND: Rapid global change is creating fundamental challenges for the persistence of natural ecosystems and their biodiversity. Conservation efforts aimed at the protection of landscapes have had mixed success, and there is an increasing awareness that the long-term protection of biodiversity requires inclusion of flexible restoration along with protection. Rewilding is one such approach that has been both promoted and criticized in recent years. Proponents emphasize the potential of rewilding to tap opportunities for restoration while creating benefits for both ecosystems and societies. Critics discuss the lack of a consistent definition of rewilding and insufficient knowledge about its potential outcomes. Other criticisms arise from the mistaken notion that rewilding actions are planned without considering societal acceptability and benefits. Here, we present a framework for rewilding actions that can serve as a guideline for researchers and managers. The framework is applicable to a variety of rewilding approaches, ranging from passive to trophic rewilding, and aims to promote beneficial interactions between society and nature. ADVANCES: The concept of rewilding has evolved from its initial emphasis on protecting large, connected areas for large carnivore conservation to a process-oriented, dynamic approach. On the basis of concepts from resilience and complexity theory of social-ecological systems, we identify trophic complexity, stochastic disturbances, and dispersal as three critical components of natural ecosystem dynamics. We propose that the restoration of these processes, and their interactions, can lead to increased self-sustainability of ecosystems and should be at the core of rewilding actions. Building on these concepts, we develop a framework to design and evaluate rewilding plans. Alongside ecological restoration goals, our framework emphasizes people’s perceptions and experiences of wildness and the regulating and material contributions from restoring nature. These societal aspects are important outcomes and may be critical factors for the success of rewilding initiatives (see the figure). We further identify current societal constraints on rewilding and suggest actions to mitigate them. OUTLOOK: The concept of rewilding challenges us to rethink the way we manage nature and to broaden our vision about how nature will respond to changes that society brings, both intentionally and unintentionally. The effects of rewilding actions will be specific to each ecosystem, and thus a deep understanding of the processes that shape ecosystems is critical to anticipate these effects and to take appropriate management actions. In addition, the decision of whether a rewilding approach is desirable should consider stakeholders’ needs and expectations. To this end, structured restoration planning—based on participatory processes involving researchers, managers, and stakeholders—that includes monitoring and adaptive management can be used. With the recent designation of 2021–2030 as the “decade of ecosystem restoration” by the United Nations General Assembly, policy- and decision-makers could push rewilding topics to the forefront of discussions about how to reach post-2020 biodiversity goals

Saving the world’s terrestrial megafauna

From the late Pleistocene to the Holocene, and now the so called Anthropocene, humans have been driving an ongoing series of species declines and extinctions (Dirzo et al. 2014). Large-bodied mammals are typically at a higher risk of extinction than smaller ones (Cardillo et al. 2005). However, in some circumstances terrestrial megafauna populations have been able to recover some of their lost numbers due to strong conservation and political commitment, and human cultural changes (Chapron et al. 2014). Indeed many would be in considerably worse predicaments in the absence of conservation action (Hoffmann et al. 2015). Nevertheless, most mammalian megafauna face dramatic range contractions and population declines. In fact, 59% of the world’s largest carnivores (≥ 15 kg, n = 27) and 60% of the world’s largest herbivores (≥ 100 kg, n = 74) are classified as threatened with extinction on the International Union for the Conservation of Nature (IUCN) Red List (supplemental table S1 and S2). This situation is particularly dire in sub-Saharan Africa and Southeast Asia, home to the greatest diversity of extant megafauna (figure 1). Species at risk of extinction include some of the world’s most iconic animals—such as gorillas, rhinos, and big cats (figure 2 top row)—and, unfortunately, they are vanishing just as science is discovering their essential ecological roles (Estes et al. 2011). Here, our objectives are to raise awareness of how these megafauna are imperiled (species in supplemental table S1 and S2) and to stimulate broad interest in developing specific recommendations and concerted action to conserve them

Felid mammalian prey over present-natural range

“Felid mammalian prey over present-natural range” is a dataset listing all the mammals that occur in each extant and recently extinct felid’s present-natural range. It also records an estimate of the importance as a prey species of each mammal to each felid

Data from: Learning from the past to prepare for the future: felids face continued threat from declining prey richness

Many contemporary species of large-felids (>15 kg) feed upon prey that are endangered, raising concern that prey population declines (defaunation) will further threaten felids. We assess the threat that defaunation presents by investigating a late Quaternary (LQ), ‘present-natural’ counterfactual scenario. Our present-natural counterfactual is based on predicted ranges of mammals today in the absence of any impacts of modern humans (Homo sapiens) through time. Data from our present-natural counterfactual are used to understand firstly how megafauna extinction has impacted felid communities to date and secondly to quantify the threat to large-felid communities posed by further declines in prey richness in the future. Our purpose is to identify imminent risks to biodiversity conservation and their cascading consequences and, specifically, to indicate the importance of preserving prey diversity. We pursue two lines of enquiry; first, we test whether the loss of prey species richness is a potential cause of large-felid extinction and range loss. Second, we explore what can be learnt from the large-scale large-mammal LQ losses, particularly in the Americas and Europe, to assess the threat any further decline in prey species presents to large-felids today, particularly in Africa and Asia. Large-felid species richness was considerably greater under our present-natural counterfactual scenario compared to the current reality. In total, 86% of cells recorded at least one additional felid in our present-natural counterfactual, and up to 4-5 more large-felids in 10% of the cells. A significant positive correlation was recorded between the number of prey species lost and the number of large-felids lost from a cell. Extant felids most at risk include lion and Sunda clouded leopard, as well as leopard and cheetah in parts of their range. Our results draw attention to the continuation of a trend of megafauna decline that began with the emergence of hominins in the Pleistocene