Assessing Ecological Restoration: In the wake of the Millennium Ecosystem Assessment, the analysis of ecosystem services, and their relationship to biodiversity, has become one of the most rapidly developing research themes in environmental science. At the same time, ecological restoration is widely being implemented as a response to environmental degradation and biodiversity loss.
Rey Benayas
et al. (p. 1121 , published online 30 July) link these themes in a meta-analysis of the impacts of ecological restoration actions on provision of ecosystem services and biodiversity conservation. The analysis of 89 published restoration projects worldwide establishes that ecological restoration does, in general, have positive impacts on both biodiversity and provision of ecosystem services. These effects are especially marked in the tropics. Thus, ecological restoration actions may indeed deliver benefits, both in terms of biodiversity conservation and supporting human livelihoods.
Facilitating “wildness”: Humans have encroached upon a majority of Earth's lands. The current extinction crisis is a testament to human impacts on wilderness. If there is any hope of retaining a biodiverse planetary system, we must begin to learn how to coexist with, and leave space for, other species. The practice of “rewilding” has emerged as a method for returning wild lands, and wildness, to landscapes we have altered. Perino et al. review this concept and present a framework for implementing it broadly and in a way that considers ongoing human interaction. Science , this issue p. eaav5570
Two billion ha have been identified globally for forest restoration. Our meta-analysis encompassing 221 study landscapes worldwide reveals forest restoration enhances biodiversity by 15–84% and vegetation structure by 36–77%, compared with degraded ecosystems. For the first time, we identify the main ecological drivers of forest restoration success (defined as a return to a reference condition, that is, old-growth forest) at both the local and landscape scale. These are as follows: the time elapsed since restoration began, disturbance type and landscape context. The time elapsed since restoration began strongly drives restoration success in secondary forests, but not in selectively logged forests (which are more ecologically similar to reference systems). Landscape restoration will be most successful when previous disturbance is less intensive and habitat is less fragmented in the landscape. Restoration does not result in full recovery of biodiversity and vegetation structure, but can complement old-growth forests if there is sufficient time for ecological succession.
Agricultural activities and their complex effects on nature conservation, and the services that ecosystems deliver to humans are controversial. We present an overview of land abandonment, its driving forces and its consequences for landscape, biodiversity and humans. A descriptive metaanalysis of independently published studies highlighted the fact that the abandonment of agricultural land is a phenomenon mostly driven by socio-economic factors such as immigration into areas where new economic opportunities are offered to rural people. Ecological drivers such as elevation and land mismanagement leading to soil erosion are of secondary importance. We identified the major problems related to abandonment of agricultural land and quantified their relative importance. In order of decreasing importance, they were biodiversity loss, increase of fire frequency and intensity, soil erosion and desertification, loss of cultural and/or aesthetic values, reduction of landscape diversity and reduction of water provision. The impacts of these problems were not equally relevant in all regions of the world. The abandonment of agricultural land may also benefit humans. The benefits include passive revegetation and active reforestation, water regulation, soil recovery, nutrient cycling and increased biodiversity and wilderness. In a world that is becoming less natural and more intensively exploited by humans, we suggest that (1) farmland must be viewed in a context of multi-functionality to take advantage of ecosystem goods and services, (2) at the global scale, the abandonment of agricultural land is mostly positive for humans and (3) there is a need for the implementation of policies based on the payments for environmental services that encourage human societies to reconcile agricultural use, nature conservation and ecological restoration.