Step back from the forest and step up to the Bonn Challenge: how a broad ecological perspective can promote successful landscape restoration

Abstract

We currently face both an extinction and a biome crisis embedded in a changing climate. Many biodiverse ecosystems are being lost at far higher rates than they are being protected or ecologically restored. At the same time, natural climate solutions offer opportunities to restore biodiversity while mitigating climate change. The Bonn Challenge is a U.N. programme to restore biodiversity and mitigate climate change through restoration of the world's degraded landscapes. It provides an unprecedented chance for ecological restoration to become a linchpin tool for addressing many environmental issues. Unfortunately, the Forest and Landscape Restoration programme that underpins the Bonn Challenge, as its name suggests, remains focused on trees and forests, despite rising evidence that many non-forest ecosystems also offer strong restoration potential for biodiversity and climate mitigation. We see a need for restoration to step back to be more inclusive of different ecosystem types and to step up to provide integrated scientific knowledge to inform large-scale restoration. Stepping back and up will require assessments of where to restore what species, with recognition that in many landscapes multiple habitat types should be restored. In the process, trade-offs in the delivery of different ecosystem services (e.g. carbon, biodiversity, water, albedo, livestock forage) should be clearly addressed. We recommend that biodiversity safeguards be included in policy and implemented in practice, to avoid undermining the biophysical relationships that provide ecosystem resilience to climate change. For ecological restoration to contribute to international policy goals will require integrated large-scale science that works across biome boundaries.

Making the UN Decade on Ecosystem Restoration a Social-Ecological Endeavour

“…Such a focus implies an interest in species composition as well as in ecosystem functioning and services [5,6]: asking, for example, how different combinations of species help to facilitate certain types of ecosystem functions or which management actions are needed to enhance especially valued ecosystem services (see the Society for Ecological Restoration Standards [7]). Like many other ecologists, we support a pluralist approach to restoration that encompasses both species composition and ecosystem functions and services [1,8], while cautioning that a narrow focus on single or a few ecosystem services to the detriment of biodiversity is not desirable (e.g., tree plantation monocultures for carbon storage [9]).…”

“…The opportunities of social-ecological telecoupling for restoration are most obvious in the context of carbon sequestration. Restoration projects for carbon sequestration take place around the world, not only to accrue local benefits but to generate benefits for the global climate, financed by people living far from actual restoration sites [8,50,51].…”

Global guidelines for the sustainable use of non-native trees to prevent tree invasions and mitigate their negative impacts

“…Within a country or region, native tree species rather than NNTs, should be used, in planning and establishing large-scale plantings, afforestation or reforestation projects, planted forest, and agroforestry (Douglas et al 2014;Peltzer et al 2015) wherever possible. This approach is particularly important in massive and global projects such as the Trillion Trees campaign, the African Green Wall initiative (Goffner et al 2019), the China's Grain-for-Green Program (Hua et al 2016), and the Bonn Challenge (Temperton et al 2019) (Table 1).…”

“…In response to climate change, trees, regardless of their biogeographical status (native or non-native), are being presented as a general panacea (Bastin et al 2019). However, emerging research suggests that trees might not help offset carbon emissions as much as some would expect (e.g., Popkin 2019), and plantations in inappropriate sites can have disastrous consequences for sustainable development, biodiversity conservation, and ecosystem functioning (Bond 2016;Bond et al 2019;Temperton et al 2019), and even may lead to a loss of soil organic carbon (Jackson et al 2002). Silveira et al (2020) highlighted the myth that tree planting is always good for biodiversity and ecosystem services and that the use of trees in the restoration of tropical and subtropical old-growth grassy biomes is misguided.…”

With Power Comes Responsibility – A Rangelands Perspective on Forest Landscape Restoration

“…Instead of promoting scientifically unfounded targets for increasing tree cover, the documents guiding landscape restoration need to include clear guidelines on where planting trees is appropriate and where it is not advisable. These resources also need to provide information on appropriate restoration strategies for the grassy biomes, such as clearing exotic vegetation, using savanna species for restoration and agroforestry, restoring grassland function through appropriate grazing management and burning, and avoiding or reversing bush encroachment (Buisson et al, 2019, Temperton et al, 2019Silveira et al, 2020).…”