A research agenda for the restoration of tropical and subtropical grasslands and savannas

Abstract

Despite growing recognition of the conservation value of grassy biomes, our understanding of how to restore biodiverse tropical and subtropical grassy biomes (grasslands and savannas; TGB) remains limited. Several tools have recently been identified for TGB restoration, including prescribed fires, appropriate management of livestock and wild herbivores, tree cutting and shrub removal, invasive species control, and the reintroduction of native grasses and forbs via seeding or transplants. However, additional research for improved TGB restoration is needed. This article aims to identify ecological research priorities for TGB restoration. The following points are crucial to scale up TGB restoration and meet the challenges of the UN Restoration Decade. Research should focus on: disentangling the reasons why TGB are often undervalued and misunderstood; mapping TGB restoration opportunities; identifying regions where TGB and other biomes naturally exist as alternative stable states; recognizing areas with natural regeneration potential to avoid unnecessary intervention; restoring soil conditions; disentangling factors driving low seed quality, determining germination requirements and developing vegetative propagation techniques for TGB species; disentangling the limiting factors and key ecological processes underlying seedling establishment and community assembly; improving and validating long‐term management to mimic natural disturbance regimes; setting the minimum attributes of desirable TGB in terms of structure, composition, functioning, and resilience; and improving monitoring of restoration outcomes. Such research has the potential to advance theory, policy, and practice in TGB restoration, ultimately resulting in long‐term benefits for people and nature in some of the more neglected ecosystems of our planet.

The present and future of grassland restoration

“…Wilsey (2021) identified several areas of need in grassland restoration research, several of which were also noted by Buisson et al (2021 a , 2021 b ). First, Wilsey (2021) pointed out that setting pre‐industrial vegetation as a restoration target of our actions is not feasible.…”

“…The papers of Buisson et al (2021 a , 2021 b ) and Wilsey (2021) identified several research gaps to be filled and challenges which grasslands face in the forthcoming decades. These include the (1) need for careful target vegetation selection and “climate‐adaptive” restoration; (2) lack of knowledge on the dynamics and restoration of several regions or grasslands types; (3) increased importance of the species arrival sequence and high likeliness of stochasticity of species establishment; and, finally, (4) issues of long‐term sustainability of restored sites/habitats in the form of post‐restoration management.…”

“…This underlines the necessity of setting realistic goals for target selection in restoration (Török & Helm 2017). In their second review, Buisson et al (2021 b ) indicated that most research has been conducted on restoration of temperate grasslands, whereas tropical grasslands have received much less attention. Scientific knowledge is especially limited on how to restore biodiverse grasslands in tropical and subtropical regions and can even lead to misunderstandings or misconceptions (see also Silveira et al 2020).…”

“…First, Wilsey (2021) pointed out that setting pre‐industrial vegetation as a restoration target of our actions is not feasible. This is for several reasons: (1) altered site conditions and land use, and modified landscapes with marked effects on dispersal and establishment in most regions (Török et al 2020); (2) biological invasions and multiple threats imposed by climate change (Wilsey 2021); and (3) increasing stochasticity means that restoration success may depend on years with particular rainfall amounts or patterns, or on the differences in reproductive and establishment success of particular target plant species between years (Buisson et al 2021 b ). This also highlights the importance of the sequence of arrival of plant species, so‐called priority effect in restoration (Weidlich et al 2021; Wilsey 2021).…”

Open Ecosystems: Ecology and Evolution Beyond the Forest Edge

“…The final chapter not only summarises the key threats to OEs in the context of global change, but particularly highlights important knowledge gaps and opens up new research questions and perspectives. This has already inspired a research agenda for the restoration of OEs (Buisson et al 2020).…”