Science for a wilder Anthropocene: Synthesis and future directions for trophic rewilding research.
Trophic rewilding is an ecological restoration strategy that uses species introductions to restore top-down trophic interactions and associated trophic cascades to promote self-regulating biodiverse ecosystems. Given the importance of large animals in trophic cascades and their widespread losses and resulting trophic downgrading, it often focuses on restoring functional megafaunas. Trophic rewilding is increasingly being implemented for conservation, but remains controversial. Here, we provide a synthesis of its current scientific basis, highlighting trophic cascades as the key conceptual framework, discussing the main lessons learned from ongoing rewilding projects, systematically reviewing the current literature, and highlighting unintentional rewilding and spontaneous wildlife comebacks as underused sources of information. Together, these lines of evidence show that trophic cascades may be restored via species reintroductions and ecological replacements. It is clear, however, that megafauna effects may be affected by poorly understood trophic complexity effects and interactions with landscape settings, human activities, and other factors. Unfortunately, empirical research on trophic rewilding is still rare, fragmented, and geographically biased, with the literature dominated by essays and opinion pieces. We highlight the need for applied programs to include hypothesis testing and science-based monitoring, and outline priorities for future research, notably assessing the role of trophic complexity, interplay with landscape settings, land use, and climate change, as well as developing the global scope for rewilding and tools to optimize benefits and reduce human-wildlife conflicts. Finally, we recommend developing a decision framework for species selection, building on functional and phylogenetic information and with attention to the potential contribution from synthetic biology.
Section for Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark; svenning@bios.au.dk.
Jens-Christian
JC
Svenning
Section for Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark;
Pil B M
PB
Pedersen
Advanced Conservation Strategies, Midway, UT 84049; Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 15853;
C Josh
CJ
Donlan
Section for Biodiversity & Conservation, Department of Bioscience, Aarhus University, DK-8410 Rønde, Denmark;
Rasmus
R
Ejrnæs
Section for Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark;
Søren
S
Faurby
Departamento de Ecologia, Universidade Estadual Paulista, 13506-900 Rio Claro, São Paulo, Brazil;
Mauro
M
Galetti
Institute of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland;
Dennis M
DM
Hansen
Section for Ecoinformatics & Biodiversity, Department of Bioscience, Aarhus University, DK-8000 Aarhus C, Denmark;
Brody
B
Sandel
Wildlife Conservation Research Unit, Department of Zoology, Oxford University, The Recanati-Kaplan Centre, Oxfordshire OX13 5QL, United Kingdom;
Christopher J
CJ
Sandom
Center for Tropical Conservation, Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708;
John W
JW
Terborgh
Community and Conservation Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Cocon, 9700 CC Groningen, The Netherlands.
Frans W M
FW
Vera
D000818:Animals; D057231:Climate Change; D003247:Conservation of Natural Resources; D017753:Ecosystem; D006801:Humans; D012106:Research; D012586:Science; D058615:Synthetic Biology
conservation; megafauna; reintroduction; restoration; trophic cascades