@article{c92265f2b1fe42e19dc6559479b94c03,
title = "Large herbivores suppress liana infestation in an African savanna",
abstract = "African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana–tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.",
keywords = "Competition and facilitation, DNA metabarcoding, Defaunation, Ecological regime shifts, Trophic rewilding",
author = "Coverdale, {Tyler C.} and O{\textquoteright}Connell, {Ryan D.} and Hutchinson, {Matthew C.} and Amanda Savagian and Kartzinel, {Tyler R.} and Palmer, {Todd M.} and Goheen, {Jacob R.} and Augustine, {David J.} and Mahesh Sankaran and Tarnita, {Corina E.} and Pringle, {Robert M.}",
note = "Funding Information: ACKNOWLEDGMENTS. We thank the Government of Kenya (NACOSTI/P/14/ 8746/1626, NACOSTI/P/20/6262), D. Martins, and Mpala Research Centre for permission to conduct this study. N. Carlson, M. Crosley, C. Coverdale, E. Coverdale, M. Dyck, J. Echekan, P. Echekan, A. Hassan, S. Kurukura, S. Mwinzi, A. Marsh, I. McGeary, and C. Muskin assisted with field work, data collection, and analyses. A. Agrawal, J. Daskin, A. Davies, and C.E.T.{\textquoteright}s research group provided valuable feedback on the manuscript. We received support from the US NSF (DEB-1601538, DEB-1355122, DEB-1457697, DEB-1930820, IOS-1656527, DEB-1556728, DEB-1149980), the American Philosophical Society, the Garden Club of America, Princeton University and the High Meadows Environmental Institute, the Universities of Florida and Wyoming, and a NatureNet Science Fellowship from The Nature Conservancy. The UHURU experiment was built with a Natural Sciences and Engineering Research Council Tools and Instruments grant. The GLADE exclosure plots were built with funding from the National Geographic Society and NSF (DEB-9813050). Funding Information: We thank the Government of Kenya (NACOSTI/P/14/ 8746/1626, NACOSTI/P/20/6262), D. Martins, and Mpala Research Centre for permission to conduct this study. N. Carlson, M. Crosley, C. Coverdale, E. Coverdale, M. Dyck, J. Echekan, P. Echekan, A. Hassan, S. Kurukura, S. Mwinzi, A. Marsh, I. McGeary, and C. Muskin assisted with field work, data collection, and analyses. A. Agrawal, J. Daskin, A. Davies, and C.E.T.?s research group provided valuable feedback on the manuscript. We received support from the US NSF (DEB-1601538, DEB-1355122, DEB-1457697, DEB-1930820, IOS-1656527, DEB-1556728, DEB-1149980), the American Philosophical Society, the Garden Club of America, Princeton University and the High Meadows Environmental Institute, the Universities of Florida and Wyoming, and a NatureNet Science Fellowship from The Nature Conservancy. The UHURU experiment was built with a Natural Sciences and Engineering Research Council Tools and Instruments grant. The GLADE exclosure plots were built with funding from the National Geographic Society and NSF (DEB-9813050). Publisher Copyright: {\textcopyright} 2021 National Academy of Sciences. All rights reserved.",
year = "2021",
month = oct,
day = "12",
doi = "10.1073/pnas.2101676118",
language = "English (US)",
volume = "118",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "41",
}