Indirect interactions among tropical tree species through shared rodent seed predators: a novel mechanism of tree species coexistence.
The coexistence of numerous tree species in tropical forests is commonly explained by negative dependence of recruitment on the conspecific seed and tree density due to specialist natural enemies that attack seeds and seedlings ('Janzen-Connell' effects). Less known is whether guilds of shared seed predators can induce a negative dependence of recruitment on the density of different species of the same plant functional group. We studied 54 plots in tropical forest on Barro Colorado Island, Panama, with contrasting mature tree densities of three coexisting large seeded tree species with shared seed predators. Levels of seed predation were far better explained by incorporating seed densities of all three focal species than by conspecific seed density alone. Both positive and negative density dependencies were observed for different species combinations. Thus, indirect interactions via shared seed predators can either promote or reduce the coexistence of different plant functional groups in tropical forest.
Groningen Institute for Evolutionary Life Sciences, University of Groningen, Box 11103, Groningen, 9700 CC, The Netherlands.|GIS and Remote Sensing Unit, Department of Biodiversity and Molecular Ecology, Fondazione Edmund Mach, Research and Innovation Centre, Via E. Mach 1, 38010 S. Michele all'Adige (TN), Italy.
Carol X
CX
Garzon-Lopez
Groningen Institute for Evolutionary Life Sciences, University of Groningen, Box 11103, Groningen, 9700 CC, The Netherlands.|Laboratorio de Genetica e Biodiversidade, ICB, Universidade Federal de Goias (UFG), Campus Samambaia 74001-970 Goiania, Goias, Brazil.
Liliana
L
Ballesteros-Mejia
Department of Bioscience, Section for Ecoinformatics and Biodiversity, Aarhus University, Ny Munkegade 114, DK-8000, Aarhus C, Denmark.
Alejandro
A
Ordoñez
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.|School of Forest Resources and Conservation, University of Florida, Box 110410, Gainesville, FL, 32611-0410, USA.
Stephanie A
SA
Bohlman
Groningen Institute for Evolutionary Life Sciences, University of Groningen, Box 11103, Groningen, 9700 CC, The Netherlands.
Han
H
Olff
Groningen Institute for Evolutionary Life Sciences, University of Groningen, Box 11103, Groningen, 9700 CC, The Netherlands.|Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.|Department of Environmental Sciences, Wageningen University, Box 47, 6700, AA Wageningen, The Netherlands.
Patrick A
PA
Jansen
D000818:Animals; D017753:Ecosystem; D060434:Herbivory; D016015:Logistic Models; D010176:Panama; D012377:Rodentia; D012639:Seeds; D014197:Trees / Q000502:physiology*; D014329:Tropical Climate
Apparent competition; Astrocaryum standleyanum; Attalea butyracea; Dipteryx oleifera; Janzen-Connell hypothesis; apparent mutualism; indirect effects; seed predation; shared enemies; tropical forest