Edge effects on species richness distributions in tropical forest protected areas

Chia Hsieh, Daniel Gorczynski, Jadelys Tonos Luciano and Lydia Beaudrot, Department of BioSciences, Rice University, Houston, TX, Chia Hsieh, Daniel Gorczynski, Jadelys Tonos Luciano and Lydia Beaudrot, Program in Ecology and Evolutionary Biology, Rice University, Houston, TX, Marion Donald, Manaaki Whenua Landcare Research, New Zealand, Luke Frishkoff, Department of Biology, University of Texas at Arlington, Arlington, TX, Daniel Karp, Wildlife, Fish, and Conservation Biology, University of California, Davis, CA, Jean-Philippe Lessard, Department of Biology, Concordia University, Montreal, QC, Canada, Rahel Sollmann, Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA, Patrick A. Jansen, Smithsonian Tropical Research Institute, Balboa, Panama, Patrick A. Jansen, Department of Environmental Sciences, Wageningen University, Wageningen, Netherlands, Fernanda Santos, Department of Mastozoology, Museu Paraense Emílio Goeldi, Belém, Brazil, Krisna Gajapersad, Conservation International Suriname, Paramaribo, Suriname, Patricia Alvarez-Loayza, Center for Tropical Conservation, Duke University, Durham, NC, Kelly Boekee, Center for Tropical Forest Science, Smithsonian Tropical Research Institute, Balboa, Panama, Wilson R. Spironello, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil, Ahimsa Campos-Arceiz, School of Geography, University of Nottingham Malaysia Campus, Mengla, Malaysia, Ahimsa Campos-Arceiz, Xishuangbanna Tropical Botanical Garden, Southeast Asia Biodiversity Research Institute, China, Mahandry Hugues Andrianarisoa, Centre ValBio, Ranomafana National Park, Ranomafana, Madagascar, Francesco Rovero, Department of Biology, University of Florence, Florence, Italy, Francesco Rovero, Tropical Biodiversity Section, MUSE-Museo delle Scienze, Trento, Italy, Charles Kayijamahe, International Gorilla Conservation Programme, Kigali, Rwanda, Santiago Espinosa, Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, Quito, Ecuador, Santiago Espinosa, Universidad Autónoma de San Luis Potosí, Mexico, Julia Salvador, Wildlife Conservation Society, Johanna Hurtado Astaiza, La Selva Biological Station, Organization for Tropical Studies, Puerto Viejo de Sarapiqui, Costa Rica, Steig E. Johnson, Department of Anthropology and Archaelogy, University of Calgary, Calgary, Canada, Jorge Ahumada, TEAM Network, Moore Center for Science, Conservation International, Marcela Lima, Universidade Federal do Pará, Douglas Sheil, Forest Ecology and Forest Management Group, Wageningen University & Research, Wageningen, Netherlands, Tim O'Brien, Global Conservation Programs, Wildlife Conservation Society, New York, NY, Badru Mugerwa, Leibniz Institute for Zoo and Wildlife Research

Background/Question/Methods
The tropics host the greatest diversity of species on the planet, yet face grave threats from habitat destruction and environmental degradation. Protected areas have long been considered bastions for biodiversity, but cross-boundary human activities and tropical species’ high sensitivity could force species to concentrate in core areas causing changes in the spatial distribution of ecosystem functions. We investigated how tropical species’ distributions responded to three types of edges: 1) forest, 2) park boundary, and 3) road, while simultaneously assessing the influence of species’ distance to range edge and environmental gradients. We obtained occurrence data of camera-trapped ground-dwelling mammals and birds from 14 protected areas monitored by the Tropical Ecology Assessment and Monitoring (TEAM) Network. We employed a multi-species occupancy model to estimate each species’ occupancy as a function of camera-trap specific covariates for each protected area. We investigated variation in drivers of species richness among protected areas by plotting community-level effect sizes of each covariate as a function of TEAM site-level characteristics. Lastly, we assessed the relationships between population-specific edge effects and species attributes.
Results/Conclusions
We found that forest protected areas experiencing greater hunting pressure and greater fragmentation showed stronger and more consistent forest edge effects in which species richness declined near forest edges. Individual populations tended to avoid forest and road edges, but preferred park boundary edges. Preference for park boundaries was particularly notable in protected areas surrounded by continuous forest rather than agricultural or patchily forested landscapes. Among species attributes, both ground-foraging birds and mammals were more sensitive to road edges compared to those foraging in other strata. Elevation was also a significant predictor of species richness. Species richness peaked at intermediate elevations and protected areas with larger elevational gradients showed stronger associations. We therefore demonstrated how anthropogenic threats may act on the spatial distribution of species richness in tropical forest protected areas and identified differential responses to anthropogenic edge types of tropical birds and mammals based on species attributes.