The response of faunal biodiversity to an unmarked road in the Western Amazon
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Roads are an increasingly common feature of forest landscapes all over the world, and while information accumulates regarding the impacts of roads globally, there remains a paucity of information within tropical regions. Here we investigate the potential for biodiversity impacts from an unmarked road within a rainforest protected area in Western Amazonia. We focus on three key taxonomic groups; amphibians, butterflies and birds, each of which have been shown to be both sensitive and reliable indicators of forest disturbance. In total, 315 amphibians of 26 different species, 348 butterflies of 65 different species, 645 birds representing 77 different species were captured using mist netting and 877 bird records representing 79 different species were recorded using point counts. We provide evidence to show that the presence of a small unmarked road significantly altered levels of faunal species richness, diversity, relative abundance and community structure. This was true to a varying degree for all three taxa, up to and potentially beyond 350 m into the forest interior. Responses to the road were shown to be taxon specific. We found increasing proximity to the road had a negative effect on amphibian and understorey bird communities, whilst butterfly and overall diurnal bird communities responded positively. We show that the impact on biodiversity extends up to at least 32 % of the whole reserve area; a serious impact under any scenario. This work provides support for recently voiced calls to limit networks of unmarked roads in order to realistically and effectively preserve natural levels of tropical biodiversity.
KeywordsRoad effects Amphibians Birds Butterflies Habitat change Edge effects Tropical forests Amazonia
Without the hard work and dedication of Global Vision International (GVI) staff members, volunteers and local partners on the GVI Amazon Expedition, this research would not have been possible. Many thanks to K. Berg and B. Clarke for letting their staff members dedicate time to the project. Other staff members significantly involved include: I. Varela, J. Sinasac, J. V. Ortega, T. Topper, P. Torres, C. Coupland, I. Moody, B. Horton-Hunter, A. Fowler and P. Silvera. Many thanks go to the Yachana Foundation in providing us with an ideal location to investigate the effects of recent habitat changes and the effects of an unmarked road within the Western Amazon. Special thanks to the Ecuadorian Museum of Natural Sciences (MECN), especially to M. H. Yanez-Muñoz for his advice and identification skills throughout the research. Finally, thanks to the Ministerio del Ambiente, Ecuador, in providing us with the permit to collect specimens during the project for accurate identification of unknown individuals in the field (N° 028-IC-FAU/FLO-DPN/MA). Thanks are also given to both The Crees Foundation (especially director Q. Meyer) and to The University of Glasgow in allowing AW to dedicate time in writing up this research. Finally, thanks to Dr. R. MacLeod and Dr. R. Reeve for their advice on aspects of the analysis.
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