Edge effects and extinction proneness in a herpetofauna from Madagascar

Authors: Lehtinen R.M.¹; Ramanamanjato J-B.²; Raveloarison J.G.³

Source: Biodiversity and Conservation, Volume 12, Number 7, July 2003 , pp. 1357-1370(14)

Publisher: Springer

Abstract:

Edge effects are thought to play a key role in fragmented habitats. It is often assumed that edge-avoiding species are more prone to local extinction than non-edge-avoiding species, but there are few data to support this assumption. Also, few data are available on the effects of edges on some groups, and there is little understanding of seasonal changes in edge effect intensity. To better understand the role that edge effects play in fragmented tropical forests, we assessed the distribution of reptiles and amphibians in six littoral rainforest fragments in southeastern Madagascar in 1999 (dry season) and 2000 (wet season). Using randomization tests, we found all three types of edge responses: edge-avoiders, interior-avoiders, and omnipresent species. However, edge responses varied considerably among seasons. For example, some species (e.g., Mantidactylus bicalcaratus, Phelsuma quadriocellata) were strong edge-avoiders in the dry season, but showed no preference for edge or interior habitats during the wet season. Also, edge-avoiding species tended to be more extinction-prone than non-edge-avoiding species. Abiotic data documented significantly higher temperatures and dew point temperatures near edges. Wind speed also tended to be higher and relative humidity tended to be lower near edges. Our results indicate that many amphibians and reptiles respond to altered microclimates near edges and these responses have a strong seasonal component. For many species, edge sensitivity does seem to be correlated with extinction vulnerability and therefore should be of primary consideration in plans to conserve biodiversity in fragmented tropical forests.

Keywords: Amphibians; Edge effects; Extinction; Habitat fragmentation; Madagascar; Matrix; Reptiles

Language: English

Document Type: Research article

Affiliations: 1: Museum of Zoology, Division of Reptiles and Amphibians, University of Michigan, 1109 Geddes Avenue, Ann Arbor, 48109-1079, USA (e-mail: rmlehtin@umich.edu) 2: QIT Madagascar Minerals S.A., Fort-Dauphin, 614, Madagascar; Departement de Biologie Animale, Université d'Antananarivo, Antananarivo, 101, Madagascar 3: Departement de Biologie Animale, Université d'Antananarivo, Antananarivo, 101, Madagascar

Publication date: 2003-07-01

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• In this Subject: Ecology
• By this author: Lehtinen R.M. ;  Ramanamanjato J-B. ;  Raveloarison J.G.

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