Where and How Are Roads Endangering Mammals in Southeast Asia's Forests?

Abstract

Habitat destruction and overhunting are two major drivers of mammal population declines and extinctions in tropical forests. The construction of roads can be a catalyst for these two threats. In Southeast Asia, the impacts of roads on mammals have not been well-documented at a regional scale. Before evidence-based conservation strategies can be developed to minimize the threat of roads to endangered mammals within this region, we first need to locate where and how roads are contributing to the conversion of their habitats and illegal hunting in each country. We interviewed 36 experts involved in mammal research from seven Southeast Asian countries to identify roads that are contributing the most, in their opinion, to habitat conversion and illegal hunting. Our experts highlighted 16 existing and eight planned roads - these potentially threaten 21% of the 117 endangered terrestrial mammals in those countries. Apart from gathering qualitative evidence from the literature to assess their claims, we demonstrate how species-distribution models, satellite imagery and animal-sign surveys can be used to provide quantitative evidence of roads causing impacts by (1) cutting through habitats where endangered mammals are likely to occur, (2) intensifying forest conversion, and (3) contributing to illegal hunting and wildlife trade. To our knowledge, ours is the first study to identify specific roads threatening endangered mammals in Southeast Asia. Further through highlighting the impacts of roads, we propose 10 measures to limit road impacts in the region.

Assessing large-scale wildlife responses to human infrastructure development

“…As a first step, we have conducted a review of five major traits, namely, body mass, home range size, reproductive rate, longevity, and trophic level, of the 232 species included in the study of Benítez-López et al (21). By creating this database (available in Dataset S1) we intend to ease the way for broader application of the insights derived from this study and give impetus to further applied research in developing regions, which are in great need of solutions and increased representation (7,42). In moving forward, we are making a call to scientists and practitioners to coordinate a database and network of studies about infrastructure-mediated impacts on wildlife populations across ecosystems and geographical areas (43) and to make use of this approach as a powerful conservation planning tool.…”

“…The largest expected infrastructural undertakings will occur in developing nations (3,4), including many regions that sustain exceptional levels of biodiversity and vital ecosystem services. These structures will alter ecological conditions, cut through highly suitable habitat, and further reduce the populations of many wildlife species (5)(6)(7). However, large-scale consequences of these trends remain unknown (8).…”

Logging Roads in Tropical Forests: Synthesis of Literature Written in French and English Highlights Environmental Impact Reduction Through Improved Engineering

“…Roads in forests directly interfere with animal populations through road kill Clements et al, 2014) but also by influencing their movement and behaviour (Chazdon et al, 2009;Lees and Peres, 2009;Van Der Hoeven, 2010). Negative effects of roads have been shown on small mammals (Malcolm and Ray, 2000), birds (Develey and Stouffer, 2001;, elephants (Blake et al, 2008) and dung beetles (Hosaka et al, 2014).…”

“…Forest clearing for road construction ( Plan and regulate land-uses, provide alternatives for settlers van Vliet and Nasi, 2007;Clements et al, 2014Allouard, 1954bHoeven, 2010Mason and Putz, 2001van Vliet and Nasi, 2007;Edwards et al, 2014bSist et al, 1998Applegate et al, 2004;van Vliet and Nasi, 2007;Bicknell et al, 2015aRobinson et al, 1999Wilkie et al, 2000;Poulsen et al, 2009 Dykstra andChomitz and Gray, 1996;Mertens and Lambin, 2000;Laurance et al, 2014 Table II. Logging-road-related environmental problems and measures to mitigate such impacts.…”

“…This includes the declaration of set-asides from logging in high conservation-value areas as well as measures to reduce the fragmenting effect of roads on animal habitats Clements et al, 2014). Given the problems with hunting and encroachment, control of access has been identified as a crucial aspect of road management.…”