The environmental and social impacts of roads in southeast Asia

Clements, Gopalasamy Reuben (2013) The environmental and social impacts of roads in southeast Asia. PhD thesis, James Cook University.

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Abstract

The expansion of road networks shows no signs of abating, especially in developing countries where economic growth is rapid and opportunities for natural resource exploitation are plentiful. When a road is built, there will invariably be environmental and social impacts. Among tropical regions, however, these impacts are probably least studied in Southeast Asia.

When studying the environmental impacts of roads, mammals are one of the ideal animal groups to focus on due to their sensitivity to disturbance. In Southeast Asia, there is an urgent need to address the environmental impacts of roads on mammals, especially when predicted extinction rates of mammals are relatively high. As such, I interviewed 36 relevant experts to identify roads that are contributing the most to habitat conversion and illegal hunting of mammals in 7 Southeast Asian countries. We have now identified 16 existing and eight planned roads - these collectively threaten 21% of the 117 endangered terrestrial mammals in those countries. Using various techniques, I demonstrated how existing roads contribute to forest conversion and illegal hunting and trade of wildlife. Such empirical evidence can also be used to inform decision-makers and support efforts to mitigate threats from existing and proposed roads to endangered mammals. Finally, I highlighted key lessons and propose mitigation measures to limit road impacts within the region.

Roads that warrant urgent conservation attention must be prioritised because conservation resources are limited. One way would be to focus mitigation measures on roads cutting through forests with mammal species whose populations are at 'tipping points'. To address this, I developed the Species’ Ability to Forestall Extinction (SAFE) index, which incorporates a benchmark population target for long-term species persistence. I found that the SAFE index better predicts the widely used IUCN Red List threat categories than do previous measures such as percentage range loss. I argue that a combined approach – IUCN threat categories together with the SAFE index – is more informative and provides a good proxy for gauging the relative "safety" of a species from extinction. Finally, I show how the SAFE index can be used to prioritise roads in Southeast Asia that warrant urgent conservation attention based on their passage through habitats with the most number of mammal species whose populations are at 'tipping points'.

There is a paucity of information on the social impacts of roads in Southeast Asia. In order to address this, I interviewed 169 indigenous people (known as the Orang Asli) living in a biodiversity-rich forest complex bisected by a highway in northern Peninsular Malaysia. My surveys revealed that the majority of respondents supported the presence of the highway and construction of additional roads to their village. Overall, respondents perceive that the highway has a net positive impact on their livelihoods, despite low actual use of the highway for livelihood activities including hunting. Therefore, under circumstances where roads need to be opposed, conservation planners and practitioners may find it difficult to garner support from indigenous people who already have direct access to a previously constructed road, and desire greater access to markets, health clinics and jobs. Before a road is built, forest-dependent indigenous peoples should ideally be consulted to better understand how their socio-economic needs can be met without negatively impacting biodiversity.

In habitats fragmented by roads, underpasses are one possible mitigation measure to facilitate animal crossings. However, the role of underpasses as crossing structures for mammals as yet to be quantified in Southeast Asia. I investigated this for 20 underpasses at two fragmented habitat linkages in Peninsular Malaysia. Camera trap surveys in forests around the underpasses revealed that despite the effects of fragmentation, both linkages are still of high conservation importance for native mammals. For seven focal large mammal species, fragmentation had some degree of effect on the forest use of every focal species. The Clouded Leopard (Neofelis nebulosa) was the most sensitive species to fragmentation, with its forest use declining with increasing proximity to the road and reservoir, and less intact forest cover. Not only has fragmentation affected forest use of large mammals around all 20 underpasses, it has also affected the efficiency at which underpasses are used as crossing structures. Overall, these underpasses appear to be effective crossing structures for only two herbivore species, Asian Elephant (Elephas maximus) and Serow (Capricornis sumatraensis). Individual underpass-use efficiencies have been sub-optimal for all focal species except Serow. For five species, the presence of underpasses at the end of trails did not have an effect on increasing trail use – this questions the ability of underpasses to mitigate road impacts on animal crossings. Conservation planners and practitioners must recognise that it may be unrealistic to expect underpasses to be effective crossing structures for all large mammal species and ecological guilds. At each linkage, management interventions to minimise the negative effects of forest fragmentation around the underpasses should be adopted to improve their efficiency of use by large mammals.

This thesis augments the body of knowledge on the environmental and social impacts of roads in Southeast Asia. While this thesis provides strategies on how to mitigate the negative impacts of roads in this region, the real challenge lies with implementing these strategies on the ground. As an example of how conservation research can be translated into action, I report how my lobbying efforts in the State of Terengganu, Peninuslar Malaysia, have prompted the state government to: (1) implement a state-wide ban on the legal hunting of Flying Foxes (Pteropus spp.) that I found threatened by roadside hunting; and (2) issue a moratorium on infrastructure development along a road cutting through a habitat linkage that is important for mammal conservation.

Item ID: 31888
Item Type: Thesis (PhD)
Keywords: fragmented habitat; impact mitigation; impact of roads; infrastructure planning; southeast Asia; species conservation
Additional Information:

Publications arising from this thesis are available from the Related URLs field. The publications are:

Chapter 2: Clements, Gopalasamy Reuben, Rayan, D. Mark, Aziz, Sheema Abdul, Kawanishi, Kae, Traeholt, Carl, Magintan, David, Yazi, Muhammad Fadlli Abdul, and Tingley, Reid (2012) Predicting the distribution of the Asian tapir in Peninsular Malaysia using maximum entropy modeling. Integrative Zoology, 7 (4). pp. 400-406.

Chapter 3: Clements, Gopalasamy Reuben, Bradshaw, Corey J.A., Brook, Barry W., and Laurance, William F. (2011) The SAFE index: using a threshold population target to measure relative species threat. Frontiers in Ecology and the Environment, 9 (9). pp. 521-525.

Chapter 3: Bradshaw, Corey J.A., Clements, Gopalasamy Reuben, Laurance, William F., and Brook, Barry W. (2011) Better SAFE than sorry. Frontiers in Ecology and the Environment, 9 (9). pp. 487-488.

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Date Deposited: 30 Apr 2014 02:44
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 34%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050104 Landscape Ecology @ 33%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060208 Terrestrial Ecology @ 33%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 34%
96 ENVIRONMENT > 9609 Land and Water Management > 960906 Forest and Woodlands Land Management @ 33%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 33%
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