The ecological consequences of logging have been and remain a focus of considerable debate. In this study, we assessed bird species composition within a logging concession in Central Kalimantan, Indonesian Borneo. Within the study area (approximately 196 km2) a total of 9747 individuals of 177 bird species were recorded. Our goal was to identify associations between species traits and environmental variables. This can help us to understand the causes of disturbance and predict whether species with given traits will persist under changing environmental conditions. Logging, slope position, and a number of habitat structure variables including canopy cover and liana abundance were significantly related to variation in bird composition. In addition to environmental variables, spatial variables also explained a significant amount of variation. However, environmental variables, particularly in relation to logging, were of greater importance in structuring variation in composition. Environmental change following logging appeared to have a pronounced effect on the feeding guild and size class structure but there was little evidence of an effect on restricted range or threatened species although certain threatened species were adversely affected. For example, species such as the terrestrial insectivore Argusianus argus and the hornbill Buceros rhinoceros, both of which are threatened, were rare or absent in recently logged forest. In contrast, undergrowth insectivores such as Orthotomus atrogularis and Trichastoma rostratum were abundant in recently logged forest and rare in unlogged forest. Logging appeared to have the strongest negative effect on hornbills, terrestrial insectivores, and canopy bark-gleaning insectivores while moderately affecting canopy foliage-gleaning insectivores and frugivores, raptors, and large species in general. In contrast, undergrowth insectivores responded positively to logging while most understory guilds showed little pronounced effect. Despite the high species richness of logged forest, logging may still have a negative impact on extant diversity by adversely affecting key ecological guilds. The sensitivity of hornbills in particular to logging disturbance may be expected to alter rainforest dynamics by seriously reducing the effective seed dispersal of associated tree species. However, logged forest represents an increasingly important habitat for most bird species and needs to be protected from further degradation. Biodiversity management within logging concessions should focus on maintaining large areas of unlogged forest and mitigating the adverse effects of logging on sensitive groups of species.

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Road-infrastructure development in Southeast Asia is opening new resource frontiers but also consolidating earlier investments in agriculture and trade, as illustrated by the 2,700-km Trans-Sumatra Highway planned for Sumatra, Indonesia. In contrast to earlier broadscale forest losses in Sumatra, driven historically in Sumatra infrastructure and agricultural expansion, the Trans-Sumatra Highway would largely affect remnant forests. We identify Kerinci Seblat National Park and its surrounds, the Leuser Ecosystem, and the Batang Toru area as three remnant-forest areas critical to Sumatra's ecological integrity and facing conservation challenges that would be significantly aggravated by the Trans-Sumatra Highway. If completed as planned, the highway will promote human incursions into the fringes of these areas. New Indonesian regulations concerning road developments in forests are unlikely to prevent such outcomes. The regulations afford weaker protections to ungazetted and noncore protected forests, which typify remnant-forest areas threatened by infrastructure expansion and are often critical for species conservation. We urge that ungazetted protected forests be given equal priority to gazetted protected forests in regard to conservation planning for road development, and also that gazetted forests be expanded in the Leuser Ecosystem and Batang Toru area to hedge against further incursions. Without such provisions, recent legal challenges to road developments in Sumatra's remnant forests have often been unsuccessful. The Trans-Sumatra Highway may conceivably promote an effective legal alliance between conservationists and agricultural communities threatened with land expropriation, given that nearly half of the highway's route remains pending contentious land-acquisition processes.

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