Tien Ming Lee

Primary forests are irreplaceable for sustaining tropical biodiversity

Human-driven land-use changes increasingly threaten biodiversity, particularly in tropical forests where both species diversity and human pressures on natural environments are high. The rapid conversion of tropical forests for agriculture, timber production and other uses has generated vast, human-dominated landscapes with potentially dire consequences for tropical biodiversity. Today, few truly undisturbed tropical forests exist, whereas those degraded by repeated logging and fires, as well as secondary and plantation forests, are rapidly expanding. Here we provide a global assessment of the impact of disturbance and land conversion on biodiversity in tropical forests using a meta-analysis of 138 studies. We analysed 2,220 pairwise comparisons of biodiversity values in primary forests (with little or no human disturbance) and disturbed forests. We found that biodiversity values were substantially lower in degraded forests, but that this varied considerably by geographic region, taxonomic group, ecological metric and disturbance type. Even after partly accounting for confounding colonization and succession effects due to the composition of surrounding habitats, isolation and time since disturbance, we find that most forms of forest degradation have an overwhelmingly detrimental effect on tropical biodiversity. Our results clearly indicate that when it comes to maintaining tropical biodiversity, there is no substitute for primary forests.

Measuring the Meltdown: Drivers of Global Amphibian Extinction and Decline

Habitat loss, climate change, over-exploitation, disease and other factors have been hypothesised in the global decline of amphibian biodiversity. However, the relative importance of and synergies among different drivers are still poorly understood. We present the largest global analysis of roughly 45% of known amphibians (2,583 species) to quantify the influences of life history, climate, human density and habitat loss on declines and extinction risk. Multi-model Bayesian inference reveals that large amphibian species with small geographic range and pronounced seasonality in temperature and precipitation are most likely to be Red-Listed by IUCN. Elevated habitat loss and human densities are also correlated with high threat risk. Range size, habitat loss and more extreme seasonality in precipitation contributed to decline risk in the 2,454 species that declined between 1980 and 2004, compared to species that were stable (n = 1,545) or had increased (n = 28). These empirical results show that amphibian species with restricted ranges should be urgently targeted for conservation.

The state and conservation of Southeast Asian biodiversity.

Southeast Asia is a region of conservation concern due to heavy losses of its native habitats. In this overview, we highlight the conservation importance of Southeast Asia by comparing its degree of species endemism and endangerment, and its rate of deforestation with other tropical regions (i.e., Meso-America, South America, and Sub-Saharan Africa). Southeast Asia contains the highest mean proportion of country-endemic bird (9%) and mammal species (11%). This region also has the highest proportion of threatened vascular plant, reptile, bird, and mammal species. Furthermore, not only is Southeast Asia’s annual deforestation rate the highest in the tropics, but it has also increased between the periods 1990–2000 and 2000–2005. This could result in projected losses of 13–85% of biodiversity in the region by 2100. Secondary habitat restoration, at least in certain countries, would allow for some amelioration of biodiversity loss and thus potentially lower the currently predicted extinction rates. Nonetheless, urgent conservation actions are needed. Conservation initiatives should include public education, sustaining livelihoods, and ways to enhance the sustainability of agriculture and increase the capacity of conservation institutions. Furthermore, these actions should be country-specific and not ignore areas heavily populated by humans, as they can also harbour high numbers of threatened species. We urge that cooperative conservation initiatives be undertaken and support (e.g., capacity-building) be given by more developed countries in the region and beyond.

Local people value environmental services provided by forested parks

Garnering support from local people is critical for maintaining ecologically viable and functional protected areas. However, empirical data illustrating local people’s awareness of the importance of nature’s services is limited; hence possibly impeding effective ecosystem (environmental)-services based conservation efforts. Using data from five protected forests in four developing Southeast Asian countries, we provide evidence that local people living near parks value a wide range of environmental services, including cultural, provisioning, and regulating services, provided by the forests. Local people with longer residency valued environmental services more. Educated as well as poor people valued forest ecosystem services more. Conservation education has some influence on people’s environmental awareness. For conservation endeavors to be successful, large-scale transmigration programs should be avoided and local people must be provided with alternative sustenance opportunities and basic education in addition to environmental outreach to reduce their reliance on protected forests and to enhance conservation support.

Perspectives in Ornithology: Effects of Disturbance or Loss of Tropical Rainforest on Birds

1Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Republic of Singapore; 2Ecology, Behavior and Evolution Section, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA; and 3Environmental Science–Biology, Memorial University, Corner Brook, Newfoundland and Labrador A2H 6P9, Canada

THE IMPORTANCE OF PROTECTED AREAS FOR THE FOREST AND ENDEMIC AVIFAUNA OF SULAWESI (INDONESIA)

Protected areas are critical for the conservation of residual tropical forest biodiversity, yet many of these are being deforested by humans both within and outside of their administrative boundaries. Therefore, it is critical to document the significance of protected areas for conserving tropical biodiversity, particularly in mega-diverse Southeast Asia. We evaluated the importance of protected areas (national parks [NP], nature reserves [NR], and wildlife reserves [WR]) in preserving avifaunal diversity, particularly the endemic and forest species, on the island of Sulawesi. This island has one of the highest numbers of endemic avifauna genera (12) globally and is also experiencing heavy deforestation. Rarefaction analyses and species estimators showed that parks and reserves consistently recorded higher number of forest, endemic, and endemic forest bird species, in addition to larger population densities, than in their surrounding human-modified areas across eight protected areas (Gunung Manembo-nembo WR, Tangkoko-Batu Angus and Dua Saudara NR, Gunung Ambang NR, Bogani Nani Wartabone NP, Gunung Tinombala NR, Gunung Sojol NR, Lore Lindu NP, and Rawa Aopa Watumohai NP). This implies that protecting natural forests must remain as one of the fundamental conservation strategies in Sulawesi. Two small reserves (Gunung Manembo-nembo WR and Tangkoko-Batu Angus and Dua Saudara NR), however, had high number of forest and endemic bird species both within and outside their boundaries, suggesting the importance of buffer areas for augmenting small reserves so as to improve their conservation value. Ordination analyses revealed the differential response of bird species to different environmental factors (e.g., native tree cover), highlighting the significance of forested habitats with dense native vegetation cover for effective conservation of forest dependent and endemic avifauna. In addition, the distinctiveness in bird species composition among protected areas highlights the importance of establishing a reserve network across major altitudinal zones so as to achieve maximum complementarity for the conservation of Sulawesis unique avifauna.

Deforestation and Avian Extinction on Tropical Landbridge Islands

There are few empirical data, particularly collected simultaneously from multiple sites, on extinctions resulting from human-driven land-use change. Southeast Asia has the highest deforestation rate in the world, but the resulting losses of biological diversity remain poorly documented. Between November 2006 and March 2008, we conducted bird surveys on six landbridge islands in Malaysia and Indonesia. These islands were surveyed previously for birds in the early 1900 s, when they were extensively forested. Our bird inventories of the islands were nearly complete, as indicated by sampling saturation curves and nonparametric true richness estimators. From zero (Pulau Malawali and Pulau Mantanani) to 15 (Pulau Bintan) diurnal resident landbird species were apparently extirpated since the early 1900 s. Adding comparable but published extinction data from Singapore to our regression analyses, we found there were proportionally fewer forest bird extinctions in areas with greater remaining forest cover. Nevertheless, the statistical evidence to support this relationship was weak, owing to our unavoidably small sample size. Bird species that are restricted to the Indomalayan region, lay few eggs, are heavier, and occupy a narrower habitat breadth, were most vulnerable to extinction on Pulau Bintan. This was the only island where sufficient data existed to analyze the correlates of extinction. Forest preservation and restoration are needed on these islands to conserve the remaining forest avifauna. Our study of landbridge islands indicates that deforestation may increasingly threaten Southeast Asian biodiversity.

Determinants of local people's attitude toward conservation and the consequential effects on illegal resource harvesting in the protected areas of Sulawesi (Indonesia).

The exploitation of tropical forest resources is a key driver of the current biodiversity crisis, and it is pivotal to understand human attitudes toward conservation and resource harvesting. This paper investigates effects of interactions, perceptions of protected areas (PAs) and sociodemographic variables on conservation attitudes, and the correlates of illegal resource extraction among 660 households from 33 villages bordering eight PAs on Sulawesi (Indonesia). Mixed-effect multiple regression analyses showed that the most important predictors of the support for PAs included the degree of involvement in management, presence/absence of PA-human conflict, perceived sustainability of forest resources and length of residency in Sulawesi. Notably, active participation in community management by transmigrants and the reconciliation of land-rights conflicts for natives may promote favourable conservation attitudes. Ordination and correlation analyses also revealed that the extent of illegal resource harvesting activities, such as hunting and logging, were significantly influenced by a negative conservation attitude and past conflict with PA establishment. Garnering support for PAs through conservation education and resolving land-rights disputes could potentially alleviate illegal resource extraction. The disparity in resource extraction patterns among the villages across all PAs confirms the importance of adopting site-specific conservation strategies that may make PAs across the biologically unique yet critically threatened Indonesian Archipelago more effective.

A century of avifaunal turnover in a small tropical rainforest fragment

Despite the alarming rate of tropical deforestation, the long-term conservation value of forest fragments remains poorly understood. We report on the avifaunal turnover in an isolated 4 ha tropical forest fragment in Singapore (i.e. Singapore Botanic Gardens rainforest fragment (SBGRF)) between 1898 and 1998. Over 100 years, the SBGRF lost 18 (49%) species and gained 20 species. More forest-dependent species (3) were lost from the SBGRF than survived (1) or colonised it (no species). Conversely, significantly more introduced species (4) colonised the fragment than were previously recorded (1 species). Significantly more nectarivores survived (8 species) or colonised (9 species) than were lost (two species). In essence, while the avian species richness in the SBGRF remained relatively constant after a century, its species composition underwent significant changes. The avian species composition in the SBGRF in 1998 appeared to be more similar to that of the contemporary smaller and younger Singaporean secondary forest patches than to either the larger and older forest reserves or to the SBGRF 100 years ago. Our study suggests that small isolated tropical forest fragments may have limited long-term conservation value for native forest bird species.

Do insectivorous bird communities decline on land-bridge forest islands in Peninsular Malaysia?

To assess the impact of habitat fragmentation on tropical avian communities, we sampled lowland forest birds on six land-bridge islands and two mainland forest sites in Lake Kenyir, Peninsular Malaysia using timed point counts, hypothesizing that insectivorous birds are the worst affected guild. We used an information-theoretic approach to evaluate the effects of area, isolation, primary dietary guild (omnivore, frugivore and insectivore) and their interactions in predicting species richness, abundance and diversity. Our analysis showed that a model that considered the effects of area, dietary guild and their interaction best explained observed patterns of species richness. But a model considering both area and dietary guild best explained the variation in abundance. Notably, insectivorous birds were singled out as the dietary guild most sensitive to fragmentation, followed by frugivorous and omnivorous birds and hence provide support for our hypothesis. Assemblages of insectivorous birds were clearly depauperate on anthropogenic forest islands in Lake Kenyir and are consistent with forest fragmentation studies in the Neotropics. Given their specialized foraging ecology and diversity, conservation of intact communities of insectivorous bird guilds in Malaysia will be critical for maintaining predator–prey interactions in lowland tropical forests.