1,721,134 research outputs found
Twenty Landmark Papers in Biodiversity Conservation
Get PDFCorey J.A. Bradshaw, Navjot S. Sodhi, William F. Laurance and Barry W. Broo
Endemic predators, invasive prey and native diversity
No full textInteractions between native diversity and invasive species can be more complex than is currently understood. Invasive ant species often substantially reduce diversity in the native ants diversity that act as natural control agents for pest insects. In Indonesia (on the island of Sulawesi), the third largest cacao producer worldwide, we show that a predatory endemic toad (Ingerophrynus celebensis) controls invasive ant (Anoplolepis gracilipes) abundance, and positively affects native ant diversity. We call this the invasive-naivety effect (an opposite of enemy release), whereby alien species may not harbour anti-predatory defences against a novel native predator. A positive effect of the toads on native ants may facilitate their predation on insect vectors of cacao diseases. Hence, toads may increase crop yield, but further research is needed on this aspect. Ironically, amphibians are globally the most threatened vertebrate class and are strongly impacted by the conversion of rainforest to cacao plantations in Sulawesi. It is, therefore, crucial to manage cacao plantations to maintain these endemic toads, as they may provide critical ecosystem services, such as invasion resistance and preservation of native insect diversity.Thomas C. Wanger, Arno C. Wielgoss, Iris Motzke, Yann Clough, Barry W. Brook, Navjot S. Sodhi and Teja Tscharntk
Effects of land-use change on community composition of tropical amphibians and reptiles in Sulawesi, Indonesia
No full textLittle is known about the effects of anthropogenic land-use change on the amphibians and reptiles of the biodiverse tropical forests of Southeast Asia. We studied a land-use modification gradient stretching from primary forest, secondary forest, natural-shade cacao agroforest, planted-shade cacao agroforest to open areas in central Sulawesi, Indonesia. We determined species richness, abundance, turnover, and community composition in all habitat types and related these to environmental correlates, such as canopy heterogeneity and thickness of leaf litter. Amphibian species richness decreased systematically along the land-use modification gradient, but reptile richness and abundance peaked in natural-shade cacao agroforests. Species richness and abundance patterns across the disturbance gradient were best explained by canopy cover and leaf-litter thickness in amphibians and by canopy heterogeneity and cover in reptiles. Amphibians were more severely affected by forest disturbance in Sulawesi than reptiles. Heterogeneous canopy cover and thick leaf litter should be maintained in cacao plantations to facilitate the conservation value for both groups. For long-term and sustainable use of plantations, pruned shade trees should be permanently kept to allow rejuvenation of cacao and, thus, to prevent repeated forest encroachment.Thomas C. Wanger, Djoko T. Iskandar, Iris Motzke, Barry W. Brook, Navjot S. Sodhi, Yann Clough, and Teja Tscharntk
Global evidence that deforestation amplifies flood risk and severity in the developing world
No full textThe definitive version is available at www.blackwell-synergy.comWith the wide acceptance of forest-protection policies in the developing world comes a requirement for clear demonstrations of how deforestation may erode human well-being and economies. For centuries, it has been believed that forests provide protection against flooding. However, such claims have given rise to a heated polemic, and broad-scale quantitative evidence of the possible role of forests in flood protection has not been forthcoming. Using data collected from 1990 to 2000 from 56 developing countries, we show using generalized linear and mixed-effects models contrasted with information-theoretic measures of parsimony that flood frequency is negatively correlated with the amount of remaining natural forest and positively correlated with natural forest area loss (after controlling for rainfall, slope and degraded landscape area). The most parsimonious models accounted for over 65% of the variation in flood frequency, of which nearly 14% was due to forest cover variables alone. During the decade investigated, nearly 100 000 people were killed and 320 million people were displaced by floods, with total reported economic damages exceeding US$1151 billion. Extracted measures of flood severity (flood duration, people killed and displaced, and total damage) showed some weaker, albeit detectable correlations to natural forest cover and loss. Based on an arbitrary decrease in natural forest area of 10%, the model-averaged prediction of flood frequency increased between 4% and 28% among the countries modeled. Using the same hypothetical decline in natural forest area resulted in a 4–8% increase in total flood duration. These correlations suggest that global-scale patterns in mean forest trends across countries are meaningful with respect to flood dynamics. Unabated loss of forests may increase or exacerbate the number of flood-related disasters, negatively impact millions of poor people, and inflict trillions of dollars in damage in disadvantaged economies over the coming decades. This first global-scale empirical demonstration that forests are correlated with flood risk and severity in developing countries reinforces the imperative for large-scale forest protection to protect human welfare, and suggests that reforestation may help to reduce the frequency and severity of flood-related catastrophes.Corey J. A. Bradshaw, Navjot S. Sodhi, Kelvin S.-H. Peh, Barry W. Broo
Conserving imperiled species: a comparison of the IUCN Red List and U.S. Endangered Species Act
No full textAbstract
The United States conserves imperiled species with the Endangered Species Act (ESA). No studies have evaluated the ESA's coverage of species on the International Union for Conservation of Nature (IUCN) Red List, which is an accepted standard for imperiled species classification. We assessed the ESA's coverage of IUCN‐listed birds, mammals, amphibians, gastropods, crustaceans, and insects, and studied the listing histories of three bird species and Pacific salmonids in more detail. We found that 40.3% of IUCN‐listed U.S. birds are not listed by the ESA, and most other groups are underrecognized by >80%. Species with higher IUCN threat levels are more frequently recognized by the ESA. Our avian case studies highlight differences in the objectives, constraints, and listing protocols of the two institutions, and the salmonids example shows an alternative situation where agencies were effective in evaluating and listing multiple (related) species. Vague definitions of
endangered
and
threatened
, an inadequate ESA budget, and the existence of the
warranted but precluded
category likely contribute to the classification gap we observed.
J. Berton C. Harris, J. Leighton Reid, Brett R. Scheffers, Thomas C. Wanger, Navjot S. Sodhi, Damien A. Fordham & Barry W. Broo
Conservation biology: rarity bites
No full text© 2006 Nature Publishing GroupRare species have to cope not only with habitat loss, genetic bottlenecks and invasive competitors, but also with a self-reinforcing cycle of human greed. This last threat has now been dragged into the spotlight.Barry W. Brook and Navjot S. Sodh
Characteristics of nocturnal roosts of house crows in Singapore
No full textRoosts of house crows (Corvus splendens) in urban Singapore are perceived as a nuisance. Public complaints primarily focus on the fouling of gardens, pedestrian paths, buildings, and vehicles beneath or near roosts. We investigated their roost-site-selection patterns to help develop management recommendations for controlling urban crows. Roost sites (n = 30) were better illuminated by 89%, closer to food centers by 672.5 m, 33.1% more enclosed by tall buildings, and located in areas of greater human activity (measured using variables such as pedestrian traffic) by 47.0% more than randomly selected non-roost sites (n = 30). Roost trees, which primarily consisted of angsana (Pterocarpus indicus), were taller by 66.7%, spaced farther apart by 4.1 m, had larger crown volume by 275.9%, and had denser crowns by 15.4% more than non-roost trees. Crow roosts were surrounded by 76.3% more built-up urban environments with 90.3% less vegetated areas and 89.8% fewer water bodies than non-roost trees. However, discriminant analysis (DA) identified only 4 variables that clearly distinguished roost from non-roost sites: average distance to surrounding buildings, clear bole height (the visible portion of tree trunk), distance between adjacent roost trees, and percentage of the area around the roost tree covered with vegetation. Discriminant analysis correctly classified 100% of roost trees and 80% of non-roost trees. We recommend measures designed to avoid the creation of new roost sites (e.g., planting short [<18 m tall] trees), making existing roost sites less attractive (e.g., tree pruning), and establishing alternate roosting sites
Do insectivorous bird communities decline on land-bridge forest islands in Peninsular Malaysia?
No full textTo 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 amodel 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.Ding Li Yong, Lan Qie, Navjot S. Sodhi, Lian Pin Koh, Kelvin S.-H. Peh, Tien Ming Lee, Haw Chuan Lim and Susan L.-H. Li
Conservation value of cacao agroforestry for amphibians and reptiles in South-East Asia: combining correlative models with follow-up field experiments
No full textSummary 1. Although agricultural expansion is a primary threat to tropical biodiversity, experimental studies evaluating the conservation value of tropical agricultural habitats are scarce. In particular, little is known about the sensitivity of amphibians and reptiles to habitat disturbance in areas of very high diversity such as South‐East Asia. 2. We used a two‐step approach to determine the relationship between habitat complexity and conservation value of cacao agroforestry for herpetological diversity in Sulawesi (Indonesia). Indonesia is the third largest cacao‐exporting country globally and forest conversion to cacao plantations is a major threat to its biodiversity. We first sampled 43 cacao plantations six times to determine the environmental variables that best explained herpetofaunal diversity patterns using a Bayesian model selection approach. Based on these results, we experimentally manipulated leaf litter thickness (LLT), number of branch piles (LOGS) and LLT + LOGS combinations in the cacao plots. The experimental data were analysed using Bayesian hierarchical regression. 3. The best supported correlative models incorporated LLT, LOGS, air temperature and the ratio between leaf litter and shrub cover, showing the importance of habitat heterogeneity and suggesting climate change sensitivity. The subsequent structural manipulation of these attributes changed amphibian and reptile species richness, and reptile abundance, but only addition of leaf litter did so in a biologically meaningful way, providing microhabitat resources. However, the main beneficiaries were common disturbance‐tolerant reptiles. 4.
Synthesis and applications. The different results from the correlative model and the independent manipulative experiments showed how important such a combined approach is to derive adequate conservation management recommendations. Increasing leaf litter in cacao agroforestry will work best if implemented on a landscape scale to incorporate sufficient environmental variation and species life histories. This will mainly enhance the richness and abundance of disturbance‐tolerant species, which still may maintain ecosystem functions such as pest removal. Particularly for rare species, native forests remain critical for herpetological richness. The direct temperature sensitivity suggests that future climate change impacts may be severe for herpetological diversity in plantation habitats and, hence, demand further research.Thomas C. Wanger, Akbar Saro, Djoko T. Iskandar, Barry W. Brook, Navjot S. Sodhi, Yann Clough and Teja Tscharntk
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