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In human-modified tropical landscapes, biodiversity is threatened by a myriad of forces, including habitat loss and fragmentation, land degradation, overexploitation of forest resources, and biological invasions. Ecological restoration offers a promising way to enhance biodiversity persistence and the delivery of ecosystem services by: 1) establishing structural elements in the landscape to enhance connectivity, 2) providing additional forest cover, 3) restoring degraded forest remnants through protection from human-mediated disturbances and reestablishment of successional trajectory, and 4) supporting sustainable socio-economic development in marginalized rural communities, where the lack of job opportunities drives deforestation, forest degradation, and overexploitation. Due to biodiversity requirements, however, this potential will only be realized if restoration is carried out on very large spatial scales. Although conservation biologists have historically doubted the potential of ecological restoration to reverse ecosystem degradation and mitigate species loss, we argue that conservation policies and programs should include restoration among the strategies adopted to mitigate extinction debts and support the creation of biodiversity friendly-landscapes. Otherwise, we will likely continue to describe a slow and irreversible loss of our biological heritage in isolated protected areas in human-modified tropical landscapes.
Little is known of the frequency of use and reliance upon tree cavities by wildlife, nor the natural availability of cavities in New Guinea forests. We surveyed the literature for records of cavity use by birds and mammals in New Guinea. We examined every standing tree on one hectare of primary forest and one hectare of secondary forest for cavities, then carefully assessed every tree for cavities after they were felled. We put up 190 artificial nest boxes of five designs in three sites and monitored occupancy. At least 50 species (23.6%) of New Guinea terrestrial mammals and 118 species (17.7%) of non-marine or aquatic bird species are recorded in the literature as using tree cavities. Ground observation identified 36 suspected cavities in a hectare of lowland primary forest and 10 in nearby secondary forest. Upon inspection of all trees after felling, these figures changed to 26 and 0 respectively. Ground censuses are not accurate. Cavities were more commonly found in large trees. In less than a year, nest box occupancy reached exceeded 33%, with Phalanger spp. and Sugar gliders, Petaurus breviceps, being most common. Some bird use was detected by the presence of feathers; snakes and geckos were also found in boxes. Occupancy increased with time and would probably be higher after a second year. The larger boxes had greater occupancy, as did boxes placed higher in the trees. Bees occupied and probably excluded other users from 10% of boxes. As Papuan forests are disturbed by logging, hunting practices and gardening, conservationists might need to manage practices to ensure cavity availability. Artificial nest boxes might have utility for wildlife conservation and research.
Asian hornbill populations are declining across their ranges because of hunting and deforestation. Five of the 32 Asian hornbill species occur in north-east India. However, vital information on their abundance from the region remains scanty. Understanding spatiotemporal variation in densities provides crucial information for formulating effective conservation strategies based on species-specific abundance patterns and population trends. We examined spatiotemporal variation in densities of four hornbill species in the Namdapha Tiger Reserve, a site identified as an important site for hornbill conservation in Asia. We collected data through variable-width line transect sampling (effort=842.1 km) in the non-breeding season from 2009-12 to estimate hornbill densities. We had 458 detections of four hornbill species. We have estimated White-throated Brown Hornbill densities (7.9 birds/km2) for the first time throughout its entire range. The mean Rufous-necked Hornbill densities (6.9 birds/km2) were higher than those reported elsewhere. Great (3.9 birds/km2) and Wreathed Hornbill (16.1 birds/km2) densities were comparable with other sites. The peak densities of all hornbill species in November-December are among the highest reported from Asia. Wreathed Hornbill densities showed temporal variation peaking in November-December (68 birds/km2) and drastically declining by March-April (1.3 birds/km2), indicating seasonal altitudinal movement to low-elevation areas outside the reserve during the breeding season. Our results underscored the spatial variation in hornbill distribution, with low densities of Great and the White-throated Brown hornbills in higher elevations. Our study demonstrates the global importance of Namdapha for hornbills, given its large area and high densities of four hornbill species.
This study determines the composition of amphibian ensembles along a vegetation gradient in the coastal Pacific rainforests in Colombia. Eight environmental and structural variables were measured to characterize the species' habitats and to determine which was most important in structuring amphibian patterns. After a total of 432 man-hours sampling effort, 513 individuals from 32 amphibian species were found. Although the species richness was similar among the vegetation cover types, the composition of the ensembles and total amphibian abundance were different in each case. In addition, a strong relationship was found between changes in the vegetation structure and the amphibian pattern, with the canopy cover being the key variable in the composition of the ensembles for each cover type. Habitats with over 76% canopy cover, combined with a high density of individual woody plants (> 176 individuals per 500 m2) and a high depth of leaf litter (> 16 cm), provide the necessary habitat conditions for typical rainforest composition of amphibian species. However, for amphibian ensembles to have a mature forest composition, the habitat must have a canopy cover over 89%, a density of woody plants exceeding 231 individuals per 500 m2, and a leaf litter depth above 23 cm. Therefore, future studies of amphibian succession and restoration in tropical forests must determine the changes in vegetation structure, rather than the possible direct effect of microclimatic variables.
Shifting cultivation, in which fields are traditionally cultivated for two or three consecutive years and left fallow for four to five years, is an ancient practice still prevalent in the dry zone of Sri Lanka. Traditionally, shifting agriculture is rain dependent and is limited to the wet season. However, traditional patterns are now changing due to population pressures. We assessed the use of shifting agriculture areas by Asian elephants (Elephas maximus) and the availability of fodder in active fields during the dry season, to evaluate the impact of changing cultivation practices on elephants. We radio-tracked a juvenile and an adult male, representative of the two social groupings of herds and adult males respectively, based on the sexually dimorphic social structure of elephants. Although the small sample size precluded definitive conclusions, the tracking data were consistent with extensive elephant use of shifting cultivation areas during the dry season. We conducted line transects and plots in fields cultivated continuously for 1-20 years, assessing the growth of grasses and four browse species selected as indicators of elephant food. Grass was plentiful in early dry season, representing an important but transient food source. Browse density and volume remained constant through the dry season. Browse density but not volume decreased with increasing number of consecutive years of cultivation. We conclude that shifting agriculture fields under active cultivation are a significant dry season food source for elephants. This benefit is likely to decrease with additional years of continued cultivation and/or longer cultivation seasons.
Noninvasive camera-traps are commonly used to survey mammal communities in the Neotropics. This study used camera-traps to survey medium and large mammal diversity in the San Juan – La Selva Biological Corridor, Costa Rica. The connectivity of the corridor is affected by the spread of large-scale agriculture, cattle ranching, and a growing human presence. An occupancy modeling approach was used to estimate corridor species richness and species-specific detection probabilities in 16 forested sites within four different matrix-use categories: eco-lodge reserves, tree plantations/general reforestation, cattle ranches, and pineapple/agricultural plantations. Rarity had a highly negative effect (β = −1.96 ± 0.65 SE) on the ability to detect species presence. Corridor richness was estimated at 20.4 ± 0.66 species and was lower than that observed in protected areas in the Neotropics. Forest cover was significantly less at pineapple plantations than other land-use matrices. Richness estimates for different land-use matrices were highly variable with no significant differences; however, pineapple plantations exhibited the highest observed richness. Given the limited forest cover at those sites, we believe that this reflects the concentrated occurrence of medium and large mammals in small forest patches, particularly because the majority of pineapple plantation communities were generalist mesopredators. Fragmentation and connectivity will need to be addressed with reforestation and limitations on pineapple production for the region to function as an effective corridor. Occupancy modeling has only recently been applied to camera-trap data and our results suggest that this approach provides robust richness and detection probability estimates and should be further explored.
The thin-spined porcupine, Chaetomys subspinosus, is an endemic mammal of the Atlantic forest of northeastern Brazil. With its population declining, it has been listed as “vulnerable” in the Brazilian Red List. Its National Action Plan, published in 2011, intended to develop awareness projects about the species in local communities, to implement alternative income projects and protein consumption, and to evaluate hunting pressure. This study investigates rural residents' knowledge of the thin-spined porcupine and its uses within two protected areas. We also examine residents' behaviour and perceptions about wildlife conservation. One hundred twenty-five semi-structured interviews were conducted with rural residents of the Una Wildlife Refuge and the Serra do Conduru State Park. Local knowledge was higher among males with lower levels of formal education who were current or past hunters. Negative behaviour occurs among residents in both protected areas. There is a need for greater control of potential threats such as hunting, use of fire and deforestation, which are inconsistent with the existence of protected areas and conservation of the thin-spined porcupine. Information provided by this study can improve and promote actions within the National Action Plan for the conservation of C. subspinosus.
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