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Habitat loss is the primary reason for species extinction, making habitat conservation a critical strategy for maintaining global biodiversity. Major habitat types, such as lowland tropical evergreen forests or mangrove forests, are already well represented in many conservation priorities, while others are underrepresented. This is particularly true for dry deciduous dipterocarp forests (DDF), a key forest type in Asia that extends from the tropical to the subtropical regions in South-east Asia (SE Asia), where high temperatures and pronounced seasonal precipitation patterns are predominant. DDF are a unique forest ecosystem type harboring a wide range of important and endemic species and need to be adequately represented in global biodiversity conservation strategies. One of the greatest challenges in DDF conservation is the lack of detailed and accurate maps of their distribution due to inaccurate open-canopy seasonal forest mapping methods. Conventional land cover maps therefore tend to perform inadequately with DDF. Our study accurately delineates DDF on a continental scale based on remote sensing approaches by integrating the strong, characteristic seasonality of DDF. We also determine the current conservation status of DDF throughout SE Asia. We chose SE Asia for our research because its remaining DDF are extensive in some areas but are currently degrading and under increasing pressure from significant socio-economic changes throughout the region. Phenological indices, derived from MODIS vegetation index time series, served as input variables for a Random Forest classifier and were used to predict the spatial distribution of DDF. The resulting continuous fields maps of DDF had accuracies ranging from R2 = 0.56 to 0.78. We identified three hotspots in SE Asia with a total area of 156,000 km2, and found Myanmar to have more remaining DDF than the countries in SE Asia. Our approach proved to be a reliable method for mapping DDF and other seasonally influenced ecosystems on continental and regional scales, and is very valuable for conservation management in this region.
Destruction of nests and predation by introduced species are among the main factors responsible for seabird declines. The red-billed tropicbird (Phaethon aethereus) is a tropical, colonially nesting seabird whose distribution in Brazil is restricted to a small, isolated breeding colony located within Abrolhos National Park. This represents the southernmost population of the species in the western Atlantic, and is among the most southerly in its global distribution. Despite its isolation, the population on Abrolhos is threatened by egg predation by two invasive rat species: the house rat (Rattus rattus) and brown rat (Rattus norvegicus). In this study we conduct a population viability analysis of P. aethereus in Abrolhos to estimate the potential long term impacts of the rats. Our results indicate that egg and chick predation by rats has the potential to quickly drive the Abrolhos tropicbird population into serious decline. Reducing this threat may require the urgent implementation of a rat control program.
In 1987 the amphibian decline crisis reached its apex in Costa Rica when at least 17 species experienced population crashes and subsequently went undetected for decades. The amphibian declines in Costa Rica were relatively well documented and came to exemplify the current global amphibian decline crisis. The Mesoamerica endemic frog clade, the Craugastor punctariolus species group, is one of most severely affected anuran clades, experiencing a loss of 26 out of 33 species throughout Mesoamerica. Eight species of C. punctariolus group frogs occur in Costa Rica, and all declined following the 1987 die-off; despite intensive surveys over the last 14 years, most remain undetected. To date, only one species in this group, the stream-breeding frog C. ranoides, in known to have a stable population, and only in the Santa Elena Peninsula. Here we document the rediscovery of another species, the South Pacific streamside frog C. taurus, in southeastern Costa Rica, representing the first sighting after fifteen years of searching. We discovered two previously unknown populations in Punta Banco, the driest section within the historical range, in an area representing only 4% of the historical distribution. Our findings add to the short but growing list of recently rediscovered amphibian species in Costa Rica and provide encouraging news in an otherwise discouraging situation for amphibian conservation. Additional research and monitoring are urgently needed to develop long-term management plans for this and other Critically Endangered species
Abandoned pastures are increasingly targeted for forest restoration in the neotropics. However, the dominance of such areas by fodder grasses imposes a challenge for efficient and low cost control. Therefore, we questioned whether alien and native grasses equally affect: (1) natural regeneration; (2) natural regeneration under artificial perches; and (3) planted seedling development. Our study was carried out in an abandoned pasture in southeastern Brazil, in the Atlantic Forest biome. For (1) we installed plots in grass patches of Melinis minutiflora (molasse grass, an alien grass) and Imperata brasiliensis (satintail, a native grass that occurs in degraded areas); for (2) we installed plots under perches in alien and native grass patches; and for (3) we compared overall planted seedling mortality and development of four tree species in alien and native grass patches. Density and diversity of woody species in natural regeneration and under perches were similar for invasive and native grass patches. However, species composition differed between alien and native grass patches (Ellenberg similarity of 28% for perches and 35% for natural regeneration in different grass patches). Seedling mortality was similar for both alien and native grasses. Except for two tree species, development was similar for both native and alien grass patches. Our results indicate that the biological barriers imposed by a given grass species for forest succession and restoration must not be estimated based only on the species' origin.
Comparative studies of streams with altered versus conserved riparian zones are important to evaluate the degree of alterations caused by inappropriate use of these streams' vital buffer zones. The aim of this study was to determine the impact of riparian deforestation on the habitat structure of southern Brazilian Amazonian headwater streams, as well as to provide elements for impact assessment and the monitoring of these water bodies. We selected ten sites and two headwater streams at each site; one stream was located in an area with preserved riparian vegetation (pristine streams) and the other stream in a deforested riparian zone (altered streams). Stretches of these streams were analyzed across hydrological periods (dry period, beginning of the rainy period, and end of the rainy period) for hydro-morphological aspects, water physical-chemical variables, and habitat integrity (proportion of forestation in buffer zones and habitat integrity index). Compared to pristine streams in all the hydrological periods analyzed, altered streams presented lower oxygen concentration (~1.0 mg/L), an increase of 1 °C in water temperature, and less organic material availability. We found that riparian deforestation affects habitat structure variability among hydrological periods, making them more homogeneous. Therefore, beyond the necessary broadening of the spatial scale of studies in this region, monitoring these understudied headwater stream environments is also crucial for determining the magnitude of deforestation effects on these vulnerable aquatic ecosystems.
Masafuera Rayadito (Aphrastura masafuerae; Furnariidae) is a Critically Endangered species endemic to Alejandro Selkirk Island (Juan Fernández Archipelago, Chile). Categorized as probably extinct in 1980, later estimates, ranging from 140 (in 2002) to 500 individuals (in 2006–2007), showed a fluctuating population size of the species. The grazing of goats and cattle has increased habitat loss for the species. Other threats are lack of nesting sites, introduced species such as feral cats and rats (Rattus rattus and R. norvegicus), and increased populations of natural predators like the Masafuera Hawk. In order to increase the availability of nesting sites, 81 nest boxes were installed in different habitats in 2006, with evidence of use during subsequent breeding seasons. Despite conservation concerns, however, no genetic studies are yet available for this furnariid. This study reports for the first time the levels of genetic divergence of the species, based on nucleotide sequences of the mitochondrial DNA (cytochrome oxidase subunit 1 gene; COI). Aphrastura masafuerae is closely related to a widespread species of furnariid distributed mainly in Chile on the mainland, the Thorn-tailed Rayadito (A. spinicauda). The Masafuera Rayadito diverged from its mainland sister species probably during the Pleistocene 0.57 ± 0.19 Myr ago. Consistent with mitochondrial and nuclear molecular clocks, the estimated time of the split between A. masafuerae and A. spinicauda is in perfect agreement with the geological origin of the Juan Fernández Archipelago, which is of volcanic origin. In order to assess genetic variability within the population of this fragile bird, further studies using a multi-locus genetic approach at the population level are necessary.
Estimates of population density are essential for the effective conservation and management of any threatened species. Accurately estimating density of elusive carnivores can be a challenge, however. One approach to this challenge is integration of DNA collected noninvasively from feces with capture-recapture modeling. To date, the bias and precision of this technique have seldom been evaluated in the field. We compared density estimates of ocelots (Leopardus pardalis) derived from fecal noninvasive genetic techniques to density estimates from camera trapping in the same population, during the same study period. Density estimates from the two techniques were comparable, especially when using spatially explicit capture-recapture models. Population density estimated using the program DENSITY was 1.74/km2 (SE = 0.584) from noninvasive genetics and 1.59/km2 (SE = 0.464) from camera trapping. These estimates also represent the highest reported ocelot population density within the species range.
In this paper we present the first ecological data of Indochinese freshwater pearl mussel, Margaritifera laosensis populations. We also provide a comparative study of the ecology of this tropical species with populations of other Margaritiferidae. We conducted surveys in ten tributaries of the River Nam Ou (Middle Mekong Drainage, Northern Laos). Reproductively viable populations were found only in the Nam Long and Nam Pe rivers, which are two of the only three known viable populations of this species in the world. The habitats of M. laosensis include mountainous oligotrophic rivers with circumneutral pH. Optimal mesohabitats are riffles and runs with a median depth of 0.2 m and median current velocity of 0.3 ms−1. Pearl mussels were more common in gravel and fine gravel riverbed substrates. Surveys revealed 252 specimens, but only 78 (31.0%) were alive. The largest mussels observed were 110 mm in length and only 11–12 years of age. The presence of smaller-sized mussels indicates recent recruitment in both populations. The most significant threats to M. laosensis populations are harvest by local people and land development in the River Nam Ou Basin.
Habitat loss and fragmentation in tropical areas have long been presumed to reduce avian nesting success due to increased predation rates. Nevertheless, this prediction remains largely untested in tropical areas, because empirical data on the impacts of forest fragmentation on nest predation at both the landscape and patch scales in the tropics are still scarce, especially in West Africa. In this study, we examined the edge effects on nest predation rates in a large montane forest block and small forest fragments. Artificial nests used for our experiments mimicked the real nests of passerines confined to montane forest undergrowth in the Bamenda-Banso Highlands, the Northwest region of Cameroon, an endemic bird area of high conservation priority. We found equal overall predation rates in the landscape dominated by the large forest block as well as in the landscape consisting of small forest fragments, implying that the probability of nest failure was not significantly affected by habitat fragmentation on a landscape scale. However, predation rates were higher close to forest edges in the small forest remnants. Since such remnants represent the majority of local montane forests, this result suggests that the edge effect on bird nest predation may reduce nest survival and the population viability of many range-restricted bird species confined to the remaining natural habitats of the Bamenda-Banso Highlands.
Tropical termites are of critical importance for ecosystem functioning and ecosystem services in woodland and savannah areas. Termite mounds can also be used as fertilizer and biological indicators of anthropogenic disturbance linked to agriculture or charcoal production. Remote sensing may help to identify and characterize termite mound density and distribution at low cost. To test its effectiveness, termite mounds were identified in the field and compared with the results of image interpretation of free Google Earth aerial photographs. This comparison was carried out for 17 sites in the hinterland of the mining city of Lubumbashi, Katanga, Democratic Republic of the Congo, which faces high population growth, food insecurity, and intense fragmentation and degradation of the original Miombo woodland cover. The influences of mound height and diameter as well as the timing of the image capture (year and dry or wet season) were statistically tested. The actual number of termite mounds observed in the field was generally overestimated on the corresponding image. Height and wet season favoured correct identification, while spatial distribution was not significantly influenced by misidentifications. A corrective model was defined and its relevance statistically verified. Mound identification using Google Earth appears efficient so long as the precise individual mound position is not concerned. This approach represents considerable cost reduction for field surveys of termite mounds.
We studied the aboveground biomass density of plants, potentially available as a food supply for elephants, Loxodonta africana, in the Waza National Park, Cameroon during the dry season, from November 2009 through March 2010. The aboveground biomass of trees in the Woodland and Acacia seyal shrubland zones, were 16.87 tonsDM/ha and 10.99 tonsDM/ha respectively (mean 13.93 ± 4.16 tonsDM/ha). Aboveground biomass density in the herbaceous layer was 2.62, 4.21 and 6.9 tonsDM/ha, in the Woodland, Acacia seyal shrubland and Floodplain zones, respectively (mean 4.58 ± 2.16 tonsDM/ha), the difference between the vegetation zones being significant. The overall aboveground plant biomass density of the park averaged 13.86 ± 6.4 tonsDM/ha, however the harvestable food supply for elephants was a small portion of that estimate. The estimated plant biomass represented an average for the dry season, which is more useful for long-term planning purposes than for annual predictions of the level of forage production in the dry season. To minimize elephant encroachment into cultivated fields, it is necessary to estimate the park's carrying capacity and regulate the population size if necessary. This however will rely on the long-term prediction of forage production in the Waza National Park through continuous measurements of plant biomass density during the dry season.
Large carnivores such as dholes (Cuon alpinus) have been persecuted and eradicated from certain areas because of the perception that they pose significant threats to livestock. We conducted interviews to examine which variables predict local people's attitude towards dholes. We opportunistically sampled 791 respondents (≥ 18 years of age) in 34 villages that were within 10 km of one of seven targeted protected areas in southeastern Thailand. We used Random Forests to analyze responses to 20 questions concerning respondent demography; knowledge of, perceived occurrence of, and personal attitudes toward dholes; and frequency of forest visits. Respondents agreed dholes should be eliminated based heavily on whether or not they 1) considered dholes dangerous and 2) believed dholes will attack a person. Most villagers, however, held neutral or positive attitudes toward dholes; only 12% of participants stated that dholes should be eliminated in the wild. Overall, we found an encouraging social climate for dholes in Thailand. Our findings support the need for enhanced efforts to teach people to distinguish dholes from jackals (Canis aureus) and to encourage students to experience nature.
Conservation conflicts can arise in biosphere reserves when local people face restrictions on resource use and access, mainly in terms of subsistence. We studied the potential conservation conflict with subsistence hunting in two Maya communities (Los Petenes and El Remate) located in the zone of influence of Los Petenes Biosphere Reserve, Mexico. Perceptions, interests and expectations of stakeholders regarding subsistence hunting in the reserve were recorded through semi-structured and in-depth interviews of peasant-hunters and reserve authorities, and participant observation was carried out in both communities. A total of 66 peasant-hunters were identified in Los Petenes (62%) and El Remate (38%). Overall, peasant-hunters acknowledged hunting for family subsistence and expressed the conviction to continue hunting in the region. They mentioned their enthusiasm for hunting, mainly individually and aimed at obtaining white-tailed deer (Odocoileus virginianus) and perceived a recent reduction in potential prey locally. Although the law in Mexico does not prohibit subsistence hunting, external authorities stated that they have announced a generalized ban on hunting based on the precautionary principle to simplify enforcement both inside and outside the reserve. The de facto restriction on wildlife use, even for subsistence purposes, which was mentioned by external actors, conflicted with the local need and expectation of the contemporary Maya hunters to continue subsistence hunting in the region. Our study confirms the existence of a conservation conflict associated with this traditional practice in the reserve and provides necessary information for managing such conflict.
Reintroduction is an increasingly important tool to restore local extinctions and ecological interactions. Evaluating the success of reintroduction projects allows conservationists to learn from previous experience. Here we report on the reintroduction of agoutis, Dasyprocta leporina, to a Brazilian Atlantic Forest reserve in order to (1) determine the short-term status of the reintroduction; (2) describe and evaluate the management procedures that contributed to reintroduction success; and (3) identify the fruits and seeds consumed and buried by the agoutis, as an indication of their role in restoring ecological processes. We captured and tagged 21 adult individuals from a semi-captive population and reintroduced four males and seven females. One male died and almost all individuals lost weight (range=0-620 g; n=11) during quarantine (median=133 days; range=67–243 days; n=20). Six males and three females died, but the others gained weight during acclimatization (range=150–260 g; n=5). Individuals abandoned the food supplement up to 87 days after release, establishing home-ranges at least three times larger than in natural populations of agoutis. The estimated annual survival rate was 0.83, and 10 nature-born cubs were observed. The reintroduction was considered successful in the short-term. Among the main recommendations for future reintroductions, we suggest the reduction of quarantine and the maintenance of acclimatization periods, with structural improvements for both. Agoutis were seen eating fruits and seeds of 10 species and burying seeds of three of them. The buried seeds are from zoochoric large-seeded trees, thus enhancing recruitment in a disperser-impoverished forest.
The distribution of many vertebrate species in the Amazon basin is delimited by large rivers, which are frequently regarded as geographic barriers related with speciation and are therefore of high conservation value. Rapid development in the region includes plans to dam one of its thirteen major rivers, the Xingu. Environmental impact assessment is required for large scale development within the Brazilian portion of the Amazon Basin. However, impacts on biodiversity are only considered at the species level, and taxonomic work is far from described for many groups. In particular, anuran diversity is underestimated, in part owing to the scale of the region and, for some taxa, by morphological conservatism. Here we describe genetic and phenotypic variation in the brilliant-thighed frog, Allobates femoralis. We show that a unique genetic lineage, with a vocal repertoire distinct from that described for the species throughout its remaining geographic range, is located within the region to be directly and indirectly impacted by damming the Xingu River. Further, genetic variation within the A. femoralis group is largely structured in accordance to river systems, despite morphological conservatism. Our data add support for conservation policy to be amended to include intraspecific measures of diversity in order to more effectively conserve current biodiversity and evolutionary processes.
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