Influence of Forest Fragmentation on Community Structure of Frogs and Lizards in Northeastern Costa Rica

Abstract:  To better understand responses of reptiles and amphibians to forest fragmentation in the lowland Neotropics, we examined community and population structure of frogs and lizards in the fragmented landscape surrounding La Selva Biological Station in the Sarapiquí region of northeastern Costa Rica. We used diurnal quadrats and nocturnal transects to sample frogs and lizards in nine forest fragments (1–7 ha each) and La Selva (1100 ha). Species richness in all fragments combined was 85% of that found in La Selva with comparable sampling effort. Richness varied from 10 to 24 species among forest fragments, compared with 36 species at La Selva. Lizard density was higher and frog density was lower in forest fragments than in La Selva. Community composition varied among sites and by fragment size class, and species occurrence was nested with respect to fragment area. Isolation and habitat variables did not significantly affect species richness, composition, or nestedness. We classified 34% of species as fragmentation sensitive because they were absent or occurred at low densities in fragments. Nevertheless, the relatively high diversity observed in the entire set of fragments indicates that preserving a network of small forest patches may be of considerable conservation value to the amphibians and reptiles of this region.     

Benthic invertebrate larval response to substrate characteristics at settlement: Shelter preferences of the American lobsterHomarus americanus

The factors controlling shelter selection by the first post-larval stage of the American lobsterHomarus americanus were studied in the laboratory in 1988 using an experimental approach. The relative importance of shelter size, light level within shelters, number of shelter entrances, and presence of algal-film cover in and around them were investigated. Post-larvae showed a strong preference for opaque versus transparent shelters. No difference in post-larval selectivity was observed either for shelters of different widths or heights or between shelters with different numbers of entrances. Post-larvae showed no preference for microhabitats colonized by microorganisms compared to others without colonization. The intensity of the response measured suggests a possible hierarchical organization of the different cues involved in shelter selection, the light level within the shelter apparently being the most important. Simple linear regression was used to assess the effect of shelter area on the number of post-larvae occupying a shelter. Up to four post-larvae were observed simultaneously in a shelter of 40 cm² basal area, indicating that they can cohabit at settlement. The minimum shelter area necessary to the first post-larval stage was estimated to be about 3.25 cm². The results are discussed with reference to recent hypotheses concerning the mechanisms controlling larval settlement in other benthic species with relatively weak mobility during the larval and the post-larval phases.Contribution to the programmes of GIROQ (Groupe interuniversitaire de recherches océanographiques du Québec) and of the Institut Maurice-Lamontagne     

Effects of Amazonian flying rivers on frog biodiversity and populations in the Atlantic rainforest

Given the speed at which humans are changing the climate, species with high degrees of endemism may not have time to avoid extinction through adaptation. We investigated through teleconnection analysis the origin of rainfall that determines the phylogenetic diversity of rainforest frogs and the effects of microclimate differences in shaping the morphological traits of isolated populations (which contribute to greater phylogenetic diversity and speciation). We also investigated through teleconnection analysis how deforestation in Amazonia can affect ecosystem services that are fundamental to maintaining the climate of the Atlantic rainforest biodiversity hotspot. Seasonal winds known as flying rivers carry water vapor from Amazonia to the Atlantic Forest, and the breaking of this ecosystem service could lead Atlantic Forest species to population decline and extinction in the short term. Our results suggest that the selection of morphological traits that shape Atlantic Forest frog diversity and their population dynamics are influenced by the Amazonian flying rivers. Our results also suggest that the increases of temperature anomalies in the Atlantic Ocean due to global warming and in the Amazon forest due to deforestation are already breaking this cycle and threaten the biodiversity of the Atlantic Forest hotspot.     

Batrachochytrium dendrobatidis and the Collapse of Anuran Species Richness and Abundance in the Upper Manu National Park,Southeastern Peru

Abstract: Amphibians are declining worldwide, but these declines have been particularly dramatic in tropical mountains, where high endemism and vulnerability to an introduced fungal pathogen, Batrachochytrium dendrobatidis (Bd), is associated with amphibian extinctions. We surveyed frogs in the Peruvian Andes in montane forests along a steep elevational gradient (1200–3700 m). We used visual encounter surveys to sample stream‐dwelling and arboreal species and leaf‐litter plots to sample terrestrial‐breeding species. We compared species richness and abundance among the wet seasons of 1999, 2008, and 2009. Despite similar sampling effort among years, the number of species (46 in 1999) declined by 47% between 1999 and 2008 and by 38% between 1999 and 2009. When we combined the number of species we found in 2008 and 2009, the decline from 1999 was 36%. Declines of stream‐dwelling and arboreal species (a reduction in species richness of 55%) were much greater than declines of terrestrial‐breeding species (reduction of 20% in 2008 and 24% in 2009). Similarly, abundances of stream‐dwelling and arboreal frogs were lower in the combined 2008–2009 period than in 1999, whereas densities of frogs in leaf‐litter plots did not differ among survey years. These declines may be associated with the infection of frogs with Bd. B. dendrobatidis prevalence correlated significantly with the proportion of species that were absent from the 2008 and 2009 surveys along the elevational gradient. Our results suggest Bd may have arrived at the site between 1999 and 2007, which is consistent with the hypothesis that this pathogen is spreading in epidemic waves along the Andean cordilleras. Our results also indicate a rapid decline of frog species richness and abundance in our study area, a national park that contains many endemic amphibian species and is high in amphibian species richness.     

Invasion by <Emphasis Type="Italic">Artocarpus heterophyllus</Emphasis> (Moraceae) in an island in the Atlantic Forest Biome,Brazil: distribution at the landscape level,density and need for control

Invasion by alien species is one of the most critical factors affecting global biodiversity, leading to homogenization and species loss worldwide. Jackfruit (Artocarpus heterophyllus Lam., Moraceae) is one of the most conspicuous invasive plants in Brazil. We studied jackfruit invasion in the Atlantic Forest in Ilha Grande State Park, located on an island (Ilha Grande), by assessing jackfruit distribution and density along 23 trails (90 km). Presence or absence was verified in a total of 857 plots. Data showed that jackfruit is spread all over Ilha Grande, and that plant density varied significantly along and between trails. Jackfruit was registered as the dominant tree species on some of the trails. Control by park managers is an urgent need in order to ensure the conservation of local biodiversity. A decision key for jackfruit management according to jackfruit density, age class and slope is provided.     

Edge Effects on Lizards and Frogs in Tropical Forest Fragments

Abstract: We investigated whether forest-pasture edges affect the distribution of an assemblage of small vertebrate ectotherms in a consistent and predictable manner. We describe the abundance and distribution of two species of anoline lizards (   Norops ) and five species of leaf-litter frogs (   Eleutherodactylus ) along the edges and in the interiors of nine forest fragments near Las Cruces, Costa Rica. Over 4 months, we surveyed 44 pairs of plots by visual encounter. In each pair of plots, one was immediately adjacent to the pasture and the second was within the forest "interior." Both plots of a pair were searched simultaneously. This block design controlled for the effects of weather, topography, and searcher ability. The distribution of all species was highly variable with respect to edges. Only two species of frogs, Eleutherodactylus podiciferus and E. cruentus , were significantly more abundant in interior plots than in edge plots, although not consistently so. Both species of Norops lizards were more abundant along forest edges during the dry season. Both Norops species and several Eleutherodactylus species, however, appeared to become more abundant in the forest interior after the onset of the wet season, suggesting a seasonal edge effect. In Norops polylepis , the most abundant anole, rates of ectoparasitism were lower along edges than in forest interiors. The magnitude of the edge effect on any one species was not influenced by the size of fragments or by the distance of the interior plot from the nearest edge. We believe that edge effects should not be defined by the distance to which they are detected. Rather, they should be viewed as highly dynamic in space and time; taxa appear to respond to different components of edge effects according to their particular biological requirements.     

Automated detection of frog calls and choruses by pulse repetition rate

Anurans (frogs and toads) are among the most globally threatened taxonomic groups. Successful conservation of anurans will rely on improved data on the status and changes in local populations, particularly for rare and threatened species. Automated sensors, such as acoustic recorders, have the potential to provide such data by massively increasing the spatial and temporal scale of population sampling efforts. Analyzing such data sets will require robust and efficient tools that can automatically identify the presence of a species in audio recordings. Like bats and birds, many anuran species produce distinct vocalizations that can be captured by autonomous acoustic recorders and represent excellent candidates for automated recognition. However, in contrast to birds and bats, effective automated acoustic recognition tools for anurans are not yet widely available. An effective automated call-recognition method for anurans must be robust to the challenges of real-world field data and should not require extensive labeled data sets. We devised a vocalization identification tool that classifies anuran vocalizations in audio recordings based on their periodic structure: the repeat interval-based bioacoustic identification tool (RIBBIT). We applied RIBBIT to field recordings to study the boreal chorus frog (Pseudacris maculata) of temperate North American grasslands and the critically endangered variable harlequin frog (Atelopus varius) of tropical Central American rainforests. The tool accurately identified boreal chorus frogs, even when they vocalized in heavily overlapping choruses and identified variable harlequin frog vocalizations at a field site where it had been very rarely encountered in visual surveys. Using a few simple parameters, RIBBIT can detect any vocalization with a periodic structure, including those of many anurans, insects, birds, and mammals. We provide open-source implementations of RIBBIT in Python and R to support its use for other taxa and communities.     

Frog, Bat, and Dung Beetle Diversity in the Cloud Forest and Coffee Agroecosystems of Veracruz, Mexico

Abstract:  We compared the species diversity of copronecrophagous beetles (Scarabaeinae) , bats, and frogs in tropical montane cloud forest (original vegetation) and shaded coffee plantations (an agroecosystem common to the region) for a landscape in central Veracruz, Mexico. We sampled in three tropical montane cloud forest fragments and in three coffee plantations with traditional polyculture shade between 1998 and 2001. The three indicator groups responded differently to the transformation of tropical montane cloud forest into shaded coffee plantations. The species richness of frogs was one-fifth less in coffee plantations than in forest fragments, and only one-third of the frog species occurred in both forest fragments and coffee plantations. The number of beetle species and their abundance was significantly greater in coffee plantations than in the forest fragments, whereas species richness and species composition of bats were virtually the same in both habitats. The majority of the abundant species remained as such in both communities, but species that were less abundant were not scarce in both habitats. We attributed differences in the species assemblages to the differing degrees of penetrability of the borders of the two habitat types (especially for the coffee plantations) and to the differences in life-history traits among species. Shaded coffee plantations form a matrix that envelops the remaining fragments of cloud forest. Together they connect the forest fragments with the other habitats of the landscape and represent a highly functional resource for the preservation of biodiversity that serves as a complement to but not a substitute for cloud forest in this notably modified landscape.     

Assessment of organochlorine pesticide contamination in waterbirds from an agricultural region,Central China

Twenty-one organochlorine pesticides (OCPs) were measured in the muscle of six predominant waterbird species from Jianghan Plain, Hubei Province, Central China. Among OCPs, DDTs were the most prevalent compounds, with average concentration ranging from 31.1 to 1445 ng/g lipid weight. Little egrets (Egretta garzetta) and Chinese pond herons (Ardeola bacchus) showed significantly higher concentrations of OCPs (p < 0.05) due to their dietary habits and migratory patterns. There were no statistically significant differences (p > 0.05) for most OCPs between sex and age groups. The accumulation profiles of HCHs and DDTs suggested that these OCPs in Jianghan Plain were largely derived from historical usage. Risk assessment indicated that heptachlor could be likely to pose adverse health effects on people consuming ducks in Jianghan Plain.     

Conspicuous displays in cryptic males of a polytypic poison-dart frog

The evolution of aposematism is linked to increased opportunities for conspicuous sexual displays since detection by potential predators is no longer disadvantageous. Therefore, phenotypic divergence in aposematic species leading to relatively cryptic forms is expected to constrain such opportunities, by restoring the trade-off between natural and sexual selection on the boldness of sexual displays. We asked if and how a derived phenotype of the poison-dart frog Oophaga granulifera that appears relatively cryptic to potential predators exhibits conspicuous sexual displays for potential mates. We used visual modeling of frog contrasts against their natural backgrounds to test if for conspecifics green frogs appear less conspicuous than red frogs as they do for birds. We conducted behavioral observations of focal red and green males to determine if green frogs adjust their display behavior to the availability of potential mates. Dorsal brightness is known to influence female preferences in at least one poison frog species. We found that, despite being less visible under some measures, green frogs may appear as bright as red frogs for conspecifics but not birds, when viewed on dark backgrounds. Additionally, green males called more intermittently than red males when advertising to distant females, but they exhibited a dramatic increase in calling activity in proximity of a female and were as active as red males in this context. Together, our results suggest that green frogs retain context-dependent conspicuousness to conspecifics despite the evolution of relative crypsis to potential predators.     

Differential parental care behaviors of arboreal and terrestrial microhylid frogs from Papua New Guinea

I studied the ecology of parental care behaviors displayed by two closely related sympatric species of microhylid frogs in Papua New Guinea that occupy different microhabitats. Adult removal experiments on the terrestrial frog Hylophorbus rufescens and the undescribed arboreal frog Oreophryne sp. A demonstrate a significant positive effect of parental attendance on offspring survivorship and differential causes of egg mortality between microhabitats. Desiccation was the primary cause of egg mortality for the arboreal frog, whereas predation was the main source of mortality for the terrestrial frog. These selection pressures (desiccation and predation) are comparable to two of Wilsons prime movers of the evolution of parental care (harsh environment and predation) and may have driven and/or are maintaining the evolution of parental care behaviors in these Papuan microhylid frogs. These results highlight microhabitat-specific selection pressures in the evolution and maintenance of parental care behaviors.Communicated by A. Mathis     

Regional Decline of an Iconic Amphibian Associated with Elevation,Land‐Use Change,and Invasive Species

Abstract: Ecological theory predicts that species with restricted geographic ranges will have the highest probability of extinction, but species with extensive distributions and high population densities can also exhibit widespread population losses. In the western United States populations of northern leopard frogs (Lithobates pipiens)—historically one of the most widespread frogs in North America—have declined dramatically in abundance and geographic distribution. To assess the status of leopard frogs in Colorado and evaluate causes of decline, we coupled statewide surveys of 196 historically occupied sites with intensive sampling of 274 wetlands stratified by land use. We used an information‐theoretic approach to evaluate the contributions of factors at multiple spatial extents in explaining the contemporary distribution of leopard frogs. Our results indicate leopard frogs have declined in Colorado, but this decline was regionally variable. The lowest proportion of occupied wetlands occurred in eastern Colorado (2–28%), coincident with urban development and colonization by non‐native bullfrogs (Lithobates catesbeianus). Variables at several spatial extents explained observed leopard frog distributional patterns. In low‐elevation wetlands introduced fishes, bullfrogs, and urbanization or suburbanization associated negatively with leopard frog occurrence, whereas wetland area was positively associated with occurrence. Leopard frogs were more abundant and widespread west of the Continental Divide, where urban development and bullfrog abundance were low. Although the pathogenic chytrid Batrachochytrium dendrobatidis (Bd) was not selected in our best‐supported models, the nearly complete extirpation of leopard frogs from montane wetlands could reflect the individual or interactive effects of Bd and climate patterns. Our results highlight the importance of considering multiple, competing hypotheses to explain species declines, particularly when implicated factors operate at different spatial extents.     

Lemurs and the Regeneration of Dry Deciduous Forest in Madagascar

Abstract: We sought to assess the role of lemurs for seed dispersal in the dry deciduous forest of western Madagascar and the possible consequences of the demise of lemurs for forest regeneration. Forest regeneration was studied in eight plots in two large blocks of primary forest and in seven fragments of primary forest (1 plot per fragment). In 4 of the 15 study plots, the abundance of saplings was negatively and significantly correlated ( p < 0.05) with the abundance of mature individuals of the same tree species. In another 10 study plots there were negative correlations, although these were not significant on the community level. Second-order statistics were significant with p < 0.001 and indicated that seed dispersal away from the parent trees was important for successful establishment of saplings. Apart from possibly the bush pig ( Potamochoerus larvatus ), only one vertebrate species of the dry forest, the brown lemur ( Eulemur fulvus ), ingested seeds> 11 mm long and passed them through its digestive tract unharmed. These results for lemurs were based on direct observations and fecal analyses. To evaluate the role of E. fulvus , we compared regeneration in forest plots with and without E. fulvus . In forest fragments without E. fulvus , fewer lemur-dispersed tree species regenerated than would be expected based on the presence of mature tree species that are lemur-dispersed ( p < 0.05). No such effect was seen in primary forests with E. fulvus or for trees whose seeds can also be dispersed by other vertebrates. Thus, regeneration of the dry deciduous forest of western Madagascar with the complete set of primary forest tree species seems to depend upon the presence of E. fulvus .     

Two‐Stage Recovery of Amphibian Assemblages Following Selective Logging of Tropical Forests

There is a lack of quantitative information on the effectiveness of selective‐logging practices in ameliorating effects of logging on faunal communities. We conducted a large‐scale replicated field study in 3 selectively logged moist semideciduous forests in West Africa at varying times after timber extraction to assess post logging effects on amphibian assemblages. Specifically, we assessed whether the diversity, abundance, and assemblage composition of amphibians changed over time for forest‐dependent species and those tolerant of forest disturbance. In 2009, we sampled amphibians in 3 forests (total of 48 study plots, each 2 ha) in southwestern Ghana. In each forest, we established plots in undisturbed forest, recently logged forest, and forest logged 10 and 20 years previously. Logging intensity was constant across sites with 3 trees/ha removed. Recently logged forests supported substantially more species than unlogged forests. This was due to an influx of disturbance‐tolerant species after logging. Simultaneously Simpson's index decreased, with increased in dominance of a few species. As time since logging increased richness of disturbance‐tolerant species decreased until 10 years after logging when their composition was indistinguishable from unlogged forests. Simpson's index increased with time since logging and was indistinguishable from unlogged forest 20 years after logging. Forest specialists decreased after logging and recovered slowly. However, after 20 years amphibian assemblages had returned to a state indistinguishable from that of undisturbed forest in both abundance and composition. These results demonstrate that even with low‐intensity logging (≤3 trees/ha) a minimum 20‐year rotation of logging is required for effective conservation of amphibian assemblages in moist semideciduous forests. Furthermore, remnant patches of intact forests retained in the landscape and the presence of permanent brooks may aid in the effective recovery of amphibian assemblages. Recuperación de Ensambles de Anfibios en Dos Etapas Después de la Tala Selectiva de Bosques Tropicales     

Wood Density as a Conservation Tool: Quantification of Disturbance and Identification of Conservation‐Priority Areas in Tropical Forests

Abstract: Inventories of tree species are often conducted to guide conservation efforts in tropical forests. Such surveys are time consuming, demanding of expertise, and expensive to perform and interpret. Approaches to make survey efforts simpler or more effective would be valuable. In particular, it would be good to be able to easily identify areas of old‐growth forest. The average density of the wood of a tree species is closely linked to its successional status. We used tree inventory data from eastern Borneo to determine whether wood density can be used to quantify forest disturbance and conservation importance. The average density of wood in a plot was significantly and negatively related to disturbance levels, with plots with higher wood densities occurring almost exclusively in old‐growth forests. Average wood density was unimodally related to the diversity of tree species, indicating that the average wood density in a plot might be a better indicator of old‐growth forest than species diversity. In addition, Borneo endemics had significantly heavier wood than species that are common throughout the Malesian region, and they were more common in plots with higher average wood density. We concluded that wood density at the plot level could be a powerful tool for identifying areas of conservation priority in the tropical rain forests of Southeast Asia.     

Effects of productivity on biodiversity in forest ecosystems across the United States and China

In the global campaign against biodiversity loss in forest ecosystems, land managers need to know the status of forest biodiversity, but practical guidelines for conserving biodiversity in forest management are lacking. A major obstacle is the incomplete understanding of the relationship between site primary productivity and plant diversity, due to insufficient ecosystem‐wide data, especially for taxonomically and structurally diverse forest ecosystems. We investigated the effects of site productivity (the site's inherent capacity to grow timber) on tree species richness across 19 types of forest ecosystems in North America and China through 3 ground‐sourced forest inventory data sets (U.S. Forest Inventory and Analysis, Cooperative Alaska Forest Inventory, and Chinese Forest Management Planning Inventory). All forest types conformed to a consistent and highly significant (P < 0.001) hump‐shaped unimodal relationship, of which the generalized coefficients of determination averaged 20.5% over all the forest types. That is, tree species richness first increased as productivity increased at a progressively slower rate, and, after reaching a maximum, richness started to decline. Our consistent findings suggest that forests of high productivity would sustain few species because they consist mostly of flat homogeneous areas lacking an environmental gradient along which a diversity of species with different habitats can coexist. The consistency of the productivity–biodiversity relationship among the 3 data sets we examined makes it possible to quantify the expected tree species richness that a forest stand is capable of sustaining, and a comparison between the actual species richness and the sustainable values can be useful in prioritizing conservation efforts.     

Phytotoxic effects of phenolic acids from <Emphasis Type="Italic">Merostachys riedeliana,</Emphasis> a native and overabundant Brazilian bamboo

Merostachys riedeliana Rupr. is a native and overabundant bamboo species in the Brazilian Atlantic Forest. Moderate to strong allelopathic activity may be one mechanism that explains this super-dominance and the changes in structure and composition of forest areas occupied by bamboo. This study evaluated the phytotoxic effect of M. riedeliana extracts and fractions and identified their putative allelochemicals. We investigated the presence of allelochemicals in soil collected from stands occupied by M. riedeliana. Furthermore, we evaluated the putative effect of tree allelochemicals, individually and combined, on germination and growth. The aqueous extract of leaves and its ethyl acetate fraction presented the highest inhibitory effects on seed germination and seedling growth. The effect of the extracts and fractions on the target species was species-specific. Neither the individual nor the combined phenolic acids significantly inhibited seed germination; however, a pronounced growth inhibition was observed in M. bimucronata seedlings treated with vanillic acid and in E. verna and M. bimucronata seedlings treated with combined phenolic acids. Isovitexin, vitexin, isoorientin, orientin, and their O-glycoside derivatives, the lactonic dimer of the p-hydroxybenzoic acid and 3,4-methylenedioxymandelic acid were identified in the aqueous extracts and ethyl acetate fraction by Liquid Chromatography-Diode Array Dectector/Electrospray Ionization/Mass Spectrometry (LC-DAD/ESI–MS/MS). The Gas Chromatography-Mass Spectrometer (GC–MS) profile of the same extract and fraction showed the presence of benzoic, benzeneacetic, salicylic, p-hydroxybenzoic, p-hydroxyphenylacetic, vanillic, p-coumaric, protocatechuic, syringic, gallic, m-coumaric vanillylmandelic, 4-methylmandelic, 3,4-methylenedioxymandelic and trans-ferulic acids. The p-benzoic acid and the apigenin 6-C-glucoside (isovitexin) were identified in the soil extract collected from under bamboo-growing areas. Even though laboratory bioassays are not completely predictive of the allelopathic effects that occur in nature, the results of this study provide preliminary evidence of allelopathy as a possible species-specific inhibition mechanism of native species that explain the impoverishment of floristic richness and the functional groups in areas where M. riedeliana is overabundant.     

Soil particle-size composition and coastal erosion and accretion study in Soc Trang mangrove forests

Coastal erosion results in loss of land, which impacts the economy, coastal residents and settlement plans, especially in the context of rising sea levels caused by climate change. Studying soil particle-size fractions in mangrove forests will help provide a better understanding of the relationship between soil proportions and coastal processes as well as the role of mangrove forests to support coastal planning and management. Soil samples were collected at 26 sampling plots at depths of 10 cm and 40 cm in the Cu Lao Dung (CLD), Long Phu (LP) and Vinh Chau (VC) mangrove forests in Viet Nam’s Soc Trang Province. The soil proportions based on six different particle-sizes (<0.074 mm, 0.074–0.1 mm, 0.1–0.25 mm, 0.25–0.5 mm, 0.5–1.0 mm, and >1.0 mm) were measured using a dry sieving method. Analysis showed that soil particle-sizes ranging between 0.074 and 0.5 mm made up 75–95 % of the soil sample weight at both depths. The high standard deviation values of soil proportions of each given particle-size among sampling plots indicated the soil proportions by particle-size varied widely across the sampling plots. Cluster analysis found similar pattern of soil particle-size proportions for samples collected in CLD and VC, and different pattern of soil particle-size proportions in samples collected at LP, which is more impacted by the Mekong River flow and has a thin mangrove forest belt.?Non-metric dimension scaling (NMDS) analysis showed that sampling plots across the landward sites of the three mangrove forest areas were distributed in the nearby locations (Stress?=?0.11). This indicated that soil proportions of particle-sizes of samples collected from areas of the natural forest composed of different species were more similar. Such similarities were not found, however, in samples collected from middle and seaward plots dominated by single-species plantations.     

Refining Biodiversity Conservation Priorities

Abstract:  Although there is widespread agreement about conservation priorities at large scales (i.e., biodiversity hotspots), their boundaries remain too coarse for setting practical conservation goals. Refining hotspot conservation means identifying specific locations (individual habitat patches) of realistic size and scale for managers to protect and politicians to support. Because hotspots have lost most of their original habitat, species endemic to them rely on what remains. The issue now becomes identifying where this habitat is and these species are. We accomplished this by using straightforward remote sensing and GIS techniques, identifying specific locations in Brazil's Atlantic Forest hotspot important for bird conservation. Our method requires a regional map of current forest cover, so we explored six popular products for mapping and quantifying forest: MODIS continuous fields and a MODIS land cover (preclassified products), AVHRR, SPOT VGT, MODIS (satellite images), and a GeoCover Landsat thematic mapper mosaic (jpg). We compared subsets of these forest covers against a forest map based on a Landsat enhanced thematic mapper. The SPOT VGT forest cover predicted forest area and location well, so we combined it with elevation data to refine coarse distribution maps for forest endemic birds. Stacking these species distribution maps enabled identification of the subregion richest in threatened birds—the lowland forests of Rio de Janeiro State. We highlighted eight priority fragments, focusing on one with finer resolved imagery for detailed study. This method allows prioritization of areas for conservation from a region >1 million km² to forest fragments of tens of square kilometers. To set priorities for biodiversity conservation, coarse biological information is sufficient. Hence, our method is attractive for tropical and biologically rich locations, where species location information is sparse.     

Bird Species' Tolerance of Secondary Forest Habitats and Its Effects on Extinction

Abstract:  Intense deforestation causes massive species losses. These losses occur because the habitats supplanting primary forest are inadequate to sustain viable populations of forest-dependent species. Despite this, certain species do seem to persist within the secondary habitats that replace original forest. This implies that there is a special class of species that might survive the loss of primary forest. Such a result would significantly influence conservation plans and extinction predictions. We tested whether species that tolerate secondary habitats survive extensive habitat loss and whether the same degree of loss threatens species that are forest obligates. To identify purported "survivors," we compared the remaining range sizes of endemic birds, their abundances, and their degree of extinction threat. We did this within the remaining Atlantic Forest of Brazil, a region extremely rich in endemics but with only approximately 10% of its forest remaining. We found no survivors. Habitat loss threatens forest-obligate birds and those using secondary habitats equally.