Influences of the vegetation mosaic on riparian and stream environments in a mixed forest-grassland landscape in "Mediterranean" northwestern California

We examined differences in riparian and aquatic environments within the three dominant vegetation patch types of the Mattole River watershed, a 789‐km² mixed conifer‐deciduous (hardwood) forest and grassland‐dominated landscape in northwestern California, USA. Riparian and aquatic environments, and particularly microclimates therein, influence the distributions of many vertebrate species, particularly the physiologically‐restricted ectotherms – reptiles and amphibians (herpetofauna), and fishes. In addition to being a significant portion of the native biodiversity of a landscape, the presence and relative numbers of these more tractable small vertebrates can serve as useful metrics of its “ecological health.” Our primary objective was to determine the range of available riparian and aquatic microclimatic regimes, and discern how these regimes relate to the dominant vegetations that comprise the landscape mosaic. A second objective, reported in a companion paper, was to examine relationships between available microclimatic regimes and herpetofaunal distributions. Here we examined differences in the composition, structure, and related environmental attributes of the three dominant vegetation types, both adjacent to and within the riparian corridors along 49 tributaries. Using automated dataloggers, we recorded hourly water and air temperatures and relative humidity throughout the summer at a representative subset of streams; providing us with daily means and amplitudes for these variables within riparian environments during the hottest period. Although the three vegetation types that dominate this landscape each had unique structural attributes, the overlap in plant species composition indicates that they represent a seral continuum. None‐the‐less, we found distinct microclimates in each type. Only riparian within late‐seral forests contained summer water temperatures that could support cold‐water‐adapted species. We evaluated landscape‐level variables to determine the best predictors of water temperature as represented by the maximum weekly maximum temperature (MWMT). The best model for predicting MWMT (adj. R²=0.69) consisted of catchment area, aspect, and the proportion of non‐forested (grassland) patches. Our model provides a useful tool for management of cold‐water fauna (e.g. salmonids, stream amphibians) throughout California's “Mediterranean” climate zone.     

Herpetofaunal species presence in buffel grass (Cenchrus ciliaris) versus native vegetation‐dominated habitats at Uluṟu‐Kata Tjuṯa National Park

Buffel grass (Cenchrus ciliaris) has been established in Ulu?u‐Kata Tjut a National Park since 1968. To date, the influence of buffel grass on the Park's flora and fauna has been largely unassessed. The objectives of this study were to determine if buffel grass dominates vegetation communities at the base of Ulu?u and if buffel grass habitats are associated with lower reptile and amphibian species richness than endemic vegetation communities. We used vegetation transects to measure the amount of buffel grass and genera of endemic vegetation at 26 sampling locations around the base of Ulu?u. The vegetation survey data were paired with pitfall trap data from reptile and amphibian captures at the same sampling locations. Indicator species analysis and non‐metric multidimensional scaling were used to analyse the vegetation and herpetofaunal community data. Our analyses determined five distinct vegetation communities around Ulu?u. At the base of Ulu?u, buffel grass dominated half of sampled areas and the rest of the inselberg's base was dominated by Themeda grasses. Buffel grass habitats had significantly higher herpetofaunal species richness than the Themeda habitats that dominated other areas at Ulu?u's base. Herpetofauna species richness in buffel grass‐dominated habitats was also significantly higher than all vegetation communities except for Triodia‐dominated habitats. These observations do not directly indicate that buffel grass presence promotes higher species richness of reptiles and amphibians since the observed patterns may be driven by factors such as proximity to breeding sites and abiotic variables not directly related to the grass itself.     

Reptile, amphibian, and lemur diversity of the Malahelo Forest, a biogeographical transition zone in southeastern Madagascar

Ambatorongorongo Mountain lies at the historical intersection betweenhumid, spiny, and littoral forests in southeastern Madagascar. We report theresults of surveys of the herpetofauna and lemurs occurring in Malahelo Forest,a small (<25 ha) forest fragment lying on the western slope ofAmbatorongorongo Mountain. There are at least 41 reptile, 11 amphibian, and 7lemur species in this forest, including several that are endemic to southeasternMadagascar and are at severe risk of extinction. The species richness of theMalahelo fauna is comparable to that of even the largest forest reserves in theregion. We also evaluate the similarity of the Malahelo herpetofauna to that ofnearby humid, spiny, and littoral forests to assess the biogeographic affinitiesof its amphibians and reptile assemblages. Both groups contain speciescharacteristic of each of the three surrounding forest types, but thebiogeographic patterns appear to differ for amphibians and reptiles. Overall,the herpetofauna and lemurs of the Malahelo Forest indicate that it is a remnantof a biogeographic transition zone between the major forest types ofsoutheastern Madagascar. The combination of high species richness, regionalendemics, and unique herpetofaunal and lemur assemblages should make MalaheloForest a high conservation priority, and we give recommendations for protectingwhat remains of this important transitional forest.     

Disentangling vegetation and climate as drivers of Australian vertebrate richness

Determining drivers of species richness is recognised as highly complex, involving many synergies and interactions. We examine the utility of newly available remote sensing representations of vegetation productivity and vegetation structure to examine drivers of species richness at continental and regional scales. We related richness estimates derived from stacked species distribution models for birds, mammals, amphibians, and reptiles to estimates of actual and potential evapotranspiration (AET and PET), forest structure, and forest productivity across Australia as a whole as well as by bioclimatic zones. We used structural equation modeling to partition correlations between climate energy and vegetation attributes and their subsequent associations with species richness. Continentally, vertebrate richness patterns were strongly related to patterns of energy availability. Richness of amphibians, mammals, and birds were positively associated with AET. However, reptile richness was most strongly associated with PET. Regionally, forest structure and productivity associations with bird, mammal, and amphibian richness were strongest. Again, reptile richness associated most strongly with PET. Our results suggest that a hierarchy of drivers of broad‐scale vertebrate richness patterns exist (reptiles excluded): 1) climate energy is most important at the continental scale; next, 2) vegetation productivity and vegetation structure are most important at the regional scale; except 3) at low extremes of climate energy when energy becomes limiting.     

Recovery of Amphibian and Reptile Assemblages During Old‐Field Succession of Tropical Rain Forests

Conversion of tropical forests to agriculture affects vertebrate assemblages, but we do not know how fast or to what extent these assemblages recover after field abandonment. We addressed this question by examining amphibians and reptiles in secondary forests in southeastern Mexico. We used chronosequence data (12 secondary forests fallow for 1–23 yr and 3 old‐growth forest sites) to analyze successional trajectories and estimate recovery times of assemblage attributes for amphibians and reptiles. We conducted 6 surveys at each site over 14 mo (1200 person‐hours) and recorded 1552 individuals, including 25 species of amphibians and 36 of reptiles, representing 96 and 74 percent of the expected regional number of species, respectively. Abundance, species richness, and species diversity of amphibians increased rapidly with successional age, approaching old‐growth forest values in < 30 yr. Species richness and species diversity of reptiles reached old‐growth forest values in < 20 yr. By contrast, the abundance of reptiles and the assemblage composition of amphibians and reptiles recovered more slowly. Along the chronosequence, we observed more species replacement in reptile assemblages than in amphibian assemblages. Several species in the old‐growth forest were absent from secondary forests. Dispersal limitation and harsh conditions prevailing in open sites and early successional environments appear to preclude colonization by old‐growth forest species. Furthermore, short fallow periods and isolation of forest remnants lead to the formation of new assemblages dominated by species favored by human disturbances.     

Nested species subsets of amphibians and reptiles on Neotropical forest islands

Nested species subsets are a common pattern of community assembly characteristic of many types of fragmented landscapes and insular systems. Here we describe nested subset patterns of amphibian and reptile occupancy on 23 forest islands in north-eastern Bolivia. We used observed occupancy patterns to differentiate five distributional guilds: widespread species, rare species, poor colonizers, area-sensitive species and supertramps. Amphibian occurrences were nested along a forest island isolation gradient, and when species from each of the distribution classes were removed from subsequent analyses of nestedness, we found that dispersal-limited poor colonizers were responsible for the association between nestedness and isolation. Amphibians associated with the grassland matrix at the study site showed a nested pattern linked with area, although this pattern did not scale up to all amphibians and could not be unequivocally attributed to any of the distributional guilds we recognized. There were no strong associations between two biological characteristics, body size and relative abundance in the matrix, and the likelihood of occupancy along either forest island area or isolation gradients. The relative importance of isolation in shaping nested patterns of amphibians on these forest islands may be a result of either (1) the greater range in isolation values included in this study compared with many others; (2) the long time since isolation in this landscape, manifesting a footprint of isolation not apparent in more recently fragmented patches; (3) the relatively homogeneous grassland matrix surrounding forest islands that likely provides little refuge for animals moving among forest islands.     

Recovery of amphibian,reptile, bird and mammal diversity during secondary forest succession in the tropics

In tropical regions, many studies have focused on how vegetation and ecosystem processes recover following the abandonment of anthropogenic activities, but less attention has been given to the recovery patterns of vertebrates. Here we conduct a meta‐analysis (n = 147 studies) of amphibian, reptile, bird and mammal recovery during tropical secondary forest succession (i.e. natural regeneration). For each taxonomic group, we compared changes in species richness and compositional similarity during natural secondary succession to reference forests (mature or old growth forest). In addition, we evaluated the response of forest specialists and the change in bird and mammal functional groups during natural secondary succession in the tropical moist forest biome. Overall, species richness of all groups reached levels of the reference forests during natural secondary succession, but this was not the case for species compositional similarity. The delay in recovery of forest specialists may be the reason for the delay in recovery of species compositional similarity. Overall, vertebrate recovery increased with successional stage, but other potential predictors of diversity recovery, such as, the geographical setting (amphibian and reptile species compositional similarity recovered more rapidly on islands), rainfall (mammal species richness and compositional similarity recovered faster in regions of low rainfall), and the landscape context (amphibian, reptile and mammal species compositional similarity recovered faster in regions with more forest patches) influenced vertebrate recovery. These results demonstrate the important role of secondary forests in providing habitat for many vertebrates, but the slow recovery of species compositional similarity, forest specialists and some functional groups (e.g. insectivorous birds) highlighted the challenge of secondary forest persistence, and strongly argues for the continued protection of old growth/mature forest as habitat for forest specialists and as sources for secondary forest sites.     

Environmental determinants of amphibian and reptile species richness in China

Understanding the factors that regulate geographical variation in species richness has been one of the fundamental questions in ecology for decades, but our knowledge of the cause of geographical variation in species richness remains poor. This is particularly true for herpetofaunas (including amphibians and reptiles). Here, using correlation and regression analyses, we examine the relationship of herpetofaunal species richness in 245 localities across China with 30 environmental factors, which include nearly all major environmental factors that are considered to explain broad-scale species richness gradients in such theories as ambient energy, water–energy dynamics, productivity, habitat heterogeneity, and climatic stability. We found that the species richness of amphibians and reptiles is moderately to strongly correlated with most of the environmental variables examined, and that the best fit models, which include explanatory variables of temperature, precipitation, net primary productivity, minimum elevation, and range in elevation, explain ca 70% the variance in species richness for both amphibians and reptiles after accounting for sample area. Although water and temperature are important explanatory variables to both amphibians and reptiles, water variables explain more variance in amphibian species richness than in reptile species richness whereas temperature variables explain more variance in reptile species richness than in amphibian species richness, which is consistent with different physiological requirements of the two groups of organisms.     

Species- and community-level responses to habitat spatial changes in fragmented rainforests: assessing compensatory dynamics in amphibians and reptiles

The rapid loss and degradation of tropical forests threatens the maintenance of biodiversity across different spatial scales. Nevertheless, the extirpation and population decline of some disturbance-sensitive species may be compensated for by colonization and proliferation of disturbance-adapted species, thus allowing distributions of community-level attributes (e.g., abundance and diversity) to be preserved in human-modified tropical landscapes. To test this poorly assessed hypothesis we evaluated species- and community-level responses of amphibians and reptiles to differences in forest patch (patch size, shape, and distance to water bodies) and landscape metrics (old-growth forest cover, degree of fragmentation, and matrix composition) in the fragmented Lacandona rainforest, Mexico. We found that the abundance of several amphibian and reptile species was strongly associated with forest patch and landscape attributes, being particularly higher in larger patches surrounded by a greater forest cover. Such changes at the species level generated notable changes in reptile communities. In particular, the abundance, diversity, and evenness of reptile communities were strongly related to patch size, patch shape, and matrix composition. Yet, because of compensatory dynamics in amphibians, this group showed weak responses at the community level. Despite such compensatory dynamics, our results indicate that forest loss at the patch and landscape levels represents the main threat to both amphibians and reptiles, thus indicating that to preserve herpetological communities in this biodiversity hotspot, conservation initiatives should be focused on preventing further deforestation.     

Spatial and Temporal Patterns of Abundance and Diversity of an East African Leaf Litter Amphibian Fauna

We present data on sample richness, relative abundance, and community structure of a leaf litter amphibian assemblage from globally important miombo-mopane woodlands characteristic of western Tanzania. We describe patterns of diversity across major habitat types and between different seasons from an annual pitfall-trapping campaign. We recorded 28 species of amphibians, which is significantly higher than existing richness estimates for other miombo woodland sites elsewhere in sub-Saharan Africa. We found that cultivation of native habitat reduces frog diversity, a conclusion that has important implications in light of the rapid conversion of miombo woodland for agriculture and fuel-wood across much of southern and central Africa. Many species showed strongly ansynchronized patterns of seasonality in relative abundance, which has significant implications for the establishment of successful monitoring programs and biodiversity surveys. These conclusions emphasize the importance of stratified long-term sampling in biodiversity studies and demonstrate that superficial levels of sampling effort can lead to erroneous conclusions regarding patterns of diversity in amphibian communities. The relatively poor focus on herpetofaunal research in African miombo-mopane woodland is out of proportion to its ecological and conservation significance.     

Biological diversity of a temporary pond herpetofauna in north Florida sandhills

From 1985 through 1990, the herpetofauna of a temporary pond in an uplands longleaf pine sandhills community in north-central Florida was monitored. A drift fence completely encircled the pond. Animals were captured in pitfall traps and marked as they entered and exited the pond basin. I captured 16 155 individuals of 42 species (16 amphibians, 26 reptiles). The species richness, diversity (using Margalef's Diversity Index) and dominance (using the Berger-Parker Index) varied among years. Between 62.5% and 87.5% of the amphibian species and 65% to 81% of the reptile species were captured in any one year. Daily amphibian capture was positively correlated with rainfall, whereas reptile capture was either not correlated or weakly negatively correlated with rainfall. Hydroperiod duration was not correlated with the numbers of either amphibians or reptiles captured. Neither the amphibian nor the reptile community showed any trends in diversity or dominance indices during the course of the study, although both communities were dominated by a few species. However, the species responsible for community dominance changed somewhat as the study progressed. Assessing the results of this study is hampered by the lack of comparable studies elsewhere, expected natural fluctuations of amphibian populations, and a prolonged drought, especially during the latter stages of the study. The herpetological community at Breezeway Pond does not appear to follow theoretical predictions of community response to stress. Temporary ponds are important centres of herpetofaunal biodiversity in uplands sandhills communities. Long-term studies are needed to monitor the composition, structure, and functional interactions of their resident species.     

Integrating field surveys and remote sensing data to study distribution, habitat use and conservation status of the herpetofauna of the Comoro Islands

We studied the non-marine reptile and amphibian species of the volcanic Comoro archipelago in the Western Indian Ocean, a poorly known island herpetofauna comprising numerous microendemic species of potentially high extinction risk and widespread, non-endemic and often invasive taxa. According to our data, the Comoro islands are inhabited by two amphibian species and at least 28 species of reptiles although ongoing genetic studies and unconfirmed historical records suggest an even higher species diversity. 14 of the 28 currently recognized species of terrestrial reptiles (50%) and the two amphibians are endemic to a single island or to the Comoro archipelago. The majority of species are most abundant at low elevation. However, a few endemic species, like the gekkonid lizards Paroedura sanctijohannis and Phelsuma nigristriata, are more common in or even confined to higher altitudes. We created habitat maps from remotely sensed data in combination with detailed species distribution maps produced using comprehensive data from field surveys between 2000 and 2010, literature, and historical locality records based on specimens in zoological collections. Using these data, we assessed the conservation status of the endemic terrestrial reptiles and amphibians according to the IUCN Red List criteria. Our results show that although little area of natural forest remains on the Comoros, many species are abundant in degraded forest or plantations. Competition and predation by invasive species appears to be the most important threat factor for the endemic herpetofauna, together with habitat degradation and destruction, which further favours invasive species. We propose the status Endangered for three species, Vulnerable for one species, Near Threatened for six species, Least Concern for four and Data Deficient for two species. The endemic subspecies Oplurus cuvieri comorensis is proposed for the status Critically Endangered. Based on the results of this study, seven areas of importance for reptile and amphibian conservation on the Comoros are identified. This study shows how remote sensing data can contribute to increasing accuracy and objectiveness of conservation assessments.     

Carabid beetle (Coleoptera: Carabidae) assemblages in the intermediate successional stage after Mt. Bandai eruption of 1888: Effects of environmental variables on carabid beetles in the Urabandai area

We studied carabid beetle assemblage structure and species diversity in an intermediate successional stage (seral) forest established in areas affected by the 1888 eruption of Mt. Bandai and a climax forest that had not been affected by the eruption at the Urabandai area, Fukushima Prefecture, Japan. In total, 2,131 carabid beetles representing 31 species were collected using pitfall traps without bait. A comparison of carabid beetle assemblages between the two forest types revealed that the number of species observed was comparable, but their abundance was greater in the seral forest. The assemblage structure clearly differed between the two forest types. In the seral forest, forest generalists, such as Synuchus arcuaticollis and Pterostichus prolongatus, along with forest specialists including Carabus vanvolxemi and Pterostichus asymmetricus, were collected. In the climax forest, forest generalists, such as Synuchus cycloderus and Carabus albrechti tsukubanus, were more abundant than forest specialists. This suggests that the current seral forest in the Urabandai area possesses environmental variables that enable the coexistence of both forest specialist and generalist beetle species. A redundancy analysis showed that six species from the genera Synuchus and Pterostichus were associated with high canopy openness and high understory vegetation cover, whereas species recorded only in the climax forest were associated with deep litter. Therefore, it seems likely that carabid beetles in the Urabandai area were affected by these three environmental variables.     

湖南壶瓶山国家级自然保护区两栖 爬行动物多样性的时空格局

本研究利用2013至2016年湖南壶瓶山国家级自然保护区巡护监测数据,评估壶瓶山保护区两栖爬行动物多样性水平。壶瓶山保护区在8个监测站点布设了25条两栖爬行动物调查样线,进行常规监测,其中,日间样线14条,夜间样线11条,日间样线平均长度4 km,夜间样线平均长度0.75 km。每个月,每条样线平均调查3次。4年共调查到62种两栖爬行动物,占湖南省两栖爬行动物总种数的38.04%。逐月计算各监测站点的alpha多样性指数和整个保护区的beta多样性指数,按季节比较不同站点间物种组成的Hellinger距离。结果显示,保护区不同位置间、不同的监测站点间以及年际间的两栖爬行动物多样性没有显著差异,提示保护区环境具有相对稳定性。但是,个别位于实验区或邻近实验区的站点,物种组成有着剧烈的波动,表明人为活动影响了两栖爬行动物的分布。另外,保护区两栖爬行动物的物种组成与多样性有着显著的季节差异,这与两栖爬行动物的生物学特性有关。以上结果说明,壶瓶山保护区两栖爬行动物的多样性结构具有稳定性和敏感性的特点,可以考虑用作保护区生物多样性水平的监测指标。     

Influence of landscape and vegetation characteristics on herpetofaunal assemblages in Gulf Coastal Plain pine forests

Longleaf pine (Pinus palustris) savanna characterized by open-canopy, diverse herbaceous vegetation, and high amounts of bare soil once covered much of the southeastern United States Coastal Plain. The unique structural and vegetative conditions of this ecosystem support endemic reptiles and amphibians that have declined as longleaf pine forests have been lost or degraded. Private working pine (Pinus spp.) forests managed for timber production now occur throughout the southeastern United States and have replaced much of the historical longleaf pine savanna. The examination of herpetofaunal (reptile, amphibian) communities in private working loblolly pine (P. taeda) landscapes, particularly in the western Gulf Coastal Plain is lacking. Using repeated field surveys and hierarchical community occupancy models, we examined occupancy and species richness of herpetofauna across 81 sites spanning gradients of management practices, vegetative conditions, and soil composition in northwestern Louisiana, USA, 2017–2019. Young pine stands (<6 yr) exhibited structural characteristics most similar to mature longleaf pine reference sites (>30 yr), while mid-aged stands (13–26 yr) often featured closed canopy and dense midstory. Vegetation conditions varied widely depending on landscape characteristics and site-specific disturbance regimes. We documented 43 species of herpetofauna, including 9 open-pine-associated species. Occupancy of open-pine-associated herpetofauna was positively associated with open-canopy and understory conditions, and sandy soil area. Sites providing open-canopy conditions were often occupied by open-pine-associated species regardless of overstory type and disturbance method. Overall richness of herpetofauna was greatest at sites with moderate canopy cover outside of sandy soil regions. Working pine landscapes in the western Gulf Coastal Plain can support diverse herpetofaunal assemblages, including open-pine-associated species, when management practices maintain open-canopy conditions on sandy, upland soils. More broadly, our results provide insight into how forest management practices affect herpetofauna and may guide practices that can contribute to conservation value of working pine forests.     

Amphibian and reptile communities of rainforest fragments: minimum patch size to support high richness and abundance

Information on animal communities inhabiting Neotropical fragmented landscapes is important for developing conservation strategies. The structure of amphibian and reptile communities in six tropical rainforest fragments (<20?ha) and two reference areas in continuous forest at Los Tuxtlas, Mexico was studied. A total of 3,481 individuals of 51 species of amphibians and reptiles were recorded across 12 bimonthly surveys during 2 years. Taxonomic composition was different between the smallest fragments and the reference areas. Six species were exclusive to large undisturbed forest and richness was significantly lower in the five smallest fragments (1.4–6.6?ha) compared with the largest patch, one or both of the reference areas. Amphibian abundance tended to be higher in large areas, while reptiles were more abundant in the five smallest fragments. Craugastor loki and Anolis uniformis were the dominant species in all sites, and particularly in the smaller fragments. Amphibian and reptile richness was positively related to larger patch sizes, deeper leaf litter, closed canopy cover, and higher relative humidity and negatively related to linear patch shape and high temperatures. Abundance of reptiles was positively associated to high temperatures, high density of woody debris, and closed canopy cover; it was negatively affected by linear patch shape, low humidity levels, and steeper slopes. While amphibian and reptile communities were strongly affected in vegetation fragments, these patches retained a considerable number of rainforest species. Fragments up to at least 17?ha have the potential for preserving communities with similar structure to those occurring in large tropical rainforests.     

Fragmentation gradients differentially affect the species range distributions of four taxonomic groups in semi‐deciduous Atlantic forest

Human activities often cause habitat fragmentation and how forest fragments affect species range distributions has implications for ecology and conservation. However, few studies have considered communities within the same landscape. Here, we analyzed metacommunity structure to determine the range distributions for species in four taxonomic groups (amphibians, birds, social wasps, and trees) in a patchy landscape of semi‐deciduous Atlantic forest in southwestern Brazil. Although trees are a key component of the environment for animals in forested patches, the ranges of bird, wasp, and amphibian species did not change in concert with the species ranges of trees. The species ranges of amphibians and social wasps were unaffected by fragmentation gradients and exhibited independent distribution patterns (i.e., random structure). In contrast, birds and trees exhibited range turnover along different fragmentation gradients, indicating that species show idiosyncratic responses to abiotic factors (i.e., Gleasonian structure). For birds, some less‐resilient species occurred only in fragments with a large area of native vegetation at a radius of 5 km from the center of the sampled forest fragments, whereas other more stress‐tolerant species occurred only in sites with small areas of native vegetation. For trees, some later succession species (e.g., animal‐dispersed seeds) occurred only in fragments with high connectivity, whereas earlier‐recruiting species (e.g., wind‐dispersed seeds) occurred in fragments with low connectivity. Thus, determining the effects of human‐modified landscapes on species range distributions, even within the same landscape, might not be a trivial task.     

Amphibian Diversity and Threatened Species in a Severely Transformed Neotropical Region in Mexico

Many regions around the world concentrate a large number of highly endangered species that have very restricted distributions. The mountainous region of central Veracruz, Mexico, is considered a priority area for amphibian conservation because of its high level of endemism and the number of threatened species. The original tropical montane cloud forest in the region has been dramatically reduced and fragmented and is now mainly confined to ravines and hillsides. We evaluated the current situation of amphibian diversity in the cloud forest fragments of this region by analyzing species richness and abundance, comparing assemblage structure and species composition, examining the distribution and abundance of threatened species, and identifying the local and landscape variables associated with the observed amphibian diversity. From June to October 2012 we sampled ten forest fragments, investing 944 person-hours of sampling effort. A total of 895 amphibians belonging to 16 species were recorded. Notable differences in species richness, abundance, and assemblage structure between forest fragments were observed. Species composition between pairs of fragments differed by an average of 53%, with the majority (58%) resulting from species replacement and the rest (42%) explained by differences in species richness. Half of the species detected are under threat of extinction according to the International Union for Conservation of Nature, and although their distribution and abundance varied markedly, there were also ubiquitous and abundant species, along with rare species of restricted distribution. The evident heterogeneity of the ten study sites indicates that to conserve amphibians in a mountainous region such as this one it is necessary to protect groups of fragments which represent the variability of the system. Both individually and together cloud forest fragments are very important to conservation because each remnant is inhabited by several threatened species, some of them at imminent risk of extinction.     

Mechanistic insights into landscape genetic structure of two tropical amphibians using field‐derived resistance surfaces

Conversion of forests to agriculture often fragments distributions of forest species and can disrupt gene flow. We examined effects of prevalent land uses on genetic connectivity of two amphibian species in northeastern Costa Rica. We incorporated data from field surveys and experiments to develop resistance surfaces that represent local mechanisms hypothesized to modify dispersal success of amphibians, such as habitat‐specific predation and desiccation risk. Because time lags can exist between forest conversion and genetic responses, we evaluated landscape effects using land‐cover data from different time periods. Populations of both species were structured at similar spatial scales but exhibited differing responses to landscape features. Litter frog population differentiation was significantly related to landscape resistances estimated from abundance and experiment data. Model support was highest for experiment‐derived surfaces that represented responses to microclimate variation. Litter frog genetic variation was best explained by contemporary landscape configuration, indicating rapid population response to land‐use change. Poison frog genetic structure was strongly associated with geographic isolation, which explained up to 45% of genetic variation, and long‐standing barriers, such as rivers and mountains. However, there was also partial support for abundance‐ and microclimate response‐derived resistances. Differences in species responses to landscape features may be explained by overriding effects of population size on patterns of differentiation for poison frogs, but not litter frogs. In addition, pastures are likely semi‐permeable to poison frog gene flow because the species is known to use pastures when remnant vegetation is present, but litter frogs do not. Ongoing reforestation efforts will probably increase connectivity in the region by increasing tree cover and reducing area of pastures.     

A predictive framework and review of the ecological impacts of exotic plant invasions on reptiles and amphibians

The invasive spread of exotic plants in native vegetation can pose serious threats to native faunal assemblages. This is of particular concern for reptiles and amphibians because they form a significant component of the world's vertebrate fauna, play a pivotal role in ecosystem functioning and are often neglected in biodiversity research. A framework to predict how exotic plant invasion will affect reptile and amphibian assemblages is imperative for conservation, management and the identification of research priorities. Here, we present a new predictive framework that integrates three mechanistic models. These models are based on exotic plant invasion altering: (1) habitat structure; (2) herbivory and predator‐prey interactions; (3) the reproductive success of reptile and amphibian species and assemblages. We present a series of testable predictions from these models that arise from the interplay over time among three exotic plant traits (growth form, area of coverage, taxonomic distinctiveness) and six traits of reptiles and amphibians (body size, lifespan, home range size, habitat specialisation, diet, reproductive strategy). A literature review provided robust empirical evidence of exotic plant impacts on reptiles and amphibians from each of the three model mechanisms. Evidence relating to the role of body size and diet was less clear‐cut, indicating the need for further research. The literature provided limited empirical support for many of the other model predictions. This was not, however, because findings contradicted our model predictions but because research in this area is sparse. In particular, the small number of studies specifically examining the effects of exotic plants on amphibians highlights the pressing need for quantitative research in this area. There is enormous scope for detailed empirical investigation of interactions between exotic plants and reptile and amphibian species and assemblages. The framework presented here and further testing of predictions will provide a basis for informing and prioritising environmental management and exotic plant control efforts.