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At least 577 records · Page 32Linked to original sources
USGS2019

Disease‐structured N‐mixture models: A practical guide to model disease dynamics using count data

Obtaining inferences on disease dynamics (e.g., host population size, pathogen prevalence, transmission rate, host survival probability) typically requires marking and tracking individuals over time. While multistate mark–recapture models can produce high‐quality inference, these techniques are difficult to employ at large spatial and long temporal scales or in small remnant host populations decimated by virulent pathogens, where low recapture rates may preclude the use of mark–recapture techniques. Recently developed N ‐mixture models offer a statistical framework for estimating wildlife disease dynamics from count data. N ‐mixture models are a type of state‐space model in which observation error is attributed to failing to detect some individuals when they are present (i.e., false negatives). The analysis approach uses repeated surveys of sites over a period of population closure to estimate detection probability. We review the challenges of modeling disease dynamics and describe how N ‐mixture models can be used to estimate common metrics, including pathogen prevalence, transmission, and recovery rates while accounting for imperfect host and pathogen detection. We also offer a perspective on future research directions at the intersection of quantitative and disease ecology, including the estimation of false positives in pathogen presence, spatially explicit disease‐structured N ‐mixture models, and the integration of other data types with count data to inform disease dynamics. Managers rely on accurate and precise estimates of disease dynamics to develop strategies to mitigate pathogen impacts on host populations. At a time when pathogens pose one of the greatest threats to biodiversity, statistical methods that lead to robust inferences on host populations are critically needed for rapid, rather than incremental, assessments of the impacts of emerging infectious diseases.

Ecology and Evolution↗
USGS2019

Spatial sampling bias and model complexity in stream-based species distribution models: A case study of Paddlefish (Polyodon spathula) in the Arkansas River basin, USA

Leveraging existing presence records and geospatial datasets, species distribution modeling has been widely applied to informing species conservation and restoration efforts. Maxent is one of the most popular modeling algorithms, yet recent research has demonstrated Maxent models are vulnerable to prediction errors related to spatial sampling bias and model complexity. Despite elevated rates of biodiversity imperilment in stream ecosystems, the application of Maxent models to stream networks has lagged, as has the availability of tools to address potential sources of error and calculate model evaluation metrics when modeling in nonraster environments (such as stream networks). Herein, we use Maxent and customized R code to estimate the potential distribution of paddlefish ( Polyodon spathula ) at a stream-segment level within the Arkansas River basin, USA, while accounting for potential spatial sampling bias and model complexity. Filtering the presence data appeared to adequately remove an eastward, large-river sampling bias that was evident within the unfiltered presence dataset. In particular, our novel riverscape filter provided a repeatable means of obtaining a relatively even coverage of presence data among watersheds and streams of varying sizes. The greatest differences in estimated distributions were observed among models constructed with default versus AIC C -selected parameterization. Although all models had similarly high performance and evaluation metrics, the AIC C -selected models were more inclusive of westward-situated and smaller, headwater streams. Overall, our results solidified the importance of accounting for model complexity and spatial sampling bias in SDMs constructed within stream networks and provided a roadmap for future paddlefish restoration efforts in the study area.

Arkansas, Colorado, Kansas, Missouri, Nebraska, Ne↗
USGS2020

Tropical understory herbaceous community responds more strongly to hurricane disturbance than to experimental warming

The effects of climate change on tropical forests may have global consequences due to the forests’ high biodiversity and major role in the global carbon cycle. In this study, we document the effects of experimental warming on the abundance and composition of a tropical forest floor herbaceous plant community in the Luquillo Experimental Forest, Puerto Rico. This study was conducted within Tropical Responses to Altered Climate Experiment (TRACE) plots, which use infrared heaters under free‐air, open‐field conditions, to warm understory vegetation and soils + 4°C above nearby control plots. Hurricanes Irma and María damaged the heating infrastructure in the second year of warming, therefore, the study included one pretreatment year, one year of warming, and one year of hurricane response with no warming. We measured percent leaf cover of individual herbaceous species, fern population dynamics, and species richness and diversity within three warmed and three control plots. Results showed that one year of experimental warming did not significantly affect the cover of individual herbaceous species, fern population dynamics, species richness, or species diversity. In contrast, herbaceous cover increased from 20% to 70%, bare ground decreased from 70% to 6%, and species composition shifted pre to posthurricane. The negligible effects of warming may have been due to the short duration of the warming treatment or an understory that is somewhat resistant to higher temperatures. Our results suggest that climate extremes that are predicted to increase with climate change, such as hurricanes and droughts, may cause more abrupt changes in tropical forest understories than longer‐term sustained warming.

Puerto Rico↗
USGS2025

The scientific benefits of a statewide, standardized, coastal wetland monitoring program in Hawaiʻi

In this viewpoint, we provide a scientific justification for a statewide, standardized, coastal wetland monitoring program for Hawaiʻi, USA. Hawaiian coastal wetlands provide important habitat for endangered waterbirds, invertebrates, plants, and the Hawaiian hoary bat (ʻōpeʻapeʻa; Lasiurus semotus ) as well as support Indigenous food systems. Currently, numerous agencies and groups in Hawaiʻi collect data on coastal wetlands, but information is not typically shared and methods are not standardized. A statewide, standardized, coastal wetland monitoring program with a centralized database would allow managers to keep better track of progress toward restoration goals, population changes of conservation-reliant species, outbreaks and impacts of avian botulism, rates of coastal salinization, and many other critical issues across space and time. Monitoring combined with targeted research could fill critical knowledge gaps about the types, functions, values, and biodiversity of Hawaiian coastal wetlands. Ultimately, the improved knowledge gained from long-term coastal wetland monitoring could inform landscape-scale restoration actions and adaptive management of coastal wetlands under sea-level rise and climate change.

Hawaii↗
USGS2025

Sapsucker wells as a keystone nutritional resource: Evaluating methods for detection of secondary sap consumers

North American sapsuckers are considered double keystone species because they (1) excavate nest cavities that are used by other birds, small mammals, and invertebrates, and (2) create and maintain sap wells, a temporary nutritional resource available to a variety of secondary consumers. Most previous reports of secondary sap consumption relied on human observers and were based on either brief or incidental observations. However, modern technology can greatly enhance observational techniques and provide additional insights into the functional, community-level importance of sap wells. We used visual surveys, camera traps, and environmental DNA (eDNA) to identify secondary consumers of sap from wells created by red-naped ( Sphyrapicus nuchalis ) and Williamson's ( S. thyroideus ) sapsuckers among three functional groups of shrubs and trees in south-central Colorado: shrub willows ( Salix spp.), Rocky Mountain maple ( Acer glabrum ), and conifer trees (Pinopsida). Camera traps and eDNA revealed additional sap-well visitors not identified from direct observations. Camera traps were effective for detecting nocturnal sap-well visitors such as small rodents as well as occasional diurnal visitors. Environmental DNA analyses corroborated findings from other methods and identified four additional taxa as possible sap consumers. The physiology of sap-well visitors, such as the ability to taste and assimilate compounds within sap, may aid in determining consumption versus contact when evaluating the results of eDNA analyses. Total vertebrate taxa detected using all 3 methods included 17 bird taxa in 10 families within 3 orders and 8 mammal taxa in 6 families within 4 orders. Shrub-willow sap wells attracted the most diverse vertebrate taxa (23), followed by Rocky Mountain maple (13) and conifer trees (10). Invertebrates in 13 families within 3 orders were observed feeding from sap wells during visual surveys. Because many secondary sap consumers perform ecological services such as pollination, seed dispersal, and pest control, the methods described here may aid in elucidating the importance of sap-well creators in supporting biodiversity and ecosystem functioning.

Colorado↗
USGS2013

Evidence for 20th century climate warming and wetland drying in the North American Prairie Pothole Region

The Prairie Pothole Region (PPR) of North America is a globally important resource that provides abundant and valuable ecosystem goods and services in the form of biodiversity, groundwater recharge, water purification, flood attenuation, and water and forage for agriculture. Numerous studies have found these wetlands, which number in the millions, to be highly sensitive to climate variability. Here, we compare wetland conditions between two 30-year periods (1946–1975; 1976–2005) using a hindcast simulation approach to determine if recent climate warming in the region has already resulted in changes in wetland condition. Simulations using the WETLANDSCAPE model show that 20th century climate change may have been sufficient to have a significant impact on wetland cover cycling. Modeled wetlands in the PPR's western Canadian prairies show the most dramatic effects: a recent trend toward shorter hydroperiods and less dynamic vegetation cycles, which already may have reduced the productivity of hundreds of wetland-dependent species.

Prairie Pothole Region↗
USGS2021

Demographic responses to climate change in a threatened Arctic species

The Arctic is undergoing rapid and accelerating change in response to global warming, altering biodiversity patterns, and ecosystem function across the region. For Arctic endemic species, our understanding of the consequences of such change remains limited. Spectacled eiders ( Somateria fischeri ), a large Arctic sea duck, use remote regions in the Bering Sea, Arctic Russia, and Alaska throughout the annual cycle making it difficult to conduct comprehensive surveys or demographic studies. Listed as Threatened under the U.S. Endangered Species Act, understanding the species response to climate change is critical for effective conservation policy and planning. Here, we developed an integrated population model to describe spectacled eider population dynamics using capture–mark–recapture, breeding population survey, nest survey, and environmental data collected between 1992 and 2014. Our intent was to estimate abundance, population growth, and demographic rates, and quantify how changes in the environment influenced population dynamics. Abundance of spectacled eiders breeding in western Alaska has increased since listing in 1993 and responded more strongly to annual variation in first-year survival than adult survival or productivity. We found both adult survival and nest success were highest in years following intermediate sea ice conditions during the wintering period, and both demographic rates declined when sea ice conditions were above or below average. In recent years, sea ice extent has reached new record lows and has remained below average throughout the winter for multiple years in a row. Sea ice persistence is expected to further decline in the Bering Sea. Our results indicate spectacled eiders may be vulnerable to climate change and the increasingly variable sea ice conditions throughout their wintering range with potentially deleterious effects on population dynamics. Importantly, we identified that different demographic rates responded similarly to changes in sea ice conditions, emphasizing the need for integrated analyses to understand population dynamics.

Ecology and Evolution↗
USGS2021

Genetic and morphological characterization of the freshwater mussel clubshell species complex (Pleurobema clava and Pleurobema oviforme) to inform conservation planning

The shell morphologies of the freshwater mussel species Pleurobema clava (federally endangered) and Pleurobema oviforme (species of concern) are similar, causing considerable taxonomic confusion between the two species over the last 100 years. While P. clava was historically widespread throughout the Ohio River basin and tributaries to the lower Laurentian Great Lakes, P. oviforme was confined to the Tennessee and the upper Cumberland River basins. We used two mitochondrial DNA (mtDNA) genes, 13 novel nuclear DNA microsatellite markers, and shell morphometrics to help resolve this taxonomic confusion. Evidence for a single species was apparent in phylogenetic analyses of each mtDNA gene, revealing monophyletic relationships with minimal differentiation and shared haplotypes. Analyses of microsatellites showed significant genetic structuring, with four main genetic clusters detected, respectively, in the upper Ohio River basin, the lower Ohio River and Great Lakes, and upper Tennessee River basin, and a fourth genetic cluster, which included geographically intermediate populations in the Ohio and Tennessee river basins. While principal components analysis (PCA) of morphometric variables (i.e., length, height, width, and weight) showed significant differences in shell shape, only 3% of the variance in shell shape was explained by nominal species. Using Linear Discriminant and Random Forest (RF) analyses, correct classification rates for the two species' shell forms were 65.5% and 83.2%, respectively. Random Forest classification rates for some populations were higher; for example, for North Fork Holston (HOLS), it was >90%. While nuclear DNA and shell morphology indicate that the HOLS population is strongly differentiated, perhaps indicative of cryptic biodiversity, we consider the presence of a single widespread species the most likely biological scenario for many of the investigated populations based on our mtDNA dataset. However, additional sampling of P. oviforme populations at nuclear loci is needed to corroborate this finding.

Indiana, Kentucky, Ohio, Pennsylvania, Tennessee, ↗
USGS2021

Identifying mismatches between conservation area networks and vulnerable populations using spatial randomization

Grassland birds are among the most globally threatened bird groups due to substantial degradation of native grassland habitats. However, the current network of grassland conservation areas may not be adequate for halting population declines and biodiversity loss. Here, we evaluate a network of grassland conservation areas within Wisconsin, U.S.A., that includes both large Focal Landscapes and smaller targeted conservation areas (e.g., Grassland Bird Conservation Areas, GBCAs) established within them. To date, this conservation network has lacked baseline information to assess whether the current placement of these conservation areas aligns with population hot spots of grassland-dependent taxa. To do so, we fitted data from thousands of avian point-count surveys collected by citizen scientists as part of Wisconsin's Breeding Bird Atlas II with multinomial N -mixture models to estimate habitat–abundance relationships, develop spatially explicit predictions of abundance, and establish ecological baselines within priority conservation areas for a suite of obligate grassland songbirds. Next, we developed spatial randomization tests to evaluate the placement of this conservation network relative to randomly placed conservation networks. Overall, less than 20% of species statewide populations were found within the current grassland conservation network. Spatial tests demonstrated a high representation of this bird assemblage within the entire conservation network, but with a bias toward birds associated with moderately tallgrasses relative to those associated with shortgrasses or tallgrasses. We also found that GBCAs had higher representation at Focal Landscape rather than statewide scales. Here, we demonstrated how combining citizen science data with hierarchical modeling is a powerful tool for estimating ecological baselines and conducting large-scale evaluations of an existing conservation network for multiple grassland birds. Our flexible spatial randomization approach offers the potential to be applied to other protected area networks and serves as a complementary tool for conservation planning efforts globally.

Wisconsin↗
USGS2022

Greater sage-grouse respond positively to intensive post-fire restoration treatments

Habitat loss is the most prevalent threat to biodiversity in North America. One of the most threatened landscapes in the United States is the sagebrush ( Artemisia spp.) ecosystem, much of which has been fragmented or converted to non-native grasslands via the cheatgrass-fire cycle. Like many sagebrush obligates, greater sage-grouse ( Centrocercus urophasianus ) depend upon sagebrush for food and cover and are affected by changes to this ecosystem. We investigated habitat selection by 28 male greater sage-grouse during each of 3 years after a 113,000-ha wildfire in a sagebrush steppe ecosystem in Idaho and Oregon. During the study period, seeding and herbicide treatments were applied for habitat restoration. We evaluated sage-grouse responses to vegetation and post-fire restoration treatments. Throughout the 3 years post-fire, sage-grouse avoided areas with high exotic annual grass cover but selected strongly for recovering sagebrush and moderately strongly for perennial grasses. By the third year post-fire, they preferred high-density sagebrush, especially in winter when sagebrush is the primary component of the sage-grouse diet. Sage-grouse preferred forb habitat immediately post-fire, especially in summer, but this selection preference was less strong in later years. They also selected areas that were intensively treated with herbicide and seeded with sagebrush, grasses, and forbs, although these responses varied with time since treatment. Wildfire can have severe consequences for sagebrush-obligate species due to loss of large sagebrush plants used for food and for protection from predators and thermal extremes. Our results show that management efforts, including herbicide application and seeding of plants, directed at controlling exotic annual grasses after a wildfire can positively affect habitat selection by sage-grouse.

Ecology and Evolution↗
USGS2022

Fijian sea krait behavior relates to fine-scale environmental heterogeneity in old-growth coastal forest: The importance of integrated land–sea management for protecting amphibious animals

The importance of terrestrial coastal ecosystems for maintaining healthy coral reef ecosystems remains understudied. Sea kraits are amphibious snakes that require healthy coral reefs for foraging, but little is known about their requirements of terrestrial habitats, where they slough their skin, digest prey, and breed. Using concurrent microclimate measurements and behavior surveys, we show that a small, topographically flat atoll in Fiji with coastal forest provides many microhabitats that relate to the behaviors of Yellow Lipped Sea Kraits, Laticauda colubrina . Microclimates were significantly related to canopy cover, leaf litter depth, and distance from the high-water mark (HWM). Sea kraits were almost exclusively observed in coastal forest within 30 m of the HWM. Sloughing of skins only occurred within crevices of mature or dying trees. Resting L. colubrina were significantly more likely to occur at locations with higher mean diurnal temperatures, lower leaf litter depths, and shorter distances from the HWM. On Leleuvia, behavior of L. colubrina therefore relates to environmental heterogeneity created by old-growth coastal forests, particularly canopy cover and crevices in mature and dead tree trunks. The importance of healthy coastal habitats, both terrestrial and marine, for L. colubrina suggests it could be a good flagship species for advocating integrated land-sea management. Furthermore, our study highlights the importance of coastal forests and topographically flat atolls for biodiversity conservation. Effective conservation management of amphibious species that utilize land- and seascapes is therefore likely to require a holistic approach that incorporates connectivity among ecosystems and environmental heterogeneity at all relevant scales.

Ecology and Evolution↗
USGS2022

Divergent responses of butterflies and bees to burning and grazing management in tallgrass prairies

Butterflies and bees contribute significantly to grassland biodiversity and play important roles as pollinators and herbivores. Grassland conservation and management must be seen through the lens of insect conservation and management if these species are to thrive. In North America, grasslands are a product of climate and natural disturbances such as fire and grazing. These natural disturbances have changed considerably since European colonization and subsequent landscape fragmentation. The aim of this study was to better understand the impacts of fire and grazing management on butterfly and bee communities in tallgrass prairie, enabling land managers and conservationists to better protect and manage remnant prairie. We examined butterfly and bee abundance, species richness, and diversity in Minnesota tallgrass prairies managed by grazing or fire. In 2016 and 2017, we surveyed butterflies, bees, vegetation, and surrounding land use at 20 remnant prairies (10 burned and 10 grazed) with known management histories. Butterfly and bee abundance at our study sites were significantly negatively correlated. Butterfly abundance, but not species richness, was higher in burned than grazed prairies, and prairie-associated grass-feeding butterflies were more abundant at sites with higher plant species richness. Bee abundance was unrelated to management type but was higher at sites with sandier soils; bee species richness was positively associated with forb frequency. These findings highlight the challenges of designing management plans tailored to wide groups of pollinators and the potential pitfalls of using one group of pollinators as indicators for another. They also point to the importance of a mosaic of management practices across the prairie landscape.

Minnesota↗
USGS2025

Pan-amphibia distribution of the fungal parasite Batrachochytrium dendrobatidis varies with species and temperature

Batrachochytrium dendrobatidis (Bd) is a globally distributed fungal pathogen of amphibians that has contributed to one of the largest disease-related biodiversity losses in wildlife. Bd is regularly viewed through the lens of a global wildlife epizootic because the spread of highly virulent genetic lineages has resulted in well-documented declines and extinctions of multiple amphibian species. However, the current state of Bd occurrence, host range, host impacts, and ecological drivers remains poorly understood outside of the most negatively affected amphibian species and regions. Our objective was to describe the macroecology of Bd occurrence and infection intensity on caudates (salamanders) across the United States and to compare these patterns with better-studied anurans (frogs and toads). We collected swabs from 11,183 amphibians at 609 sites from 54 species across the United States from 2015 to 2017. We analyzed the prevalence and intensity of Bd infection jointly using a Bayesian hurdle model with covariates of site-level temperature and precipitation, as well as individual characteristics and species identification. Bd was distributed widely across sites and species sampled across the spatial extent of the conterminous United States. We found that Bd prevalence and intensity were most strongly influenced by temperature in the month preceding sampling and by differences among taxon groups. We estimated that temperature had a strong and nonlinear influence on both Bd prevalence and intensity with peak infection at intermediate temperatures and lower infection at low and high temperatures. We found Caudate hosts tended to have higher prevalence than Anuran hosts and Anuran hosts tended to have higher intensity at optimal temperatures for Bd infection. Our findings suggest that Bd has an amphibian-wide host range, temperature gradients exert a strong influence on Bd, and enzootic transmission likely encompasses a much larger spatial and species distribution than previously recognized across North America.

conterminous United States↗
USGS2019

Landscape controls on the distribution and ecohydrology of central Oregon springs

Small springs in semiarid landscapes are essential for maintaining aquatic biodiversity and supporting livestock grazing operations. However, little is known about controls on the distribution and physical characteristics of small springs, the aquatic species they support, or their sensitivity to disturbance. We address this information gap in the Crooked River subbasin, a tributary of the Deschutes River in Oregon. We conducted spatial analyses on 2,519 mapped springs to investigate the influence of landscape controls (precipitation and bedrock permeability) on spring density in the Crooked River subbasin and the adjacent Upper Deschutes subbasin. Spring density was highest in areas of low bedrock permeability ( P < 0.0001) and high annual precipitation ( P < 0.0001). We suggest that the high density of small springs on low‐permeability bedrock indicates that these springs generally have short, shallow flow paths and thus may be susceptible to forecasted climate changes. A survey of 137 springs in the Crooked River subbasin revealed the hydrogeologic setting affects spring discharge type ( P = 0.017), temperature ( P = 0.011), and pH ( P = 0.026). We found a high frequency of anthropogenic impacts on springs: 95% of diffuse‐discharge springs and 79% of discrete‐discharge springs were disturbed by livestock grazing. Species inventories at 10 of the most intact surveyed springs confirm that small springs are biologically diverse, with 151 total species of plants and 135 total taxa of macroinvertebrates. Springs in the Crooked River subbasin are ecologically important habitats but require careful management to protect against livestock disturbance and development.

Oregon↗
USGS2026

Relative influence of flow regime, natural and anthropogenic environment on multidimensional stream fish diversity

The flow regime is considered a ‘master variable’ in riverine ecology because it directly influences stream geomorphology and biological communities. However, other environmental and anthropogenic factors have direct and synergistic effects with flow on fish diversity, complicating estimates of the flow regime's true importance. Moreover, most flow-ecology studies focus only on taxonomic diversity (i.e., species), without considering functional (trait-focused) or phylogenetic (evolution-focused) dimensions of diversity. In this study, we used linear regression with variation partitioning to parse out the independent and shared roles of the flow regime, physical environmental factors (e.g., soil characteristics) and the anthropogenic environment (e.g., developed land cover) for structuring multidimensional diversity of 365 stream fish communities in two biogeographic regions across South Carolina, USA. These variables explained between 8% and 18% of total variation of the local diversity. The flow regime contributed to diversity in all cases, but frequently covaried with physical and/or anthropogenic environmental variables. This covariation indicated that the independent role of flow would have been inflated if other environmental variables were not considered. The three dimensions of stream fish diversity were weakly correlated with one another and were associated with different environmental variables, indicating that each of them represents unique and complimentary facets of fish diversity. Accordingly, only considering the independent effects of instream flow on fish diversity may miss meaningful interactions between the flow regime and the other components of the environment that influence biodiversity patterns, leading to over simplified flow–ecology relationships.

South Carolina↗
USGS2017

Model parameters for representative wetland plant functional groups

Wetlands provide a wide variety of ecosystem services including water quality remediation, biodiversity refugia, groundwater recharge, and floodwater storage. Realistic estimation of ecosystem service benefits associated with wetlands requires reasonable simulation of the hydrology of each site and realistic simulation of the upland and wetland plant growth cycles. Objectives of this study were to quantify leaf area index (LAI), light extinction coefficient ( k ), and plant nitrogen (N), phosphorus (P), and potassium (K) concentrations in natural stands of representative plant species for some major plant functional groups in the United States. Functional groups in this study were based on these parameters and plant growth types to enable process-based modeling. We collected data at four locations representing some of the main wetland regions of the United States. At each site, we collected on-the-ground measurements of fraction of light intercepted, LAI, and dry matter within the 2013–2015 growing seasons. Maximum LAI and k variables showed noticeable variations among sites and years, while overall averages and functional group averages give useful estimates for multisite simulation modeling. Variation within each species gives an indication of what can be expected in such natural ecosystems. For P and K, the concentrations from highest to lowest were spikerush ( Eleocharis macrostachya ), reed canary grass ( Phalaris arundinacea ), smartweed ( Polygonum spp.), cattail ( Typha spp.), and hardstem bulrush ( Schoenoplectus acutus ). Spikerush had the highest N concentration, followed by smartweed, bulrush, reed canary grass, and then cattail. These parameters will be useful for the actual wetland species measured and for the wetland plant functional groups they represent. These parameters and the associated process-based models offer promise as valuable tools for evaluating environmental benefits of wetlands and for evaluating impacts of various agronomic practices in adjacent areas as they affect wetlands.

Ecosphere↗
USGS2019

Negative impacts of summer heat on Sierra Nevada tree seedlings

Understanding the response of forests to climate change is important for predicting changes in biodiversity and ecosystem services, including carbon storage. Seedlings represent a key demographic stage in these responses, because seedling establishment is necessary for population persistence and spread, and because the conditions allowing seedlings to survive and grow are often more restrictive than those adults can tolerate. However, detailed long‐term data on the responses of individual seedlings to climatic variation are rare. Here, we analyze a decade of seedling growth and survival data collected in 25 long‐term plots located in Sequoia and Yosemite National Parks. The forest types represented range from lower‐elevation mixed conifer, to red fir‐dominated, to high‐elevation western white pine stands. Twelve species, including two oaks and ten conifers, are found across these plots. Survival and transition to larger size classes are modeled within a Bayesian framework as a function of species, size, fire, and various climate variables. We initially expected that precipitation‐related variables would have a strong effect on seedling survival and growth in this Mediterranean‐climate region and that some species might respond positively to higher temperatures if they are adapted to warmer low‐elevation areas or to higher‐than‐average temperatures if they are high‐elevation species whose growing seasons are limited by cold. However, we found that higher July maximum temperature or temperature anomalies were associated with lower survival and growth for most species, while precipitation and snow effects were weaker and more variable. Higher precipitation had a positive effect on survival of most species, but snow effects and precipitation effects on growth could be negative. Given the estimated climate responses, under potential future scenarios of higher summer temperatures and altered precipitation, most species are predicted to have lower survival and reduced growth. This is likely to favor species that have relatively high survival and growth and less negative responses to climatic shift (such as several of the pines) and perhaps lead to a more open forest structure—or potentially transition to non‐forest vegetation types where seedling recruitment does not keep pace with adult mortality.

California↗
USGS2019

Floodplains provide important amphibian habitat despite multiple ecological threats

Floodplain ponds and wetlands are productive and biodiverse ecosystems, yet they face multiple threats including altered hydrology, land use change, and non‐native species. Protecting and restoring important floodplain ecosystems requires understanding how organisms use these habitats and respond to altered environmental conditions. We developed Bayesian models to evaluate occupancy of six amphibian species across 103 off‐channel aquatic habitats in the Chehalis River floodplain, Washington State, USA. The basin has been altered by changes in land use, reduced river–wetland connections, and the establishment of non‐native American bullfrogs ( Rana catesbeiana = Lithobates catesbeianus ) and centrarchid fishes, all of which we hypothesized could influence native amphibian occupancy. Despite potential threats, the floodplain habitats had relatively high rates of native amphibian occupancy, particularly when compared to studies from non‐floodplain habitats within the species’ native ranges. The biggest challenge for native amphibians appears to be non‐native centrarchid fishes, which strongly reduced occupancy of two native amphibians: the northern red‐legged frog ( Rana aurora ) and the northwestern salamander ( Ambystoma gracile ). Emergent vegetative cover increased occupancy probability for all five native amphibian species, indicating that plant management may offer a strategy to counter the negative effect of centrarchids by providing refuge from predation. We found that temporary and permanent hydroperiod sites supported different species; hence, both should be conserved on the landscape. Lastly, human‐created and natural ponds had similar amphibian occupancy patterns, suggesting that pond construction offers a viable strategy for adding habitats to the floodplain landscape. Overall, floodplain ponds and wetlands provide important amphibian habitat, and we offer management strategies that will bolster amphibian occupancy in an altered floodplain landscape.

Washington↗