Ecosphere最新文献

{"title":"Spatial and temporal patterns of mammalian roadkill across subtropical protected areas in Nepal","authors":"Dayaram Pandey,&nbsp;Pemba Sherpa,&nbsp;Dipesh Kumar Sharma,&nbsp;Pratistha Shrestha,&nbsp;Gopal Khanal","doi":"10.1002/ecs2.70383","DOIUrl":"10.1002/ecs2.70383","url":null,"abstract":"<p>Wildlife–vehicle collisions are a major source of anthropogenic wildlife mortality, making it essential to understand their spatial and temporal patterns for effective mitigation. In this study, we conducted a multisite, multiyear analysis of wildlife roadkill incidents recorded across six subtropical protected areas in Nepal over a five-year period (2017–2022). A total of 618 individual animals from 37 vertebrate species were killed in vehicle collisions, averaging five roadkills per 10 km annually. Roadkill accounted for approximately 27% of all recorded wildlife mortalities, highlighting it as a significant source of mortality and a growing threat to wildlife in protected areas. We found a clear taxonomic bias in roadkill, with ungulates and primates accounting for ~65% of all incidents. However, during the COVID-19 lockdown, carnivores were disproportionately affected, suggesting a potential shift in risk linked to altered traffic conditions. Multiscale regression modeling showed that roadkill risk increased with Normalized Difference Vegetation Index (NDVI), annual rainfall, and canopy cover, with consistent effects across scales of analysis (100-, 250-, and 500-m buffers). Seasonal differences were evident, with peak roadkill in winter, followed by autumn. Roadkill incidents increased modestly (3%) over the five-year period, but trends varied, with three of six protected areas showing an increasing trend. Importantly, the three key metrics (total magnitude, kill rate, and temporal trend) did not align; the protected area with the highest number of total roadkill did not exhibit the highest kill rate per km or increasing trend, but the one with the shortest road length passing through its area experienced an increasing trend. This mismatch likely reflects a complex interplay of factors, including road length and site-specific factors. This variation suggests that protected areas vary in their vulnerability to roadkill, underscoring the need for context-specific mitigation strategies tailored to each metric and site condition. As Nepal's road network continues to expand, targeted research and monitoring will be essential for identifying roadkill hotspots, assessing mitigation effectiveness, and informing conservation planning.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70383","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144861676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Successful eastern oyster (Crassostrea virginica) recruitment on intertidal artificial substrates in Virginia, USA","authors":"Rochelle D. Seitz,&nbsp;Kathleen E. Knick,&nbsp;Emily Suchonic,&nbsp;Amanda Pysher","doi":"10.1002/ecs2.70380","DOIUrl":"10.1002/ecs2.70380","url":null,"abstract":"<p>Declines of eastern oyster (<i>Crassostrea virginica</i>) populations and scarcity of natural oyster shell necessitate quantifying the effectiveness of artificial oyster reef substrates over varying environmental conditions. Oyster castles are often used in intertidal areas with moderate wave energy; however, new concrete, natural-looking substrates, GROW Reef Tiles, are now available. Eastern oyster recruitment and size on oyster castles (OC) and GROW Reef Tiles (GT), with 27% higher surface area on OC, were assessed three times over 25 months in locations with varying salinity. Four sites in the Chesapeake Bay region were examined: Cherrystone Inlet, Mockhorn Bay, Elizabeth River, and Lynnhaven Bay. At each site, 10 OC and 10 GT were randomly placed parallel to shore in the low-intertidal zone in May 2019. Sites were sampled non-destructively in October 2019, July 2020, and June 2021. A quadrat (0.30 m × 0.30 m) was placed on top of the structure, and one of four quadrants was randomly chosen to count and measure oysters for shell height and mortality status. Data from each year and combined data (2019–2021) were analyzed using the response variables oyster density and shell height along with combinations of year, site, and substrate type. Both substrate types had high oyster recruitment (&gt;400 oysters m⁻²). At 25 months post-deployment, mean oyster densities differed significantly by substrate, with 553.3 oysters m⁻² on OC and 423.0 oysters m⁻² on GT (24% higher on OC). Oyster densities differed by site, with highest densities in Mockhorn Bay. Growth was ~60–70 mm over the 25 months, and oysters were smallest at the highest-salinity and highest-density site. Mean oyster shell height was greater on GT (61.7 ± 2.2 mm) than on OC (57.3 ± 2.1). Both substrates had high oyster recruitment (well above the Chesapeake Bay success metric: 50 oysters m⁻²), large oysters, and developed multiple cohorts, suggesting that both substrates could be used effectively for restoration. Given that GT is a natural-looking substrate, it may be preferable for nearshore restoration. This is important particularly for management agencies concerned with both appearance and functionality in large-scale restoration projects.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70380","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144861678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduction in nitrification during the early transition from conventional to organic farming practices","authors":"Jacob R. Price,&nbsp;Diana Oviedo-Vargas,&nbsp;Marc Peipoch,&nbsp;Melinda D. Daniels,&nbsp;Jinjun Kan","doi":"10.1002/ecs2.70375","DOIUrl":"10.1002/ecs2.70375","url":null,"abstract":"<p>Little is known about the nitrogen transformation dynamics during the early transition phase from conventional to organic farming. We investigated changes in microbial N-cycling in agricultural fields transitioning from conventional to organic farming practices by quantifying nitrification/mineralization rates, extracellular enzyme activity (EEA), and nitrogen transformation genes (nitrification and denitrification). The farming practices we investigated contained three binary treatments: Management System (denoting both general approach and fertility source), Tillage, and Cover Crop. Four years after the transition, we found that the process of converting conventionally managed fields to organic agricultural practices significantly reduced net nitrification rates, likely as a result of lower abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). In addition to terms pertaining to the experimental treatments, we included a term, Year, in our models to control for noise due to the cash/cover crop rotation and weather-related differences. We found that the Year covariate to have highly significant variation related to net nitrification, soil NH₄⁺-N concentration, the EEA ratio of NAG:BG, and the abundances of AOA, AOB, and the denitrifying gene <i>nos</i>Z. In contrast to much of the published literature, our results showed the absence of a significant response to the Tillage and Cover Crop treatments after four years of conversion. Combined with year-to-year variation being generally more important of an influence than the Tillage and Cover Crop treatments, our results suggest that nutrient processes change gradually in response to farming practices. Therefore, incorporating research about the inter-year variations may yield predictive models that would be useful not just to researchers but also to guide farmers engaged in conventional-to-organic conversion projects.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70375","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Different processes and constraints drive the assembly of deep-sea hydrothermal vent and sunken wood communities","authors":"Joan M. Alfaro-Lucas,&nbsp;Florence Pradillon,&nbsp;Daniela Zeppilli,&nbsp;Maurício Shimabukuro,&nbsp;Gauthier Schaal,&nbsp;Loïc N. Michel,&nbsp;Pedro Martinez-Arbizu,&nbsp;Hayato Tanaka,&nbsp;Martin Foviaux,&nbsp;Jozée Sarrazin","doi":"10.1002/ecs2.70351","DOIUrl":"10.1002/ecs2.70351","url":null,"abstract":"<p>Niche processes mainly dictate the successful establishment and coexistence of species along gradients of community drivers such as energy availability and environmental stress. Deep-sea chemosynthetic habitats such as hydrothermal vents and wood falls show concomitant gradients of energy availability and stress because productivity is fueled by potentially toxic, chemically reduced compounds. However, the specific processes and constraints driving the assembly of these eco-evolutionarily related communities remain poorly understood. Here, we infer community assembly processes from species, functional, and isotopic diversity patterns of vent and wood-fall assemblages using a colonization experiment along a hydrothermal gradient, from vent periphery to diffuse-flow habitats. We hypothesized that despite the high environmental stress, the high productivity of vent diffuse-flow and wood-fall habitats increases niche space due to niche partitioning and/or competitive exclusion processes, allowing more species to coexist in high densities. As predicted, at moderate levels of stress at vent diffuse-flow habitats, productivity increases niche space and supports denser and more species-rich assemblages with many ecological strategies, suggesting niche partitioning and/or competitive exclusion of functionally similar species. However, as stress increases at habitats under higher venting influence, species richness, abundance, and functional diversity decrease, suggesting environmental filtering and/or competitive dominance of better adapted species. Similarly, the vent periphery supports fewer species, individuals, trophic levels, and reduced niche space, suggesting that the scarcer food resources act as an environmental filter. Unexpectedly, food resources at wood substrata at the vent periphery, harboring typical wood-fall communities, support very speciose and dense assemblages of reduced functional diversity. This suggests that compared to vent diffuse-flow habitats, the reduced habitat availability, or longevity, of wood falls reduces niche space and promotes environmental filtering and/or competitive dominance processes. Thus, different processes and constraints appear to drive the assembly of communities along hydrothermal vent gradients and between the eco-evolutionarily related vent and wood-fall communities.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70351","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Some of these are not like the others: Relative thermal sensitivity among anuran species of the Southeast United States","authors":"Traci P. DuBose,&nbsp;Chloe E. Moore,&nbsp;Vincent R. Farallo,&nbsp;Abigail L. Benson,&nbsp;William A. Hopkins,&nbsp;Sam Silknetter,&nbsp;Meryl C. Mims","doi":"10.1002/ecs2.70366","DOIUrl":"10.1002/ecs2.70366","url":null,"abstract":"<p>Estimating how close a species is to its upper thermal limits (i.e., warming tolerance, a thermal sensitivity index) and how that proximity changes across space enables spatially explicit identification of species with increased extinction risk as temperatures increase. Yet, thermal sensitivity is often difficult to calculate because it is the result of many traits. We aimed to synthesize multiple traits into a single estimate of relative terrestrial thermal sensitivity for 13 anuran species in the southeastern United States. We employed models that incorporate traits and microclimate variation to (1) estimate species warming tolerance (the difference between species critical thermal maximum and modeled operative temperature, an estimate of body temperature) and (2) investigate how warming tolerance varied with latitude (whereby latitude represents different temperature regimes and external drivers of thermal sensitivity). We ran mechanistic niche models across a 12° latitudinal gradient and 10 years to estimate individual operative temperature. We calculated the minimum, 25th percentile (hottest quarter), and median daily minimum warming tolerance. Estimates of minimum warming tolerance spanned −5 to 10°C (<i>Lithobates palustris</i> and <i>Gastrophryne carolinensis</i> respectively) and differed among species. For most species, modeled operative temperatures exceeded species' critical thermal maximum during extreme warm temperatures (i.e., heat waves) in part of their range, and warming tolerance increased with latitude. During heat waves, five species had lower warming tolerance at higher latitudes, and three species' warming tolerance did not change with latitude. We identified species that are approaching their thermal limits in the Southeast and characterized spatial patterns of warming tolerance. Increased temperatures could increase anuran extinction risk, posing an additional challenge for threatened anuran species. Spatial patterns of warming tolerance were not consistent among species in our study, highlighting that patterns identified at higher taxonomic categories could be inconsistent at lower taxonomic categories.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70366","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dung beetles, but not rodents, contribute to brown bear feces removal, disaggregation, and secondary seed dispersal","authors":"Grégoire Pauly,&nbsp;Cécile Vanpé,&nbsp;Mélanie Roy,&nbsp;Jérôme Sentilles,&nbsp;Jean-David Chapelin-Viscardi,&nbsp;Tanguy Daufresne,&nbsp;Christophe Baltzinger","doi":"10.1002/ecs2.70382","DOIUrl":"10.1002/ecs2.70382","url":null,"abstract":"<p>Seed dispersal by endozoochory is essential to plant dynamics, but once released in the feces, the seeds face a hostile environment that is not always favorable to germination. Indeed, feces may contain inhibitors, have high seed density, and be densely structured. However, feces visitors such as vertebrates and invertebrates may play an essential role in secondary seed dispersal (SSD) and can alleviate the chemical and physical constraints of the feces. Yet, their relative roles in the dispersal of small- and medium-sized seeds are not well documented. In this study, we designed a field experiment in the French Pyrénées mountains to disentangle the relative role of vertebrate and invertebrate on feces removal, disaggregation, and secondary dispersal of small- and medium-sized seeds. We thus used 30 brown bear (<i>Ursus arctos</i>) fresh feces and separated each of them into three sub-samples submitted to different treatments allowing total access of any visitor, access restricted to invertebrates, and no visitor access, respectively. We inserted eight raspberry (<i>Rubus idaeus</i>) and five blueberry (<i>Vaccinium myrtillus</i>) marked seeds in each sub-sample to assess SSD. In parallel, we used camera and pitfall traps to document the presence of vertebrate and invertebrate visitors, respectively. After ten days, we weighed the fecal matter remaining, counted the remaining seeds, and assessed the feces disaggregation based on visual examination and objective criteria. We observed a significant effect of invertebrates on feces removal, disaggregation, and secondary dispersal of both seed species. Vertebrates did not visit the feces. Dung beetles caught in pitfall traps appear as the main secondary seed dispersers and disaggregation agents in this area. We also pinpointed that diet composition and structure of brown bear feces affect dung beetle attraction and activities. Our study in a temperate mountainous area identifies dung beetles as key agents in the disaggregation of large feces and secondary dispersal of small- and medium-sized seeds, with no evidence of rodents. Diet composition and the fecal matter trapping the seeds affect seed fate by modulating dung beetle activity. By releasing variable fecal contents, omnivorous primary seed vectors have an even more complex effect on seed fate than expected.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70382","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"All you can eat: Artificial feeding sites affect large herbivores and their predator in a human-dominated landscape","authors":"Marco Salvatori,&nbsp;Claudia Pellegrini,&nbsp;Enrico Ferraro,&nbsp;Luca Roner,&nbsp;Alessandro Brugnoli,&nbsp;Federico Ossi,&nbsp;Francesca Cagnacci,&nbsp;Giulia Bombieri","doi":"10.1002/ecs2.70368","DOIUrl":"10.1002/ecs2.70368","url":null,"abstract":"<p>The re-expansion of large mammals in European human-dominated landscapes poses new challenges for wildlife conservation and management practices. Supplementary feeding of ungulates is a widespread practice with several motivations, including hunting, yet the known effects on target and non-target species have yet to be disentangled. According to optimal foraging theory, such concentrated food sources may attract herbivores and carnivores in turn. As such, feeding sites may skew the spatial distribution of wildlife and alter intra-and interspecific interactions, including predator–prey dynamics. Here, we investigated the use of ungulate-specific feeding sites by target and non-target species in a human-dominated and touristic area of the Alps, using systematic camera trapping. We assessed potential temporal segregation between roe deer and red deer at feeding sites and whether these concentrated artificial food sources influenced the occurrence and site use intensity of ungulates and wolves at the broader scale. We found that feeding site frequentation by roe deer was influenced by the presence of red deer, with a higher crepuscular and diurnal activity and a longer time span between visits at feeding stations strongly used by red deer, indicating potential temporal niche partitioning between the two ungulates. We also found that ungulates occurred with a higher probability at shorter distances from feeding sites and used sites with high human outdoor activity less intensively than less disturbed ones. Wolves' site use intensity was higher closer to feeding sites, indicating a potential effect of supplemental feeding sites on both prey's and predators' space use. Our results reveal side effects of artificial feeding sites, thus contributing to a more informed and evidence-based management, with high relevance especially in light of the considerable recovery of large mammals across anthropized regions of Europe and the popularity of artificial feeding of ungulates for hunting or recreational purposes. We thus advise limiting this practice in areas where large herbivores, predators, and humans closely coexist.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70368","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extremely large fires shape fire severity patterns across the diverse forests of British Columbia, Canada","authors":"L. Collins,&nbsp;K. Morrison,&nbsp;M. S. Buonanduci,&nbsp;L. Guindon,&nbsp;B. J. Harvey,&nbsp;M.-A. Parisien,&nbsp;S. Taylor,&nbsp;E. Whitman","doi":"10.1002/ecs2.70364","DOIUrl":"10.1002/ecs2.70364","url":null,"abstract":"<p>Warming and drying conditions are driving increases in wildfire size and annual area burned across the forests of British Columbia, Canada. The impact of increasing fire activity on these forests remains unclear as examination of concurrent changes to fire severity is lacking. Here, we assess how fire severity patterns change with the amplification of wildfire size across the bioregions of British Columbia using fire severity mapping from 1986 to 2021. First, we examine trends in extremely large fires (i.e., largest 5% of fires) and their influence on annual area burned; then we examine scaling relationships between wildfire size and fire severity to determine if extremely large fires are more severe than smaller fires. Extremely large fires explained much of the variation in annual area burned and accounted for a large proportion of cumulative area burned (33%–71%) across the study area. Consequently, shifts in the size of extremely large fires, which increased by an order of magnitude over our study period, have driven a substantial increase in annual area burned. Scaling relationships revealed that bigger wildfires consisted of larger and more homogenous patches of high-severity fire than smaller fires, resulting in a greater proportional contribution of high-severity fire to fire extent. Patterns in scaling relationships were qualitatively similar for all bioregions, indicating shifts in fire regimes are widespread across the province. Our results demonstrate that recent increases in the extremes of wildfire size across the forests of British Columbia have driven a sharp increase in area burned, which was associated with a disproportionate increase in the size and extent of patches of high-severity fire.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70364","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Offspring number, size, and survival: State-dependent optimization of litter size in a long-lived capital breeder","authors":"Marwan Naciri,&nbsp;Jon Aars,&nbsp;Magnus Andersen,&nbsp;Marie-Anne Blanchet,&nbsp;Andrew E. Derocher,&nbsp;Marlène Gamelon,&nbsp;Øystein Wiig,&nbsp;Sarah Cubaynes","doi":"10.1002/ecs2.70370","DOIUrl":"10.1002/ecs2.70370","url":null,"abstract":"<p>Seventy-five years ago, Lack proposed that there should be an optimal clutch size shared by all individuals in a population and favored by natural selection, which maximizes the number of recruited offspring. While some studies support this “common optimum” hypothesis, others have shown that the optimal clutch size depends on maternal state (e.g., age and body condition, “state-dependent optimization”). These contrasting results suggest that the degree of state dependency might itself depend on the ecological context (e.g., capital vs. income breeding). Furthermore, almost all these studies were conducted on fast-living species and have ignored interdependencies among variables such as maternal age and condition. Here, we test whether females share a common optimal litter size or have a state-dependent optimal litter size in a slow-paced capital breeder, the polar bear (<i>Ursus maritimus</i>). To do so, we assess the influences of (1) maternal state on litter size, (2) maternal state and litter size on cub mass, and (3) maternal state, litter size, and cub mass on cub survival, using path analysis to account for interdependencies among variables and capture–recapture modeling to estimate cub survival. We use 34 years (1992–2025) of individual-based data from a polar bear subpopulation in the Svalbard region of Norway. In accordance with the state-dependent optimization hypothesis, litter size varied with maternal age and size. Middle-aged and sized females had the highest probability of having twins. Old and large females more often had triplet litters. Cub mass decreased with increasing litter size, whereas litter mass increased, meaning females with a large litter allocated more resources to reproduction. Cub mass in turn strongly predicted cub survival, indicating that offspring survival was traded against offspring number. In middle-aged and old females, productivity—the number of cubs surviving their first year—increased with litter size, in accordance with the state-dependent optimization hypothesis. Overall, our results are consistent with a state-dependent optimization of litter size in this large, slow-paced mammal producing small litters. State dependence of litter size may be more likely in capital breeders as the amount of energy available for reproduction is known in advance.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70370","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ephemeral vegetation drivers of occupancy dynamics of Mojave desert tortoises (Gopherus agassizii)","authors":"Seth M. Harju,&nbsp;Scott M. Cambrin,&nbsp;Stefanie Ferrazzano","doi":"10.1002/ecs2.70381","DOIUrl":"10.1002/ecs2.70381","url":null,"abstract":"<p>Understanding the factors associated with the probability of a species occurring across the landscape has become a foundational component of wildlife management and monitoring. Static factors (e.g., plot characteristics that are consistent across time, such as topography or permanent woody vegetation) are often investigated, but changing vegetation factors may also drive apparent occupancy dynamics as energy-minimizing species respond to ephemeral changes in food resources. We analyzed the role of ephemeral forbs and grasses in the occupancy dynamics of Mojave desert tortoises (<i>Gopherus agassizii</i>), expecting higher occupancy when food plants (forbs) were abundant and lower occupancy when non-food plants (grasses) were widespread. We found that none of the static plot-level factors explained initial occupancy in the first year, but vegetation factors did influence interannual occupancy dynamics. Plots that were unoccupied in a given year were 14.4% less likely to become occupied in the following year for every 1% point increase in grass cover within the plot (i.e., a negative effect of grass cover on annual plot occupancy). Conversely, occupied plots were 72.5% less likely to become unoccupied in the subsequent year for every 1% point increase in the cover of forbs, and we unexpectedly found that occupied plots were 76.9% less likely to become unoccupied for every additional grass species present in the plot. However, credible intervals were wide, indicating strong but inconsistent patterns of ephemeral vegetation driving occupancy dynamics of Mojave desert tortoises.</p>","PeriodicalId":48930,"journal":{"name":"Ecosphere","volume":"16 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1002/ecs2.70381","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}