Ecological Applications最新文献

The loss and fragmentation of natural habitats due to the intensification of agricultural land use have detrimental impacts on the biodiversity of arthropods. The reduction of natural habitats results in a decreased availability of essential resources, which may select for rapid development and phenotypes enhancing dispersal ability. We here compared replicated populations of the butterfly Coenonympha pamphilus in field-caught females and their laboratory-reared offspring across two landscape types: highly fragmented and intensified "modern" and less fragmented "traditional" agricultural landscapes. We also examined the effects of food stress and landscape parameters representing compositional and configurational landscape heterogeneity on intraspecific trait variation at different spatial scales. The differences between the two landscape types in butterfly traits were nonsignificant throughout, but both field-caught females and their offspring exhibited various responses to the measured landscape parameters. In particular, landscapes with (1) high heterogeneity of habitat patches (i.e., relatively smaller grassland patches with high boundary length), (2) higher proportion of non-crop habitats (i.e., grassland, forests, and woodland), and (3) lower proportion of crop fields seemed to select for phenotypes enhancing dispersal ability. Flight propensity of male offspring was increased under food stress, indicating plastic responses to resource scarcity. In conclusion, our findings suggest that the compositional and configurational landscape heterogeneity, namely parameters indicative of agricultural intensification, select for enhanced dispersal in C. pamphilus. As higher investment in dispersal often comes at a cost to reproduction, such trait shifts may reduce population viability, which may have important implications for insect declines in agricultural landscapes.

Understanding the interplay between environmental factors and operational practices is essential to overcoming the bottlenecks that often hinder post-fire restoration success. Selecting favorable microsites can enhance initial seed establishment by offering conditions conducive to survival and growth, although these same sites may also increase vulnerability to seed predation. Practical interventions, such as adjusting the timing of sowing, can help mitigate this risk. This is particularly relevant for endangered, large-seeded gymnosperms with limited post-fire dispersal, such as Araucaria araucana in southern South America. These forests face major regeneration challenges due to increasingly severe wildfires, highlighting the urgent need for effective restoration strategies. This study evaluates how two sowing seasons (spring and autumn), fire severity (unburned, low, and high), and microsite characteristics (proximity to fallen logs) interact to influence the early post-fire establishment of A. araucana seedlings following direct sowing. We sowed 2400 seeds in spring and autumn across unburned and burned stands of varying burn severity, distributing seeds either close (0.1 m) or far (2 m) from fallen logs in 60 plots. Over two growing seasons, we monitored seed predation, seedling emergence, seedling survival (live seedlings from those that emerged), annual height growth, and successful establishment (live seedlings relative to seeds sown at the beginning). We also recorded temperature, relative humidity, and soil moisture near and far from fallen logs in 30% of the sowing plots. Seed predation was 50% lower, and height growth rate and successful establishment were nearly twice as high in spring compared to autumn sowings. Successful establishment was greater in high-severity stands when seeds were sown in spring. These high-severity stands experienced higher temperatures, higher vapor pressure deficits, and lower soil moisture compared to unburned stands. However, at the microsite scale, proximity to fallen logs buffered microclimatic extremes, lowering temperature and vapor pressure deficit, and promoting seedling establishment in the high-severity stand. We demonstrate that proper microsite selection and timing of sowing significantly improve seed establishment, especially in adverse environments following a wildfire. Our study offers valuable guidance for managing other large-seeded species threatened by global change.

Robust estimation of wildlife populations represents a cornerstone of wildlife research and provides critical information to guide management, including identifying at-risk species, setting harvest rates, and evaluating predator and invasive species control programs. Efforts to enhance population estimation have long included influences one species may have on another, beginning with direct effects of predation on prey populations. More recently, researchers have incorporated co-occurrence effects, such as fear of a competitor, into Lotka-Volterra competition models to generate more robust wildlife population estimates. Here, we introduce two modified Lotka-Volterra competition models, which incorporate one- and two-way co-occurrence effects, to estimate populations of two competing species. Using the test case of northern spotted (Strix occidentalis caurina) and barred owl (Strix varia) populations in the Pacific Northwest region of the United States, we evaluate if these new co-occurrence models can generate more robust population estimates than previous models. We then evaluate if potential co-occurrence effects among barred and northern spotted owls are uni- or bidirectional. Lastly, we leverage the best-performing model to evaluate the degree to which a recently proposed barred owl culling program may help recover northern spotted owl populations. Our model results suggest that incorporating co-occurrence effects improves model fit compared to classical Lotka-Volterra competition models. We found strong evidence for unidirectional co-occurrence effects of barred owls on northern spotted owls, but not vice versa. Our simulations of barred owl culling suggest that barred owls would need to be culled from approximately 40% of all occupied barred owl territories each year to reverse ongoing northern spotted owl population declines.

Human activities are increasingly driving the co-occurrence of multiple ecological stressors, resulting in interactive and cumulative impacts that can reshape ecosystem dynamics and accelerate population declines of climate-sensitive species. Here, we use over two decades of rocky intertidal monitoring data from 17 sites spanning over 1200 km of coastline to assess how two unprecedented stressors-a multiyear marine heatwave and the disease-driven loss of a keystone predator (Pisaster ochraceus)-impacted populations of the canopy-forming intertidal kelp Postelsia palmaeformis. We show that Postelsia experienced rapid and severe declines during the 2014-2016 northeast Pacific marine heatwave, with an average population decline of 50%, multiple site-level extirpations, and particularly striking losses in the southern portion of the species' geographic range. Concurrently, Pisaster declines triggered mussel bed expansion into habitats previously occupied by Postelsia, further inhibiting kelp recoveries. Our findings reveal how converging stressors can drive persistent, broad-scale ecological shifts through both direct and indirect pathways. These results also highlight the critical role of long-term, spatially extensive monitoring in detecting and understanding global change impacts and provide a foundation for guiding Postelsia conservation and restoration efforts.

Many heterotroph species perish when faced with severe food limitation; others can persist, adapt, and thrive. Sea urchins are emblematic of this paradox: they can overgraze kelp forests to form barren habitats, but can then survive for decades in these nutritionally depauperate seascapes. Understanding the mechanisms enabling persistence under starvation and rapid recovery when food returns provides insights into how consumer resilience shapes ecosystem dynamics. We quantified how food abundance, quality, deprivation, and reintroduction influence bioenergetic performance in the red sea urchin (Mesocentrotus franciscanus), integrating field observations of kelp forest and barren populations with a controlled feeding experiment. We measured respiration, feeding rates, gonadal growth, and fatty acid biomarkers to test how habitat history and diet jointly govern metabolic plasticity and nutrient assimilation. Resting metabolic rates (RMRs) were nearly twofold higher in kelp forest urchins than in barren conspecifics; yet, feeding rates were equivalent across habitats, indicating that metabolic depression does not constrain food intake. Reciprocal shifts emerged in the experiment: starvation reduced RMR and lipid reserves in kelp forest urchins, while feeding elevated both traits in barren urchins to levels comparable with kelp forest conspecifics. These results demonstrate rapid physiological compensation in response to both food deprivation and reintroduction. Diet quality strongly modulated performance. Urchins fed nutritionally poor monospecific diets consumed more biomass and calories than those on diverse, polyunsaturated fatty acid (PUFA)-rich diets, but did so with markedly lower efficiency of conversion to gonadal tissue. Fatty acid assimilation revealed that starvation elevated bacterial and biofilm biomarkers in tissues, whereas algal diets enriched essential PUFA profiles, particularly when diets were diverse. These results highlight that both quantity and quality of food influence consumer recovery trajectories, with nutritional geometry shaping efficiency of energy and nutrient use. Together, our findings show that M. franciscanus exhibits pronounced metabolic resilience, allowing persistence in barren habitats and rapid reactivation of grazing and reproduction when food becomes available. This work links nutritional ecology to ecosystem feedbacks by showing how compensatory feeding and metabolic flexibility enable consumers to maintain pressure on primary producers, thereby influencing the stability, hysteresis, and recovery of degraded ecosystems.

European forests play an important role for climate change mitigation and biodiversity conservation. As they have been shaped by silviculture for centuries, it is important to understand how management practices affect forest structure and in turn influence the role of forests in achieving both goals. We analyzed data on a wide range of temperate European forests encompassing the most widespread management regimes to understand the interplay of forest structure, aboveground carbon stocks, and the richness of several taxonomic groups. Using structural equation modeling, we identified the forest structural characteristics that are positively correlated with both carbon stocks and species richness. We found that stand age and tree species richness are related to other forest structural characteristics, which had positive links to carbon stocks in deadwood. Increasing stand age was associated with an increase in deadwood carbon stocks. There were no direct negative relationships between stand age or tree species richness and the richness of different taxonomic groups. An increasing richness of deadwood types had positive links with the species richness of birds, saproxylic beetles, and saproxylic fungi, as with deadwood carbon stocks. However, increases in the species richness of birds and understory vascular plants were negatively related to increasing carbon stocks in living wood, while beetle species richness was positively related to this carbon stock. Birds' species richness was directly and positively associated with increasing mean tree diameter. Conversely, a higher richness of tree species was indirectly linked to lower carbon stocks in living wood. Additionally, an increase in mean tree diameter was indirectly correlated with a decrease in bird and vascular plant species richness. Our findings highlight potential trade-offs between carbon stocks in living wood and the species richness of several taxonomic groups in European forests, while the species richness of some taxonomic groups was positively correlated to deadwood carbon stocks. Policies focused on increasing living biomass may not target both the climate and biodiversity crises. Instead, the diversity of deadwood emerges as a key factor in explaining the relationship between carbon storage and biodiversity, and should hence play a prominent role in forest management strategies and related policies.

Invasive plant species pose a major threat to wetland ecosystems. One effective way to control the spread of invasive plants is to intercept them early in the invasion process. Species distribution models (SDMs), fit with covariates related to habitat suitability, can predict where new invasions are likely to occur. For species that have not yet filled their niches during early invasions, dispersal dynamics such as proximity to known presences and/or human vectors may control spread as much as habitat suitability. Yet, many SDMs assume that the species has filled its niche, incorporate only biophysical predictors, and do not consider spatial processes. Including dispersal dynamics can account for nonequilibrium processes, thereby improving the utility of invasive SDMs. We quantified the importance of environmental (abiotic and biotic) and dispersal-related drivers (anthropogenic and endogenous) on the occurrence and abundance of Hydrocharis morsus-ranae (European frogbit; EFB), a floating aquatic plant. We fit Bayesian hurdle models with integrated nested Laplace approximations (INLAs) to 2487 quadrat observations recorded across coastal wetlands in Michigan, USA from 2011 to 2021. We found that EFB occurrence was most strongly associated with distance to the nearest known population (m), a proxy of local dispersal. EFB occurrence also exhibited a nonlinear relationship with water depth (cm), demonstrating an optimal range of water depth for EFB. Occurrence was negatively associated with wave energy and positively associated with cattail (Typha spp.) abundance, which we attribute to protection from waves. Surprisingly, none of our predictors had any meaningful associations with EFB abundance, suggesting that it may be too early in EFB's invasion stage to quantify important drivers of abundance once at a site, or we did not include important factors that operate at the scale at which these growth processes occur. Moreover, the dispersal model yielded slightly better predictive capacity of EFB across Michigan. Overall, our results indicate that local dispersal is the primary driver of occurrence for an invasive species that has not yet filled its niche, whereas additional data or SDMs may be necessary to (a) better predict its abundance once established in coastal wetlands and (b) identify susceptible areas to future invasions.

Human-induced threats to terrestrial and marine wildlife are on the rise, and while some species face a single major threat, others face multiple concurrent threats. Harp seals, an abundant pinniped in the North Atlantic that was historically depleted by human harvest, are one such species. Although commercial and subsistence harvests remain a significant source of mortality, in recent decades their environment has undergone significant changes, which could also impact population dynamics. Inferring the relative importance of various threats as drivers of population dynamics can be challenging, particularly for marine species where monitoring abundance is difficult: the use of integrated population models (IPMs), which leverage multiple data sources to parameterize process-based models of population dynamics, provides one solution. We developed a hierarchical Bayesian IPM with which to explore the shifting roles of anthropogenic and environmental factors in driving trends. We used a competing hazards formulation for survival, enabling the partitioning of mortality into multiple discreet causes and allowing us to assess variation in hazards over 7 decades (1952–2019). We fit the model to available data on pup production, fecundity, age structure, human removals, and environmental conditions. We conducted a Bayesian life stage simulation analysis (LSA) to compare the contributions of various hazards to variation in population growth. We found that harvests of young of the year (YOY) and adults were the primary contributors to variation in trends from 1951 to 1982; however, after 1983, the relative importance of harvest mortality decreased while the impacts of natural mortality increased, especially for YOY. Since 2000, the impacts of YOY mortality from ice cover anomalies have become one of the strongest drivers of trends, while harvest mortality has declined. Based on current climate models, which project warmer water and decreasing ice cover, we expect continued high levels of YOY mortality from environmental factors such as deteriorating ice conditions. These climate-related hazards are likely to become the dominant drivers of population dynamics in coming decades, which will in turn affect sustainable harvest levels for both Canada and Greenland. Our model will provide a useful tool for exploring future scenarios of climate impacts and management strategies.

Anthropogenic noise (anthrophony) can have significant negative effects on wildlife, causing both physiological (i.e., increased stress hormone production) and behavioral (i.e., altered anti-predator behaviors, space use, or diel activity) changes in individuals. Roads are a major source of anthrophony, often contributing the most to the anthrophony in rural areas. Most efforts to reduce road effects on wildlife have focused on decreasing road-associated mortality through the construction of wildlife crossing structures (WCSs) with little consideration for the anthrophony associated with these structures. Given the impacts of anthrophony on wildlife behavior, the effectiveness of WCSs could be altered without consideration of noise pollution. Therefore, understanding how anthrophony is structured in space and time and how it impacts WCS use is an important aspect of assessing the effectiveness of WCSs. We developed a framework for assessing anthrophony at WCS using an array of autonomous recording units to monitor overall acoustic conditions. We then examined how wildlife crossing rates were associated with anthrophony using camera traps. We monitored five underpass-style WCSs built in the Lower Rio Grande Valley of South Texas, USA, using camera traps and acoustic recording units. We measured sound pressure level (SPL [dB]) and relative level of anthrophony (using the normalized difference soundscape index [NDSI]) at six positions around each WCS: two at elevation (road grade) with the road surface (west and east), two at the WCS entrances, and two in the middle of the WCSs. We then used SPL and NDSI to predict the probability of a successful crossing by Virginia opossum (Didelphis virginiana), a common, disturbance-tolerant mammal. While the relative amount of anthrophony did not differ, smaller WCSs and those with less traffic were up to 40 dB quieter than larger WCSs and those with more traffic. Opossums spent more time at WCSs when it was quieter on average and were more likely to successfully cross through a WCS when there was less vehicle noise. Our study highlights the importance of considering soundscapes in assessing WCS effectiveness and represents a framework that can be used for further exploration of the impacts of anthrophony on WCS use.