Ecological Applications最新文献

Across much of the semiarid conifer forests of western North America (“dry conifer forests”), the dominant tree species are non-serotinous, lack soil seedbanks, and rarely disperse seeds much farther than 100 m, so tree regeneration in large, high-severity burned patches is expected to be highly seed-limited. Conifer seedlings do, however, sometimes establish at high densities deep within high-severity patches in these forests, implying that seeds can sometimes survive intense wildfire even when all overstory trees die. Does seed survival in the canopies of non-serotinous trees provide an unexpected source of forest resilience? To answer this question, we surveyed tree survival, fire severity, and seedling abundance across two very large wildfires in the first year after fire. Several of the study species had a good seed cone production year at the time of the fires. We stratified many of our plots deep within high-severity patches far from surviving trees, where existing models predict regeneration failure due to lack of viable seeds. Contrary to such expectations, we found that conifer seedling densities in these areas were generally far greater than needed to replace the fire-killed stand and sometimes approached seedling densities observed near surviving trees. Seedling densities in high-severity areas far from surviving trees correlated negatively with local burn intensity (canopy foliage consumption), supporting the idea that the seeds originated locally and highlighting a critical driver of post-fire recovery that is easily missed by traditional surveys conducted >2 years following fire. Seedling density was also strongly associated with burn date, suggesting that persistence of viable canopy seeds depends on synchrony between wildfire and cone ripening dates. Together, our results demonstrate that under the right conditions, canopy seed survival can lead to dense seedling establishment across large severely burned areas and may substantially support the resilience of dry conifer forests to the uncharacteristically severe fires that are becoming increasingly prevalent in this system.

Understanding the mechanisms that maintain the productivity of grassland communities is crucial for ecosystems to provide functions and services under climate change and for developing grassland management and restoration strategies. Plant traits, such as phenological (timing) and morphological (size) traits, are essential for predicting ecosystem function under climate change. However, how plant traits respond to warming and precipitation change and their combined consequences on ecosystem function (e.g., biomass) remain poorly understood. Here, we conducted a 5-year field warming and precipitation change experiment in an alpine meadow on the Tibetan Plateau, and measured six plant phenological and morphological traits of 10 common species to research how functional traits regulate plant biomass under warming and precipitation change. Warming rather than precipitation advanced plant leaf emergence and lengthened the growing season and reduced mean plant height for sedges and forbs, while it reduced leaf area of sedges and grasses. Moreover, the negative effects of warming-induced reductions in plant height and leaf area on sedge biomass were offset by the positive effects of advanced leaf emergence, which did not completely mitigate the negative effects of low plant height on forb biomass production. Our results suggest that the negative effect of warming on the biomass of sedges and forbs through reduced plant size will be partially mitigated by the compensatory effect of advanced leaf emergence. This finding further emphasizes that the crucial and opposing roles of phenological and morphological traits should be considered when assessing biomass production and sustainable services in alpine grasslands under climate change.

Natural recovery of degraded coral reefs is constrained by low larval recruitment, limiting restoration at ecologically meaningful scales. While propagule-based approaches have proven effective in plant-dominated systems, scaling larval restoration for sessile invertebrates like corals remains challenging. Traditional coral larval methods rely on net enclosures, restricting impact to small areas (<75 m²). We developed and tested a modular, passive larval delivery system—the larval seedbox—to overcome these spatial constraints. Each unit (600 × 500 × 300 mm; 11 kg) enables delayed release of competent larvae near the benthos, enhancing substrate encounter rates over broader areas. At Lizard Island (Great Barrier Reef), five seedboxes delivered ~14 million larvae across ~2 ha of degraded reef. Larval release coincided with slack currents to facilitate local retention and subsequent dispersal. Settlement was assessed on 234 tiles placed in concentric arrays around each seedbox. After 48 h, 85% of tiles had settlers (up to 1041 per tile), with mean densities 24 times greater than background levels. Enhanced settlement was directly quantified across ~470 m², with spatial modeling estimating >3000 m² via tidally driven dispersal. The larval seedbox enables unrestrained, scalable coral larval seeding and represents a practical advance toward broad-scale reef restoration.

Early studies and theory suggested that complex landscapes harboring remnants of natural land should support natural enemy populations and reduce pest buildup in adjacent crops, whereas landscapes interspersed with urban land often provide alternate host plants of crop pests, facilitating pest spillover and amplifying pest pressure. However, recent meta-analyses have demonstrated that both pest and beneficial agricultural arthropods respond inconsistently to surrounding landscapes. These meta-analyses relied on studies of one to two pests per crop across many different crop and landscape contexts, which limits inferences about how growers might design landscapes for effective control of a full suite of pests attacking a given crop. Here, we harnessed an ecoinformatics dataset from California Citrus to examine the effects of surrounding natural and urban land on the densities of a complete suite of seven major pest species (6489 observations) and one beneficial predator (346 observations). We also explored landscape effects on pesticide use and fruit production. Despite restricting this analysis to data collected in the same region and cropping system, we found that arthropods still exhibited mixed responses to surrounding landscapes. Among the eight Citrus-associated arthropods surveyed, greater amounts of nearby natural land resulted in two beneficial outcomes for farmers (lower pest densities or fewer pesticide applications targeting that pest), three adverse outcomes, and three neutral outcomes. Similarly, greater amounts of urban land resulted in two beneficial outcomes, four adverse outcomes, and two neutral outcomes for farmers. Our economic analysis demonstrated that Citrus groves with more nearby natural land resulted in increased total pesticide use and reduced total fruit yield. More urban land resulted in reduced total pesticide use and no effect on total fruit yield. Neither land use type significantly impacted fruit quality. Taken altogether, our results do not demonstrate clear support for the retention of natural habitat or minimization of urban land near cropland solely for the purpose of enhancing conservation biocontrol. Nonetheless, the value of natural land extends far beyond its utility for conservation biocontrol, and agricultural landscapes must still be managed to strike a balance between crop production and the preservation of biodiversity and ecosystem function.

Movement is essential for animal life and significantly influences community dynamics. Landscape-scale disturbances, such as mining, alter habitat structure, introducing new stressors that can severely disrupt animal movement. Understanding how landscape modification impacts animal movement and landscape connectivity is vital for effective conservation in the Anthropocene. Here, we used movement simulations and landscape scenarios to evaluate how mining influences movement, using an endangered mesopredator as a focal species. We aimed to determine the effects of different configurations of mining on the movement costs, habitat accessibility, and landscape connectivity of this species. We used GPS data collected from a mining landscape in the Pilbara region of Western Australia to assess temporally dynamic habitat selection. This informed movement simulations across four landscape scenarios: current mining, dispersed mining, aggregated mining, and non-mining. We compared animal movements, energetic costs, and landscape connectivity across all landscape scenarios. The presence of mining habitats increased energetic movement costs through unfavorable habitats and led to significant changes in landscape connectivity. For example, simulated movements visited fewer favorable habitat patches in mining landscapes and required more steps between them. Mining configuration affected movement differently, with current mining conditions having the greatest impact on movement, increasing simulated home ranges and funneling movement through unfavorable habitats more than the other landscapes. Our study highlights the influence of disturbance configuration and altered habitat structure on animal movement. It also emphasizes that effective management and development planning must consider impacts on animal movement and landscape connectivity.

Bees are focal pollinators, essential for maintaining biodiversity and crop production. Thus, reports of high annual honey bee colony losses and population declines among many wild bees in different parts of the world are of major concern. The spread of viruses is highlighted as a potential threat to bee communities. Viruses infect a wide range of bee species and can be transmitted interspecifically through shared floral resources. Therefore, the role of flowers as hubs of bee virus transmission requires a community ecology perspective. Here, we investigate local and landscape-scale characteristics of floral communities potentially associated with the spread of viruses in the solitary Andrena spp. (mining bees). We surveyed 14 sites in a Mediterranean agroecosystem with varying local densities of honey bee (Apis mellifera) foragers and diversity of flowering species and assessed the prevalence of four common Hymenoptera-associated viruses (deformed wing virus [DWV], black queen cell virus [BQCV], sacbrood virus [SBV], and Lake Sinai virus-2 [LSV-2]) in co-foraging honey bees and mining bees. We found that the probability of virus presence in mining bees was generally associated with the diversity and composition of the local (site level) floral community, and with floral resource availability at the landscape scale (up to 1000-m range). In addition, SBV and DWV prevalence in mining bees were positively related to the density of SBV-infected, and total honey bee foragers, respectively. These findings demonstrate the focal role that the floral community at multiple spatial scales, and co-foraging pollinator species, may play in virus spread and, potentially, pollinator health.

Expanding urbanization introduces various environmental stressors, such as artificial light at night, anthropogenic noise, and human presence. Although these stressors are commonly blamed for biodiversity decline, urban development also coincides with severe habitat transformations, leading to the loss of natural habitats and key ecological features essential for diverse biota. How these environmental changes interact to shape urban biodiversity remains unresolved, posing substantial challenges for conservation policies. Here, we address this issue using multilevel structural equation modeling (MSEM) across 90 wooded green spaces in Kraków, Poland, focusing on local communities of birds (28 species) and bats (5 genera). We found that environmental stressors are widespread correlates of bird and bat occurrences but also strongly correlate with habitat degradation, reflected in reduced green space size and diminished availability of structural features, such as deadwood, tree cavities, and epiphytes—critical resources for these taxa. In MSEM predictions, environmental stressors primarily affected communities indirectly by driving habitat changes. Secondarily, stressors acted as both direct and indirect predictors for some taxa (combined within a single model), though purely direct effects were rare and often co-occurred with habitat effects. Overall, habitat alterations were more significant drivers of taxon loss than stressors, with green space size, crown or lying deadwood, tree cavities, and epiphytic plants emerging as the most critical features for supporting biodiversity. Habitat degradation was primarily correlated with human presence, less strongly with light, and only weakly with noise levels. However, the direct effects of each were similarly rare and could be either positive or negative. Our findings suggest that the seemingly prominent effects of human-associated stressors on biodiversity may often be artifacts of coinciding habitat degradation, with habitat loss and the removal of nuanced habitat features playing a more direct and critical role. While reducing noise, light, and restricting human activity might be effective conservation strategies for some species, they are insufficient without preserving habitat remnants and fostering structural diversity to resemble that of natural ecosystems. These habitat-centric approaches are keystones that should be prioritized, offering a promising roadmap to reconcile human well-being with biodiversity preservation in future sustainable cities.

Grazing is the common agricultural land-use in mountain regions. It is of high socioeconomic importance but also essential for conservation as extensive mountain pastures are hotspots of biodiversity. Climate change is causing earlier growing seasons, prompting earlier livestock turnout. The effects of grazing on biodiversity, however, may differ depending on the time of the year, yet our understanding of these effects is limited. Here, we evaluate how short-term effects of different livestock turnouts affect taxonomic, phylogenetic, and functional diversity of pollinators (wild bees and butterflies) and phytophagous insects (leafhoppers) as well as plant–insect interactions on eight mountain pastures in the northern Alps, Germany. At each pasture, we established three grazing treatments including an ungrazed control, early and late livestock turnout. We sampled wild bees and butterflies during two and leafhoppers during one growing season twice a year (summer onset and summer peak). To account for effects of grazing through changes in vegetation, we surveyed vegetation characteristics, such as the number of inflorescences and sward height. Early-grazing plots had lower wild bee and leafhopper diversity during summer onset, but this pattern shifted later in the season after grazing had stopped. During summer peak, wild bee diversity was higher at early-grazing plots than at late-grazing plots and structural equation modeling indicated that this could be partly explained by a higher number of inflorescences. Phylogenetic network diversity of wild bee– and leafhopper–plant networks was higher at late than at early-grazing plots. Our study shows that grazing in general, and also the timing of grazing, affects vegetation characteristics, insect diversity, and plant–insect interactions in mountain pastures. Effects of grazing on insect diversity were mostly positive, which supports the notion that extensive grazing is important to maintain insect diversity in mountain pastures below the timberline. Although negative effects of early livestock turnout treatments occurred, they disappeared and even turned positive later in the season. Thus, earlier livestock turnout does not appear to threaten insect diversity in mountain pastures, but further research is needed to understand long-term effects.

The Anthropocene is defined by rapid environmental changes such as biological invasions and shifting disturbance regimes that threaten native species. Understanding the drivers of endangerment for species facing multiple simultaneous threats is challenging without experimental methods. Here, we examined the relative and combined effects of severe wildfires and an early-stage barred owl (Strix varia) invasion on an assemblage of three native forest owl species in the Sierra Nevada, California, USA, leveraging manipulative (lethal barred owl removals) and natural (severe wildfires) experiments and a regional passive acoustic monitoring program from 2018 to 2023. Wildfires reduced flammulated owl (Psiloscops flammeolus) occupancy by 71% in severely burned areas (sites experiencing near-complete high-severity fire) for at least 3 years postfire but did not affect great horned (Bubo virginianus) or northern pygmy owl (Glaucidium californicum) occupancy. Because flammulated owls have small home ranges and an insectivorous diet that depends on nearby mature forest foraging habitat and secondary-cavity nest sites, they showed a strong negative response to extensive high-severity burn areas that eliminate these resources. Flammulated owl occupancy increased approximately twofold from 0.09 (85% CI: 0.03, 0.20) to 0.18 (85% CI: 0.07, 0.36) following lethal barred owl removals (with only 4% posterior distribution overlap), but removals did not affect the other two native species. Despite evidence of habitat segregation between barred owls and the native species, where barred owls typically occupied intermediate-to-late seral forests in flatter, lower elevation areas, this niche partitioning was insufficient to prevent nonconsumptive or predatory effects on flammulated owls. In contrast, the resilience of great horned and pygmy owls may have stemmed from their larger body size and diurnal activity, respectively, suggesting that life history mediates forest owl vulnerability to invasive barred owls. The negative effects of barred owls on flammulated owls, even during the early invasion stage, coupled with well-documented effects on other small, nocturnal forest owl species in regions with high barred owl densities, reinforce the conservation value of proactive invasive species management. Our study demonstrates the power of regional-scale experimentation, facilitated by bioacoustic monitoring, for understanding biological community responses—mediated by species' life history—to rapid environmental changes.

Conservation scientists have long used population viability analysis (PVA) on species count data to quantify critical decline risk, thereby informing conservation actions. These assessments typically focus on a single species rather than assemblages and assume that risk is consistent within a given life stage (e.g., across the different seasons or months of a year). However, assessing risk at overly broad temporal or spatial scales may obscure diverging population declines between predators and prey, potentially disrupting biotic interactions. In this study, we used time-series-based PVA for age-0 forage fishes and their potential zooplankton prey for each month of the year in the San Francisco Estuary, over 1995–2023 (N = 175 time series). The PVA were parameterized using Multivariate Autoregressive (MAR) models that estimate long-term population trends and variability (i.e., process error) for each population. We found widespread negative population trends across fish species (56.8%) and observed that critical decline risk is often higher in months when species peak in abundance compared to “shoulder” months. Although current decline risk is somewhat balanced between predators and their prey (mean 23.7% for fish and 21.1% for zooplankton), our time-series models indicate trophic levels are poised to diverge over the next 10 years, with fish generally accumulating risk faster than their prey. Additionally, zooplankton showed 11.2% higher uncertainty about their near-term critical decline risk relative to fish. These observations suggest strong, previously unreported potential for future trophic mismatches. Our results underscore the need to assess risk over finer temporal scales within and across trophic levels to better understand vulnerability, and thus inform conservation of imperiled species. Our approach is transferable and highlights the benefits of time-series-based PVA to understand risk of food-web collapse in the face of climate-induced phenological shifts.