Ecological Applications最新文献

Environmental DNA (eDNA) metabarcoding is increasingly applied to a variety of questions and challenges across basic and applied ecology. Although streams and rivers (i.e., lotic ecosystems) can serve as conveyor belts of both aquatic and terrestrial eDNA from upstream or riparian areas, precipitation can dilute eDNA due to increasing discharge and/or mobilize eDNA into rivers from adjacent terrestrial ecosystems. Previous research has examined eDNA detectability of single species after high flow events, but no studies have compared aquatic and terrestrial communities recovered by eDNA metabarcoding together in response to rainfall. For this study, we used eDNA metabarcoding to sample three rivers before and after precipitation over six sampling events to evaluate if terrestrial eDNA exhibits a mobilization effect and aquatic eDNA exhibits a dilution effect after rainfall. We found that as rainfall increased, terrestrial taxa richness significantly increased and aquatic taxa richness decreased but not significantly. As such, researchers using eDNA metabarcoding from lotic ecosystems to characterize terrestrial communities might not need to avoid, and could even seek out, precipitation events in their sampling design. However, our study should be replicated over more lotic ecosystems and ecoregions and larger gradients of precipitation events.

Vegetated field margins generally increase plant biodiversity and connectivity in agricultural landscapes. They can deliver ecosystem services, such as providing food and shelter for insects, or maintaining biotic regulation. But they can also represent a risk, for example by hosting competitor plants or cultivated crop pests. In this work, we evaluated the effects of agricultural practices on indicators of three ecosystem services (providing floral resources for pollinators, reducing soil erosion and conserving plant biodiversity), and one ecosystem disservice (competing with the crop by hosting problematic weeds). We used a French nationwide-scale monitoring network, composed of more than 450 fields of cereals, vineyards, and market gardening. Plant sampling and agricultural practices surveys were conducted from 2013 to 2018. We unambiguously found that pesticide use, at either field or municipality levels, or both, had detrimental effects on ecosystem service indicators. Herbicide use and fertilization quantity decreased floral resources, affecting both their quantity and diversity. Pesticide use was also associated with fewer nature-value species and more problematic weeds. Margin management could also sometimes affect the service and disservice indicators. This work not only increases the knowledge on the unintentional negative impacts of agricultural practices on ecosystem service indicators, and then probably on their delivery, but also demonstrates that pesticide reduction is positively associated with proxies for ecosystem services. It also stresses the fact that these practices have to be implemented at both field and municipality levels.

Understanding and predicting the effects of climate change on populations requires linking the environmental conditions to demographic rates and the demographic rates to population-level consequences, but often this complete demographic pathway is not studied. Integrated population models (IPMs) incorporate demographic data into a single analytical framework, allowing for the inclusion of environmental covariates to test hypotheses considering how the environment influences demographic rates, and consequently, to which demographic rates population growth rate is most sensitive. In birds, there is strong evidence that environmental conditions impact population growth, and that long-distance migrant avian species with short phenological windows are at greatest risk of population decline due to changing environmental conditions. We built a Bayesian IPM with over 40 years of mark-recapture, fecundity, and nest box occupancy data and incorporated environmental covariates hypothesized to be driving the observed changes in two populations of a fast-lived long-distance migrant, the European pied flycatcher. Using variance decomposition methods, we identified the demographic pathways through which environmental covariates were acting. While several environmental covariates impacted fecundity and survival, only precipitation acted via apparent juvenile and adult survival contributed significantly to variation in population growth rate. Increased precipitation during the nest initiation, incubation, and hatchling stages had negative carry-over effects on juvenile survival during the post-fledging and overwintering period, and increased precipitation negatively impacted adult apparent survival, likely due to the increased energetic demands of caring for eggs and hatchlings in challenging conditions and reduced availability of aerial prey. We show that linking environmental covariates to demographic rates does not sufficiently explain or predict population-level consequences, and that decomposing variation along the complete demographic pathway is a necessary step to appropriately identify how covariates influence population dynamics.

Mangrove forests-vital for global carbon storage and coastal protection-are increasingly threatened by salinity intrusion resulting from sea-level rise and alterations in the hydrological regimes. While the functional importance of mangroves is well recognized, the mechanistic pathways through which salinity reorganizes community-level trait composition and compresses functional diversity remain unresolved. This gap is particularly acute in megadeltaic systems like the Sundarbans, where biodiversity and ecosystem service provisioning co-occur with steep salinity gradients. Elucidating how trait syndromes shift and diversity contracts across these gradients is critical to forecasting mangrove ecosystem responses and informing adaptive conservation strategies. This study quantified eight foliar traits (leaf area, specific leaf area, leaf dry matter content, total chlorophyll, stomatal density, leaf shape index, leaf succulence, and leaf carbon content) and four functional diversity indices (Rao's quadratic entropy, functional richness, evenness, and divergence) across a continuous soil salinity gradient using plot-level data from 59 sites in the Sundarbans. Trait-environment relationships were analyzed using linear regressions, spatial mapping, and multivariate ordination (principal components analysis [PCA], non-metric multidimensional scaling [NMDS]), while controlling for biotic factors such as species richness and abundance. Salinity significantly reduced functional diversity, particularly trait dissimilarity (RaoQ), supporting the hypothesis of abiotic filtering that favors functionally similar, salt-tolerant species. These reductions were most pronounced in high-salinity western zones dominated by generalist stress-tolerant species. Foliar traits shifted predictably with salinity, with reductions in leaf area, dry matter content, stomatal density, chlorophyll, and carbon content, and increases in leaf succulence and specific leaf area-indicating trade-offs toward conservative resource-use strategies under osmotic stress. Species abundance strongly influenced functional diversity independent of salinity. High abundance reduced trait dissimilarity and evenness, reinforcing the dominance of a few trait syndromes under stress. By integrating spatially explicit trait, salinity, and abundance data, this study provides novel evidence that abiotic filtering and biotic dominance jointly constrain community-level functional diversity in mangroves. Trait convergence and dissimilarity collapse under salinity stress indicate narrowing ecological strategies with reduced resilience. Conservation strategies should prioritize freshwater inflow and low-salinity habitat restoration. Trait-based indicators offer a predictive framework to sustain mangrove function under accelerating climate stress.

Wild pollinator diversity has been widely studied in agricultural habitats and increasingly also in cities, but the value of small settlements like villages in rural areas for pollinators is mainly unknown. Public green spaces and village gardens could serve as refuges from agricultural intensification and habitat loss. Moreover, semi-natural habitats in the surrounding landscape may influence pollinator communities within villages. Here, we asked how suitable different village habitats are for wild pollinators and how this relates to floral resources and landscape context. We recorded solitary bees, bumble bees, hoverflies, honey bees, and flowering plants in five habitat types-cemeteries, fallows, farmhouse gardens, green areas, and house gardens-across 40 villages in Bavaria, Germany (200 plots in total). We recorded 208 wild bee species and 56 hoverfly species representing approximately 40% and 14% of the Bavarian fauna, respectively, along with 1258 flowering plant species. Generally, pollinator richness and abundance increased with floral species richness and cover. The proportion of semi-natural habitats surrounding villages at larger spatial scales was positively associated with solitary bee richness and influenced bumble bee abundance, highlighting the importance of landscape context. Based on predictions from floral resources, solitary bee richness in green areas and bumble bee richness in fallows exceeded expectations, whereas cemeteries were less species-rich. This suggests that factors beyond flower richness and abundance, such as nesting opportunities and the composition of preferred flower species, play important roles. Using 38,620 recordings of flower visits and respective flower abundance, we compiled a list of plant genera that were most visited, most preferred (corrected for plant abundance), or non-preferential (corrected for plant abundance) for the pollinator groups. The list serves as a decision-making tool for local stakeholders to ensure the most effective pollinator promotion within villages. Our results suggest that measures enhancing flower resources alone will not result in the best possible increase in pollinators in villages but should be accompanied by actions that enhance nesting sites in local habitats for a broad spectrum of pollinators. In conclusion, villages hold a substantial, yet underexploited, potential for pollinator conservation, achievable through targeted management and public engagement.

As trait-based restoration practices continue to gain momentum, there is still an absence of effective methods to monitor ongoing restoration and, if necessary, amend species composition to achieve multiple restoration targets. This challenge is even greater in long-term restoration projects, as a result of different techniques and restoration strategies, leading to a heterogeneous landscape with different levels of ecosystem functions (multifunctionality). During the restoration process, it may be necessary to increase multifunctionality, or a particular ecosystem function, either from scratch or beyond what has already been provided by planted species or species established through natural regeneration. However, these aspects remain underexplored in restoration ecology, primarily because of the lack of operational frameworks. Using data from a 40-year ongoing quarry restoration in Portugal, we evaluated current levels of multifunctionality and how to restore or increase drought resistance, fire resilience, pollination, seed dispersal, and vegetation structure. We found that multifunctionality varies significantly across restoration sites within the landscape. Natural regeneration plays a central role in maintaining current levels of multifunctionality, but we demonstrate that it can be considerably increased by trait-based planting of additional individuals-whether of resident or new species-into restored sites. Furthermore, we show that enhanced levels of multifunctionality can be achieved in future restoration sites by using optimized species combinations. Our study provides important insights into the adaptive management of trait-based restoration and provides a framework to achieve multiple objectives in ongoing restoration projects. We expect the proposed framework will enhance both the appeal and practical application of trait-based and functional enrichment approaches in restoration practice.

Urban environments pose a threat to biodiversity through processes such as habitat degradation and biotic homogenization. Despite this, cities are increasingly recognized for their potential to conserve bees and other pollinators. Planting understory vegetation is one way of providing more floral resources to support urban bee communities and the ecosystem services they provide. However, the influence of vegetation origin and landscape context on urban bee communities is unclear, particularly in the Southern Hemisphere. We sampled the bee communities at 32 understory plantings dominated by exotic or indigenous (native to the local bioregion) vegetation around inner Melbourne, Australia. For each site, we recorded the amount of impervious surface and irrigated turf in 200-m buffers. Indigenous plantings were found to promote significantly greater alpha and beta diversity in bee communities compared to exotic plantings. Particular plant taxa were highly effective at attracting a variety of bees, with a maximum of 19 bee species (including specialists) hosted by indigenous Wahlenbergia capillaris (Campanulaceae). Apis mellifera was highly dominant and strongly associated with exotic plantings, whereas many indigenous bee species were positively associated with indigenous plantings. This study shows indigenous understory plants have a positive influence on indigenous bee communities relative to exotic plantings which tend to attract only A. mellifera. Planting indigenous plants in cities is therefore recommended as a conservation action for local bee species.

Despite the ecological expression and conservation importance of diverse behavioral tactics in animals, there is often friction associated with conventional analytical approaches and inference concerning variation in spatial behavior. Implicitly or explicitly, population-level inferences are generally the main objective of studies, but interpretations can be ambiguous in the presence of divergent behavioral tactics across individuals or cohorts, as with generalist species. We pursued a novel analytical approach and assessed the underlying mechanisms driving variation in spatial behaviors of generalist species using the American black bear (Ursus americanus) as our focal species. We quantified individual variation in habitat selection expressed by black bears using individual models for 35 collared bears across four study areas in Wyoming, USA. We modeled how state-dependent factors (age, sex, δ¹⁵Nitrogen, and body fat) and resource availability influenced behavioral variation in resource selection. We observed vast variation among individuals, demonstrating patterns consistent with a generalist species. Black bear resource selection differed with changes in state dependence and resource availability. Specifically, traits uniquely important to black bear success, body fat and carnivory, explained variation in selection for forage indexed by normalized difference vegetation index (NDVI), forests, and riparian areas. Environmental heterogeneity via differences in resource availability magnified behavioral variation in resource selection by black bears. Selection trends for NDVI and deciduous shrubs were explained by resource availability, indicating black bears exhibited functional responses in habitat selection. These insights emerged from our analytical approach; had we implemented a more conventional, population-level assessment, we would have simply concluded that black bears displayed behavioral neutrality with respect to forage resources. Acknowledgment of behavioral variation when considering spatial behavior of generalist species provides a more representative understanding of individuals within a population, and our analytical approach offers a solution to uncovering drivers of individual variation in spatial behavior.

Biodiversity is highly affected by ecological processes at the landscape level. To facilitate management decisions at a landscape level, we present an end-user-oriented framework that assesses the biodiversity capacity of individual biotopes in a fragmented landscape and ranks the importance of the biotope patches. The framework can be applied to any biotope and landscape. Analyses can further be done on planned or predicted future scenarios and changes in the landscape structure. There has been continuous exchange with stakeholders and case study testing with the purpose to build a tool that answers the important questions of end users, and provides results that are useful for decision-makers and environmental managers in environmental management and land use planning. The framework is novel in its calculations of the combined effects of connectivity and survival of biodiversity in the biotope patches. It uses land cover data and the concept of umbrella focal species as input. The framework strongly builds on ecological theory and ecological modeling, and produces three outputs of interest: a heatmap visualizing individual patch importance for upholding landscape biodiversity, an indicator metric of the ability of a biotope landscape to support biodiversity, and the number of unsustainable individual patches. The theoretical foundation and structure of the framework are thoroughly explained. The use of its output is further demonstrated by one selected case study where the calculations are applied to a biotope of fragmented old coniferous forest in Sweden. We additionally examine and show how the overall biodiversity potential of the biotope landscape is dependent on which types of species communities are in focus by applying different umbrella focal species. The case study demonstrates the importance of landscape structure for sustainable biodiversity. Results further demonstrate that it is essential to consider the type of species community that is the primary biodiversity conservation target.

The loss of plant diversity in grasslands is implicated as one of the main causes of arthropod decline. The loss of a single plant species can have a cascading effect on specialized arthropod species. It is thus critical to expand our understanding of plant–arthropod interactions. Detecting plant–arthropod interactions, however, has been difficult, as it requires the observation of individual plant visits. A possible solution to this problem is offered by environmental DNA (eDNA) analysis. Here, we test the utility of eDNA to detect fine-scaled community differentiation in grassland arthropods in Germany. Based on eDNA from 13 plant species, we explore community differentiation between plant species, and between flower and green parts of individual plants. We show that eDNA successfully recovers extremely fine-scaled community differentiation. Plant species, as well as plant compartment, emerge as major drivers of arthropod community composition in grasslands, with the differentiation being particularly pronounced in herbivorous arthropods. Terrestrial eDNA on plants thus appears to be deposited in a very localized fashion, making this tool ideally suited to detect very fine-scaled community differentiation. Considering the high specificity we observe in our analysis, our results highlight the necessity of integrating vegetation surveys into future monitoring of arthropod communities.