Ecosphere最新文献

Northern raccoons (Procyon lotor; hereafter raccoon) are a widely distributed mesocarnivore that is common throughout North and Central America. Already the source of many human–wildlife conflicts, recent range expansions and abundance increases may cause additional management issues. However, raccoons adapt their behavior and site use to their surroundings, necessitating further research into the factors driving raccoon site use intensity in less studied systems. To address this, we used camera traps to collect data on raccoons at 95 forest and grassland sites between December 2021 and May 2023 across the state of Illinois, USA (149,996 km²), and applied a Bayesian N-mixture modeling approach to investigate factors driving raccoon site use intensity at two spatial scales: patch (100 m) and landscape (1 km). We included factors that we a priori hypothesized would affect raccoon site use intensity, including habitat, anthropogenic influences, and interspecific interactions. We collected 8634 photographs of raccoons over 13,948 trap nights and observed raccoons at 95.8% of all survey sites. At the patch scale, raccoon site use intensity decreased as impervious surface area (i.e., constructed materials that do not allow water to infiltrate the ground) increased and increased as road density increased. At the landscape scale, raccoon site use intensity also decreased as impervious surface area increased and increased as distance to nearest habitat edge increased. The effect of impervious surface area was over three times stronger than the other modeled factors at both spatial scales. These results contrast with some previous research regarding the effects of environmental factors on raccoons. Our findings highlight how anthropogenic influences (i.e., impervious surface, road density) and habitat characteristics were more influential than interspecific interactions on raccoons in forest and grassland areas. Management and conservation efforts involving raccoons need to account for the variable nature of the species and how natural land cover types may affect raccoon behavior or site use.

Climate-driven phenological mismatches have the potential to disrupt plant–pollinator interactions, emphasizing the need to uncover drivers behind spatial and temporal dynamics of floral resource availability. This is especially important in habitats such as mountain meadows, where climate change is not only likely to have outsized impacts, but topographic complexity creates a mosaic of microclimate and habitat heterogeneity. We investigated the impacts of elevation, canopy cover, and their interaction on the temporal availability of floral resources by deploying 35 trail cameras in open and forested habitats below and near the tree line in the Swiss Alps. We hypothesized that tree cover would lower species richness and floral abundance, especially at high elevations where low light might interact with harsh climates. However, we also hypothesized that a mosaic of open and forested habitats at any elevation may offer temporal benefits to pollinators by extending the flowering season and potentially providing complementary flower resources during critical life history phases. We applied machine learning approaches to images to extract first and last flowering dates, overall flowering duration, and flowering species richness, and then tested how these flowering metrics varied by site (low vs. high) and canopy categories (open vs. closed) and their interactions. We also explored temporal changes in species richness and the individual flowering phenology of the most abundant species. We found that canopy cover extended the entire flowering period while higher elevations shortened it, with both factors delaying the start of the flowering season. Flowering species richness was highest at the tree line, and floral abundance increased at and above the tree line relative to lower elevations. These results highlight the complex interactions between habitat structure and elevation in influencing flowering phenology and flower resource diversity. Understory wildflowers emerge as a potentially complementary resource for pollinators in mountain ecosystems, potentially benefiting them during the early season. This work also highlights the benefit of combining machine learning technologies with automated image capture (in our case, wildlife cameras) that allowed us to quantify phenology at an extremely fine temporal scale.

Global change is affecting native species and communities through multiple anthropogenic drivers which likely interact, complicating our ability to predict the net effects of global change. In the Pacific Northwest region (USA), Cytisus scoparius (L.) Link (Scotch broom) invasion has dramatically altered many ecosystems, including postharvest timber lands. Simultaneously, the intensity of summer drought conditions associated with climate change is making successful reforestation increasingly difficult. We investigated how Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) responds to the multiple stressors of drought and Cytisus invasion. We further evaluated whether the soil microbial community, including mycorrhizal fungi, ameliorates or exacerbates Douglas-fir's response to drought and Cytisus competition. Drought and the presence of the invader both increased stress (measured by chlorophyll fluorescence) and decreased survival of Douglas-fir seedlings, and their combined effects on stress were more than additive. Douglas-fir grew bigger in live than in sterile soil, but this effect was strongly reduced in the presence of Cytisus; we also found that mycorrhizal colonization was reduced in the presence of the invader. Surprisingly, however, Douglas-fir survival in live soil was lower than in sterile soil, especially in the presence of Cytisus. Our results suggest that the impact of drought on Douglas-fir seedlings is likely to be exacerbated by the invasion of Cytisus. Our results further suggest that in a warming climate, the presence of impactful invasive species can affect whether soil microbes have a net positive or negative effect on native plant performance. Our results illustrate the value of studying multiple stressors simultaneously to understand their interactions and combined impacts on native species.

European mountain grasslands are affected by abandonment and are being colonized by shrubs and forest. Grassland fragmentation is caused when the forest matrix grows, and surrounding grassland is split into fragments. Multiple studies have been done on grassland fragmentation but in anthropic matrices. Grassland isolation would not be a constraint for plant dispersion since the distance between grassland fragments is usually short. However, when they are abandoned, the surrounding forest can change the environmental characteristics and small fragments can disappear. We studied abandoned Mediterranean mountain grasslands in an oak forest matrix. We surveyed the grassland communities and their soil properties in multiple fragments of different sizes and isolation distances. We classified the grassland species into different groups by habitat preference and life form and calculated the landscape fragmentation variables. We analyzed the effect of fragmentation on the richness of the grassland groups and communities. Results showed that the fragmentation variables did not have any effect on the grasslands, except at the extreme ends of the gradient of the vegetation succession. The smallest grasslands favored perennial and wetter species over annual or drier species due to wetter soil conditions and less availability of light. Annual species are more abundant in southern aspect fragments with drier conditions across the fragments. The lack of connectivity among fragments is not a problem for grassland communities at a fine scale. Annual and drier grassland species remain even in the smallest fragments, but their conservation requires maintaining a minimum fragment size more than it does landscape connectivity.

Behavioral plasticity, the alteration of behavior in response to stimuli, is becoming increasingly important in the context of human-induced rapid environmental change. Theoretical and empirical studies suggest that the expression and magnitude of behavioral plasticity are likely facilitated or constrained primarily by two factors: environmental variation and endogenous traits such as body size. The contextual role of these factors on behavioral plasticity, however, is poorly understood; there are relatively few studies that have compared the magnitude and potential drivers of behavioral plasticity at different levels (i.e., population and individual) across species, especially in free-ranging animals with diverse behavioral traits such as large mammals. Here, we quantify and test potential hypotheses for the mechanisms underpinning behavioral plasticity at the individual and population level in response to variation in summer temperatures for 1068 animal-years in 17 populations across nine species of large mammals. All populations displayed behavioral plasticity in response to increased temperatures, modifying their relative selection for heat-relieving habitat attributes (e.g., elevation) and heat-generating behavior (i.e., movement speed). We found strong support for the hypothesis that the variability of the physical environment is an important driver of behavioral plasticity—both mean population behavioral plasticity and variation among individuals within each population in plasticity were lower with increased heterogeneity of habitat attributes such as tree cover. Yet, the variability in environmental conditions (i.e., the magnitude of the temperature increase) had no effect on behavioral plasticity within and among populations. We did not detect an effect of endogenous traits on the expression of behavioral plasticity; however, we note that data availability limited our tests of this hypothesis to a select few endogenous traits (body size, feeding guild, and sex of the tracked individuals) that predominantly vary at the species level, for which we had one to three replicate populations per species. Our results provide an integrative and generalizable understanding of the expression of behavioral plasticity among populations of large mammals in temperate environments and emphasize the important but nuanced role of environmental variation in determining the scope of behavioral plasticity in these populations.

Japanese encephalitis virus (JEV), a zoonotic, mosquito-borne virus, has broad circulation across the Central Indo-Pacific biogeographical region (CIPBR) and has recently expanded dramatically within this region across southeastern Australia over the summer of 2021–2022. Preliminary investigation of the landscape epidemiology of the outbreaks of JEV in Australian piggeries found associations with particular landscape structure as well as ardeid species richness. The ways in which waterbird species from diverse taxonomic pools with substantial functional variation might couple with JEV-associated landscape structure were not explored, and therefore, key questions regarding the landscape epidemiology and disease ecology of JEV remain unanswered. Moreover, given the established presence of JEV within the CIPBR, the extent to which waterbird species pools in JEV-associated landscapes in Australia reflect broader regional patterns in functional biogeography presents a further knowledge gap, particularly with respect to potential virus dispersal via maintenance hosts. This study investigated waterbird species presence, ecological traits, and functional diversity distribution at landscape scale and how these aligned with confirmed JEV detections in eastern Australia and the wider CIPBR. The results showed that waterbird habitat associated with JEV detection in Australia in 2022 and more widely across the CIPBR over the last 20 years reflects a range of species representing eight families in four orders. Increasing waterbird functional diversity (trait-based mean pairwise dissimilarity) was associated with landscapes delineating JEV occurrence. However, after accounting for species richness, this association did not persist for Australia but did persist for the CIPBR as a whole. Only one individual trait, high hand-wing index, was consistently associated with species presence in these JEV-associated landscapes in both Australia and the broader CIPBR. This suggests that dispersal capacity among the waterbird species pools that dominate JEV-associated landscapes might be important. By taking an agnostic approach to JEV maintenance host status, this study indicates a relatively large, CIPBR-wide pool of waterbird families associated with JEV landscapes, challenging the narrow view that JEV maintenance is limited to ardeid birds. In addition, these findings highlight the potential for leveraging functional biogeography in high-risk landscapes across broad geographic extent to guide landscape-specific selection of species for JEV surveillance.

Widespread declines in North American birds have elevated the need for proactive conservation planning and delivery to promote recovery. Long-term monitoring at large spatial and temporal extents has been critical to identifying declines, but there is also a need for monitoring designs that can track species at scales relevant to management activities, which often occur within smaller jurisdictions. We highlight Integrated Monitoring in Bird Conservation Regions (IMBCR), a rigorous monitoring program in the western United States providing population estimates at multiple spatial scales from individual management units to state and region-wide. Additionally, we publicize the availability of program trend estimates to management professionals via the Rocky Mountain Avian Data Center (RMADC). Here, we explore contemporary IMBCR trends in three western states, Colorado, Montana, and Wyoming, and document the continued decline of grassland bird species as well as declines in common generalists. We also provide an example of spatial heterogeneity in trends among management boundaries and discuss potential applications of fine-resolution trend data, such as evaluating the effects of management. Finally, we provide an example application demonstrating the value of regional IMBCR trends in species prioritization efforts by state management agencies as a part of State Wildlife Action Plan (SWAP) revisions.

Ecological community data are used to infer levels of environmental stressors; for example, epiphytic lichen communities can be used to estimate levels of air pollutants. If stressors are so severe that the community of interest disappears altogether, then “empty” plots are recorded. The problem compounds when multiple environmental stressors strongly influence the community. We explore this problem using simulated data and a case study of epiphytic lichens in the Sierra Nevada mountains of the United States. This area experiences relatively high amounts of nitrogen (N) deposition that can suppress lichen communities, but this signal is confounded at high elevations where epiphytic lichens become absent. This combination of severe stressors interferes with extracting a lichen community gradient that corresponds with the air quality gradient for the full elevation range in this study area. We evaluated three general approaches: (1) methods of nonmetric multidimensional scaling that allow inclusion or exclusion of empty plots, (2) the “dummy species” method that populates empty plots with a consistent low abundance, and (3) bypassing problematic distance measures by nonparametric regression of the environmental parameter of interest (N deposition) against total abundance. In the simulated gradient, we added stressors at one or both ends of a dataset with a dominant environmental gradient to demonstrate the effect of extreme suppression of communities by environmental conditions. With lichen and simulated data that are “stressed” at one or both ends of the community gradients, Euclidean and Gower distances distorted the primary gradients in a circular manner that weakened relationships with environmental variables. This is similar to the “horseshoe effect” that is recognized as a problem in ordinations of ecological communities. If one excluded empty plots, ordination axes represented the underlying gradients better with quantitative Sørensen (Bray–Curtis) distance than with Euclidean and Gower distances, but this limits the scope of its application in bioindication. The distortion of environmental gradients can be revealed with ordination phase plots, a new method of projecting environmental gradients, whether linear or nonlinear, onto any community ordination space. The regression-based alternative to ordination extracted the strongest relationship between N deposition and lichen community data, and included empty plots.

Vertebrate herbivores require symbiotic gastrointestinal (GI) microbes to extract energy and nutrients from fibrous and sometimes toxic plant diets. Because GI microbes vary in their relative abundance, function, and degree of specialization, the microbial community depends on both the characteristics of plants consumed and the anatomical, physiological, and behavioral characteristics of the herbivore host. To tease apart the relative contribution of diet and herbivore phylogeny to the microbiome, we leveraged a unique study system in which mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) had been hand-raised from neonates to adulthood in identical conditions on a pelleted ration, then transitioned over 2 weeks in the spring onto natural plant diets as they foraged together in the same habitats across summer, then transitioned back onto the pelleted ration in late summer. We determined the plant composition and nutritional quality of the deers' diets using bite count techniques and analyzed 16S rRNA genes of their feces to determine microbial diversity and composition. Our experiments demonstrated that the GI microbial community of congeneric deer responded to characteristics of both diet and deer species. Alpha and beta microbial diversity and microbial composition differed when deer consumed the pelleted ration versus natural browse and varied with other dietary characteristics including plant diversity, composition of plant functional groups, and nutritional constituents. Microbial communities of the two deer species responded differently to dietary changes, but most strongly when deer selected different natural plant diets. Despite controlling early experience, innate behavior and physiological differences between species likely influenced the GI microbiome. Our findings underscore the potential disruption in GI microbial communities with rapid diet changes and the importance of diverse, high-quality forages for wild ruminants. A better understanding of how sympatric herbivores use the same available resources is crucial for predicting the consequences of increasing overlap in wildlife distributions with climate change and human disturbances.

Beaver-based restoration is emerging as a cost-effective conservation and climate adaptation strategy, but efforts are constrained by limited knowledge of pre-colonial beaver distribution and their long-term ecosystem impacts. Here, we apply sedimentary ancient DNA (sedaDNA) techniques to investigate the history of beaver occupancy at three lakes in Grand Teton National Park, Wyoming, over the last ~10,000 years, as well as interactions with the local plant community. We document a dynamic history of beaver presence in two subalpine lakes (Taggart and Jenny Lakes) and demonstrate no history of beaver occupancy at the higher elevation alpine lake (Lake Solitude). Beavers were first detected at Jenny Lake around 7200 years BP and intermittently thereafter. At nearby Taggart Lake, beavers were first detected at ~5900 years BP and continuously from 5200 years BP onward. Vegetation metabarcoding revealed a shift in plant community coinciding with beaver establishment in these two subalpine lakes, as well as an increase in taxonomic diversity. These changes coincide with regional trends toward wetter conditions. Notably, beavers persist at Taggart Lake during inferred droughts, indicating a potential role in maintaining wetlands through extended periods of climatic stress. Our results demonstrate sedaDNA as a powerful, novel technique for reconstructing robust time series data of historical beaver occupancy dynamics.