Ecology最新文献

Food web theory has illustrated that mobile top predators, such as lake trout (Salvelinus namaycush), can be potent stabilizers of food webs due to their ability to shift foraging behaviors in response to changing conditions. Consistent with this, research has demonstrated that mean lake trout food web attributes (i.e., trophic position and nearshore coupling) structurally change across environmental gradients; however, intraspecific variation in these attributes across gradients has not been fully explored. Here, we used stable isotope-based food web metrics to investigate how both mean and intraspecific variation in trophic structure changes in Canadian boreal shield lakes across gradients in ecosystem size, temperature, and competition. Consistent with earlier findings, we find nearshore coupling decreases and trophic position increases with warmer summer climate. In contrast to previous findings, increasing lake area predicted increased nearshore coupling and was not associated with lake trout trophic position. Our results show that warmer temperatures and smaller ecosystem sizes reduce the expression of intraspecific variation in food web structures. Specifically, larger lakes increased variation in nearshore coupling and trophic position, resulting in larger niche areas, and warmer lakes reduced variation in nearshore coupling and tended to generate smaller niche areas. Interestingly, we found little evidence for the relative abundance of lake trout or other predator taxa (surrogates of intra- and interspecific competition) influencing mean and variance in lake trout trophic structure. Intraspecific variation can promote ecosystem resilience by enabling diverse individual responses that help buffer populations against environmental change. Therefore, reduction in intraspecific variation in smaller, warmer lakes may have undesirable consequences for lake trout and the biota in these Canadian boreal shield lakes, leaving these ecosystems less able to adjust to future perturbations.

Arctic ecosystems present unique opportunities for community-wide monitoring, in part due to their relatively low species richness. However, conducting research in these remote environments poses significant logistical challenges, resulting in long-term monitoring being exceedingly rare. Here, we focus on the long-term, intensive ecological monitoring efforts conducted on the south plain of Bylot Island (~400 km², Nunavut, Canada), which has generated a remarkable dataset spanning up to 30 years, a rarity in tundra ecosystems. Our goals are to (1) provide long-term time-series of annual vertebrate density measured at various spatial scales and for the broadest possible range of species and years, to allow the assessment of interannual variability and trends in species density; and (2) upscale annual vertebrate abundance or sometimes long-term averages to the landscape scale (400 km²) to allow food web modeling. Monitoring data include intensive capture–mark–recapture density estimates of lemmings on trapping grids, systematic or opportunistic nest monitoring conducted across the entire study area or within specific plots for all bird species, transects of vertebrate counts distributed throughout the study area, daily incidental observations of vertebrates, and satellite tracking of foxes. We standardized data obtained with different field methods to provide a readily usable dataset for community ecologists. Long-term time-series of vertebrate densities span 3–27 years, with a median of 16.5 years for 22 species. We estimated landscape-scale abundance for all 35 species of the community based on annual time-series for 15 of them and average abundance for the remaining 20 species. Furthermore, we provide body mass data for each species, based on empirical onsite measurements for 18 species and from the literature for the remaining species. Body mass is essential to convert species abundance into biomass for studies of trophic fluxes and ecosystem processes. Daily climatic data recorded since 1992 from weather stations within the study area are also available and complement the vertebrate dataset. The ecological data presented offer a rare opportunity for holistic empirical studies of community structure and dynamics. Considering that the study site is a pristine and protected area that has experienced minimal direct anthropogenic impact, it also provides an ideal baseline for investigating the impacts of global changes on high-latitude terrestrial ecosystems. There are no copyright restrictions on the data or code, and this data paper should be cited when these items are reused.

Juvenile survival and growth rates are commonly studied demographic rates with consequences for population growth. For species that can achieve a size refuge from juvenile predators, the time spent at smaller vulnerable sizes is expected to affect population dynamics. But the interactive effects of juvenile growth and survival on population growth are rarely illustrated theoretically, and most studies of these concepts have been in experimental settings. The interactive effects of the two rates have applications to field studies of recruitment variation for a diversity of species that could be assessed with demographic models and isoclines. We conceptually illustrate the potential use of demographic isoclines for marine, terrestrial, and freshwater examples in the literature, and then demonstrate the use of a demographic isocline for an annual freshwater gastropod (Florida Apple Snail, Pomacea paludosa). Using a published size-indexed demographic model, we constructed a zero-population growth isocline for theoretical combinations of juvenile growth and survival rates. We then quantified daily juvenile survival and growth in two wetlands twice during the recruitment period, incorporating variable predator assemblages and seasonal environmental conditions (i.e., water depth and temperature). Daily juvenile survival rates were lower in the cooler dry season and juvenile growth was faster in the warmer wet (rainy) season. Parameter combinations of juvenile growth and survival in the dry season predicted declining populations (λ < 1), while rates from the wet season predicted populations at replacement (λ = 1) or increasing. When parameters were combined for the full annual recruitment window, populations were projected to decline in both wetlands. The qualitative predictions were robust to variation in hydrologic conditions affecting reproductive rates, but with better hydrologic conditions, one population was near replacement. Our demographic isocline approach provided population-dynamic context to field-measured demographic rates, identified important temporal variation in survival and growth for the population, and generated new hypotheses for future investigation and management. We encourage others to consider developing demographic isoclines to interpret variation of early life stage demographic rates across spatially and temporally variable environmental conditions.

Climate change is altering habitat suitability and driving shifts in species distributions. To understand potential responses by mobile animals, it is essential to assess levels of plasticity in habitat use, ranging from transience to long-term fidelity. Here, we evaluate the fidelity of hawksbill sea turtles (Eretmochelys imbricata) to habitats used while foraging (our primary focus), migrating, and nesting. After satellite tracking 17 adult females from three Western Atlantic nesting areas, we then re-tracked them in a subsequent year. Of 15 turtles with sufficient data to assess interannual foraging area fidelity, 14 returned to the same home range, exhibiting overlap between successive 50% utilization distributions (UDs); the 15th individual shifted <10 km. Mean precision of fidelity, here expressed as the distance between centroids of successive foraging UDs, was 1.45 ± SD 2.3 km—less than the error associated with many satellite fixes. We also observed fidelity to inter-nesting home ranges and migratory pathways, though distinct deviations in migratory routes occurred. A paradigm of precise habitat fidelity is likely appropriate for adult hawksbills, yet merits further investigation across life history stages and global populations. Our results suggest that adult transience may have limited potential to contribute to projected distributional shifts.

Nutrient limitation of forest growth has been difficult to predict, and in temperate forests, long-term tests of single-nutrient versus multiple-element limitation are few. Nutrient co-limitation is the expected outcome of the ability of plants to adjust allocation to minimize limitation by any single resource. Nutrient limitation of productivity in northern hardwood forests was predicted by the Multiple Element Limitation (MEL) model to shift over time since harvest from single limitation by N to P at ~30 years and then, in mature forests, to co-limitation by N and P. Our work tested those predictions for tree growth in a fully factorial N and P addition experiment in 13 forest stands that we grouped in young (20–30 years), mid-age (40–50 years), and mature (>100 years old) age classes in New Hampshire, USA. Over 8 years of treatment, we found evidence of additive co-limitation of tree growth by N and P. We did not find evidence that limitation varied with time since disturbance. Our results suggest that processes contributing to co-limitation in these northern hardwood forests are effective across stands that vary widely in N status and are not sensitive to disturbance by forest harvest over time periods of several decades.

Spatial resource heterogeneity (SRH; the variable spatial distribution of resources) is a surprisingly understudied component of oscillatory predator–prey dynamics. SRH may be particularly important in large, ecologically realistic networks where different patterns of resource distribution can manifest, which have important implications for spatial synchrony. Here, we explore how SRH in large spatial networks influences both local and regional predator–prey stability. To do so, we employ a spatially explicit Rosenzweig–MacArthur model and vary resource distribution accordingly: homogeneously distributed resources of low, medium, and high productivity and heterogeneously distributed resources. The latter includes networks with SRH of random variability in productivity (“random networks”) or a spatial productivity gradient (“gradient networks”). We analyze the effects of local patch factors (i.e., productivity and connectivity) and regional factors (i.e., productivity distribution and structure) as components of SRH. First, we find that SRH, regardless of productivity distribution type, stabilizes regional dynamics via statistical stabilization of asynchronous oscillations and local dynamics by reducing the amplitude of oscillations and bounding them further from zero. Local stabilization, in particular, is enhanced in networks with SRH compared to those with homogeneously distributed resources. Second, the local-level stabilizing effect in networks with SRH increases with patch productivity and connectivity. Lower productivity patches are subsequently destabilized in return, albeit minimally. Lastly, random variability in productivity provides the greatest effects observed at the local level, because high-productivity patches are often highly connected to lower ones in a way not possible in gradient networks. We conclude that SRH is a particularly strong driver of predator–prey stability in that it provides local-level stability in a way that other forms of heterogeneity do not. To promote predator–prey stability in managed systems, stability in oscillatory predator–prey systems is likely to arise from (1) variable resource distribution patterns in large spatial networks and (2) high connectivity between patches of different productivity levels.

Apex consumers are declining worldwide. While the effects of apex predator declines on ecosystems are widely documented, the cascading effects of apex scavenger declines are poorly understood. We evaluated whether disease-induced declines of an apex scavenger, the Tasmanian devil (Sarcophilus harrisii), increased carrion use by invertebrate scavengers. We manipulated devil access to 36 carcasses across a gradient of devil density from east to west Tasmania and measured carcass use by invertebrates. We found the amount of carcass removed within 5 days was 3.58 times lower at sites with the lowest devil densities. Adult carrion beetle (Ptomaphila lacrymosa) and blow fly (Calliphoridae) larvae abundances were two times higher at open-access carcasses at low-density sites than at intermediate- and high-density sites. Adult beetles persisted for 10 days at the low-density site but declined after 5 days when devils had access to carcasses in intermediate- and high-density sites. Blow fly larvae abundance was not affected by devils in the low-density site but decreased with devil access in intermediate- and high-density sites. Our results suggest that apex scavenger declines may increase invertebrate scavenger abundance and their contribution to carrion decomposition, with potential cascading effects on nutrient cycling and ecosystems.

Trait-based ecology relies on high-quality, well-documented data to explore how plant traits relate to environmental conditions, community assembly, and ecosystem functioning. However, the reuse and synthesis of trait data across studies remain limited by several constraints: a lack of detailed metadata, heterogeneous protocols, absence of individual-level measurements, and underrepresentation of certain trait types—particularly below-ground traits. Many existing datasets also lack the environmental details necessary to investigate trait–environment relationships at local scales. Here, we present FAIRTraits, a comprehensive dataset that addresses these limitations by compiling 189,452 records of quantitative trait measurements collected between 1997 and 2023 from 1955 populations of 240 vascular plant species in the Northern Mediterranean Basin, a region known both for its exceptional biodiversity and as a climate change hotspot. All data were collected by a single research group using consistent and well-documented field and laboratory protocols, ensuring internal consistency across traits, species, sites, and years. FAIRTraits includes 180 traits measured at the individual or replicate level, with no aggregation. It features an unprecedented diversity of traits spanning all major plant organs—leaves, stems, roots, and reproductive parts. These include widely used traits such as specific leaf area and plant height, but also traits that are rarely reported, especially below-ground traits related to root morphology, as well as mechanical properties, phenology, and microbial associations. In addition to raw measurements, species are annotated with categorical descriptors (e.g., life form, photosynthetic pathway, and successional status), and species-level values taken from a Mediterranean flora, for key traits such as reproductive phenology and maximum height. To support analyses that account for environmental variability, each observation is linked to detailed descriptors of the plot where the individual was sampled, including climate data, soil physicochemical properties, and disturbance regime. Full metadata on sampling protocols and measurement methods are provided for every trait and environmental variable. FAIRTraits was built in compliance with the FAIR principles of data management (Findable, Accessible, Interoperable, and Reusable). Metadata are described using the Ecological Metadata Language (EML); trait definitions are standardized using community-endorsed semantic resources. The data are archived across two interoperable repositories: GBIF (via Darwin Core and trait-specific extensions) for taxon–trait associations and InDoRES for environmental and contextual data. These efforts ensure long-term preservation, data traceability, and seamless integration with plant trait databases such as BROT or TRY, and cross-organism initiatives such as the Open Traits Network or the Encyclopedia of Life. FAIRTraits offers a robust, richly document

Changing snow conditions due to climate warming may negatively affect the northern fauna that depend on it for their winter survival. To avoid cold temperatures, Arctic lemmings seek refuge in areas with deep snowpack where they build nests in which they can reproduce if conditions are favorable. The presence of a soft depth hoar layer ensures efficient digging and facilitates lemming movement in the snow, but such favorable conditions are highly dependent on weather conditions at the beginning of winter. Using a 17-year time series, we assessed the impact of snow conditions and specific weather events on lemming winter reproduction and population growth on Bylot Island in the Canadian High Arctic, a site characterized by a cold and dry Arctic climate. We focused on snow onset date, snow depth, and weather events leading to a hardening of the snow basal layer (i.e., rain-on-snow, melt-freeze, and freezing rain) at the beginning of winter. We also examined possible differences between two lemming species, the brown lemming (Lemmus trimucronatus) and the collared lemming (Dicrostonyx groenlandicus), the latter presenting unique morphological adaptations to snowy environments. We found that the intensity of winter reproduction of both species was negatively related to the intensity of rain-on-snow, melt-freeze, and freezing rain events. Winter population growth was also negatively related to the intensity of rain-on-snow and melt-freeze events in brown lemmings but not in collared lemmings. Contrary to our expectation, no relationship was found between lemming demography and snow onset date or snow depth. We found a higher reproductive rate in collared than in brown lemmings, suggesting a more effective strategy to save energy for winter reproduction in the former species. Overall, this study shows that even moderate weather events, in comparison with other Nordic sites, can impact lemming population growth in winter, likely by reducing their capacity to reproduce due to a hardening of the snowpack. The expected increase in such weather events with climate change may threaten lemming populations even in the High Arctic, as well as predators that depend upon them.