Ecology最新文献

Understanding the relationship between biodiversity and ecological stability is increasingly urgent as rapid species extinction continues. Though evidence of positive diversity–stability relationships is accumulating, empirical results are inconsistent, and effect sizes tend to be small, raising questions about relative contributions of intrinsic (i.e., species composition/interactions) and extrinsic (i.e., environmental) drivers of stability. Community stability may be more strongly influenced by environmental conditions than by community diversity in some contexts, yet little is known about the comparative importance of diversity and climate means, extremes, and variability in regulating stability. We used a half-century of continental-scale bird data to quantify avian community temporal variability (a metric often used to approximate ecological stability) at 1379 sites and compared relative effects of climatic variables and species richness. We found that extreme heat and extremely low precipitation at decadal scales are associated with high bird community variability and these climate variables outperformed species richness in terms of variance explained and magnitude of effect. This provides empirical support for the theoretical concept that, at a continental, decadal scale, environmental conditions can play a larger role than intrinsic factors in determining community stability. Our findings also increase understanding of how climate extremes cause diverse ecological responses.

Large carnivores commonly scavenge on kills made by other species, but if and how this phenomenon is influenced by urbanization remains unclear. To address this knowledge deficit, we investigated whether housing density, along with demographic and environmental covariates, impacted the probability of American black bear (Ursus americanus) occurrence at cougar (Puma concolor) killed prey along the wildland–urban gradient of western Washington, USA. Under the refuge hypothesis, which stipulates that residential development reduces opportunities for black bears to visit cougar prey carcasses by (1) altering cougar kill composition and/or (2) drawing black bears to human subsidies, we expected the probability of bear presence at cougar kills to decline as housing density increased. Alternatively, under the pileup hypothesis whereby reduced green space drives a greater overlap and thus more frequent interactions among carnivores, we predicted that bear presence at cougar kills would increase with housing density. Occupancy models derived from forensic and remote camera evidence of bear visitation to carcasses at kill sites identified from 12 GPS-collared cougars indicated that the probability of bear presence at kill sites decreased when cougars foraged on small-bodied prey, increased in summer compared with autumn, and declined with increasing housing density. Indeed, the top model indicated a multiplicative decrease of 500 in the odds of black bear carcass visitation for every additional house per hectare on the landscape, supporting the refuge hypothesis. These results suggest that residential development has the potential to alter intraguild relationships among large carnivores, even at modest levels where robust carnivore populations persist on the landscape, and may alter scavenger dynamics at carcasses where black bear presence is virtually eliminated.

Current theoretical frameworks on alternative ecosystem states in boreal forests do not contain a clear prediction on how the sensitivity for state transitions depends on site productivity, which forms a major gap in understanding how disturbances impact these ecosystems. Here, we compared 26 historical reindeer (Rangifer tarandus L.) corrals used in animal husbandry between the late 1800s and early 1960s with reference forests in the northern boreal forest zone in Finland. We found that mesic forests experienced strong forest reorganization that involved shifts in both tree species composition and density. Sub-xeric forests were most commonly on a trajectory toward the pre-disturbance state due to strong self-thinning. No state transitions in understory vegetation occurred. There was little difference in understory vegetation recovery between mesic and sub-xeric forests; however, disturbance increased spatial heterogeneity in understory vegetation. These findings from historical sites support a high resilience of northern boreal forests to disturbances. They also indicate that disturbances may more likely induce reorganization in more productive mesic sites. Although stronger environmental constraints in less productive sub-xeric sites may slow down recovery, they also direct post-disturbance trajectories toward the pre-disturbance state.

Recreational diving is an important activity in reef environments worldwide, providing income and employment for coastal communities and connecting visiting divers to these ecosystems promoting conservation and stewardship. However, if poorly managed, diving has the potential to cause detrimental effects on benthic communities via mechanical damage caused by physical contact of divers with the reef, often in the form of unintentional fin kicks resulting from poor buoyancy. Understanding diver–reef interaction patterns is important to elucidate the potential impacts of diving tourism on the reef biota. The DiverReef database provides the first public dataset on the underwater behavior of recreational divers in shallow reef environments (<25 m depth) globally and their interactions with the reef seascape and/or reef benthic sessile organisms. The dataset comprises 20 years of data (2004–2023) by observing the behavior of 2311 recreational divers in nine countries at 19 diving destinations and 176 diving sites; 93% of the observations were in marine protected areas. The data were collected through on-site observations of divers' behavior during tourism activities and their physical interactions with the reef structure and/or benthic sessile reef organisms. Observers discreetly followed divers and recorded their behavior and interactions with the reef over set periods. Interactions were described as “contact” or “damage,” the latter referring to when physical damage to a benthic organism or the reef structure was observed. Besides behavior, observers also recorded data on the type of diving activity (scuba or snorkeling), profiles of the divers (gender and experience), use of cameras by the divers, visibility, type of reef formation, and marine protection status of the dive site. The authors of this research expect that the data provided will be useful in advancing knowledge of how divers interact with reefs and in developing strategies to mitigate the potential detrimental effects of the diving industry on reef biota. Part of the data has already been used in reports and scientific articles. This dataset can be freely used for noncommercial purposes; we request that users of these data cite this data paper in all publications resulting from the use of this dataset.

Dispersal and dormancy serve as strategies for persistence in varying and uncertain environments and are critical to ecological models of biodiversity maintenance. Theories of specific ecological scenarios that favor dispersal, dormancy, or their covariance are rarely tested empirically, particularly in response to realistically complex patterns of spatiotemporal environmental variation. To resolve these complexities, we collected 20 populations of Vulpia microstachys, an annual grass native to California, from the field and grew them in a greenhouse, and on the offspring generation measured seed dispersal ability and seed dormancy rates. We hypothesized that seed dormancy rates, but not dispersal abilities, would be highest in populations from more productive, temporally variable sites, causing dispersal and dormancy to evolve independently—in other words, we leveraged evolved differences among populations to identify what ecological strategy (i.e., dispersal, dormancy, or both) is most likely to evolve at different parts of a variability gradient. Our data suggest that both dispersal and dormancy evolve to combat different axes and scales of spatial heterogeneity and can evolve independently (thus, they are not forced to covary). Most surprisingly, seed dormancy appears to have evolved as a strategy for overcoming microgeographic heterogeneity, an outcome that to our knowledge has not been considered by theory; we confirm the plausibility of this conclusion with a simulation. In sum, we provide much needed empirical data on the evolution of ecological strategies for coping with environmental variance, as well as a new perspective on the ecological function dormancy provides in heterogeneous landscapes.

The distribution and abundance of foraging resources are key determinants of animal habitat use and persistence. Decades of agricultural expansion and intensification, along with the introduction of exotic species, have dramatically altered resource distributions in space and time. The nature of contemporary landscapes requires new approaches to understand how mobile organisms utilize the resulting highly fragmented, heterogeneous resources. We used colonies of the native bumble bee (Bombus vosnesenskii) deployed among habitat types and a land use gradient to characterize how resource availability and use change as a function of landscape composition throughout the season in a diverse agricultural region of Northern California. We employ a novel probabilistic framework to identify the spatiotemporal patterns of bumble bee resource use in different habitats. Bumble bee resource preference (i.e., pollen foraging) and availability (i.e., flowering plant abundance) are driven by the composition of the surrounding landscape and the time of year. Bumble bees strongly preferred pollen from native plants, which was overrepresented in samples across the season relative to its estimated availability. Our probabilistic model framework also revealed a strong reliance on seminatural habitat in the landscape (e.g., oak savannahs, chapparal, and riparian corridors)—features that are increasingly rare in anthropogenically dominated landscapes. In fact, pollen resource use by colonies even in the most intensive landscapes was largely limited to interstitial habitat (e.g., field and road edges) despite available mass-flowering crops. Our results highlight the importance of mosaic landscapes (i.e., landscape heterogeneity) in allowing bumble bees to link resources through the season. The framework we develop also serves to enhance predictions of insect resource use within fragmented landscapes.

Quantification of different processes affecting the assembly of ecological communities remains challenging, especially in species-rich communities. While the role of environmental filtering has generally been well established, fewer studies have experimentally shown how other ecological assembly processes, such as biotic filtering, structure species-rich communities. Here, we studied the relative roles of biotic and environmental filtering in the colonization of wood-inhabiting fungi, a species-rich, highly interactive, and environment-sensitive group of species. We conducted a field experiment where we simulated colonization with inoculations of nine fungal species in habitat patches (i.e., logs) with varying biotic and abiotic conditions. We characterized the local resident communities before the inoculations and the colonization success of the inoculated species after one and two years using DNA metabarcoding. We asked what determined the colonization success of the inoculated species by comparing the predictive performance of alternative models. These models included either only abiotic environmental predictors (i.e., physical log properties) or additionally different aspects of the resident fungal communities (i.e., resident fungal species richness, community composition, and DNA amount) as biotic predictors. While all nine species successfully colonized the logs, the rate of success and the factors explaining their colonization success varied among species. The colonization success of four of the inoculated species was explained mostly by the abiotic environmental variables, while the colonization success of three species was additionally explained by the resident communities. The influential biotic predictors varied from the presence of individual species to the collective presence of multiple species. Finally, for two of the inoculated species, all the models showed poor predictive performance. Our results indicate how environmental and biotic filtering may jointly structure species-rich communities. Overall, the results show that species vary idiosyncratically in their response to biotic and environmental factors, highlighting the need to consider the complexity of species-level responses when predicting community-level changes.

Species phenology is being altered by ongoing climate changes with yet underappreciated consequences for ecological processes and ecosystem stability. Contrary to what happens with some key life events of flowering plants, comparatively little information exists about fern and lycophyte phenology and how it is affected by the current climatic changes. In part, this stems from the lack of long-term datasets. Here we provide information on the collection day and site of the spores of 121 native and introduced fern (Polypodiopsida) and lycopod (Lycopodiopsida) taxa for the Index Seminum of the Botanic Garden of the University of Coimbra. Spores were collected from spontaneous and cultivated individuals across Portugal between 1926 and 2013. The database includes 3383 curated records with information on the species, or infraspecific taxa (including authority), and are fully georeferenced and provided with a confidence interval for the collection site. Taxonomy was first curated manually by in-house botanists and then harmonized according to the Global Biodiversity Information Facility (GBIF) backbone taxonomy. The data are released under a Creative Commons Attribution Non Commercial (CC-BY-NC 4.0) license.