Ecological Monographs最新文献

Temperature and resources are fundamental factors that determine the ability of organisms to function and survive, while influencing their individual and population growth. Major bodies of ecological theory have emerged, largely independently, to address temperature and resource effects. It remains a pressing challenge to unite these ideas and determine the interactive effects of temperature and resources on ecological patterns and processes, and their consequences across ecological scales. Here, we propose a simple, physiologically motivated model capturing the interactive effects of temperature and resources (specifically, inorganic nutrients and light) on the growth of microbial ectotherms over multiple ecological scales. From this model we derive a set of key predictions. At the population level, we predict (1) interactive effects of resource limitation on thermal traits (parameters describing effects of temperature on growth), (2) consistent differences in the temperature sensitivity of auto- and heterotrophs, and (3) the existence of specific trade-offs between traits that determine the shape of thermal performance curves. At the community level, we derive predictions for (4) how limitation by nutrients and light can change the relationship between temperature and productivity. All four predictions are upheld, based on our analyses of a large compilation of laboratory data on microbial growth, as well as field experiments with marine phytoplankton communities. Collectively, our modeling framework provides a new way of thinking about the interplay between two fundamental aspects of life—temperature and resources—and how they constrain and structure ecological properties across scales. Providing links between population and community responses to simultaneous changes in abiotic factors is essential to anticipating the multifaceted effects of global change.

Climate change is altering the phenology of interacting species, potentially leading to mismatches in the timing of their interactions. This may affect the delivery of key ecosystem services such as pollination. Temperature-mediated phenological variation has been widely studied at the species level, showing that increased temperatures lead to earlier activity periods for both plant flowering and pollinator emergence. However, some classic examples of tracked interacting pairs show that phenological mismatches can occur between plants and pollinators. Even though plants and pollinators are embedded in complex interaction networks, it remains unclear how phenological shifts scale up to the community level and what role biodiversity may play in buffering negative outcomes. We analyzed an 8-year time series of plant and pollinator seasonal abundances across 12 Mediterranean scrublands increasingly affected by drought and extreme temperatures, focusing on the subset of common species whose phenology could be reliably described each year. Our aim is to understand how climate change has altered plant–pollinator interactions from the species to the community level. We found that plants and pollinators have been advancing their phenologies over time at similar rates, with an average advance of 5 days per decade. Changes in rainfall and temperature patterns are key drivers of these advances. Despite the congruent shifts and no consistent change in pairwise phenological overlap, total overlap between each species and its potential partners has slightly declined over time. While more diverse communities show higher potential overlap, biodiversity is not directly buffering the reduction in interaction overlap in the studied rich communities. However, in silico experiments show that the buffering effect of biodiversity becomes apparent at lower diversity levels (i.e., fewer than 10 species). In the context of ongoing climate change, protecting diverse communities with high interaction overlap is crucial, as phenological shifts may gradually erode network structure in Mediterranean plant–pollinator systems. Sustained long-term data collection is also essential to understand the fate of most species, including those whose low abundances may conceal early signs of biodiversity loss.

Observations on the North Slope of Alaska have revealed patches of Sphagnum peat within the widespread matrix of tussock tundra on mineral soils. Little is known about the developmental history of these Sphagnum patches and whether they represent incipient peatlands established in response to warming-related environmental changes. Nine peat cores were collected from nine Sphagnum-dominated peat patches spanning an approximately 300-km longitudinal gradient on the North Slope to determine their development and establishment history. Stratigraphically constrained cluster analysis was applied to plant macrofossil data, carbon-to-nitrogen ratios, and total organic matter measured from bulk peat to delineate developmental phases, and radiocarbon dating was used to constrain the timing of Sphagnum peat patch establishment. We compared these data to changes in testate amoeba community composition and amoeba-inferred water-table depth and pH in six of the peat cores. We also compared Sphagnum peat-patch development and establishment history to paleoclimate and local instrumental temperature records. Results indicated a predictable pattern that describes the transition from moist tussock tundra to Sphagnum peat. Furthermore, although Sphagnum has been present on the North Slope for millennia, our data suggest that Sphagnum-dominated peat patches constitute recent landscape features, mainly established in the 1800s and 1900s, and with rapidly increasing Sphagnum abundance in the past 50 years. Sphagnum expansion was associated with pronounced changes in testate amoeba communities, including an increase in mixotrophic taxa and species associated with densely growing Sphagnum, and community changes consistent with drying and increased acidity. The recent development of Sphagnum-dominated peat patches has been associated with warming air and soil temperatures, active layer deepening, and earlier snowmelt. Sphagnum expansion has also been observed in other arctic regions, and understanding the extent and growth potential of Sphagnum peat patches has implications for understanding and anticipating changes in carbon cycling, edaphic conditions, permafrost thermal regimes, and floristic diversity.

The enchanting diversity of large mammalian herbivores in African savannas has long challenged ecologists: How can so many species of large, generalist plant eaters coexist? Variation in body size and craniofacial/dental anatomy are key morphological determinants of ecological niche differentiation, shaping foraging behavior in ways that stabilize coexistence by limiting interspecific competition for space and food. Variation in water requirements may be another important dimension of niche differentiation, but whether and how variability in water requirements affects the partitioning of other resources is unknown. Here, we investigate how body size, dental morphology, and water requirements interactively affect space use and diet of 15 large-herbivore species in Serengeti National Park. Water requirements predicted space use in relation to permanent water sources, while diet type (percentage grass) was best predicted by dental morphology. Food partitioning was best predicted by a combination of all three traits in both wet and dry seasons. Furthermore, the total explained variation of diet dissimilarity explained almost tripled when these three traits were combined compared to single traits, emphasizing the importance of multiple dimensions of niche differentiation. Our results show that variation in water requirements is strongly associated with spatial and dietary niche differentiation among large herbivores, emphasizing the importance of spatial heterogeneity in surface water and vegetation structure for maintaining the world's last mega-diverse megafaunal assemblages. Integrating multiple dimensions of resource partitioning is a crucial step toward predicting how species will respond to homogenization of savanna landscapes due to changes in land use, surface water availability, and rainfall.

Plant nutrient foraging depends on roots and mycorrhizal fungi, which are affected by plant carbon (C) investment and soil nutrient availability. The C supply for root metabolism and associated fungi might be diminished as the host plant size or age increases, while the quality and quantity of soil nitrogen (N) change with forest age. There is still no holistic understanding of how the organization of belowground mycorrhizal root structure and fungi in the nutrient acquisition continuum shifts with forest age and soil resources, which restrains our understanding of the functional relations among roots, fungi, and soil. Here, we examined shifts in the absorptive root, mycorrhizal strategies, and soil-associated fungal community compositions after 9 years of nitrogen manipulation (0, 20, and 50 kg N ha⁻¹ year⁻¹) in temperate larch forests across three age cohorts (11, 20, and 45 years). We found that the effect of forest age on root and fungal traits outweighs that of nitrogen treatment. Specifically, with increasing forest tree age, root respiration and specific root length decreased, while protective investments such as tissue density and phenolics increased. Meanwhile, the proportion of ectomycorrhizal fungi of the long-distance exploration type decreased, but those of the short-distance exploration type increased. Together, these patterns suggest a forest age-mediated nutrient acquisition continuum spanning from “explorative roots with long-distance exploration types” to “conservative roots with short-distance exploration types.” We propose that this nutrient acquisition continuum is functionally constrained by the “size vs. rate” trade-off between the root architecture and root segment metabolism, and the “roots vs. mycorrhizal fungi” complementarity between root architecture and mycorrhizal exploration types. Our results suggest that forest age explains shifts in systemic functional trade-offs in root architecture, root segment metabolism, and mycorrhizal exploration types.

The ability of species to form diverse communities is not fully understood. Species are known to interact in various ways with their neighborhood. Despite this, common phenomenological models of species coexistence assume that per capita interactions are constant and competitive, even as the environment changes. In this study, we investigate how neighbor density-dependent variation in the strength and sign of species interactions changes species and community dynamics. We demonstrate that incorporating these sources of variation significantly improves predictions of ecological dynamics compared to the outcomes of typical models, which hold interaction strengths constant. We compared the performance of models based on different functions of neighbor density and identity in describing population trajectories (i.e., persistence over time) and community dynamics (i.e., temporal stability, synchrony, and degree of oscillation) in simulated two-species communities and a real, diverse annual plant system. In our simulated communities, we observed the highest level of coexistence between species pairs when species interactions varied from competitive to facilitative, depending on neighbor density (i.e., following a sigmoid function). Introducing within-guild facilitation through a nonlinear bounded function allowed populations, both simulated and empirical, to avoid extinction or runaway growth. In fact, nonlinear bounded functions (i.e., exponential and sigmoid functions) accurately predicted population trends over time within the range of abundances observed over the last 10 years. With the sigmoid function, the simulated communities of two species exhibited a higher probability of synchrony and oscillation compared to other functional forms. These simulated communities did not always show temporal stability, even when they were predicted to coexist. Overall, varying species interactions lead to realistic ecological trajectories and community dynamics when bounded by asymptotes based on neighbor density. These findings are crucial for advancing our understanding of how diverse communities are sustained and for applying ecological theory to real-world studies.

Martin, Ellen C., Brage Bremset Hansen, Aline Magdalena Lee, and Ivar Herfindal. 2025. “Life History Traits Influence Environmental Impacts on Spatial Population Synchrony in European Birds and Butterflies.” Ecological Monographs 95(3): e70029. https://doi.org/10.1002/ecm.70029.

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Open-access publishing facilitated by Schweizerische Vogelwarte, as part of the Wiley - Schweizerische Vogelwarte agreement via the Consortium Of Swiss Academic Libraries.

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In ecology and related sciences, missing data are common and occur in a variety of different contexts. When missing data are not handled properly, subsequent statistical estimates tend to be biased, inefficient, and lack proper confidence interval coverage. Missing data are often grouped into three categories: missing completely at random (MCAR), missing at random (MAR), and missing not at random (MNAR). We review each category and compare their benefits and drawbacks. We review several approaches to handling missing data including complete case analysis, imputation, inverse probability weighting, and data augmentation. We clarify what types of variables should accompany imputation methods and how those variables are influenced by the analysis methods. Additionally, we discuss missing data that lack a formal basis for measurement and hence are fundamentally different from MCAR, MAR, and MNAR missing data. Throughout, we introduce concepts and numeric examples using both simulated data and data from the United States Environmental Protection Agency's 2016 National Wetland Condition Assessment. We conclude by providing five considerations for ecologists and other scientists handling missing data.

Theory and experiments show that diverse ecosystems often have higher levels of function (for instance, biomass production), yet it remains challenging to identify the biological mechanisms responsible. We synthesize developments in coexistence theory into a general theoretical framework linking community coexistence to ecosystem function. Our framework, which we term functional coexistence theory, identifies three components determining the total function of a community of coexisting species. The first component directly corresponds to the niche differences that enable pairwise species coexistence and to the complementarity component from the additive partition of biodiversity effects. The second component measures whether higher functioning species also have higher fitness under competition, providing a missing link between the additive partition's selection effect and modern coexistence theory's concept of equalization. The third component is least well studied: reducing functional imbalances between species increases niche difference's positive effect on function. Using a mechanistic model of resource competition, we show that our framework can link the structure and function of multispecies communities and that it can predict changes in coexistence and ecosystem function along gradients of resource availability. In particular, we expect the effect of resource level on biodiversity–function relationships to be limited in magnitude and variable in sign because it should be primarily mediated by fitness. Next, we confirm our theoretical expectations by fitting this model to data from a classic plant competition experiment. Finally, we apply our framework to simulations of multiple ecosystem functions, demonstrating that relationships between niche, fitness, and function also predict a community's multifunctionality, or ability to simultaneously show high levels of multiple functions. Taken together, our results highlight fundamental links between species coexistence and its consequences for ecosystem function, providing an avenue toward mechanistic and predictive understanding of community–ecosystem feedbacks.

Interactions between plants and soil microbes play a key role in structuring plant communities. In a rapidly changing Arctic environment, we urgently need to uncover how these interactions are responding to environmental changes. Here, we disentangle two contributions to variation in plant–fungus interactions along geographic and environmental gradients of the Arctic: abiotic impacts on the pool of fungal species present in the soil, and abiotic and biotic impacts on variation in the pool of fungi associated with plant roots. Given the low species richness and harsh conditions in the Arctic, we expected opportunistic associations to emerge, along with strong impacts of the environment on interaction structure. Across multiple spatial scales, we sampled roots of 12 widely distributed plant taxa. To characterize the pool of species available for colonization, we quantified the pool of fungi present in the soil, and to characterize realized interactions, we quantified root-associated fungal communities. Data from DNA metabarcoding of each fungal community were modeled by Hierarchical Modeling of Species Communities (HMSC). To determine whether the realized networks deviated from random expectations, we compared the observed networks to those expected under null models. Overall, we found strong support for opportunistic associations, along with some level of selectivity. Fungal communities within the soil and rhizosphere shared 85% of their fungal genera, but the composition of these communities significantly differed among ecosystem compartments. The two compartments showed similar responses to the environment, with low levels of partner fidelity among both plant and fungal taxa. Plant–fungus networks showed a distinctly nonrandom structure, which was driven by gradients in pH and temperature. Across the Arctic, the structure of fungal communities in the plant rhizosphere is thus mainly driven by abiotic rather than by biotic conditions (i.e., host identity or microbes–microbes associations). Environmental conditions will dictate what interaction partners occur where, but interactions among locally occurring plants and fungi are dominated by opportunistic partner choice. Overall, our findings suggest that the dynamics and structure of plant–root-associated interactions will be altered by abiotic changes in the Arctic realm, and that the flexibility of associations may contribute to the resilience of the system.