Land degradation due to unsustainable land use is of major concern worldwide and recovery is often slow. A potential mechanism behind slow recovery of degraded ecosystems is the retarding impacts of allelopathic plant species on the establishment of species that might facilitate the recovery process. However, the strength of the retarding impact may depend on soil type. In this study, we investigated the potential role of an abundant, evergreen and allelopathic dwarf shrub, Empetrum nigrum, in trapping tundra ecosystems in a degraded state in Iceland after centuries of unsustainable land use. We first run a series of bioassays to assess the potential allelopathic legacy effects of the Empetrum-associated volcanic soils (Andosol and Vitrosol) on seed germination and root elongation of the common grass species Festuca richardsonii in comparison with non-volcanic Histosol and Podzol soil types. Then we assessed the Empetrum leaf-soil interactions for all soil types using leaves from a degraded site in Iceland. We found no potential allelopathic legacy effects of Empetrum associated volcanic soils, whereas the non-volcanic soils negatively impacted Festuca root elongation. Empetrum leaves alone affected both seed germination and root elongation. These effects were strongly alleviated by the volcanic soils, but not by the non-volcanic soils. We conclude that abundant allelopathic plant species may significantly contribute to trapping tundra ecosystems in a degraded state, but the strength of this trapping mechanism depends on the soil environment .

In natural environments, competition between species is a crucial factor for the survival or demise of populations. Therefore, understanding the mechanisms that promote species coexistence is crucial in community and evolutionary ecology. The Phylogenetic Limiting to Similarity Hypothesis (PLSH) posits that closely related species should experience greater competition due to niche conservatism, leading to higher overlap in resource use. However, studies have shown mixed results regarding the influence of phylogenetic distance and other abiotic and biotic factors on interspecific competition. This study explores the role of phylogenetic relatedness, body mass differences, and environmental factors such as primary productivity, in shaping trophic niche overlap among mesocarnivores across ten global biomes. Our extensive bibliographic review of more than 200 sources over nearly five decades suggests that while phylogenetic distance and body mass differences are significant predictors of niche overlap, environmental factors like primary productivity also play a crucial role. The findings highlight the complexity of species interactions, emphasizing that niche overlap is influenced by a combination of intrinsic and extrinsic factors. This study contributes to a deeper understanding of the dynamics governing species coexistence and the assembly of ecological communities.

Climate warming and anthropogenic activities have led to an increase in the prevalence of non-native plants in mountainous regions that previously exhibited limited occurrences. This phenomenon has resulted in detrimental effects on endemic plants and ecosystem functions. Yet, how traits of non-native plants that successfully spread to high elevation vary along the elevation gradient, as well as the underlying drivers of these changes, remain sparsely understood. In this study, we use Erigeron annuus, a cosmopolitan non-native plant that has invaded to high elevation, as our model to explore its individual biomass pattern along a 1900 m elevation gradient. We also contrast this pattern with the native Artemisia lavandulifolia, which has the same distribution range as E. annuus. We found that the biomass of E. annuus displayed a hump-shape pattern along elevation, while the biomass of native A. lavandulifolia gradually decreased with elevation. By evaluating the effect of climate variables, soil properties, rhizosphere fungal communities and its spatial mid-domain effect (i.e. geographic limitation) on plant biomass, we found that the biomass of E. annuus was primarily influenced by the spatial mid-domain effect, while the biomass of A. lavandulifolia resulted from a complex interplay of climatic variables and rhizosphere microbial communities. Our findings emphasize the importance of a spatial mid-domain effect on the growth of non-native E. annuus along elevation, indicating the impact of E. annuus probable be greatest at mid-elevations and thus, where management priority should be set. Further investigations considering more non-native plant species and species’ traits will allow to scrutinize this vision.

Phenotypic plasticity is often considered a key mechanism enabling organisms to tolerate global change stress, yet its adaptive role remains debated. We suggest that this uncertainty stems from inconsistency in how global change is defined, insufficient consideration of context dependency, and analyses conducted at species or metapopulation scale. To address these issues, we propose a framework that emphasizes partitioning global change into distinct dimensions---mean change, variability, stochasticity, and episodic events---all of which present unique challenges for organisms. We also highlight the importance of considering the tradeoffs between cost, speed, and flexibility of trait plasticity to predict when different types of traits may facilitate adaptation. Recognizing that global change impacts vary across geographic ranges, we advocate for population-level approaches that incorporate historical environmental conditions, multivariate trait responses, and region-specific stressors. Our synthesis provides methodological guidance for designing experiments and leveraging natural gradients to better understand the interplay between global change dimensions and functional traits. While we focus on animals due to their diverse trait repertoires, the concepts presented here are broadly applicable across taxa. By refining definitions and linking trait plasticity to distinct global change dimensions, this framework offers a pathway to more predictive, actionable insights into species resilience under rapidly changing environmental conditions.

The spatial configuration and management of agricultural and other land-use practices can affect ecological assemblages, but how resident and migratory species respond to land uses is not well known, hindering our understanding of the effects of land use on biodiversity. Here, we compare alpha and beta diversity and ecosystem functioning for resident and migratory birds across three land uses: (1) primary forest, (2) secondary forest, and (3) cattle pasture. Compositionally, resident bird assemblages exhibited gradual shifts across habitats with diversity steadily declining with increasing distance from a protected area and reductions in understory vegetation. In contrast, migratory bird community composition clustered into five distinct groups, shifting 50-60% less than resident assemblages across the same gradients with no declines in richness. We found that migratory bird abundance was greater in secondary forest and cattle pasture, and migratory insectivores compensated for 68% of the abundance losses of resident forest insectivores in secondary forests and cattle pastures. Among the insectivores, increases of migratory birds in secondary forest and cattle pasture compensated for the abundance declines of resident birds that utilize foliage gleaning and sallying foraging methods. Our findings underscore the importance of local landscape evaluation and management around protected areas, highlighting the unique responses of resident and migratory birds to land use and the potential mechanisms sustaining ecosystem functions in modified habitats.

Raptor populations on islands are limited by resource availability and the dispersal possibilities for young birds, which are often determined by the size of the island. This leads to differences in population dynamics and viability compared to mainland populations. Human land use modifications on islands—such as agriculture, forestry, excessive hunting, and urban infrastructure development—may affect resource availability and increase risks to these populations. Consequently, many island raptor populations have been dramatically reduced or driven to extinction and have never fully recovered. The conditions necessary for their long-term persistence remain uncertain. Gotland, a large, human-dominated island located in the Baltic Sea, is home to one of the densest populations of Golden Eagles (Aquila chrysaetos). However, the drivers of population dynamics remain unknown, and many speculations exist that require empirical testing. Approximately 86 Golden Eagle territories were identified and surveyed across Gotland. We investigated the spatial drivers of breeding dynamics in this eagle population, evaluating the effects of habitat composition, prey density, and neighborhood effects on territorial productivity. The average productivity was 0.41 fledglings per pair, which varied annually, with approximately 72% of territories occupied and 32% being successful. Despite significant variation in habitat composition across territories, spatial differences in productivity were primarily influenced by the proportion of coniferous forest (nesting habitat), greater prey diversity, the density of non-native roe deer (Capreolus capreolus), and the reproductive status of neighboring territories. Several novel findings emerged: the role of roe deer as a potential prey species introduced by humans has been previously underappreciated, proximity to the coast was associated with increased productivity, and the variation in spatio-temporal reproductive dynamics across neighboring territories appears to influence overall population dynamics. We discuss the general implications of these novel findings for the long-term conservation and persistence of this iconic island population and similar populations worldwide.

Invasive species are non-native plants and animals that can significantly harm societal and natural values such as agriculture, social amenity, the environment and native ecosystems and species. Efficient preparation for their incursion requires understanding their potential impact, influenced by factors such as introduction pathways, host material availability, climate suitability, and the value of affected agriculture. A crucial factor that is specific to the incursion and therefore unpredictable beforehand is the size of the outbreak at the time of detection, which can curtail the range of management options: if the invading population is small then eradication may be affordable, whereas if it is large then eradication may be impossible. We propose a statistical model for this random variable to aid decision-support systems. We analyze the relationship between surveillance and organism detection using survival analysis, treating detection as analogous to a failure event. This approach links the distribution of infestation size at detection with the probability of detecting an incursion—specifically, the hazard function describing the instantaneous detection rate. Under this survival model, we connect the probability density function of infestation size at detection to the hazard function. Moreover, we introduce an approximation using the Weibull distribution to model the population size before pest detection. This approximation holds when dealing with a small fixed number of traps or a low probability of detection per trap. By assuming a relationship between the invasive population size and the time it remains undetected, we estimate the probability density function for the population’s duration of occupancy. We develop a computer program to perform the analysis, using the Mediterranean fruit fly as a case study to demonstrate its application. We believe that representing the invasive population size at detection provides valuable insights into control and eradication strategies, potentially applicable to broader invasive species management efforts.

Humans are driving unprecedented environmental change, causing the loss of species from local ecosystems. This local species loss is likely to result in declines in ecosystem functioning, but understanding why these so-called biodiversity-ecosystem functioning relationships vary is crucial for conservation efforts. Previous studies have shown that variation among biodiversity-ecosystem functioning (BEF) relationships can be explained by a ’function-dominance correlation’, i.e., the correlation of species’ biomass in monoculture (‘functioning’) vs. mixtures (‘dominance’). One potential reason for the importance of the function-dominance correlation is its relationship to underlying plant traits. Here, we explore which traits control species’ biomass in monoculture and mixture and thereby drive the function-dominance correlation, and hence BEF relationships. To do this, we perform a modeling experiment with six trait-based models of plant community dynamics and classify model traits as either ‘size’ or ‘resource’ traits. This approach allows us to better generalize across systems that differ in terms of their key traits and/or how a given trait affects individual performance and ecosystem functioning. We found that size traits, but not resource traits, predicted species’ monoculture biomass in five out of the six models. However, in mixture, resource traits became more important and – in addition to size traits - explained substantial variation in species’ biomass in four models. In models where size traits were consistently important predictors of biomass variance in monoculture and mixture, the function-dominance correlation was high, and BEF relationships were strongly positive. Our analysis shows how generalizable categories of functional traits allow predicting BEF relationships across simulated systems, and thereby the potential effects of losing species on ecosystem functioning.

Rewiring, the ability of species to establish new interactions or reorganize existing ones, is important in the persistence of ecological networks under human-driven environmental changes, such as habitat loss, climate change, and species extinctions. In this paper, we (1) review the current state of knowledge regarding studies that investigate rewiring in mutualistic interactions; (2) identify important caveats and research gaps; and (3) explore rewiring in the interactions between vertebrates and fruiting plants by proposing and recommending a comprehensive list of mechanisms that may either facilitate or limit rewiring, that should be considered in future research. We argue that, while rewiring is often viewed as a flexible response driven by species abundances, co-occurrence and morphological matching, this perspective oversimplifies the complexity of ecological and evolutionary processes shaping the reorganization of mutualisms. For instance, intraspecific variation in traits, fruit chemistry, competition dynamics, the role of rare or infrequent interactions, forbidden links, and alternative modes of seed dispersal all have the potential to determine the likelihood and ecological consequences of rewiring, and should be considered in future studies. Additionally, we highlight how methodological issues, such as biased or incomplete sampling, can difficult our understanding of rewiring potential. By integrating these overlooked elements, we propose a more comprehensive approach for predicting how mutualistic networks will respond to current and future environmental change. This deeper understanding is essential for designing effective conservation strategies with the aims at understanding the resilience and functionality of ecosystems.

Characterizing the temporal changes of biotic communities and disentangling the importance of their driving mechanisms are central themes in ecology and environmental management. Non-native species have multiple adverse impact on native communities and species. However, there is a dearth of information on how non-natives influence the long-term dynamics of native communities. In this study, we compared the role of non-native species alongside various local and regional factors in the long-term dynamics of stream fish assemblages in the catchment area of Lake Balaton, Hungary, the largest lake in Central-Europe. Although, we found no consistent trend in species re-ordering between native and non-native species, native fish assemblages indicated significantly lower temporal stability with increasing relative abundance of co-occurring non-natives. Structural equation modelling revealed that assemblage dynamic patterns were also determined by a habitat degradation gradient. Moreover, habitat degradation and the presence of fishponds increased the relative abundance of non-native species, further affecting native assemblages through indirect interactions. Fish assemblage dynamics showed also some degree of finer-scale spatial structure. Non-metric multidimensional scaling further reinforced the destabilizing effect of non-native species but highlighted that native fish assemblages could generally be described by non-directional gradual or saltatory changes over time, regardless of the relative abundance of non-natives. Our results thus revealed that the studied native fish assemblages may possess some degree of resilience against biological invasions. However, increasing temporal variability induced by non-natives makes native assemblages more vulnerable to environmental stochasticity threatening their long-term persistence. This is especially worrying, since the frequency and intensity of environmental disturbances are expected to rise in the future due to climate change and increasing anthropogenic pressure on aquatic ecosystems.

As biodiversity is declining, the dynamics of species interactions is a growing conservation concern. However, estimating and monitoring species interactions across large spatial and temporal scales remain challenging, and thus changes in species interactions and the subsequent networks of interactions remain relatively unexplored. Here, we assess changes in the network structure of common bird communities from France. We estimate associated species pairs using spatial and temporal information for 109 species monitored across 1,969 sites during 17 years. We validate the ecological significance of associated species pairs by testing the relationship between the propensity to be associated and species functional proximity or shared habitat preference. We reconstruct association networks for these intra-guild bird communities and track temporal changes in network layout in terms of size, density of links, modularity and degree distribution. We show that, beyond species change, birds' local association networks become smaller with a similar relative number of associations that becomes unevenly distributed. These structural changes vary among types of bird communities and may impact community functioning and how communities can cope with global change.

Coevolution in trophic interactions is often considered as a major factor underlying diversification in both interacting species. Empirical examples of tight cospeciation are however rare. We argue that this lack of examples may reflect reality, and one reason is that speciation through bottom-up and top-down processes are not symmetric, partly because enemies are able to select the best host whereas hosts are not able to choose their enemies. In the paper, we discuss how the oscillation hypothesis through network rewiring and geographic range shifts have different consequences for the two interacting partners, leading up to differences in their capacity for local adaptations. We also argue that these processes have been poorly explored in theoretical models that focus mainly on the gene dynamics and then overlook trait asymmetries.

Fire is a key driver of the structure of plant communities. Fuel traits are important determinants of fire behavior in tropical savannas and, thus, of the effects of fire. However, whether these traits are predictable and how they are influenced by biotic and abiotic drivers remain to be rigorously evaluated. We tested the hypothesis that fuel traits are mutually correlated and change in response to abiotic factors and fire history. We sampled 31 plots in Serra da Canastra National Park (Brazil) distributed in five soil classes and measured the following fuel traits: fuel loads, height, continuity, bulk density, and bed flammability. We determined soil clay content, fire history, climate, canopy cover and elevation. We also obtained data on future fire frequency. To test for correlations among fuel traits, we used Pearson correlation tests and a principal component analysis. For the effect of abiotic factors on the traits and principal component axes, and for the effect of fuel traits on future fire regime, we used generalized linear models. We found two leading axis of fuel trait variability. The first was positively correlated to fuel height, continuity, loads, bed flammability, and grass cover, and was predicted positively by time since last fire. The second axis was positively correlated to fuel bulk density and continuity, shrub and litter cover, negatively to fuel bed flammability, and was predicted by canopy cover and soil clay content (positive associations). Grass fuel loads were the best predictor of future fire frequency and were negatively correlated to canopy cover and positively to time since last fire. Our results suggest that fuel traits change predictably in space and time, that canopy cover and time since last fire are the main factors controlling community flammability, and that grass fuel cover is a key predictor of fire frequency in savannas.

Parasite occurrence and infection estimates vary through time and space, making understanding the underlying drivers highly complex. Comparative studies based on empirical data must consider the factors of variation involved in estimating infection metrics in natural populations to make appropriate and reliable comparisons. Using a multi-scale approach, we explored the sources of variation in the estimation of infection prevalence, focusing on black spot disease in littoral freshwater fish communities sampled across 15 lakes in Québec, Canada. Our results show that infection prevalence is spatially heterogeneous across the landscape with evidence of infection hotspots and coldspots. Method-related sampling biases led to significant variations in prevalence estimates and spatial patterns of disease occurrence. Our results also indicated that low sampling efforts tend to overestimate the prevalence of infection in the landscape, and that the sampling effort required to estimate an accurate infection prevalence depends on the sampling method employed. Physico-chemical characteristics of the sites and local fish community structure were found to be the best drivers of infection at smaller spatial scales. Furthermore, our results suggest dilution effects due to obstruction and compatibility barriers limit the survival of the free-living cercaria parasite lifestage. Several relationships between infection prevalence and environmental drivers revealed non-linearity, suggesting complex interactions. Examining infection prevalence data at various spatial scales revealed method-induced biases, sampling effort effect and environment driven relationships underscoring the importance of context-dependencies and scale-dependencies in studies on host-parasite interactions.

The degree of spatial overlap between size groups within a population (hereafter, spatial overlap) influences key biological processes, such as connectivity and competition within a population. However, how changes in spatial overlap with abundance vary across populations, particularly in relation to life history traits, is largely unknown. In this study, we analyzed spatial time series data from 1982 to 2019 to investigate how spatial overlap responded to changing abundance in 56 marine fish populations across four regions. Our results show that 33 populations exhibited positive relationships between spatial overlap and abundance in over 50% of size group pairs. In the North Sea and on the Scottish West Coast, certain size group pairs showed a stronger spatial overlap-abundance relationship in populations characterized by slower growth (higher growth coefficient, longer lifespan, later maturity) and larger body sizes (greater maximum and asymptotic size), compared to populations with faster growth and smaller body sizes. This suggests that size groups within slower-growing and larger-bodied populations tend to spatially segregate more rapidly when abundance declines, making them vulnerable to local disturbances such as in hotspots of fishing pressure and habitat destruction. Our analytical approach suggests that the spatial overlap-abundance relationship could serve as a useful vulnerability index for conservation and management efforts.

Nutrient composition varies greatly across landscapes, influencing the spatiotemporal variation and dynamics of populations, yet few studies have investigated this pattern across multiple scales. We tested how nutrient limitation affects herbivore populations, from individual behavior to landscape-level population dynamics, using the Australian plague locust, Chortoicetes terminifera (Walker), with field populations and long-term survey data from across their range. At the individual level, juvenile locusts selected for a carbohydrate-biased intake target of 1 protein (p) to 2 carbohydrate (c), and exhibited the highest growth and shortest development time when fed artificial diets with that same 1p:2c ratio during the final juvenile instar. At the field level, locusts kept in cages with protein-biased plants redressed their nutritional imbalance by selecting carbohydrate-biased diets (up to a 1p:20c ratio) for over a week after being removed from the protein-biased environment, returning to the 1p:2c intake target once the deficiency was met. At the landscape level, locust outbreaks were negatively correlated with soil nitrogen and showed a non-linear relationship with soil phosphorus, peaking at approximately 4% soil phosphorus. We disentangled the interaction between mean annual precipitation and soil nitrogen using comprehensive locust surveys and remotely sensed soil and weather data spanning decades. This study is the first to integrate lab, field, and remote sensing approaches, demonstrating the importance of nutrient balancing and acquisition across scales for herbivores. Specifically for locusts, we show that low-nitrogen environments promote outbreaks, likely by reducing plant protein-to-carbohydrate ratios. Incorporating soil quality data into locust plague forecasting models could help improve prediction accuracy.

Resources, such as nitrogen, are widely hypothesized to underlie the expression and evolution of plant defenses to herbivory. However, resource availability can affect selection on plant defense traits in contrasting ways: resource availability can 1) weaken selection on defense traits by reducing the costs of herbivory, or 2) strengthen selection on defense traits by increasing herbivore pressure. Previous studies have compared herbivore resistance in populations across natural resource gradients to infer how resource availability affects the microevolution of plant defenses. However, because these studies do not manipulate resource availability, they are unable to directly test the effects of resources of plant defense trait evolution. We used a three-decade-long nitrogen fertilization field experiment to test how nitrogen availability affects the evolution of an architectural plant defense trait: stem nodding in Solidago altissima. Stem nodding is a genetic dimorphism that helps plants to evade apex-galling herbivores. By comparing the frequency of defensive nodding versus erect morphs in experimentally fertilized or unfertilized plots, we assessed how nitrogen addition affects the evolution of this defense trait. We found that the defensive nodding morph was 3-4 times more common in plots that evolved under nitrogen fertilization compared to those that evolved in unfertilized control plots. This study provides empirical evidence for resource availability driving plant defense evolution and demonstrates that this evolution can occur on time-scales conducive to study at many long-term nutrient fertilization experiments.

Understanding how metacommunities respond to natural and anthropogenic disturbances is a key objective in ecology. In this study, we introduce a robust analytical framework to identify communities whose extirpation triggers stronger (hereafter keystone communities) or weaker (hereafter idle communities) cascading effects on extinction and colonization events that ultimately drive temporal changes in compositional patterns of the remaining communities. These cascading dynamics reflect the impact of extirpated communities on connectivity and subsequent dispersal dynamics. Since the framework uses spatial information on compositional similarities to infer changes that would unfold over time due to the extirpation of one or more communities, we describe it as a space-for-time approach. Through mechanistic simulation models that replicate removal experiments, we demonstrate that our framework accurately estimates ”keystoneness”, ranking local communities by their role in maintaining the metacommunity’s compositional patterns. As such, our models demonstrate that the relationship between patch characteristics and our keystoneness metric is closely linked to the structure and dynamics of their metacommunities. A key feature of our framework is its ability to generate community keystoneness estimates that are statistically independent of local diversity, providing a valuable tool for assessing the relevance and conservation value of local communities. This is particularly important in cases where high local diversity reflects an influx of individuals into demographic sinks, a common consequence of human activities near natural areas. To showcase the unique insights of this framework, we examined and contrasted the effects of artificial light at night on the diversity and keystoneness of a moth metacommunity sampled over two decades. We conclude with a discussion of the framework’s potential applications and underlying assumptions, emphasizing its relevance for addressing both conceptual and applied ecological questions, particularly its potential to assess the conservation value of local communities under ecological stress.