Functional Trait Approach Research Articles

Toward a Functional Trait Approach to Bee Ecology.

Functional traits offer an informative framework for understanding ecosystem functioning and responses to global change. Trait data are abundant in the literature, yet many communities of practice lack data standards for trait measurement and data sharing, hindering data reuse that could reveal large-scale patterns in functional and evolutionary ecology. Here, we present a roadmap toward community data standards for trait-based research on bees, including a protocol for effective trait data sharing. We also review the state of bee functional trait research, highlighting common measurement approaches and knowledge gaps. These studies were overwhelmingly situated in agroecosystems and focused predominantly on morphological and behavioral traits, while phenological and physiological traits were infrequently measured. Studies investigating climate change effects were also uncommon. Along with our review, we present an aggregated morphological trait dataset compiled from our focal studies, representing more than 1600 bee species globally and serving as a template for standardized bee trait data presentation. We highlight obstacles to harmonizing this trait data, especially ambiguity in trait classes, methodology, and sampling metadata. Our framework for trait data sharing leverages common data standards to resolve these ambiguities and ensure interoperability between datasets, promoting accessibility and usability of trait data to advance bee ecological research.

Unveiling Arthropod Responses to Climate Change: A Functional Trait Analysis in Intensive Pastures.

This study investigates the impact of elevated temperatures on arthropod communities in intensively managed pastures on the volcanic island of Terceira, Azores (Portugal), using a functional trait approach. Open Top Chambers (OTCs) were employed to simulate increased temperatures, and the functional traits of ground dwelling arthropods were analyzed along a small elevation gradient (180-400 m) during winter and summer. Key findings include lower abundances of herbivores, coprophagous organisms, detritivores, and fungivores at high elevations in summer, with predators showing a peak at middle elevations. Larger-bodied arthropods were more prevalent at higher elevations during winter, while beetles exhibited distinct ecological traits, with larger species peaking at middle elevations. The OTCs significantly affected the arthropod communities, increasing the abundance of herbivores, predators, coprophagous organisms, and fungivores during winter by alleviating environmental stressors. Notably, iridescent beetles decreased with elevation and were more common inside OTCs at lower elevations, suggesting a thermoregulatory advantage. The study underscores the importance of considering functional traits in assessing the impacts of climate change on arthropod communities and highlights the complex, species-specific nature of their responses to environmental changes.

A complex relationship between cropping systems and soil macrofauna: Influence of practice intensity, taxa and traits

Larger soil organisms have often been reported as the most sensitive to disturbances caused by cropping practices. However, soil macrofauna comprises groups with a wide diversity of morphological and ecological features, which may respond differently to applied practices. In order to further assess the effect of cropping systems on soil macrofauna, macrofauna organisms were extracted from soil blocks over 21 fields (each comprising three plots) located in the Paris basin, in autumns 2020 and 2021. Fields belonged to conventional, conservation or organic systems, either long-established (≥ 7 years) or in transition (≤ 3 years). Tillage, pesticide treatment and organic matter input intensity were assessed in each field using composite indexes of practice intensity. Macrofauna density and diversity, earthworm ecological categories, species richness and functional traits were investigated. Our results showed that the density and diversity of macrofauna demonstrated few differences regarding different cropping systems, with highly variable effects across groups and years. Specific macroarthropod groups responded differently to tillage, pesticide treatment and organic input intensity, but not over the two years of the study. Regarding earthworms, high tillage intensity had a negative effect on the density and biomass of epi-anecic juveniles and on species with a small body size. Higher organic matter inputs had a negative effect on the density and biomass of endogeic earthworms, and could be related to several earthworm functional traits (body length, mass/length ratio, carbon preferences). Effects of pesticide treatments were less clear, although they could have impacted some earthworm species. More generally, taxonomic and functional trait approaches of earthworm community led to similar conclusions. Overall, our results support the need to account for (i) the actual intensity of practices in cropping systems and (ii) the different taxonomic, trophic and ecological groups of macrofauna, in order to assess the effects of cropping systems on soil biodiversity.

Understanding woody plant encroachment: A plant functional trait approach

AbstractThe increasing density of woody plants threatens the integrity of grassy ecosystems. It remains unclear if such encroachment can be explained mostly by direct effects of resources on woody plant growth or by indirect effects of disturbances imposing tree recruitment limitation. Here, we investigate whether woody plant functional traits provide a mechanistic understanding of the complex relationships between these resource and disturbance effects. We first assess the role of rainfall, soil fertility, texture, and geomorphology to explain variation in woody plant encroachment (WPE) following livestock grazing and consequent fire suppression across the Serengeti ecosystem. Second, we explore trait‐environment relationships and how these mediate vegetation response to fire suppression. We find that WPE is strongest in areas with high soil fertility, high rainfall, and intermediate catena positions. These conditions also promote woody plant communities characterized by small stature and seed sizes smaller relative to a comparative baseline within the Serengeti ecosystem, alongside high recruit densities (linked to a recruitment‐stature trade‐off). The positioning of species along this “recruitment‐stature axis” predicted woody stem density increase in livestock sites. Structural equation modeling suggested a causal pathway where environmental factors shape the community trait composition, subsequently influencing woody recruit numbers. These numbers, in turn, predicted an area's vulnerability to WPE. Our study underscores the importance of trait‐environment relationships in predicting the impact of human alterations on local vegetation change. Understanding how environmental factors directly (resources) and indirectly (legacy effects and plant traits) determine WPE supports the development of process‐based ecosystem structure and function models.

Plant-soil feedback and plant invasion: effect of soil conditioning on native and invasive Prosopis species using the plant functional trait approach.

Invasive species have been identified as a major threat to native biodiversity and ecosystem functioning worldwide due to their superiority in spread and growth. Such superiority is explained by the invasional meltdown phenomena, which suggests that invasive species facilitate the establishment of more invasive species rather than native species by modifying the plant-soil feedback (PSF). We conducted a two-phase plant-soil feedback experiment using the native Prosopis cineraria and the invasive Prosopis juliflora in Oman. Firstly, we conditioned the soil by planting seedlings of native species, invasive species, native and invasive species "mixed", and unconditioned soil served as a control. Secondly, we tested the feedback of these four conditioned soil on the two species separately by measuring the productivity (total biomass) and the performance in the form of plant functional traits (plant height, specific leaf area (SLA), leaf nitrogen content (Nmass), leaf carbon content (Cmass) and specific root length (SRL) of native and invasive species as well as the nutrient availability in soil (soil organic carbon (SOC) and soil total nitrogen (STN)). We found that the native species produced more biomass, best performance, and higher SOC and STN when grown in soil conditioned by native species, additionally, it gave lower biomass, reduced performance, and lower SOC and STN when grown in the soil conditioned by invasive and mixed species. These results suggest negative PSF for native species and positive PSF for invasive species in the soil conditioned by invasive species, which can be considered as red flag concerning the restoration of P. cineraria as an important native species in Oman, as such positive PSF of the invasive species P. juliflora will inhibit the regeneration of P. cineraria.

Herbivorous Reef Fish Interaction with the Habitat and Physicochemical Variables in Coral Ecosystems in the Mexican Tropical Pacific

Herbivorous fish can mediate spatial competition between algae and corals, which is crucial for coral ecosystems. However, in areas with limited coral coverage like the Mexican tropical Pacific (MTP), this dynamic is not fully understood. This study, using a functional trait approach and ordination analysis, explores whether herbivorous reef fish assemblage influences the benthic habitat components or if physicochemical factors define the habitat variability in the MTP’s Cleofas and Marietas insular systems. We analyzed if this relationship persisted across systems and over time, and identified species traits tied to habitat variability. Island comparison analyses between Cleofas and Marietas reveal that both herbivorous reef fish and physicochemical variables shape the habitat. Cleofas had larger mobile herbivorous fish that formed groups related mostly to macroalgae cover. In contrast, temporal analysis of Marietas shows that the habitat is primarily shaped by physicochemical variables with herbivorous fish being mainly small farmer species related to branching corals. Notably, these closely situated insular systems present varied ecosystem mediators, influenced by diverse drivers including fish traits and environmental factors. This study underscores the potential of employing a framework of ecological species traits combined with ordination methods to unravel the distinct site dynamics that contribute to the persistence of coral ecosystems within the MTP.

Functional diversity in relation to the longitudinal gradient of a species-rich Neotropical river

Abstract A functional traits approach was adopted to examine patterns of fish diversity in relation to environmental and spatial variables and for comparison with findings from earlier analyses of fish taxonomic diversity in a nearly pristine river in the Llanos region of Colombia. Fishes were surveyed during the low-water period at 34 sites along the longitudinal fluvial gradient of the Bita River, a clearwater tributary of the Orinoco River. We compiled a matrix of 37 traits associated with locomotion, feeding, and defense for 132 species to compute functional β diversity metrics among four reaches along the entire longitudinal fluvial gradient and also within reaches. Functional redundancy (trait under-dispersion) was found to be common throughout the fluvial gradient. Functional β diversity was high at both spatial scales, with widespread evidence of functional nestedness and functional turnover, especially in upper reaches. In the Bita River, environmental filtering and stochastic processes, such as random dispersal, appear to be the dominant mechanisms influencing fish functional diversity. Inferences derived from analysis of functional versus taxonomic diversity are largely congruent, although analysis of functional β diversity found more evidence of nestedness than turnover at both spatial scales. Both lines of evidence stress the importance of habitat heterogeneity and aquatic habitat connectivity for conservation of high species diversity in this system.

Biochar application can mitigate the negative impacts of drought in invaded experimental grasslands as shown by a functional traits approach

Climate, land-use, and invasive plants are among the important drivers of ecosystem functions through the changes in functional composition. In this study, we studied the effects of climate (drought), land-use (Biochar application), and the presence of invasive species on the productivity and performance of invaded experimental grasslands. We ran a greenhouse experiment under controlled conditions, in which we grew a combination of the three native species Silene gallica, Brassica nigra and Phalaris minor and the invasive species Avena fatua, being subjected to four different treatments: Biochar+drought, Biochar, drought, and control. We measured the productivity of native and invasive species as total biomass and root to shoot ratio (RSR) and the performance by measuring several plant functional traits (plant height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (Nmass), leaf carbon content (Cmass) and total chlorophyll (Chltotal) of all individuals occurring in each plot. The study showed that invasive species were more productive (higher total biomass and lower RSR) and performed better (taller plants, higher SLA, Nmass, Cmass and Chltotal and lower LDMC) than the native species under drought conditions as well as with Biochar application. Accordingly, in contrast to our expectations, the lower productivity and performance of native compared to invasive species under drought were not mitigated by Biochar application. These results provided a deeper understanding of the interplay between climate, land-use, and biological invasion, which is crucial for predicting the consequences of changes in functional composition on ecosystem functions and consequently restoration of grasslands.

A feedback loop between management, intraspecific trait variation and harvesting practices.

Intraspecific variation in plants is a major ecological mechanism whose local determinants are still poorly understood. In particular, the relationship between this variation and human practices may be key to understanding human-nature relationships. We argue that it is necessary to consider how human practices both influence and depend on the phenotypic variability of species of interest. Arnica montana (arnica) is a good model to study the complex interactions between human actions and plant phenotype, as (i) its ecological niche is shaped by human management actions and (ii) its variability has consequences for harvesters. Using a functional trait approach, we examined feedback loops linking management actions, plant phenotype and harvesting practices. In 27 sites in southeastern France, we measured vegetative and reproductive functional traits of arnica of interest for harvesters, and recorded management actions (grazing; mowing) and ecological variables (including height of surrounding vegetation and tree cover). We examined their effects on plant traits with linear mixed models and used path analysis to test if the effects of human management on traits are mediated by the height of surrounding vegetation. Management actions affected functional traits of arnica. Biomass removal practices (grazing, mowing) were associated with smaller plants producing smaller leaves with reduced specific leaf area. We uncovered the core role of the height of surrounding vegetation in determining this phenotype. Tree cover was associated with reduced flowering. The observed intraspecific variation in response to management actions differentially impacts the two main harvesting practices. Flower-head harvesting depends on reproductive traits that are not impacted by mowing (which is done in winter) but adversely affected by tree cover. In contrast, traits associated with large biomass under tree cover or with high surrounding vegetation are favourable for whole-plant harvesters. Our trait-based approach unveiled clear links between management actions and plant phenotype, with impacts on both vegetative and reproductive traits. These changes induced by management also affect the practices of harvesters. We thus demonstrated a feedback loop between human actions and plant phenotype and provided a novel perspective on human-related causes and consequences of plant intraspecific variability.

Assessing the Impact of Anthropic Pressures on Aquatic Macroinvertebrates: A Functional Trait Approach in the Irtysh River Watershed.

Little is known about how changes in the biodiversity and functional traits of macroinvertebrates in rivers respond to the responses of anthropic pressures and their driving factors. Macroinvertebrates were sampled at 17 sites in the Irtysh River Basin and classified macroinvertebrates into 10 traits and 38 categories between May and August 2022. Then, we performed R-mode linked to Q-mode (RLQ) analysis and calculated functional richness, evenness, divergence, and Rao's quadratic entropy (RaoQ) for each site and community-weighted means for each trait category. Our results indicated that there were pronounced alterations in species variability in the urban region. Functional divergence indicated fierce competition among species and considerable niche overlap in the urban region. Functional evenness indicated that species abundance distribution and interspecific functional distance were not uniform in the urban region. Functional richness indicated that the urban region was the strongest region in terms of niche occupation, resource utilization, and buffering capacity for environmental fluctuations. Rao's quadratic entropy showed that the trait difference of macroinvertebrates was the largest in all regions, which was caused by the gradient environmental difference. Research has revealed that urbanization significantly influences the evolutionary trajectory of macroinvertebrate fauna, culminating in an upsurge in pollution-tolerant species and a convergence of functional traits. We recommend strengthening the control of urban and industrial pollution and wise planning and management of land and water resources to mitigate the impact of anthropogenic destruction on habitat fragmentation in the Irtysh River Basin.

Alternative measures of trait-niche relationships: A test on dispersal traits in saproxylic beetles.

Functional trait approaches are common in ecology, but a lack of clear hypotheses on how traits relate to environmental gradients (i.e., trait-niche relationships) often makes uncovering mechanisms difficult. Furthermore, measures of community functional structure differ in their implications, yet inferences are seldom compared among metrics. Community-weighted mean trait values (CWMs), a common measure, are largely driven by the most common species and thus do not reflect community-wide trait-niche relationships per se. Alternatively, trait-niche relationships can be estimated across a larger group of species using hierarchical joint species distribution models (JSDMs), quantified by a parameter Γ. We investigated how inferences about trait-niche relationships are affected by the choice of metric. Using deadwood-dependent (saproxylic) beetles in fragmented Finnish forests, we followed a protocol for investigating trait-niche relationships by (1) identifying environmental filters (climate, forest age, and deadwood volume), (2) relating these to an ecological function (dispersal ability), and (3) identifying traits related to this function (wing morphology). We tested 18 hypothesized dispersal relationships using both CWM and Γ estimates across these environmental gradients. CWMs were more likely than Γ to show support for trait-niche relationships. Up to 13% of species' realized niches were explained by dispersal traits, but the directions of effects were consistent with fewer than 11%-39% of our 18 trait-niche hypotheses (depending on the metric used). This highlights the difficulty in connecting morphological traits and ecological functions in insects, despite the clear conceptual link between landscape connectivity and flight-related traits. Caution is thus warranted in hypothesis development, particularly where apparent trait-function links are less clear. Inferences differ when CWMs versus Γ estimates are used, necessitating the choice of a metric that reflects study questions. CWMs help explain the effects of environmental gradients on community trait composition, whereas the effects of traits on species' niches are better estimated using hierarchical JSDMs.

Calcareous grassland restored by clearance and subsequent sheep grazing show fast recovery of plant functional traits – Results from a 25-year-long experiment

In this study, the long-term restoration success of calcareous grasslands was investigated using a functional trait approach. The study site is located in the Swabian Alb, Germany, where a former calcareous grassland patch was restored in the 1990s by clearance of a spruce (Picea abies (L.) H. Karst.) afforestation and subsequent reintroduction of sheep grazing as mobile dispersal vector. Vegetation development was monitored over a period of 25 years, both on the restored and an adjacent never afforested ancient grassland which is still managed by traditional sheep grazing. Changes in the functional composition of fifteen ecological meaningful traits were investigated by comparing the respective attribute expressions of the restored with the ancient reference grassland for each year of observation. A RLQ-analysis was conducted in order to identify plant functional groups. The comparison of attribute expressions showed that differences between restored and ancient grassland decreased rapidly over time. The greatest differences were found in persistence-related traits (e.g., life span and growth form) while dispersal- and establishment-related traits recovered faster. The clustering of plant functional groups showed similarities with Grime’s CSR-strategy, as cluster analysis grouped species with either ruderal, competitive or stress-tolerant trait attributes. 20 years after restoration, stress-tolerators dominated, while the ruderal cluster could not longer be detected and only a small group of competitive, mostly woody species remained. In 2018, RLQ analysis revealed no differences in the functional composition between restored and ancient grassland. The quick functional recovery is most likely attributed to the reestablishment of the traditional low-intensive grazing management but also to the close vicinity of the ancient grassland as no spatial isolation prevented dispersal of plant species. Hence, the functional trait approach showed that restoration by clearance and subsequent sheep grazing was a suitable management in our study.

Direct and indirect effects of a fishing ban on lacustrine fish community do not result in a full recovery

Abstract Protected areas are increasingly being promoted as an important means of protecting freshwater biological diversity and ecological processes. A robust assessment of ecological changes in protected areas is fundamental to optimize conservation policies and adaptive management. China's efforts to establish aquatic reserves have attracted worldwide attention, especially the “10‐year fishing ban” implemented in the Yangtze River basin. We focused on Liangzi Lake, a freshwater protected area in the Yangtze River basin, to understand the effect of a fishing ban occurring after a short period of overfishing. In this aim, the time series of fish community taxonomic and functional structure encompassing the overfishing period and a post‐ban period have been analysed. Fish community metrics with direct, indirect and no responses to fishing bans were identified. The results indicate that in the early period of the fishing ban, the trophic level and body size structure of the fish community were in the way of recovery. However, species that prefer benthic habitats did not recover after fishing‐induced habitat degradation. Functional traits were more sensitive than taxonomic indices and revealed subtle community changes, such as the recovery of some ecological functions, despite a non‐recovering species richness. Synthesis and applications. This study provides a rare case of a freshwater protected area in which the effects of conservation measures are studied with a temporal survey. The effectiveness of the functional trait approach in the application of protected area assessment was demonstrated by revealing the recovery of trophic level and body size structure of fish communities after the implementation of fishing ban, and the inadequacy of habitat restoration efforts. We suggest that in freshwater protected areas, insistence on fishing ban is necessary but not sufficient for full biodiversity recovery, and other measures are needed, such as habitat restoration and species‐focused stocking.

Warming, drought, and disturbances lead to shifts in functional composition: A millennial-scale analysis for Amazonian and Andean sites.

Tropical forests are changing in composition and productivity, probably in response to changes in climate and disturbances. The responses to these multiple environmental drivers, and the mechanisms underlying the changes, remain largely unknown. Here, we use a functional trait approach on timescales of 10,000 years to assess how climate and disturbances influence the community-mean adult height, leaf area, seed mass, and wood density for eight lowland and highland forest landscapes. To do so, we combine data of eight fossil pollen records with functional traits and proxies for climate (temperature, precipitation, and El Niño frequency) and disturbances (fire and general disturbances). We found that temperature and disturbances were the most important drivers of changes in functional composition. Increased water availability (high precipitation and low El Niño frequency) generally led to more acquisitive trait composition (large leaves and soft wood). In lowland forests, warmer climates decreased community-mean height probably because of increased water stress, whereas in highland forests warmer climates increased height probably because of upslope migration of taller species. Disturbance increased the abundance of acquisitive, disturbance-adapted taxa with small seeds for quick colonization of disturbed sites, large leaves for light capture, and soft wood to attain fast height growth. Fire had weak effects on lowland forests but led to more stress-adapted taxa that are tall with fast life cycles and small seeds that can quickly colonize burned sites. Site-specific analyses were largely in line with cross-site analyses, except for varying site-level effects of El Niño frequency and fire activity, possibly because regional patterns in El Niño are not a good predictor of local changes, and charcoal abundances do not reflect fire intensity or severity. With future global changes, tropical Amazonian and Andean forests may transition toward shorter, drought- and disturbance-adapted forests in the lowlands but taller forests in the highlands.

Environment- and scale-dependent changes in the functioning of invertebrate communities associated with Fucus vesiculosus

The functional trait approach focuses on the diversity of species characteristics, and can reveal much more about community functioning and trophic structure, compared to classical biodiversity concepts. In this study, we assessed large- and small-scale patterns in the functional traits of invertebrate communities associated with the marine macroalga Fucus vesiculosus. Large-scale comparisons were done across coastal areas representing different water quality (good, moderate, and poor) and small-scale comparisons across communities from sites with different exposures (sheltered, exposed) within the areas. Functional richness differed between areas of different water quality, with higher richness generally observed in areas with clearer waters. On a smaller scale, functional richness and dispersion were highest at sheltered sites, whereas the effect of exposure on functional divergence varied between study areas. Community trait composition differed among areas of different water quality with opportunistic traits becoming more prevalent in areas in poorer state. For example, community-weighted body sizes differed between areas and the smallest body sizes were observed in areas with moderate or poor water quality. The results illustrate how faunal traits within the same habitat type can differ geographically and how the functioning of communities may change due to anthropogenic pressures and natural drivers at different scales.

A functional trait approach reveals the effects of landscape context on ecosystem services provided by urban birds

A functional trait approach reveals the effects of landscape context on ecosystem services provided by urban birds

Testing the predictive value of functional traits in diverse ant communities.

Associating morphological features with ecological traits is essential for understanding the connection between organisms and their roles in the environment. If applied successfully, functional trait approaches link form and function in an organism. However, functional trait data not associated with natural history information provide an incomplete picture of an organism's role in the ecosystem. Using data on the relative trophic position of 592 ant (Formicidae) samples comprising 393 species from 11 subfamilies and 19 widely distributed communities, we tested the extent to which commonly used functional proxies (i.e., morphometric traits) predict diet/trophic position as estimated from stable isotopes (δ15N). We chose ants as a group due to their ubiquity and abundance, as well as the wealth of available data on species traits and trophic levels. We measured 12 traits that have previously been identified as functionally significant, and corrected trait values for size and evolutionary history by using phylogenetically corrected trait residuals. Estimated trophic positions varied from 0.9 to 4.8 or roughly 4 trophic levels. Morphological data spanned nearly the entire size range seen in ants from the smallest (e.g., Strumigenys mitis total length 1.1 mm) to the largest species (e.g., Dinoponera australis total length 28.3 mm). We found overall body size, relative eye position, and scape length to be informative for predicting diet/trophic position in these communities, albeit with relatively weak predictive values. Specifically, trophic position was negatively correlated with body size and positively correlated with sensory traits (higher eye position and scape length). Our results suggest that functional trait-based approaches can be informative but should be used with caution unless clear links between form and function have been established.

Changes in functional traits and diversity of typical alpine grasslands after a short-term trampling disturbance

Alpine grassland ecosystem supports high diversity of terrestrial flora and fauna species. Despite the ecological importance and economic potential of this unique ecosystem type, it experiences increasing anthropogenic disturbances such as trampling, which impose negative impact on the health and integrity of alpine grasslands. Previous studies of trampling impact on alpine vegetation mainly focus on changes in vegetation cover and taxonomic diversity after trampling disturbance, but rarely test community-level responses of alpine vegetation to trampling from a functional trait perspective. Through the lens of vegetation functional traits, the present study evaluates the impacts of simulated trampling on typical alpine grasslands in Shangri-la, China. The results showed that although increased trampling intensity did not always lead to changes in functional diversity across all three experimental sites, characteristics of community-weighted mean trait values had consistently changed toward plant species with shorter height, reduced leaf area and lower leaf dry matter content, and such strong shifts in functional attributes may further affect ecosystem goods and services provided by alpine grasslands. Therefore, a functional trait approach can help us better understand the mechanisms that drive trait changes, function shifts and vegetation stability following anthropogenic disturbances.

Effects of Hydrologic Regime Changes on a Taxonomic and Functional Trait Structure of Earthworm Communities in Mountain Wetlands.

Disturbances, both natural and anthropogenic, influence the patterning of species and species traits. The shift in species composition and distribution pattern of functional traits can demonstrate if the community is resistant, sensitive or resilient to the disturbance. Based on species- and trait-based approaches, we examined the response of the earthworm community to changing hydrologic conditions caused by the artificial drainage of mountain fens, in which cumulative effects of disturbance events over space and time are much less dynamic than in riverine wetlands. We hypothesized that the drainage-related changes of mountain fen peat soils have an effect on the earthworm community composition and its functional structure. We assume that the shift in species composition and value of community-weighted functional traits reflect changes in the resilience or resistance of the earthworm community to environmental change. Our results demonstrate that the total density of earthworms was almost three times lower under drained conditions compared to natural ones. Artificial drainage of fens had a neutral effect on the species-based diversity indices. However, there were species-specific traits that responded to hydrologic changes and which led to the species' replacements and to the co-occurrence of eurytopic, surface-browsing and more drought- and low-pH-resistant earthworm species in the drained fens. Based on these results, we conclude that abiotic-based environmental filtering was the main process responsible for sorting earthworms according to species and traits in the disturbed hydrologic conditions. The greater earthworm functional trait variations in semi-natural hydrologic conditions emphasizes the impact of transient dynamics in an altered disturbance regime on the earthworm assembly. Results also showed that in the changing hydrologic conditions of mountain fens, the functional trait approach revealed only slightly more predictive power than the taxonomic one, but it proved better with processes responsible for earthworm species filtering.

Island plant functional syndromes and competition with invasive species

AbstractIsland floras are diverse with exceptionally high rates of endemicity, and they are also severely threatened. Invasive plants are widespread on islands, but whether islands are particularly susceptible to invasion or island species are more vulnerable to displacement, or both, remains unclear. As part of the “island plant syndrome,” it has been predicted that island plants have convergently evolved conservative resource use, slow growth rates, and weak competitive abilities in response to moderate climates and the presumed absence of competition in communities with relatively low species richness. Yet, functional trait approaches have provided mixed evidence to support this prediction, and direct tests of competition as neighbour effects on plant performance are lacking. Considering the extensive environmental heterogeneity that exists within islands and among islands, it seems more likely that diverse functional strategies, spanning conservative to acquisitive, have evolved in island plants. Furthermore, assessing island plant syndrome predictions through comparisons with invasive species, which are nonrandom subsets of continental plants, is a flawed approach. Future studies that compare functional strategies of native island versus native continental plants and direct tests for competition between native and invasive island plants within the local scale at which competition occurs, and that consider non‐additivities with other simultaneous global threats, are urgently needed to conserve these biodiversity hotspots.