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Positive plant–plant interactions (facilitation) may enhance the recruitment and establishment of species less adapted to local macroclimatic conditions. A major cause of this effect is climatic buffering, which implies an increased mismatch between the macroclimatic conditions and the climatic requirements of the existing community – climatic disequilibrium – of plants living under canopies. Here we explore the effect of drought‐induced defoliation of Mediterranean shrubland canopy on the recruitment of woody species. We analyzed the differences in the climatic disequilibrium across different categories of canopy defoliation and plant–plant interactions: facilitation, neutral and inhibition. Climatic disequilibrium was estimated as the Euclidean distance in the multivariate environmental space between observed macroclimate and community inferred climate. The inferred climate was calculated by averaging the coordinates of the species' climatic niche centroids, obtained from species distribution, weighted by the species' relative abundances in each community. We found that the recruiting community growing under canopy showed higher climatic disequilibrium than the community growing in the gaps. The facilitated recruiting community growing under dead and living canopy showed the highest disequilibrium, followed by the community growing under mid‐affected canopy. The climatic disequilibrium of the recruiting communities experiencing neutral and inhibited interaction was not affected by canopy defoliation. These findings indicate that the climatic disequilibrium of the recruiting community is determined by the facilitation–competition balance. Living canopy provides climatic buffering, but it also implies competition, while dead canopy may provide some structural climatic buffering, without implying competition for resources. These results highlight the relevance of incorporating plant–plant interactions, particularly facilitation, to better forecast plant community responses to extreme climate events and climate change. [ABSTRACT FROM AUTHOR]

Indirect interactions among species within ecological communities govern ecological and evolutionary processes as much as, or even more, than direct effects. In insect‐pollinated plant communities, indirect interactions between plants can be mediated by shared pollinators, and may influence plant fitness, population growth and community structure. As individuals are the entities actually interacting in nature, rather than species, downscaling a hierarchical level (i.e. from species to individuals) is essential to understand the underlying processes promoting these indirect interactions. We combined empirical data on plant–pollinator interactions collected in Mediterranean shrublands with a novel modelling framework to assess how the patterns of heterospecific and conspecific pollinator sharing between plant individuals are generated and their fitness implications. We found that the effects of flowering synchrony on pollinator sharing among conspecific and heterospecific plant individuals outperformed those of spatial distance. Our results revealed that plant individuals that shared more pollinators with conspecifics were also involved in a higher pollinator sharing with heterospecifics. For most plant species, the sharing of pollinator species between heterospecific plant individuals produced positive mean fitness outcomes, as long as plants did not share many pollinator interactions, which had negative effects on their fitness. At the level of plant individuals, we found that specific combinations of conspecific and heterospecific pollinator sharing lead to distinct reproductive outcomes that placed each individual along a competition–facilitation continuum. Interestingly, most plant species included a higher proportion of individuals likely experiencing competition compared to those potentially involved in facilitation processes. Our contribution provides novel insights into the factors responsible for local‐scale indirect interactions within communities and their individual‐level functional consequences. Such intricate patterns of indirect interactions have far‐reaching implications, as the transitions of plant individuals along competitive or facilitative processes mediated by shared mutualists may contribute significantly to the functioning and coexistence of ecological communities. [ABSTRACT FROM AUTHOR]

Climate change is increasing the weather persistence in the mid‐latitudes, prolonging both dry and wet spells compared to historic averages. These newly emerging environmental conditions destabilize plant communities, but the role of species interactions in this process is unknown. Here, we tested how direct and higher‐order interactions (HOIs) between species may change in synthesized grassland communities along an experimental gradient of increasing persistence in precipitation regimes. Our results indicate that species interactions (including HOIs) are an important determinant of plant performance under increasing weather persistence. Out of the 12 most parsimonious models predicting species productivity, 75% contained significant direct interactions and 92% significant HOIs. Inclusion of direct interactions or HOIs respectively tripled or quadrupled the explained variance of target species biomass compared to null models only including the precipitation treatment. Drought was the main driver of plant responses, with longer droughts increasing direct competition but also HOI‐driven facilitation. Despite these counteracting changes, drought intensified net competition. Grasses were generally more involved in competitive interactions whereas legumes were more involved in facilitative interactions. Under longer drought, species affinity for nutrient rich or wet environments resulted in more negative direct interactions or HOIs, respectively. We conclude that HOIs, crucially depending on species identity, only partially stabilize community dynamics under increasing weather persistence. Keywords: drought, facilitation and competition, grasslands, higher‐order interactions, increasing weather persistence, species interactions [ABSTRACT FROM AUTHOR]

Phenotypic plasticity can increase the extent of the environmental gradient occupied by a species (niche breadth) and modify the portion of niche space shared among co‐occurring species (niche overlap). Thus, phenotypic plasticity may play a role in community assembly processes. Given that plants deal with a multivariate environment, and that functional traits are often correlated, plastic responses to different environmental factors are likely correlated. However, the implications of correlations of plasticities for niche overlap remain unexplored. Here, we present and evaluate a conceptual framework that links correlations of plasticities and niche overlap patterns among co‐occurring plant species. We specifically tested in an arid shrubland whether positive, negative, or null correlations between plasticity to light and water availability would be associated with patterns of high, low, or random niche overlap, respectively. Field data identified light and water availability as key factors shaping herbaceous plant community structure. We estimated species' niche breadth and niche overlap using two‐dimensional kernel–density estimations (NOK) and standardised effect sizes of Pianka's niche overlap index (OSES). We measured phenotypic plasticity to light and water availability in the six most abundant species in a greenhouse experiment. We used the plasticity index (PI) to test 1) the relationship between plasticity to light and water availability, and 2) the association between overall plasticity (average PI across traits) and niche breadth. We found a positive relationship between plasticity to light and water availability. Increased overall plasticity was associated with a broader niche breadth. Both NOK and OSES estimations indicated a significant niche overlap pattern. Results supported one of the predictions of our conceptual framework: that a positive correlation of plasticities would lead to increased niche overlap. The verified conceptual framework broadens our understanding of the role of phenotypic plasticity in plant community coexistence. [ABSTRACT FROM AUTHOR]

Numerous biodiversity–ecosystem functioning (BEF) experiments have shown that plant community productivity typically increases with species diversity. In these studies, diversity is generally quantified using metrics of taxonomic, phylogenetic, or functional differences among community members. Research has also shown that the relationships between species diversity and functioning depends on the spatial scale considered, primarily because larger areas may contain different ecosystem types and span gradients in environmental conditions, which result in a turnover of the species set present locally. A fact that has received little attention, however, is that ecological systems are hierarchically structured, from genes to individuals to communities to entire landscapes, and that additional biological variation occurs at levels of organization above and below those typically considered in BEF research. Here, we present cases of diversity effects at different hierarchical levels of organization and compare these to the species‐diversity effects traditionally studied. We argue that when this evidence is combined across levels, a general framework emerges that allows the transfer of insights and concepts between traditionally disparate disciplines. Such a framework presents an important step towards a better understanding of the functional importance of diversity in complex, real‐world systems. [ABSTRACT FROM AUTHOR]

Within‐species genetic diversity is shaped by multiple evolutionary forces within the confines of geography, and has cascading effects on the biodiversity of other taxa and levels. Invasive species are often initially limited in genetic diversity but still respond rapidly to their new range, possibly through 'pre‐adapted' genotypes or multiple sources of genetic diversity, but little is known about how their genetic structure differs from that of native species and how it alters the genetic‐species diversity relationship. Here, we selected a widespread native species Phragmites australis and its co‐occurring invasive competitor Spartina alterniflora as our model plant species. We investigated the genetic structure of P. australis using two chloroplast fragments and ten nuclear microsatellites in 13 populations along the Chinese coastal wetlands. We discovered a distinct geographical differentiation, showing that the northern and southern populations harbored unique genotypes. We also found a significant increase in genetic diversity (allelic richness and expected heterozygosity) from south to north. Combined with previous studies of S. alterniflora, the Mantel tests revealed a significant correlation of genetic distances between P. australis and S. alterniflora even when controlling for geographic distance, suggesting that the invasive species S. alterniflora might exhibit a phylogeographic pattern similar to that of the native species to some extent. Furthermore, our results suggest that the S. alterniflora invasion has altered the relationship between the genetic diversity of the dominant native plant and the associated species richness of soil nematodes. The reason for the alteration of genetic‐species diversity relationship might be that the biological invasion weakens the environmental impact on both levels of biodiversity. Our findings contribute to understanding the latitudinal patterns of intraspecific genetic diversity in widespread species. This work on the genetic diversity analysis of native species also provides significant implications for the invasion stage and ecological consequences of biological invasions. [ABSTRACT FROM AUTHOR]

In primary successions, assembling plant communities are key for ecosystem functioning and stability. Often, plant successions are described on a taxonomic, functional and/or phylogenetic level, where species' identities, traits or evolutionary histories are considered. In this study, we exploited community features characterizing whole plant assemblages to capture emerging properties only available at the community level. Next to features aggregating over multiple plant species, we used a customized multispectral 3D plant scanner extracting digital community features as proxies for the frequency distribution of traits, productivity, prevalence of plant competition, and plant strategies and functions. Using these community features, we provide a comprehensive description of plant successions along glacier forefield. Additionally, we used a community feature‐based framework assessing the covariance of community feature dissimilarities and environmental dissimilarity to explore the mechanisms underlying plant community assemblies. Our data indicate a shift from fast‐growing and acquisitive, to slow‐growing and conservative plant strategies; increased productivity; higher competition between plant species; and an increasing contribution to the biogeomorphic stability along the successional gradient. Our results further indicate that stochastic processes dominate in early succession, whereas communities are mainly shaped by deterministic processes including environmental filtering and species interactions at late succession. We conclude that assessments of plant community features, facilitated by the use of field‐ready 3D scanners, provide complementary information to trait‐based approaches on the species level with implications for ecological processes. [ABSTRACT FROM AUTHOR]

Plant communities in nature are often challenged by multiple global change factors (GCFs) and also ubiquitously encountered with soil nutrient heterogeneity. So far, however, we know little about the interactive effect of multiple GCFs and soil nutrient heterogeneity on plant communities. We conducted an outdoor mesocosm experiment in which a plant community was either grown in heterogeneous soils consisting of high‐ and low‐nutrient patches, or in homogeneous soils where the same amount of nutrients was evenly distributed. These plant communities were exposed to none (control), single, or a combination of two or four GCFs (i.e. drought, nitrogen deposition, microplastic and cadmium). Biomass of the plant community exposed to drought and nitrogen deposition were greater in heterogeneous than in homogeneous soils, but evenness of the plant community exposed to microplastics was lower. Increasing the number of GCFs increased community biomass more in heterogeneous than in homogeneous soils, but it generally reduced community evenness, independent of soil nutrient heterogeneity. These contrasting responses were related to changing competitive hierarchies and root foraging responses under different treatments. Our results suggest that soil nutrient heterogeneity can alter community productivity and diversity via changing competitive interactions of the component species, depending on both the identity and the number of GCFs acting on the community. These results have important implications for the maintenance of ecosystem functions and services under rapid and complex ongoing global changes. [ABSTRACT FROM AUTHOR]

Warming in mountain regions is projected to be three times faster than the global average. Pronounced climate change will likely lead to species reshuffling in mountain plant communities and consequently change ecosystem resilience and functioning. Yet, little is known about the role of inter‐ versus intraspecific changes of plant traits and their consequences for functional richness and evenness of mountain plant communities under climate change. We performed a downslope translocation experiment of intact plant‐soil mesocosms from an alpine pasture and a subalpine grassland in the Swiss and Austrian Alps to simulate an abrupt shift in climate and removal of dispersal barriers. Translocated plant communities experienced warmer and dryer climatic conditions. We found a considerable shift from resource conservative to resource acquisitive leaf‐economy in the two climate change scenarios. However, shifts in leaf‐economy were mainly attributable to species turnover, namely colonization by novel lowland species with trait expressions for a wider range of resource use. We also found an increase in vegetative height of the warmed and drought‐affected alpine plant community, while trait plasticity to warming and drought was limited to few graminoid species of the subalpine plant community. Our results highlight the contrast between the strong competitive potential of novel lowland species in quickly occupying available niche space and native species' lack of both the intraspecific trait variability and the plant functional trait expressions needed to increase functional richness under warming and drought. This is particularly important for the trailing range of many mountain species (i.e. subalpine zone) where upward moving lowland species are becoming more abundant and abiotic climate stressors are likely to become more frequent in the near future. Our study emphasizes mountain plant communities' vulnerability to novel climates and biotic interactions under climate change and highlights graminoid species as potential winners of a warmer and dryer future. Keywords: alpine grassland, functional diversity, invasion, species turnover, traitspace, translocation [ABSTRACT FROM AUTHOR]

Invertebrate herbivores are important and diverse, and their abundance and impacts will likely shift under climate change. Yet, past studies of invertebrate herbivory have documented highly variable responses to changing temperature, making it challenging to predict the direction and magnitude of these shifts. One explanation for these responses is that changing environmental conditions drive concurrent changes in plant communities and herbivore traits. The impacts of changing temperature on herbivory might therefore depend on how temperature combines and interacts with characteristics of plant and herbivore communities. To test this, we surveyed damage to leaves by invertebrate herbivores on 4400 plant individuals in 220 sampling plots along a 1101 m elevational gradient. Increasing temperature drove community‐level herbivory via at least three overlapping mechanisms: increasing temperature directly reduced herbivory, indirectly affected herbivory by reducing plant‐community phylogenetic diversity, and indirectly affected herbivory by altering the effects of plant‐community functional and phylogenetic diversity on herbivory. Consequently, increasing plant functional diversity reduced herbivory in colder environments while increasing plant phylogenetic diversity increased herbivory in warmer environments. Moreover, different herbivore feeding guilds varied in their response to temperature and plant community composition. These results indicate that, even along a single elevation gradient in a single year, a variety of mechanisms can concurrently drive herbivory, thereby supporting the hypothesis that a universal response of herbivory to changing environmental conditions is unlikely to exist. Instead, our results highlight the importance of considering both plant and herbivore community context to predict how climate change will alter invertebrate herbivory. [ABSTRACT FROM AUTHOR]

To understand, how the diversity and hence functioning of tundra ecosystems might respond to altering environmental conditions, fine‐scale studies are needed as local conditions may buffer broad‐scale environmental changes. Furthermore, species functional traits and phylogeny may provide complementary insights to taxonomic diversity patterns as they link plant communities to ecosystem processes often more closely than species count. Here, we examined taxonomic, functional and phylogenetic plant diversity in relation to fundamental environmental factors, namely, growing degree days, snow persistence, soil moisture, pH and fluvial disturbance in northern Norway. The relationships between eight diversity metrics and environmental predictors were investigated using hierarchical generalised additive models. Our results indicated that taxonomic, functional and phylogenetic plant diversity in tundra are all strongly linked to local snow and fluvial conditions, with average variable importance of 0.19 and 0.14, respectively, whereas the importance of other predictors was low (average variable importance < 0.06). The average explained deviance by the models was 0.23. Predicted hotspots of different diversity metrics overlapped notably and were mostly located along the streams. However, when the effect of taxonomic richness was removed from the phylogenetic and functional diversities their connections with environmental predictors were weaker but indicated strongest relationships with snow and soil pH showing distinct diversity hotspots in areas with low species richness. Our study demonstrates that investigating multiple facets of biodiversity enhances understanding on community patterns and their drivers. Furthermore, our results highlight the importance of addressing local hydrological conditions that represent both resources and disturbances for vegetation. As arctic and alpine areas are probably shifting from snow to rain dominated, incorporating snow and fluvial information into the models might be particularly important to better understand tundra ecosystems under global change. [ABSTRACT FROM AUTHOR]

Like many top consumers, parasites can regulate feeding of their prey via trait‐mediated means. If parasites modify the feeding behavior of ecologically important grazers, they may have cascading effects on the structure and functioning of whole plant communities. The extent to which parasites can influence plant communities in this way is largely dependent on the strength of their behavioral alteration, their prevalence in host grazers, and the density of those hosts. Recent experiments and comparative surveys in southeastern USA salt marshes revealed that common larval trematode parasites suppress the per capita grazing impacts of the marsh periwinkle Littoraria irrorata, generating a trophic cascade that protects foundational marsh plants from drought‐associated overgrazing. Here, we conducted a field manipulation wherein we modified grazer host density while holding infection prevalence constant at an ecologically relevant level (20%) to determine whether the indirect, facilitative effects of parasites on marsh plants varied with the density of grazers. We found that parasites had significant positive impacts on marsh net primary productivity at moderate densities of snails (≥50 snails/0.5 m2), but that the positive effects of parasites were negligible at lower densities. Our results confirm the findings of previous studies that parasites can protect marsh plants from overgrazing at sufficiently high prevalence, but show that their ability to do so depends on host density. [ABSTRACT FROM AUTHOR]

The consequences of community metrics (e.g. co‐flowering diversity and floral density) and plant traits (e.g. pollinator dependency and trait similarity) on pollen limitation (PL) may depend on pollinator‐mediated competitive or facilitative interactions among plants in co‐flowering communities, which could vary with community contexts (i.e. different altitude communities) and under human disturbances (e.g. livestock grazing). However, the mechanisms to alleviate PL under different contexts, considering pollinator‐mediated interactions among neighboring plants are unclear. We investigated PL under grazing versus ungrazing conditions in low versus high altitude alpine meadows on the Tibetan Plateau to uncover the underlying mechanisms mediating PL associated with livestock grazing. We found that PL is prevalent in alpine grasslands, irrespective of community contexts. Grazing exclusion decreased PL in the two sites but in different ways. At the high‐altitude site, PL was reduced by the exclusion of grazers through increased trait similarity (suggesting facilitation). While PL was reduced by decreased trait similarity (suggesting competition avoidance) under grazing exclusion at the low‐altitude site. Our results provide a mechanistic understanding of PL in co‐flowering alpine grassland communities under distinct human disturbances at different altitudes, emphasizing the role of pollinator‐mediated interactions among plants on plant reproductive success. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition is a primary driver of species loss in plant communities globally. However, the mechanisms by which high N availability causes species loss remain unclear. Many hypotheses for species loss with increasing N availability highlight density‐dependent mechanisms, i.e. changes in species interactions. However, an alternative set of hypotheses highlights density‐independent detrimental effects of nitrogen (e.g. N toxicity). We tested the role of density‐dependent and density‐independent mechanisms in reducing species performance. For this aim, we used 120 experimental plant communities (mesocosms) comprised of annual species growing together in containers under four fertilization treatments: 1) no nutrient addition (control), 2) all nutrients except N (P, K, and micronutrients), 3) low N (3 gN m−2) + other nutrients, and 4) high N (15 gN m−2) + other nutrients. Each fertilization treatment included two sowing densities to differentiate between the effects of competition (N × density interactions) and other detrimental effects of N. We focused on three performance attributes: the probability of reaching the reproduction period, biomass growth, and population growth. We found that individual biomass and population growth rates decreased with increasing sowing density in all nutrient treatments, implying that species interactions were predominantly negative. The common grass Avena barbata had a higher biomass and population growth under N enrichment, regardless of sowing density. In contrast, the legume Trifolium purpureum showed a density‐independent reduction in biomass growth with increasing N. Lastly, the small forb Silene palaestina showed a density‐dependent reduction in population growth, i.e. the decline occurred only under high density. Our results demonstrate that density‐dependent and density‐independent mechanisms operate simultaneously to reduce species performance under high N availability. Yet, their relative importance varies among species and life stages. [ABSTRACT FROM AUTHOR]

Relationships between area, heterogeneity and species richness are fundamental concepts in ecology yet questions remain about how area and heterogeneity tradeoff (AHTO) to constrain biodiversity. Although there is growing evidence for unimodal heterogeneity diversity relationships (HDR's) and an AHTO, tests of the concept and consequences for species richness across a landscape‐scale gradient of human‐modified ecosystems are rare. Using data from a national (Wales) field survey we analysed relationships between environmental heterogeneity and plant species richness (α and γ). We used ordination to produce a composite metric of heterogeneity and compared this to commonly used metrics. We used niche hypervolumes to categorise the breadth of plant species' ecological preferences and analysed relationships between species richness, niche width and heterogeneity. The HDR was unimodal with α diversity at the smallest scale and positive with α and γ diversity (non‐linear) at the 1 km scale although in low intensity landscapes the HDR with γ diversity was unimodal. There was a unimodal relationship between habitat diversity and γ diversity. Land use intensity was unimodally related to diversity. There were significant interactions between niche width and heterogeneity. Richness of broad niche species increased with heterogeneity with flattening of the curve at higher levels. Narrow niche species were rare and mostly unresponsive. The expected decline in narrow niche species with increasing heterogeneity was not found although they did decline with land‐use intensity. Using a unique dataset, an analysis of a large‐scale mosaic of ecosystems found that the shape of the HDR varies with land use intensity, the heterogeneity metric, spatial scale, diversity type and niche width. Although heterogeneity can increase species richness, there may be tradeoffs at higher heterogeneity. A fundamental constraint on realising the benefit of heterogeneity is the low availability of narrower niche species in local species pools in modified landscapes. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) influence plant nitrogen/phosphorus (N/P) by modifying plant N and P uptake, which further affects plant stoichiometric N/P homeostasis. Plant species and community stoichiometric N/P homeostasis can impact plant species and community stability, respectively, in response to variations of soil N and P availabilities. We investigated interspecific plant interactions via AMF in regard to plant and soil microbial N/P stoichiometry across different soil N and P availabilities induced by N and P addition (0 mg N kg−1, 25 mg N kg−1, 50 mg N kg−1, 30 mg P kg−1 and 100 mg P kg−1). We selected one dominant (Bothriochloa ischaemum; C4 grass) and one subordinate (Lespedeza davurica; legume) species in a natural grassland climax community. We examined how AMF influences stoichiometric N/P homeostasis in monoculture and mixed culture systems, and the resulting consequences for temporal stability of plant species and community in response to variations in soil N and P availability. The AMF mitigated the P limitation of soil microbial communities and decreased the degree of stoichiometric N/P homeostasis of host plants in monoculture. Through their resource‐scavenging and soil organic matter mineralisation functions, AMF enhances plant 'luxury consumption', promoting species stability in monoculture in response to soil N and P availability variations. Compared with plants in monoculture, the interaction between B. ischaemum and L. davurica via AMF increased shoot N/P under soil N‐poor conditions, leading to an enhanced degree of stoichiometric N/P homeostasis in both plant species, especially the legume. Our results suggest that interspecific plant interaction between C4 grass and legume mediated by AMF confers an advantage in complementarity in plant N acquisition under N‐poor conditions, leading to increased stability of plant communities and better maintenance of subordinate species (legume) in response to soil N deficiency. [ABSTRACT FROM AUTHOR]

The identification of drivers of bioelement concentrations in plant communities is crucial for our understanding of ecosystem functioning. In this respect, soil nutrients, plant biodiversity and functional groups are reported to affect the plant community bioelement composition. However, given the predominant focus on species richness and single elements (or stoichiometric ratios) so far, only little is known about the patterns of the whole suite of bioelements at the community level and whether these patterns can be predicted by evolutionary relationships between co‐occurring species (phylogenetic diversity). To explore this knowledge gap, we used a comprehensive dataset of soil nutrients, plant community composition, phylogeny and aboveground tissue bioelement data from experimental sites established in central European semi‐natural grasslands. Plant community bioelement composition was strongly and exponentially related to community calcium and magnesium (bioelements reflecting deep phylogenetic differences). Plant community bioelement composition and stoichiometry were best indicated by functional group composition (graminoids and forbs) and phylogenetic regularity, whereas phylogenetic richness, phylogenetic divergence and species richness were poor predictors. Bioelement‐rich communities were poor in graminoids and rich in forbs, and tended to have evenly distributed phylogenetic distances (high regularity). No confounding effect of soil nutrients was observed. The links between functional group composition, phylogenetic regularity and plant community bioelement composition suggest that functional groups and phylogenetic diversity are mechanistically connected to ecosystem functions, such as primary production, decomposition, biogeochemical cycling or plant–herbivore interactions, through bioelements. [ABSTRACT FROM AUTHOR]

Changes in some combination of niche availability, niche overlap and the strength of interspecific interactions are thought to drive changes in plant composition along resource gradients. However, because these processes are difficult to measure in the field, their relative importance in driving compositional change in plant communities remains unclear. In an Australian temperate grassland, we added seeds of three native and three exotic grasses to 1875 experimental plots in a way that allowed us to simultaneously estimate niche availability, niche overlap and the strength of pairwise interspecific interactions along a gradient of nutrient availability, obtained by adding 0, 5 or 20 g m−2 each of nitrogen, phosphorous and potassium jointly to plots. Niche availability (the proportion of microsites suitable for establishment and growth) was generally low and did not vary in response to nutrient addition. Most species co‐occurred along the nutrient gradient by partitioning the available niche space. Where species interacted due to niche overlap, the abundance of one species, the native Chloris truncata, was usually facilitated by other species, with each of the five other species increasing the niche availability to C. truncata under at least one nutrient treatment. Chloris truncata also competitively excluded two species from some but not all sites they could otherwise have occupied. These outcomes did not clearly differ across nutrient treatments. Our results show that fine‐scale spatial heterogeneity in establishment microsites can enable species to co‐occur via niche partitioning, and competitive exclusion is rare. This finding contributes to an emerging picture that niche partitioning is common and frequently a stronger influence on recruitment outcomes than interspecific competition. The importance of competition in structuring plant communities may be overestimated if recruitment processes are overlooked. [ABSTRACT FROM AUTHOR]

Heteroblastic variations among leaf traits is a well‐known process, especially in bromeliad species that show abrupt changes, but little effort was directed to test whether comparable ontogenetic variation occurs among root traits and their fungal partners. Usually considered for their mechanical role, roots of bromeliads may also play a role in resource use that we expect to differ between ontogenetic stages, namely nutrient pulse‐supplied atmospherics (young stage) and continuously‐supplied tanks (later stage). On a selection of adventitious roots of the heteroblastic epiphyte Lutheria splendens, we explored 1) ontogenetic variations in morphological and anatomical root traits, namely the number of adventitious roots and tips, total root length, average root diameter, root tissue density, specific root length and root tissue areas, and 2) ontogenetic changes in the composition of the root‐associated fungal communities using ITS1 region‐based high‐throughput sequencing. Plant size, taken as an indicator of gradual ontogenetic variations, and plant stage had significant effects on root traits, unless for root tissue density. The number of adventitious roots and tips, the total root length, average root diameter and all root tissue areas (i.e. velamen, outer cortex, inner cortex, vascular cylinder) increased gradually with ontogeny while the specific root length decreased abruptly. The root‐associated fungal communities varied with plant stage. The tank stage showed higher proportion of mycorrhizal fungi and a lower abundance of dark septate endophyte as compared to atmospheric stage. Overall, we demonstrated significant ontogenetic variations of root traits and fungal partners in bromeliad species that suggest important changes in the strategy for resource use as plants mature. We invite future root trait studies to better account for ontogenetic variations. [ABSTRACT FROM AUTHOR]

Elevational gradients are useful for predicting how plant communities respond to global warming, because communities at lower elevations experience warmer temperatures. Fine root traits and root trait variation could play an important role in determining plant community responses to warming in cold‐climate ecosystems where a large proportion of plant biomass is allocated belowground. Here, we investigated the effects of elevation‐associated temperature change on twelve chemical and morphological fine root traits of plant species and plant communities in a Swedish subarctic tundra. We also assessed the relative contributions of plant species turnover and intraspecific variation to the total amount of community‐level root trait variation explained by elevation. Several root traits, both at the species and whole community levels, had significant linear or quadratic relationships with elevation, but the direction and strength of these relationships varied among traits and plant species. Further, we found no support for a unidirectional change from more acquisitive root trait values at the lower elevations towards trait values associated with greater nutrient conservation at the higher elevations, either at the species or community level. On the other hand, root trait coefficients of variation at the community level increased with elevation for several root traits. Further, for a large proportion of the community‐level traits we found that intraspecific variation was relatively more important than species turnover, meaning that trait plasticity is important for driving community‐level trait responses to environmental factors in this tundra system. Our findings indicate that with progressing global warming, intraspecific trait variation may drive plant community composition but this may not necessarily lead to shifts in root resource–acquisition strategy for all species. [ABSTRACT FROM AUTHOR]

The complex interactions between plant roots and soil microorganisms are, broadly, well described. Yet the patterns of microbe–microbe interaction and their association with the root functional traits are less known especially in plant communities at the edges of agricultural landscapes. To address this gap, we measured the active soil microbial communities with and without the presence of plant roots, using in situ root exclusions, in four plant communities at the edges of agricultural fields: undisturbed natural deciduous forests (FOREST1), coniferous forests (FOREST2), rehabilitated agroforests (AGROFOREST) and perennial herbaceous grass buffers (GRASS). Amplicon‐based analysis of 16S rRNA and ITS transcripts was used to evaluate soil bacterial, archaeal and fungal communities, and their interactions, with 'roots' and with 'no roots'. Plants roots were measured for a suite of functional traits and explored in association with microbial community composition. Significant differences in bacterial and archaeal but not fungal diversity were observed between soil plots with 'roots' and with 'no roots'. Network analysis illustrated intra and inter kingdoms co‐occurrence patterns respond to the presence of plant roots, with GRASS exhibiting distinct patterns in comparison to tree‐dominated soils. A shift in microbial hub from bacterial to fungal was observed with the exclusion of roots; Planctomycetes (OM190)_10 was replaced by Archaeorhizomyces in AGROFOREST site. Microbial taxa strongly correlate with root traits especially specific root length, root diameter and root tissue density indicating root traits are predictors of microbial community composition. This study validates the vital role of root traits in predicting plant–microbe interactions and highlights the key role of fungi in microbial interkingdom interactions when roots are absent. These findings have significant ecosystem level implications, with the rising interest in associated biodiversity in and at the edges of agricultural landscapes, this work suggests that plant community selection for specific root traits may drive microbial community structure and ecosystem services. [ABSTRACT FROM AUTHOR]

Characterizing plant functional diversity is essential to decipher community assembly rules and ecosystem functioning. Most studies focused on above‐ground traits whereas the analysis of root diversity lags far behind. We analyzed the structure of fine root (< 2 mm) diameter distribution at the community level as an indicator of root morphological diversity, and hypothesized that the shape of the distribution provide insights on root types and root exploration strategies. We tested this hypothesis along a successional gradient (6–69 year‐old) with yearly mowing to better understand assembly rules regarding to belowground processes, and explored the relations between the parameters describing its modes and the vegetation composition and ecological properties of plant communities. Most communities showed a multimodal distribution, with two main modes corresponding to absorptive roots (thinner root mode) and transport roots (coarser root mode), and a third mode of lower importance corresponding to large transport roots. In early succession, the thinnest root mode was prominent, reflecting the dominance of thin absorptive roots and a low proportion of transport roots, resulting in a low root morphological diversity. As succession proceeds, the relative proportion of the second mode increased, and the proportions of the two main modes were more balanced, resulting in an increased variance and root morphological diversity. Furthermore, the first root mode (absorptive roots) became wider and shifted from very thin to thicker roots, suggesting the coexistence of various root strategies for resource exploration. Yearly mowing did not affect root diameter distribution, which may relate to the relative low mowing pressure that enabled woody species to remain, with stunted stature. Overall, our study demonstrates that the distribution of fine root diameters sheds light on root morphological diversity at the community level, and provide hints on the co‐existence of root types and strategies for resource use and exploration. [ABSTRACT FROM AUTHOR]

The analysis of the spatial phylogenetic and phenotypic structure of plant communities can provide insight into the underlying processes and interactions governing their assembly, and how these may change during plant ontogeny. We used point pattern analysis to find out if saplings and adult plants are surrounded by phylogenetically and phenotypically more similar or more dissimilar neighbours than expected by chance, and whether these associations change from the sapling to the adult stage. To this end, we combined information on the phylogenetic structure and eight phenotypic traits of 15 woody plant species in two Mediterranean mixed forests of southeastern Spain. At the community level, we found that the sapling bank at both sites did not show phylogenetic or phenotypic spatial patterns, but adults showed phylogenetic clustering (i.e. heterospecific neighbours were more similar than expected). At the species level, we found frequently repulsive patterns in the sapling bank of less abundant species (i.e. heterospecific sapling or adult neighbours were more dissimilar than expected) in both, phylogenetic and phenotypic analyses. For the adult stage, we found phylogenetic attraction (i.e. more similar neighbours) in just one species and phenotypic clustering in four species. The processes driving the assembly of the communities of saplings and adults leave detectable signals in the spatial phylogenetic and phenotypic structure of our two forest communities. Our findings reinforce the existence of ontogenetic shifts in the mechanisms involved in plant community assembly. Facilitation between phylogenetically distant and phenotypically divergent species favours the recruitment of less abundant species. However, processes acting later in the ontogeny ameliorate the competition between close relatives and determine the spatial structure of adult plants. Nevertheless, the role of phenotype in shaping the interactions between adult plants was context‐ and trait‐dependent. The use of spatial point pattern analysis allowed a nuanced interpretation of the phylogenetic and phenotypic structures of plant communities. [ABSTRACT FROM AUTHOR]

Global climate change threatens to substantially rearrange species interactions, yet we lack clear predictions on how these changes will cascade through communities. Many perturbations associated with climate change, such as droughts, will change resource levels, with consequences for species interactions and thus ecological network structure. Diet theory predicts foraging niche expansion when preferred resources are scarce, yet under severe resource reduction interspecific competition could alternatively increase niche partitioning. Such niche expansion and/or contraction could profoundly shape ecological network structure following perturbations, but whether these predictions hold at the community level is unclear. We studied the impacts of drought on plant–pollinator networks in long‐lived perennial plant communities in which drought affects flower and floral reward production. We assessed whether drought effects on available floral resources altered pollinator dietary niche breadth to drive higher network‐level generalization. Accounting for interaction abundance and species turnover, we compared plant–pollinator networks in two drought years and three non‐drought years. We found that drought restructured plant–pollinator networks, resulting in more generalization in terms of presence–absence of links, yet more specialization when accounting for quantitative network intensities. Our results support the application of diet theory to understanding how perturbations may impact ecological network structure. [ABSTRACT FROM AUTHOR]

Species diversity (SD) and genetic diversity (GD) are fundamental aspects of biodiversity and are dependent because they are sympatrically affected by biotic and abiotic factors. Species–genetic diversity correlations (SGDCs) range from positive to negative among multiple focal species even across same communities. As determinant mechanisms of SGDCs, previous studies identified neutral processes related with habitat size and connectivity, environmental filtering and interspecific interactions. Theoretically, similar responses of SD and GD to these mechanisms can lead to positive SGDCs. The quantitative evaluation and comparison of similarity in each mechanism have not been performed. Here, we tested whether α‐ and β‐SGDCs could be determined by similarity in ecological characteristics (ecological similarity), such as environmental responses (responses of GD to moorland area, altitude, pH, electric conductivity and spatial autocorrelation based on regression analysis), dispersal ability (seed dispersal and pollination mode) and functional traits associated with competitions (leaf height, leaf size and specific leaf area (SLA)). We investigated SD and GD of 11 species based on single nucleotide polymorphisms across 20 moorland plant communities in northern Japan, and evaluated correlations between SGDCs and principal components of the ecological characteristics across the focal species. α‐SGDCs varied from positive to negative, which was explained by ecological similarity in the response of GD to pH, seed dispersal and pollination mode, leaf height and SLA. In contrast, β‐SGDCs were almost consistently positive, which resulted from spatial autocorrelation and could not be explained by ecological similarity. We emphasized that not only environmental filtering and neutral process via dispersal limitation but also competitions can contribute to SGDCs. The incorporation of trait‐based approaches is effective for understanding spatial patterns of combinations of SD and GD. Evaluating SGDCs and spectrums of functional traits highly related to community assembly may lead to spatial predictions of GD in whole members of communities. [ABSTRACT FROM AUTHOR]

Native plant communities are often invaded by multiple alien species. It is still unclear how increasing diversity of alien invasive species suppresses the growth of native species and thus contributes to invasion success. In the subtropical monsoon region of southeast China, we experimentally created a native plant community with 18 herbaceous species. One week later, we let it be invaded by either zero (controls without invasion), one, two, four or eight alien plant species, with either high or low species evenness. After a four‐month growth period we harvested the aboveground biomass of each species. We found that increasing invasive species richness significantly increased invasive plant biomass, the biomass of all invasive and native plant species within the community, and invasion success (the ratio of invasive plant biomass to the biomass of all native and invasive plants), but it did not significantly reduce native plant biomass. Experimentally manipulating invasive species evenness did not influence invasion success and did not show any differential suppression effects on native plants. One invasive species, Sesbania cannabina, became dominant in terms of plant biomass, irrespective of its proportion in the alien plant mixtures. Throughout this experiment, effects of invasive species richness on invasion success were mainly due to such selection effects among the invasive species. On the other hand, the unchanged biomass of native species under increasing invasive plant richness suggests the presence of at least partly complementary resource niches between invasive and native species. [ABSTRACT FROM AUTHOR]

Plant–soil feedback (PSF) is recognized as an important mechanism shaping plant communities and determining plant abundance and coexistence. Under natural conditions, plants affect the outcome of plant–soil interactions simultaneously by conditioning the soil by living roots and by litter inputs into the soil. However, most experimental studies only focus on one of the pathways, which limits our understanding of PSF in the field. Here, we simultaneously explored the effect of soil conditioning by living roots and of root and shoot litter addition on the performance of seven Impatiens species grown in a two‐phase garden experiment. Soil conditioning negatively affected plant performance, which was at least partly explained by nutrient depletion. Root litter addition affected plant performance negatively and the results suggest that biotic effects such as pathogen transmission via the root litter played a role. The effects of root litter addition were more pronounced in control soil which, contrary to the conditioned soil, supposedly did not accumulate pathogens during the conditioning phase. Shoot litter addition increased soil nutrient levels, but had no impact on plant performance. However, presence of shoot litter aggravated the negative effects of root litter, probably due to increased amounts of nutrients available for soil biota and thus their faster growth and intensified effect on the plants. Overall, our study suggests that root and shoot litter have contrasting roles in plant–soil interactions and understanding their separate and interactive effects together with effects of soil conditioning is crucial for assessing the complexity of PSF. [ABSTRACT FROM AUTHOR]

Urbanisation is known to change biodiversity patterns and plant–animal interactions such as pollination – a key ecological process. Floral traits like colour, size or UV‐patterns are essential attractors for many pollinators. It is largely unknown, though, how the distribution of such floral traits within plant communities changes along an urbanisation gradient. This study aims to understand to which extent floral traits known to attract pollinators are filtered by urban environments. We used dry grassland, spanning a broad urbanisation gradient in the Berlin metropolitan area, Germany, as a model ecosystem and identified the distribution of plant traits related to bee‐perceived flower colours, UV reflection and flower size in 47 grassland patches. We analysed how these traits were related to abiotic and biotic factors at different spatial scales. The most influent predictor was an abiotic factor measured at the landscape scale: the proportion of impervious surface, found to be positively related to UV‐reflectance strength and floral UV patterns, but negatively to floral size diversity. At the local scale, abiotic factors showed an intermediary number of relationships. Temperature was negatively associated with the bee‐colour 'green + UV‐green' and with flower size. The light environment was negatively related to the same bee‐colour and to floral size diversity. Biotic factors related to local pollinator communities were less important: species richness was negatively related to flower size, while proportion of bees to floral sizes diversity. This study shows that floral traits known to attract pollinators are mostly filtered by abiotic factors related to urbanisation (share of impervious surface) or the urban heat island (local temperature). Biotic factors related to local pollinator communities were less important. These results increase our functional understanding of plant–animal interactions in cities by illustrating how urban environments modulate the attractiveness of plant communities to pollinators by filtering for floral plant traits. [ABSTRACT FROM AUTHOR]

Droughts affect plant communities, but their impacts may be mediated by soil biota. Soil communities may ameliorate drought stress, and droughts may leave legacies of altered soil communities that may affect future plant growth. However, it is not yet understood which groups of soil biota in particular affect plant performance under drought, nor which groups contribute to drought‐legacy effects on future plant growth. We hypothesized that increasing soil‐community complexity ameliorates drought stress and that drought‐legacy effects are species‐specific and soil‐community‐dependent. To test these hypotheses, we performed a two‐phase experiment with six grassland species. In the first phase, we examined plant performance under drought and ambient conditions, in soils inoculated with a sterilized inoculum, or increasingly complex soil communities created by wet‐sieving through 20‐, 40‐ and 200‐µm mesh sieves. In the second phase, we examined drought‐legacy effects on conspecific plant performance. We separately analysed plant performance in both phases, and integrated data from both phases using structural equation models. Drought effects on first‐phase root biomass depended on soil inoculum, and this interaction differed among plant species, while effects on shoot biomass differed among species, but did not depend on inoculum. Only one species experienced drought‐stress‐ameliorating effects of soil biota. Drought‐legacy effects on plant performance were positive, but depended on soil inoculum in case of root biomass, and on soil inoculum and species identity in case of shoot biomass. Drought‐legacy effects were often mediated by first‐phase biomass. In some species this effect was independent of inoculum, suggesting an abiotic legacy effect. In others, low first‐phase biomass corresponded with high second‐phase performance in presence of the most complex soil community. We conclude that drought‐legacy effects on plant performance were soil‐community‐dependent but positive, suggesting that plants establishing after drought may benefit from increased nutrient availability and more positive impacts of soil biota. [ABSTRACT FROM AUTHOR]

Fungal and arthropod consumers constitute the vast majority of global terrestrial biodiversity. Yet, the link from richness and composition of producer (plant) communities to the richness of consumer communities is poorly understood. Fungal and arthropod species richness could be a simple function of producer species richness at a site. Alternatively, it could be a complex function of chemical and structural properties of the producer species making up communities. We used databases on plant–fungus and plant–arthropod trophic links to derive the richness of consumer biota per associated plant species (coined link score). We assessed how well link scores could be predicted by simple attributes of plant species. Next, we used a multi‐taxon inventory of 130 sites, representing all major habitat types in a country (Denmark), to investigate whether link scores summed over plant species in communities (coined link sum) could outperform simple plant species richness as predictor of fungal and arthropod richness at the sites. We found plant species' link scores for both fungi and arthropods to be positively related to plant size, regional occupancy, nativeness and ectomycorrhizal status. Link‐based indices generally improved the prediction of richness of fungal and arthropod communities. For fungal communities, both observed link sum (from databases) and predicted link sum (from plant attributes) had high predictive power, while plant richness alone had none. For arthropod communities, predictive performance varied between functional groups. For both fungi and arthropods, richness predictions were further improved by considering abiotic habitat conditions. Our results underline the importance of plants as niche space for the megadiverse groups of arthropods and fungi. The plant–attribute approach holds promise for predicting local and regional consumer richness in areas of the world lacking detailed plant–consumer databases. [ABSTRACT FROM AUTHOR]

In ecosystems where trees and grasses coexist, some grass species are found only in open habitats and others persist under trees. The persistence of shade intolerant grasses in ecosystems such as open woodlands and savannas depends on recurrent fires to open the tree canopy. Therefore, grasses that depend on open sites might benefit from high flammability. We tested if shade intolerant grasses are more flammable than shade tolerant grasses and if flammability differences affected post‐fire grass growth. We examined the relationship between shade tolerance and flammability by determining individual‐level flammability and species shade tolerance of 17 grass species. We also measured grass traits to determine trait effects on flammability and the post‐fire response. Grass species varied in flammability, mainly in the amount of heat produced during burning. Shade tolerant species produced less heat at 50 cm above the ground. Biomass and live fuel moisture had the greatest effects on heat release. However, the negative effect of live fuel moisture on heat release at the soil surface was weakened in plants with high specific leaf area. In addition, grass bulk density negatively influenced heat release at 50 cm height. Heat release at the soil surface negatively influenced post‐fire growth. However, the influences of soil heating and species‐specific traits on individual survival were more complex with 2‐ and 3‐way interactions. Shade tolerance was negatively correlated with a major axis of flammability variation: shade tolerant grasses produced less heat where that heat could damage tree boles. Such heterogeneity in grass flammability may help maintain the tree–grass mixture in natural plant communities. If shade tolerant grasses near trees cause less fire damage to woody plants, especially tree saplings, this may weaken positive grass‐fire feedbacks and thus aid the long‐term coexistence of trees and grasses. [ABSTRACT FROM AUTHOR]

The diversity of tropical forests is strongly shaped by mutualistic interactions involving plants and frugivores that disperse their seeds. However, it is little known how decreases in the diversity of frugivores can affect seed dispersal patterns, plant community composition and species' coexistence in tropical forest landscapes. Here, we investigated the effects of bird frugivore diversity on seed dispersal of rare plant species and on the magnitude of equalizing effects on the seed rain in open areas within 12 fragmented landscapes in the Brazilian Atlantic Forest. We monitored the production of bird‐dispersed seeds and bird abundance in forest fragments, and sampled the seed rain and the activity of birds attracted to experimental tree nuclei established in neighboring pastures. The activity of frugivores in tree nuclei was positively correlated with the diversity of birds recorded in nearby forest fragments, and the seed rain diversity increased with frugivore activity. The proportion of seeds dispersed more frequently than expected by chance in tree nuclei increased linearly with the species' richness of birds. The richness and abundance of active frugivores in deforested areas promoted a seed rain with evenness and diversity up to five times greater than the seed pool available in forest fragments due to the proportional increase in the dispersal of rare plant species and a concomitant proportional decrease in the dispersal of dominant fruiting plants. Furthermore, every additional bird species detected in a site was associated with a 10% increase in the equalizing effect on dispersed seeds' relative abundance. Our results show that the aggregated behavior of avian frugivore communities on deforested areas results in higher species richness in the seed rain of plant communities and underscore the urgency to reduce bird species' loss and the simplification of their communities in tropical landscapes. [ABSTRACT FROM AUTHOR]

While plant–animal interactions occur fundamentally at the individual level, the bulk of research examining the mechanisms that drive interaction patterns has focused on species or population levels. In seed‐dispersal mutualisms between frugivores and plants, little is known about the role of space and individual‐level variation among plants in structuring patterns of frugivory and seed dispersal in a plant community. Here we use a zoocentric approach to examine how space and variation between individual plants affect movement and visitation by frugivores foraging on individual fruiting plants. To do this, we used a spatially explicit network approach informed by observations of the movement and foraging of a frugivorous lemur species Eulemur rubriventer among individual plants in a diverse plant community in Madagascar. The resulting hierarchical networks show a few individual plants receiving the bulk of the interactions, demonstrating that a generalist frugivore species could act as an individual‐plant specialist within a plant community. The few individual plants that dominated interactions with lemurs shaped the modular spatial structure of frugivory interactions in the community and facilitated visitation to near neighbors. This interaction structure was primarily driven by extrinsic factors, as lemur movements among plants were significantly influenced by the individual plant's spatial position and the fruiting plant richness in its immediate neighborhood. Individual plants in central spatial locations with large fruit crops received the most visits. The observed inequality in the interactions of a generalist frugivore within a highly diverse plant community highlights the importance of considering individual‐level variation for essential ecosystem processes such as seed dispersal. [ABSTRACT FROM AUTHOR]

Interactions among animals and plants are key to understanding seed dispersal, plant regeneration and plant community patterns. These interactions can be dynamic, with changes of species and functional roles across space and time. Despite fluctuations in species abundances and resources over time being the rule in natural communities, most studies approach plant–frugivore interactions as temporally static. We documented changes in bird and ant species in interactions with plants producing carbohydrate‐ (Miconia rubiginosa) or lipid‐rich diaspores (Xylopia aromatica) comparing two fruiting seasons 15 years apart in a savanna in southeastern Brazil. We tested if abundance and body size of dispersal vectors (birds and ants) affected the frequency of interactions and the quantitative effectiveness of seed dispersal (QTC). Rich bird (26 species) and ant (18 genera) assemblages interacted with the diaspores. A core of bird and ant taxa was temporally consistent, and responsible for most seed removal across the two years for both plants. Temporal transience was more common for sporadic partners of interactions, and for species with similar functional roles. Abundance and body size of birds affected the interspecific contributions to QTC. Large‐bodied birds dispersed large quantities of seeds of our relatively small‐seeded plants, even if their visits were sporadic. For ants, variations in temperature and rainfall across time seems more important in driving variations in the contributions to QTC. The combined effect of birds and ants in the same system helps to stabilize the temporal fluctuations in the amount of seeds dispersed. However, ants alone are unlikely to replace the functional roles of vertebrate dispersers. Even though species in the assemblage change either their quantitative contribution to seed dispersal or their presence or absence in the interaction network, species persisting in interaction over time are the most important quantitative partners for plants. [ABSTRACT FROM AUTHOR]

Heterospecific pollen deposition (HPD) is ubiquitous across plant communities, especially for generalized species which use a diversity of pollinators, and may have negative effects on plant reproduction. However, it is unclear whether temporal changes in the co‐flowering community result in changes in HPD patterns. Moreover, community‐level studies are required to understand which factors influence HPD and how the reproduction of different species is affected. We investigated the temporal variation of HPD, its relationship with level of specialization on pollinators and floral phenotypic specialization, and its association with reproductive success (pollen limitation and fruit set) in 31 hummingbird‐pollinated plant species in a tropical Campo Rupestre. We found seasonality in HPD, with species flowering in the dry season having greater diversity of heterospecific pollen on stigmas and a higher frequency of stigmas containing heterospecific pollen, compared to the rainy season. Stigmas of ecologically generalized species had more heterospecific pollen, while the relationship for ecologically specialized species depended on floral phenotype. Surprisingly, and in contrast to theory, we found a positive relationship between HPD and reproductive success. Our results indicate benefits of generalization and facilitation, in which sharing pollinators brings greater reproductive success via increased conspecific pollen deposition, even if it incurs more HPD. We demonstrated how assessing HPD at a community‐level can contribute to understanding the ecological causes and functional consequences of pollinator sharing. [ABSTRACT FROM AUTHOR]

The relative influence of ecological assembly processes, such as environmental filtering, competition and dispersal, vary across spatial scales. Changes in phylogenetic and taxonomic diversity across environments provide insight into these processes, however, it is challenging to assess the effect of spatial scale on these metrics. Here, we outline a nested sampling design that fractally spaces sampling locations to concentrate statistical power across spatial scales in a study area. We test this design in northeast Utah, at a study site with distinct vegetation types (including sagebrush steppe and mixed conifer forest), that vary across environmental gradients. We demonstrate the power of this design to detect changes in community phylogenetic diversity across environmental gradients and assess the spatial scale at which the sampling design captures the most variation in empirical data. We find clear evidence of broad‐scale changes in multiple features of phylogenetic and taxonomic diversity across aspect. At finer scales, we find additional variation in phylodiversity, highlighting the power of our fractal sampling design to efficiently detect patterns across multiple spatial scales. Thus, our fractal sampling design and analysis effectively identify important environmental gradients and spatial scales that drive community phylogenetic structure. We discuss the insights this gives us into the ecological assembly processes that differentiate plant communities found in northeast Utah. [ABSTRACT FROM AUTHOR]

The factors governing invasiveness and invasibility are important for understanding invasions in plant communities, but most previous work does not incorporate network‐level interaction structure. We addressed this gap by simulating perennial plant communities at multiple life stages that varied in species richness and interaction network structures (transitive and intransitive), characteristics associated with species coexistence, using a stochastic lattice model that incorporated local competition, facilitation, and dispersal. Resident communities were invaded with alien species that varied in their fecundity, dispersal, and competitive abilities. We found that community structures that are known to promote coexistence also increased invasibility; communities with intransitive interaction networks on the whole were more invasible than transitive communities. However, the interaction between species richness and network structure was complex, as intransitive communities with few species were relatively resistant and transitive communities with many species were relatively invasible. Thus, simple rules linking intransitivity and diversity may not reflect the complex relationships between community structure and dynamics that occur in more realistic spatial systems. Spatial patterns of clustering and segregation were associated with higher invasibility and successful invaders intensified these patterns in communities, particularly at large spatial scales. Invasiveness and alien species abundance were associated with species‐level characteristics (fecundity and dispersal), but community‐level characteristics were also important, particularly competitive tolerance to the resident community. These results emphasize the importance of a community‐level approach, involving network‐level structure and spatial patterns, in adding nuance to our understanding of invasions in plant communities. [ABSTRACT FROM AUTHOR]

Spatial resource partitioning between species via differences in rooting depth is one of the main explanations for the positive biodiversity–productivity relationship. However, evidence for the importance of this mechanism is limited. This may be due to the community scale at which these interactions are often investigated. Community measures represent net outcomes of species interactions and may obscure the mechanisms underlying belowground interactions. Here, we assess the performance of ~1700 individual plants and their heterospecific neighbours over three growing seasons in experimental grassland plots containing one, four or sixteen different plant species and tested whether their performance in mixtures compared to monocultures was related to their own rooting depth versus the rooting depth of their heterospecific neighbours. Overall, individuals of deep‐rooting species performed better in mixtures and this effect significantly increased when surrounded by more shallow‐rooting species. This effect was not apparent for the shallow rooting species. Together, including both deep and shallow rooting species increased mixture performance. Our results show that taking the perspective of the individual rather than the community can elucidate the interactions between species that contribute to positive biodiversity effects, emphasizing the need for studies at different scales to disentangle the myriad interactions that take place in diverse communities. [ABSTRACT FROM AUTHOR]

Invasions constitute a major driver of biodiversity changes. Insular plant communities are particularly vulnerable to invasions and are relevant models for investigating mechanisms supporting the establishment and spread of introduced plants. Terrestrial flora of sub‐Antarctic islands must often thrive in highly windy habitats, thus imposing strong mechanical constraints on individuals. Many alien plants at the sub‐Antarctic islands are of tropical or temperate origins, where they were exposed to less stringent wind conditions. As wind likely represents a strong environmental filter for the successful establishment and further geographic spread of plants, they should have developed responses to resist and successfully colonize the Iles Kerguelen. We studied responses to wind of three herbaceous species that are invasive at Iles Kerguelen. We sampled plant individuals at different locations, under windy and sheltered conditions. Traits related to wind avoidance and tolerance and to resource acquisition were measured. We additionally assessed individual performance (biomass) to determine the consequences of trait variations. We focused on trait mean and variance, in particular, through the calculation of hypervolumes. This study emphasized that wind has important effects on plant economics spectrum, including traits involved in mechanical avoidance and light acquisition, with varying strategies, which seem to depend on the biological type of the species (grass versus non‐grass). Wind generally reduces individual performance, and this negative effect is not direct but operates through the modification of plant trait values. Furthermore, analyses performed at the hypervolume scale indicate that not only functional trait mean but also its variability account for plant performance. The existence of contrasting growth strategies to cope with local environmental conditions suggests that invaders will be able to occupy different niches, which may ultimately impact local communities. Our results highlight the importance of considering multi‐traits responses to meaningfully capture plant adjustments to stress. [ABSTRACT FROM AUTHOR]

In cities, humans directly and indirectly affect plant and wildlife communities. These human–species interactions are not included in traditional ecological approaches used to understand why and how organisms are distributed. Here, we incorporate human behaviors into urban community assembly theories and detail all the complex ways humans affect the dispersal, selection and persistence of species in cities. To do this, we integrate human behaviors and actions into traditional filter frameworks used to study community assembly. We use our framework to develop testable hypotheses to predict patterns of urban diversity as well as pose key considerations for future research. In order to have a predictive understanding of how urban biodiversity responds to environmental, social and land use change, it is necessary to better understand interactions between humans and other organisms. [ABSTRACT FROM AUTHOR]

Herbivorous insect communities are structured by multiple processes operating locally (e.g. bottom–up effects of plants) and regionally (e.g. dispersal limitation). Although the relative strength of these processes has been well documented, how it varies in time is less understood, especially in relation with the temporal dynamics of plant communities. If temporal turnover of local plant species composition is too rapid for insect community assembly to keep up with, bottom–up effects are expected to be weak. Here, in plant and herbivorous insect communities in Japanese grasslands, we studied how the relative importance of local (bottom–up effects of plants, structures of plant communities and top–down effects of predators) and regional (dispersal limitation) processes varies over the growing season. In addition, we tested the hypothesis that larger temporal turnover of plant species composition is related to the weaker bottom–up effects, that is, the lower explanation power of plant communities for insect communities. We found that, throughout the growing season, the insect species composition was mainly explained by local variables (plant species composition, vegetation height and predator abundance), and their explanation power was higher during later phases of the season (late summer). Furthermore, the variation not explained by plant species composition was correlated with the degree of temporal turnover of plants, suggesting that insect communities failed to track the temporal turnover of plant species. These results were pronounced when we focused on leaf sucker insects, whose host plant range is presumably more limited. We conclude that herbivorous insect communities are mainly regulated by local processes, especially bottom–up effects from plants, while stochasticity may have played a role in early phases of the season. Furthermore, we underscore the importance of considering relative time scale of community assembly and environmental shifts, especially in systems characterized by dynamic changes. [ABSTRACT FROM AUTHOR]

Tradeoffs between intra and interspecific distances of individual plants determine the spatial distributions of local plant communities and small‐scale community assembly. Here we use an individual based approach and null model standardization to compare intra‐ and interspecific nearest neighbour distances of plant ramets as well as mean differences in functional trait expression to nearest heterospecifics within local communities of temperate forest understorey plants in northern Poland. We found a general tendency towards clustered intraspecific and segregated interspecific ramet distributions. Spatial distribution patterns of understorey plants differed considerably between two nearby forest sites that mainly differed in the age structure of trees. Individuals of clonal species tended to have significantly smaller intraspecific and larger interspecific nearest neighbour distances than seed dispersing species. Our results indicate a major influence of dominant plant species on the spatial distributions of subdominants. Trait expressions related to plant growth (specific leaf area and leaf mass) and reproduction (seed mass) were significantly segregated in comparison to the spatial distribution of conspecific individuals and less so in comparison to heterospecific individuals. We argue that spatially explicit analyses of plant community assembly need to consider respective distributions of important traits and that the tradeoffs of contrasting trait distributions trigger small scale plant community composition and species distributions. We present a general framework for the analysis of plant community assembly based on the spatial distributions of individual plants and functional traits. [ABSTRACT FROM AUTHOR]

The relationship between species richness and productivity (SRPR) has been a long‐studied and hotly debated topic in ecology. Different studies have reported different results with variable shapes (i.e. unimodal, linear) and directions (i.e. positive, negative) of SRPRs depending on spatial grain (i.e. size of sampling unit for species richness), productivity estimates and study extent. In this study, we quantified the effect of multiple estimates of productivity (aboveground, belowground and total biomass, and various measures of soil fertility) on species richness across three spatial grains (0.04, 1 and 25 m2) across temperate grasslands from two regions in central Europe. We analyzed SRPR in each of the two regional datasets separately, as well as the two datasets pooled together. Our results have revealed that differences caused by spatial grain were unexpectedly small, and the direction of the SRPR was consistent within each productivity estimate, but differed between regions. Productivity estimates (across all spatial scales) had different, sometimes contrasting effects on SRPR (together with predictive power) within a region, and this pattern was more pronounced when compared between regions. The combination of different datasets led to very different results than when these were analyzed separately. We did not find any evidence for a unimodal response. This study points to the necessity of careful assessing when combining datasets from different regions, even if the plant communities belong to the same vegetation type. The dataset combination may blur the role of different drivers, which likely determine the shape and strength of SRPR. We suggest that data and study comparability may be enhanced by consistently using the same productivity estimates, which would allow for more robust interpretation of possible ecological drivers underlying the SRPR. [ABSTRACT FROM AUTHOR]

Species and community‐level responses to warming are well documented, with plants and invertebrates known to alter their range, phenology or composition as temperature increases. The effects of warming on biotic interactions are less clearly understood, but can have consequences that cascade through ecological networks. Here, we used a natural soil temperature gradient of 5–35°C in the Hengill geothermal valley, Iceland, to investigate the effects of temperature on plant community composition and plant–invertebrate interactions. We quantified the level of invertebrate herbivory on the plant community across the temperature gradient and the interactive effects of temperature, plant phenology (i.e. development stage) and vegetation community composition on the probability of herbivory for three ubiquitous plant species, Cardamine pratensis, Cerastium fontanum and Viola palustris. We found that the percentage cover of graminoids and forbs increased, while the amount of litter decreased, with increasing soil temperature. Invertebrate herbivory also increased with soil temperature at the plant community level, but this was underpinned by different effects of temperature on herbivory for individual plant species, mediated by the seasonal development of plants and the composition of the surrounding vegetation. This illustrates the importance of considering the development stage of organisms in climate change research given the variable effects of temperature on susceptibility to herbivory at different ontogenetic stages. [ABSTRACT FROM AUTHOR]

Mycorrhizal fungi are key components of whole‐plant adaptive strategies to cope with different abiotic and biotic constraints. Although they are particularly sensitive to different global change drivers, there are still many gaps on the mechanisms underpinning shifts in mycorrhizal associations under different climatic and management scenarios. We carried out a field manipulative experiment of rainfall exclusion and increased temperature aimed to evaluate the impact of forecasted warming and drying on mycorrhizal associations of savanna plant communities subjected to different grazing history. Additionally, we compiled detailed information on the abiotic and biotic environment with the final aim of disentangling the direct and indirect effects of climate change on this widespread mycorrhizal symbiosis. Our results suggest that climate change could induce relevant changes in mycorrhizal associations, primarily promoted by warming, which decreased the abundance of mycorrhizae but induced higher activity of nutrient exchange between the host–plant and the mycosymbiont. Temperature did not only affect this symbiosis in a direct way, but also exerted relevant indirect effects via changes in soil functioning and other root‐colonizing microorganisms such as dark septate endophytes. Grazing history influenced the allocation of fungal structures inside the host‐root, but its effect differed as a function of the climatic treatment. Results from this study suggest that mycorrhizal fungi might become less prevalent in plant communities inhabiting savanna ecosystems under future scenarios of increasing aridity. In agreement with this finding, higher temperatures also promoted the predominance of plants with root traits that favour efficient resource acquisition by themselves without the help of a mycorrhizal partner. Our results provide new insights into the interactive effects of the two main threats facing Mediterranean savanna ecosystems, as well as potentially useful information to be applied in ecologically‐based management strategies aimed at attenuating the potential impact of global change on mycorrhizal fungi. [ABSTRACT FROM AUTHOR]

Competition is ubiquitous in plant communities with various effects on plant fitness and community structure. A long‐standing debate about different approaches to explain competition is the controversy between David Tilman and Philip Grime. Grime stated that the importance of competition relative to the impact of the environment increases along a productivity gradient, while Tilman argued that the intensity of competition is independent of productivity. To revisit this controversy, we assumed that the effects of plant–plant interactions are additive and applied the new competition indices by Díaz‐Sierra et al. (2017) in a field experiment along a productivity gradient in S‐Germany, using the rare arable plant Arnoseris minima as a study species. The 'target technique' was applied, to separate the effects of root and shoot competition. The study plants were exposed to five competition treatments with three replicates in 18 sites, respectively. We investigated the expectation that root competition is more intense in unproductive sites than shoot competition. Additionally, we predicted survival to be less affected by competition than growth‐related plant parameters. Using the biomass of individuals without competition as a proxy for site productivity there was a positive relationship with competition importance but no relationship with competition intensity when plants experienced full competition. Survival of the target plants was unaffected by competition. Root competition was the main mechanism determining the performance of the target plants, whereas the effect of shoot competition was relatively low albeit increasing with productivity. We conclude that when considering plant–plant interactions additive both Grime's and Tilman's theories can be supported. [ABSTRACT FROM AUTHOR]

The response of populations and species to changing conditions determines how community composition will change functionally, including via trait shifts. Selection from standing variation has been suggested to be more efficient than acquiring new mutations. Yet, studies on community trait composition and trait selection largely focus on phenotypic variation in ecological traits, whereas the underlying genomic traits remain understudied. Using a genome‐explicit, niche‐ and individual‐based model, we address the potential interactions between genomic and ecological traits shaping communities under an environmental selective forcing, namely temporal positively autocorrelated environmental fluctuation. In this model, all ecological traits are explicitly coded by the genome. For our experiments, we initialized 90 replicate communities, each with ca 350 initial species, characterized by random genomic and ecological trait combinations, on a 2D spatially explicit landscape with two orthogonal gradients (temperature and resource use). We exposed each community to two contrasting scenarios: without (i.e. static environments) and with temporal variation. We then analyzed emerging compositions of both genomic and ecological traits at the community, population and genomic levels. Communities in variable environments were species poorer than in static environments, and populations more abundant, whereas genomes had lower genetic linkage, mean genetic variation and a non‐significant tendency towards higher numbers of genes. The surviving genomes (i.e. those selected by variable environments) coded for enhanced environmental tolerance and smaller biomass, which resulted in faster life cycles and thus also in increased potential for evolutionary rescue. Under temporal environmental variation, larger, less linked genomes retained more variation in mean dispersal ability at the population level than at genomic level, whereas the opposite trend emerged for biomass. Our results provide clues to how sexually‐reproducing diploid plant communities might react to variable environments and highlights the importance of genomic traits and their interaction with ecological traits for eco‐evolutionary responses to changing climates. [ABSTRACT FROM AUTHOR]