Search

[Background and Aims] The observed positive diversity effect on ecosystem functioning has rarely been assessed in terms of intraspecific trait variability within populations. Intraspecific phenotypic variability could stem both from underlying genetic diversity and from plasticity in response to environmental cues. The latter might derive from modifications to a plant’s epigenome and potentially last multiple generations in response to previous environmental conditions. We experimentally disentangled the role of genetic diversity and diversity of parental environments on population productivity, resistance against environmental fluctuations and intraspecific phenotypic variation. [Methods} A glasshouse experiment was conducted in which different types of Arabidopsis thaliana populations were established: one population type with differing levels of genetic diversity and another type, genetically identical, but with varying diversity levels of the parental environments (parents grown in the same or different environments). The latter population type was further combined, or not, with experimental demethylation to reduce the potential epigenetic diversity produced by the diversity of parental environments. Furthermore, all populations were each grown under different environmental conditions (control, fertilization and waterlogging). Mortality, productivity and trait variability were measured in each population. [Key Results] Parental environments triggered phenotypic modifications in the offspring, which translated into more functionally diverse populations when offspring from parents grown under different conditions were brought together in mixtures. In general, neither the increase in genetic diversity nor the increase in diversity of parental environments had a remarkable effect on productivity or resistance to environmental fluctuations. However, when the epigenetic variation was reduced via demethylation, mixtures were less productive than monocultures (i.e. negative net diversity effect), caused by the reduction of phenotypic differences between different parental origins. [Conclusions] A diversity of environmental parental origins within a population could ameliorate the negative effect of competition between coexisting individuals by increasing intraspecific phenotypic variation. A diversity of parental environments could thus have comparable effects to genetic diversity. Disentangling the effect of genetic diversity and that of parental environments appears to be an important step in understanding the effect of intraspecific trait variability on coexistence and ecosystem functioning., This work was supported by the Czech Science Foundation (GACR 20-00871S) and the Estonian Research Council (project PSG293 to C.P.C.) and the European Union through the European Regional Development Fund (Centre of Excellence EcolChange to C.P.C.).

Functional and phylogenetic diversity (FD and PD respectively) of the resident community are expected to exert a key role in community resistance to colonization by surrounding species, and their establishment success. However, few studies have explored this topic experimentally or evaluated the interactive effects of these diversity measures. We implemented a diversity experiment to disentangle the role of FD and PD by sowing mixtures of 6 species, drawn from a pool of 19 species naturally coexisting in central European mesic meadows. The mixtures were designed to cover four independent combinations of high and low FD and PD. Species covers were estimated in spring and late summer over two growing seasons. We then assessed the establishment success of colonizers as a function of their mean traits and phylogenetic distance to the resident (i.e. sown) communities, as well as the resistance of the resident communities to natural colonizers as a function of their functional and phylogenetic structure. Results generally indicated a temporal shift regarding which trait values made a colonizer successful, from an acquisitive strategy in early stages to a more conservative trait syndrome in later stages. FD decreased community resistance to natural colonization. However, PD tempered this effect: with high PD, FD was not significant, suggesting complementary information between these two components of biodiversity. On average, colonizing species were more functionally distant from the resident species in sown communities with high functional diversity, i.e. those that were more colonized. Synthesis. Our results confirm an interplay between FD and PD during community assembly processes, namely resistance to colonizers, suggesting that these two descriptors of biodiversity only partially overlap in their contribution to the overall ecological structure of a community. The hypothesis that higher FD increases resistance through a more complete use of resources was challenged. Results rather suggested that greater FD could provide an unsaturated functional trait space allowing functionally unique species to occupy it., The study was supported by Czech Science Foundation grant GA16‐15012S. C.P.C. was supported by a Marie Curie Intra‐European Fellowship within the European Commission 7th Framework Programme (TANDEM; project 626392) and the Estonian Research Council (project PSG293). E.V. was funded by the 2017 program for attracting and retaining talent of Comunidad de Madrid (no. 2017‐T2/AMB‐5406).

Understanding the mechanisms that underlie species assembly is a central concern in community ecology. Abiotic and biotic filters are probabilistic ‘sieves’ that allow species with certain functional traits to become a part of the community, or not. We manipulated natural plant assemblies in order to identify variations in the timings of biotic and abiotic filters that determine community trait assemblies. We extracted soil portions when the investigated annual plant community was in its seed phase (‘community monolith’), thereby maintaining the structure and similar soil characteristics to the field conditions. Community monoliths were subjected to experimental manipulation in terms of the rainfall timing and amount, and perturbations of the biological soil crust (BSC; intact vs. perturbed). We surveyed the experimental community assembly over time based on the functional diversity by considering important functional traits in different life stages. We found that autumn droughts acted as abiotic filters by favouring the germination and establishment of species with greater investment in the root biomass. Under severe droughts (66% water reduction), the experimental assemblies were dominated by species with functional traits adapted to water shortage conditions: high leaf dry matter content, low specific leaf area, small individual size, low reproductive ratio and high root:shoot ratio. We identified two roles of BSCs in annual plant species assemblies: (a) as a biotic filter that limited the establishment of species based on seed size, and (b) as a buffer against water stress conditions by reducing soil evapotranspiration. Synthesis. We demonstrated the importance of the timing and amount of rainfall for shaping annual plant communities, and identified germination filters as the main process that determined community assemblies. Our results suggest that the phenotypic integration of functional traits facilitates resistance to drought during the life cycle. The BSC–annual plant relationship shifted from negative, by acting as a germination filter, to positive, by acting as a buffer in later stages. Climatic fluctuations and fine scale biotic determinants of spatial heterogeneity emerged as sources of changes in the community assembly in time and space to possibly promote species coexistence and trait differences among the communities studied., We give special thanks to Carlos P. Carmona for his help with plots, statistics, R and his good ideas. A.L.P. was supported by an FPU grant (grant no. AP2012–6702). This study was supported by the Spanish Science and Technology Commission (Roots CGL2015‐66809‐P and AGORA CGL2016‐77417), by the Regional Government of Madrid (Remedinal 3‐CM: S2013/MAE‐2719), and by the European Union (Gypworld H2020‐MSCA‐RISE‐2017‐777803).

The stability of ecological communities is critical for the stable provisioning of ecosystem services, such as food and forage production, carbon sequestration, and soil fertility. Greater biodiversity is expected to enhance stability across years by decreasing synchrony among species, but the drivers of stability in nature remain poorly resolved. Our analysis of time series from 79 datasets across the world showed that stability was associated more strongly with the degree of synchrony among dominant species than with species richness. The relatively weak influence of species richness is consistent with theory predicting that the effect of richness on stability weakens when synchrony is higher than expected under random fluctuations, which was the case in most communities. Land management, nutrient addition, and climate change treatments had relatively weak and varying effects on stability, modifying how species richness, synchrony, and stability interact. Our results demonstrate the prevalence of biotic drivers on ecosystem stability, with the potential for environmental drivers to alter the intricate relationship among richness, synchrony, and stability., We were supported by US NSF Grants DEB-8114302, DEB8811884, DEB-9411972, DEB-0080382, DEB-0620652, DEB-1234162, and DEB0618210; the Nutrient Network (https://nutnet.org/) experiment from NSF Research Coordination Network Grant NSF-DEB-1042132; the New Zealand National Vegetation Survey Databank; and Institute on the Environment Grant DG-0001-13. Data (Dataset 56, SI Appendix, Supplementary Text S4) owned by NERC Database Right/Copyright NERC. Further support was provided by the Jornada Basin Long-Term Ecological Research project, Cedar Creek Ecosystem Science Reserve, and the University of Minnesota. The Rothamsted Long-term Experiments National Capability is supported by UK Biotechnology and Biological Sciences Research Council Grant BBS/E/C/000J0300 and the Lawes Agricultural Trust. This research was funded by Czech Science Foundation Grant GACR16-15012S and Czech Academy of Sciences Grant RVO 67985939. E.V. was funded by 2017 Program for Attracting and Retaining Talent of Comunidad de Madrid Grant 2017-T2/AMB-5406.

Questions. Compensatory dynamics are described as one of the main mechanisms that increase community stability, e.g., where decreases of some species on a year‐to‐year basis are offset by an increase in others. Deviations from perfect synchrony between species (asynchrony) have therefore been advocated as an important mechanism underlying biodiversity effects on stability. However, it is unclear to what extent existing measures of synchrony actually capture the signal of year‐to‐year species fluctuations in the presence of long‐term directional trends in both species abundance and composition (species directional trends hereafter). Such directional trends may lead to a misinterpretation of indices commonly used to reflect year‐to‐year synchrony. Methods. An approach based on three‐term local quadrat variance (T3) which assesses population variability in a three‐year moving window, was used to overcome species directional trend effects. This “detrending” approach was applied to common indices of synchrony across a worldwide collection of 77 temporal plant community datasets comprising almost 7,800 individual plots sampled for at least six years. Plots included were either maintained under constant “control” conditions over time or were subjected to different management or disturbance treatments. Results. Accounting for directional trends increased the detection of year‐to‐year synchronous patterns in all synchrony indices considered. Specifically, synchrony values increased significantly in ~40% of the datasets with the T3 detrending approach while in ~10% synchrony decreased. For the 38 studies with both control and manipulated conditions, the increase in synchrony values was stronger for longer time series, particularly following experimental manipulation. Conclusions. Species’ long‐term directional trends can affect synchrony and stability measures potentially masking the ecological mechanism causing year‐to‐year fluctuations. As such, previous studies on community stability might have overemphasised the role of compensatory dynamics in real‐world ecosystems, and particularly in manipulative conditions, when not considering the possible overriding effects of long‐term directional trends., We thank multiple entities for the financial support necessary to obtain the different databases: the U.S. National Science Foundation under grant numbers DEB‐8114302, DEB‐8811884, DEB‐9411972, DEB‐0080382, DEB‐0620652, DEB‐1234162, DEB‐9707477, DEB‐0316402, DEB‐08‐16453, and DEB‐12‐56034, DEB‐0618210, the Nutrient Network (http://www.nutnet.org) experiment from the National Science Foundation Research Coordination Network (NSF‐DEB‐1042132), the New Zealand National Vegetation Survey Databank, the Spanish MINECO (Project CGL2014‐53789‐R), the Madrid Regional Government (Projects REMEDINAL‐3 and REMEDINAL‐TE), the European Research Council Synergy grant 610028 (IMBALANCE‐P), the Institute on the Environment (DG‐0001‐13), the SOERE‐ACBB financed through French National Agency for Research (ANAEE‐F, ANR‐11‐INBS‐0001), the Estonian Research Council (IUT 20‐28, IUT 20‐29), Czech Science Foundation (GAČR 17‐05506S and 19‐28491X), the European Regional Development Fund (Centre of Excellence EcolChange), the German Federal Environmental Foundation (DBU) for a grant to the NABU Hamburg (management experiment Calamagrostis epigejos), and the German Federal Ministry of Education and Research within the framework of the project BIOTA Southern Africa (promotion numbers 01LC0024, 01LC0024A and 01LC0624A2), Task 159 of SASSCAL (promotion number 01LG1201) and the Scottish Government's Rural and Environmental Science and Analytical Services division. Acknowledgement Data owned by NERC© Database Right/Copyright NERC. Further support was provided by the Jornada Basin Long‐Term Ecological Research (LTER) project, Cedar Creek Ecosystem Science Reserve and the University of Minnesota. We also thank the Lawes Agricultural Trust and Rothamsted Research for data from the e‐RA database. The Rothamsted Long‐term Experiments National Capability (LTE‐NCG) is supported by the UK Biotechnology and Biological Sciences Research Council (Grant BBS/E/C/000J0300) and the Lawes Agricultural Trust.

Aims: Floral traits are frequently studied in population biology and evolutionary ecology but are rarely considered in functional trait-based studies focusing on the assembly of communities. We address this gap in trait-based community assembly by synthesizing the existing literature on processes driving floral and pollination-related trait patterns at community scales. We highlight limitations of the field due to lack of data and suggest potential directions of future research. Methods: We conducted a systematic literature search collating studies that investigated floral traits in the context of plant community assembly, which allowed us to synthesize the current state of the art and point out important gaps in our knowledge. Conclusions: The literature review shows that including pollination-related traits in community assembly studies can shed new light on species coexistence patterns not accounted for by other types of traits. The synthesis presented here shows the diversity of approaches and existing techniques which can generate a step forward in this open field of research. What currently seems to hinder comprehensive analyses of floral traits at community levels is the lack of data, particularly in existing large repositories for traits worldwide, as well as a gap in linking modern coexistence theory with floral traits., Akademie Věd České Republiky. Grant Number: RVO 67985939 Grantová Agentura České Republiky. Grant Number: GACR 16‐15012S

Phenotypic plasticity, within and across generations (transgenerational plasticity), allows organisms and their progeny to adapt to the environment without modification of the underlying DNA. Recent findings suggest that epigenetic modifications are important mediators of such plasticity. However, empirical studies have, so far, mainly focused on plasticity in response to abiotic factors, overlooking the response to competition. We tested for within‐generation and transgenerational phenotypic plasticity triggered by plant–plant competition intensity, and tested whether it was mediated via DNA methylation, using the perennial, apomictic herb Taraxacum brevicorniculatum in four coordinated experiments. We then tested the consequences of transgenerational plasticity affecting competitive interactions of the offspring and ecosystem processes such as decomposition. We found that, by promoting differences in DNA methylation, offspring of plants under stronger competition developed faster and presented more resource‐conservative phenotypes. Further, these adjustments associated with less degradable leaves which have the potential to reduce nutrient turnover and might, in turn, favour plants with more conservative traits. Greater parental competition enhanced competitive abilities of the offspring by triggering adaptive phenotypic plasticity, and decreased offspring leaf decomposability. Our results suggest that competition‐induced transgenerational effects could promote rapid adaptations and species coexistence, and feed back on biodiversity assembly and nutrient cycling., The study was financially supported by a 477 Czech Science Foundation grant (GACR 20-00871S). C.P.C. was supported by the Estonian 478 Research Council (project PSG293) and the European Union through the European Regional 479 Development Fund (Centre of Excellence EcolChange).

[Background] Alternative organism designs (i.e. the existence of distinct combinations of traits leading to the same function or performance) are a widespread phenomenon in nature and are considered an important mechanism driving the evolution and maintenance of species trait diversity. However, alternative designs are rarely considered when investigating assembly rules and species effects on ecosystem functioning, assuming that single trait trade-offs linearly affect species fitness and niche differentiation. [Scope] Here, we first review the concept of alternative designs, and the empirical evidence in plants indicating the importance of the complex effects of multiple traits on fitness. We then discuss how the potential decoupling of single traits from performance and function of species can compromise our ability to detect the mechanisms responsible for species coexistence and the effects of species on ecosystems. Placing traits in the continuum of organism integration level (i.e. traits hierarchically structured ranging from organ-level traits to whole-organism traits) can help in choosing traits more directly related to performance and function. [Conclusions] We conclude that alternative designs have important implications for the resulting trait patterning expected from different assembly processes. For instance, when only single trade-offs are considered, environmental filtering is expected to result in decreased functional diversity. Alternatively, it may result in increased functional diversity as an outcome of alternative strategies providing different solutions to local conditions and thus supporting coexistence. Additionally, alternative designs can result in higher stability of ecosystem functioning as species filtering due to environmental changes would not result in directional changes in (effect) trait values. Assessing the combined effects of multiple plant traits and their implications for plant functioning and functions will improve our mechanistic inferences about the functional significance of community trait patterning., This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. F.d.B. is funded by the Czech Science Foundation, grant P505/12/1296. F.d.B. and N.P. were supported by Brazilian CAPES PVE (grant no. 88881.068053/2014-01). N.P. is supported by a PNPD/CAPES grant. A.T.C.D. was supported by the Brazilian BJT [grant no. A011/2013 (Bolsista CAPES/BRASIL)] and CNPq grant [405579/2016-0]; B.H.P.R is supported by FAPERJ (Bolsa Jovem Cientista do Nosso Estado-JCNE, E-26/203.199/2016) and Prociência.

Traditional approaches in trait‐based community ecology typically expect that trait filtering across broad environmental gradients is largely due to replacement of species, rather than intraspecific trait adjustments. Recently, the role of intraspecific trait variability has been largely highlighted as an important contributor mediating the ability of communities to persist under changing conditions and determining the community‐level trait variation, particularly across limited environmental gradients. Unfortunately, few studies quantify the relative importance of species turnover versus intraspecific variability mediating the response of communities different from vascular plants. Here, we studied the functional changes in epiphytic lichen communities within 23 beech forests across large latitudinal (ca. 3,000 km) and environmental gradients in Europe to quantify the relative contribution of species turnover and intraspecific variability and the role of climate controlling community‐level trait changes. For 58 lichen species, we focused on a set of 10 quantitative functional traits potentially affected by climatic conditions and related to photosynthetic performance (n = 1,184 thalli), water use strategy (n = 1,018 thalli), and nutrient uptake (n = 1,179 thalli). Our results showed that intraspecific trait variability explained most of the functional changes in lichen communities in response to the latitudinal gradient. Further, such functional changes were determined by the covariation between intraspecific trait variability and species turnover, which varied in sign depending on the trait considered. Finally, different climatic predictors explained functional variation due to both intraspecific trait variability and species turnover. We propose that lichen communities cope with contrasting climatic conditions by adjusting the functional trait values of the most abundant species within the communities rather than by the replacement of the species. Consequently, intraspecific variability should be explicitly incorporated to understand the effect of environmental changes on lichen communities, even over large environmental variations, better. Our results challenge the universality of the hypothesis that species turnover chiefly drives functional trait changes across large environmental gradients and call for a wider test of such important assumptions in trait ecology in different organism types and ecosystems., Ministerio de Economía y Competitividad. Grant Numbers: CGL2013‐47010‐P, CGL2016‐80562‐P, EEBB‐I‐17‐12573 REMEDINAL TE-CM. Grant Number: S2018/ EMT-4338

Functional redundancy is considered a major component of the insurance mechanism, which theoretically maintains ecosystem stability by preventing the loss of ecosystem functions with species loss. Over the past decades, examination of functional trait patterns to elucidate processes of community stability and ecosystem functioning have stimulated considerable amount of research in ecology. As a result, a multitude of indices have been developed, describing community functional structure with various levels of overlap in their methodology. Here, we review the set of indices that have been suggested to measure the level of redundancy in traits among species in ecological communities. We first evaluate the correlations among redundancy indices and classical indices of community taxonomic and functional structure (species richness, Simpson diversity, functional richness, evenness and divergence). Second, we estimate the predictive power of these indices in terms of community vulnerability to species loss. Finally, we assess the sensitivity of the results to scenarios with different species loss orders. We simulated communities with different levels of taxonomic and functional structure (richness, evenness and divergence). Then, we simulated four scenarios of species loss order (abundance, functional uniqueness, environmental sensibility and random). The vulnerability of communities was estimated by the changes in community structural parameters (functional richness, functional divergence and biomass) as species were progressively removed from the initial communities. Our results showed that four out of the five redundancy indices tested were strongly correlated (Pearson R > ∣0.6∣) with at least one of the classical indices of community structure. Those correlations partly explained why the redundancy indices did not outperform classical indices in predicting community vulnerability to species loss. The fifth redundancy index (FredD) was the least correlated with classical indices of community structure (Pearson R < ∣0.24∣), however it also reached the lowest performance in predicting community vulnerability to species loss (R2 < 0.07). The order in which species – and their functional traits – are lost, and the community parameters assessed had a strong impact on communities’ vulnerability to species loss. In contradiction to theoretical predictions of the insurance hypothesis, the current redundancy indices might not be good indicators of vulnerability to species loss., We are grateful to the editor and the two anonymous reviewers for their valuable comments that contributed to improve the manuscript. The study was supported by Czech Science Foundation grant GA16‐15012S. F.d.B. was supported by the Agencia Estatal de Investigacion (Plan Nacional de I+D+i, project PGC2018-099027-B-I00). C.P.C. was supported by the Estonian Research Council (project PSG293). E.V. was funded by the 2017 program for attracting and retaining talent of Comunidad de Madrid (no. 2017‐T2/ AMB‐5406).

Traditionally, trait-based studies have explored single-trait-fitness relationships. However, this approximation in the study of fitness components is often too simplistic, given that fitness is determined by the interplay of multiple traits, which could even lead to multiple functional strategies with comparable fitness (i.e. alternative designs). Here we suggest that an analytical framework using boosted regression trees (BRT) can prove more informative to test hypotheses on trait combinations compared to standard linear models. We use two published datasets for comparisons: a botanical garden dataset with 557 plant species (Herben, 2012, Journal of Ecology, 100, 1522) and an observational dataset with 83 plant species (Adler, 2014, Proceedings of the National Academy of Sciences, 111, 740). Using the observational dataset, we found that BRTs predict the role of traits on the relative importance of survival, growth and reproduction for population growth rate better than linear models do. Moreover, we split species cultivated in different habitats within the botanical garden and observed that seed and vegetative reproduction depended on trait combinations in most habitats. Our analyses suggest that, while not all traits impact fitness components to the same degree, it is crucial to consider traits that represent different ecological dimensions. Synthesis. The analysis of trait combinations, and corresponding alternative designs via BRTs, represent a promising approach for understanding and managing functional changes in vegetation composition through measurement of suites of relatively easily measurable traits., N.P. and F.d.B. were supported by Brazilian PVE/CAPES grant number 88881.068053/2014‐01. F.d.B. and L.G. are supported by the Czech Science Foundation, grant GA16‐15012S. A.T.C.D. was supported by the Brazilian BJT grant number A011/2013 (Bolsista CAPES/BRASIL) and by the Brazilian Council for Scientific and Technological Development (CNPq), grant 405579/2016‐0. R.S.‐G. was supported by NERC IRF R/142195‐11‐1. B.H.P.R. is supported by FAPERJ (Bolsa Jovem Cientista do Nosso Estado‐JCNE, E‐26/203.199/2016) and Prociência. C.P.C. was supported by the Estonian Research Council (projects MOBJD13 and PSG293), and by the European Union through the European Regional Development Fund (Centre of Excellence EcolChange).