Search

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (<10 y). In contrast, long-term (≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

Locally, plant species richness supports many ecosystem functions. Yet, the mechanisms driving these often‐positive biodiversity–ecosystem functioning relationships are not well understood. Spatial resource partitioning across vertical resource gradients is one of the main hypothesized causes for enhanced ecosystem functioning in more biodiverse grasslands. Spatial resource partitioning occurs if species differ in where they acquire resources and can happen both above‐ and belowground. However, studies investigating spatial resource partitioning in grasslands provide inconsistent evidence. We present the results of a meta‐analysis of 21 data sets from experimental species‐richness gradients in grasslands. We test the hypothesis that increasing spatial resource partitioning along vertical resource gradients enhances ecosystem functioning in diverse grassland plant communities above‐ and belowground. To test this hypothesis, we asked three questions. (1) Does species richness enhance biomass production or community resource uptake across sites? (2) Is there evidence of spatial resource partitioning as indicated by resource tracer uptake and biomass allocation above‐ and belowground? (3) Is evidence of spatial resource partitioning correlated with increased biomass production or community resource uptake? Although plant species richness enhanced community nitrogen and potassium uptake and biomass production above‐ and belowground, we found that plant communities did not meet our criteria for spatial resource partitioning, though they did invest in significantly more aboveground biomass in higher canopy layers in mixture relative to monoculture. Furthermore, the extent of spatial resource partitioning across studies was not positively correlated with either biomass production or community resource uptake. Our results suggest that spatial resource partitioning across vertical resource gradients alone does not offer a general explanation for enhanced ecosystem functioning

A substantial body of evidence has demonstrated that biodiversity stabilizes ecosystem functioning over time in grassland ecosystems. However, the relative importance of different facets of biodiversity underlying the diversity–stability relationship remains unclear. Here we use data from 39 grassland biodiversity experiments and structural equation modelling to investigate the roles of species richness, phylogenetic diversity and both the diversity and community-weighted mean of functional traits representing the ‘fast–slow’ leaf economics spectrum in driving the diversity–stability relationship. We found that high species richness and phylogenetic diversity stabilize biomass production via enhanced asynchrony in the performance of co-occurring species. Contrary to expectations, low phylogenetic diversity enhances ecosystem stability directly, albeit weakly. While the diversity of fast–slow functional traits has a weak effect on ecosystem stability, communities dominated by slow species enhance ecosystem stability by increasing mean biomass production relative to the standard deviation of biomass over time. Our in-depth, integrative assessment of factors influencing the diversity–stability relationship demonstrates a more multicausal relationship than has been previously acknowledged.

Protected Areas are a key component of nature conservation. They can play an important role in counterbalancing the impacts of ecosystem degradation. For an optimal protection of a Protected Area it is essential to account for the variables underlying the major Ecosystem Services an area delivers, and the threats upon them. Here we show that the perception of these important variables differs markedly between scientists and managers of Protected Areas in mountains and transitional waters. Scientists emphasise variables of abiotic and biotic nature, whereas managers highlight socio-economic, cultural and anthropogenic variables. This indicates fundamental differences in perception. To be able to better protect an area it would be advisable to bring the perception of scientists and managers closer together. Intensified and harmonised communication across disciplinary and professional boundaries will be needed to implement and improve Ecosystem Service oriented management strategies in current and future Protected Areas

Are we entering a new ‘Golden Age’ of biogeography, with continued development of infrastructure and ideas? We highlight recent developments, and the challenges and opportunities they bring, in light of the snapshot provided by the 7th biennial meeting of the International Biogeography Society (IBS 2015). We summarize themes in and across 15 symposia using narrative analysis and word clouds, which we complement with recent publication trends and ‘research fronts’. We find that biogeography is still strongly defined by core sub-disciplines that reflect its origins in botanical, zoological (particularly bird and mammal), and geographic (e.g., island, montane) studies of the 1800s. That core is being enriched by large datasets (e.g. of environmental variables, ‘omics’, species’ occurrences, traits) and new techniques (e.g., advances in genetics, remote sensing, modeling) that promote studies with increasing detail and at increasing scales; disciplinary breadth is being diversified (e.g., by developments in paleobiogeography and microbiology) and integrated through the transfer of approaches and sharing of theory (e.g., spatial modeling and phylogenetics in evolutionary–ecological contexts). Yet some subdisciplines remain on the fringe (e.g., marine biogeography, deep-time paleobiogeography), new horizons and new theory may be overshadowed by popular techniques (e.g., species distribution modelling), and hypotheses, data, and analyses may each be wanting. Trends in publication suggest a shift away from traditional biogeography journals to multidisciplinary or open access journals. Thus, there are currently many opportunities and challenges as biogeography increasingly addresses human impacts on, and stewardship of, the planet (e.g., Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). As in the past, biogeographers doubtless will continue to be engaged by new data and methods in exploring the nexus between biology and geography for decades

Global change drivers are rapidly altering resource availability and biodiversity. While there is consensus that greater biodiversity increases the functioning of ecosystems, the extent to which biodiversity buffers ecosystem productivity in response to changes in resource availability remains unclear. We use data from 16 grassland experiments across North America and Europe that manipulated plant species richness and one of two essential resources—soil nutrients or water—to assess the direction and strength of the interaction between plant diversity and resource alteration on above-ground productivity and net biodiversity, complementarity, and selection effects. Despite strong increases in productivity with nutrient addition and decreases in productivity with drought, we found that resource alterations did not alter biodiversity–ecosystem functioning relationships. Our results suggest that these relationships are largely determined by increases in complementarity effects along plant species richness gradients. Although nutrient addition reduced complementarity effects at high diversity, this appears to be due to high biomass in monocultures under nutrient enrichment. Our results indicate that diversity and the complementarity of species are important regulators of grassland ecosystem productivity, regardless of changes in other drivers of ecosystem function.

It remains unclear whether biodiversity buffers ecosystems against climate extremes, which are becoming increasingly frequent worldwide1. Early results suggested that the ecosystem productivity of diverse grassland plant communities was more resistant, changing less during drought, and more resilient, recovering more quickly after drought, than that of depauperate communities2. However, subsequent experimental tests produced mixed results. Here we use data from 46 experiments that manipulated grassland plant diversity to test whether biodiversity provides resistance during and resilience after climate events. We show that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. Across all studies and climate events, the productivity of low-diversity communities with one or two species changed by approximately 50% during climate events, whereas that of high-diversity communities with 16–32 species was more resistant, changing by only approximately 25%. By a year after each climate event, ecosystem productivity had often fully recovered, or overshot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events. Anthropogenic environmental changes that drive biodiversity loss thus seem likely to decrease ecosystem stability14, and restoration of biodiversity to increase it, mainly by changing the resistance of ecosystem productivity to climate events.

Climate change is likely to alter decomposition rates through direct effects on soil biotic activity and indirect effects on litter quality with possible impacts on the global carbon budget and nutrient cycling. Currently, there is a need to study the combined effects of climatic drivers and agricultural practises on decomposition.In an in situ litter bag experiment, we studied the effects of rainfall variability (including drought combined with heavy rain pulses as well as regular irrigation) interacting with winter warming and increased winter precipitation and with changes in cutting frequency, on decomposition in a temperate grassland. Litter bags contained mixed and species-specific litter of all different climate and land-use manipulations and were placed within the plots of litter origin. Moreover, we aimed to disentangle the causes of changes in decomposition by investigating two further approaches: Firstly, we studied the effects of changes in leaf chemicals as a result of the manipulations by removing litter from the experiment that has been pre-exposed to the manipulations before placing it on an untreated standard plot outside the experiment. Secondly, we assessed the effects of changes in soil faunal activity by investigating the decomposition of standard material under differing rainfall variability.As a result, decomposition was reduced when litter bags were exposed to drought for six weeks within an 11 months period. Neither additional winter rain nor winter warming had an effect on decomposition, likely because winter warming reduced snow cover and increased variability of surface temperatures. Climate manipulations did not change litter quality. Furthermore, decomposition on the untreated standard plot was not affected by the climate manipulations that the litter was previously exposed to. Thus, reduced decomposition under extreme rainfall variability and drought may mainly be caused by a decrease in soil biotic activity, as indicated by reduced de

Water availability and plant community composition alter plant nutrient availability and the accumulation of plant defence compounds therefore having an impact on herbivore performance. Combined effects of drought stress and plant community composition on leaf chemicals and herbivore performance are largely unexplored. The objective of our study was, therefore, to find out the impact of extreme drought and of plant community composition on plant–herbivore interactions. Larvae of the generalist butterfly Spodoptera littoralis were reared on leaves of the grass Holcus lanatus which was grown in experimental communities, differing in species- and functional group richness. These communities were either subjected to extreme drought or remained under ambient climatic conditions. Drought decreased relative water content, soluble protein content, nitrogen and total phenol content and increased the content of carbohydrates in the grass. As a consequence, the larvae feeding on drought-exposed plants revealed a longer larval stage, increased pupal weight and higher adult eclosion rates. Plant community composition mainly caused changes to the defensive compounds of the grass, but also marginally affected protein and carbohydrate content. Larvae feeding on species-richest communities without legumes showed the highest mortality. Our findings imply that climate change that is projected to increase the frequency of severe droughts, as well as alter plant community compositions, is likely to affect arthropod–plant interactions through an alteration of leaf chemicals. Climate change; EVENT-experiments; Drought; Diversity; Legume

The frequency of extreme drought events is projected to increase under global climate change, causing damage to plants and crop yield despite potential acclimation. We investigated whether grasses remain acclimated to drought even after a harvest and remember early summer drought exposure over a whole vegetation period. For this, we compared the response of Arrhenatherum elatius plants under a second, late, drought (they were pre-exposed to an early drought before), to plants exposed to a single, only late, extreme drought. Surprisingly, the percentage of living biomass after a late drought increased for plants that were exposed to drought earlier in the growing season compared to single-stressed plants, even after harvest and resprouting after the first drought. Relative leaf water content did not differ between the two treatments. Net photosynthesis was non-significantly reduced by 25% in recurrent drought treatment. Maximum quantum efficiency (Fv/Fm) and maximum fluorescence (Fm) were reduced in plants that were exposed to recurrent drought. These findings indicated improved photoprotection in double-stressed plants. Our results provide first hints towards a "drought memory" over an entire vegetation period, even after harvest and resprouting. However, the advantage of improved photoprotection might also cause reductions in photosynthesis that could have adverse effects on crop yield under more severe or longer droughts.

1. Studying the effects of extreme climatic or weather events such as drought and heat waves on biodiversity and ecosystem functions is one of themost important facets of climate change research. In particular, primary production is amounting to the common currency in field experiments worldwide. Rarely, however, are multiple ecosystem functions measured in a single study in order to address general patterns across different categories of responses and to analyse effects of climate extremes on various ecosystemfunctions.2. We set up a long-term field experiment, where we applied recurrent severe drought events annually for five consecutive years to constructed grassland communities in central Europe. The 32 response parameters studied were closely related to ecosystem functions such as primary production, nutrient cycling, carbon fixation, water regulation and community stability. 3. Surprisingly, in the face of severe drought, above- and below-ground primary production of plants remained stable across all years of the drought manipulation.4. Yet, severe drought significantly reduced below-ground performance of microbes in soil indicated by reduced soil respiration, microbial biomass and cellulose decomposition rates as well as mycorrhization rates. Furthermore, drought reduced leaf water potential, leaf gas exchange and leaf protein content, while increasing maximum uptake capacity, leaf carbon isotope signature and leaf carbohydrate content. With regard to community stability, drought induced complementary plant-plant interactions and shifts in flower phenology, and decreased invasibility of plant communities and primary consumer abundance.5. Synthesis. Our results provide the first field-based experimental evidence that climate extremes initiate plant physiological processes, whichmay serve to regulate ecosystemproductivity. A potential reason for different dynamics in various ecosystem services facing extreme climatic events may lie in the temporal hierarchy of

Soil freeze-thaw cycles (FTC) influence nutrient cycling, but their consequences for productivity and composition of vegetation are not well investigated. Ongoing global warming will increase the recurrence of FTC in cool-temperate and high-latitude regions. Here, we report on the above- and belowground biomass production as well as the nitrogen nutrition of two common vegetation types, grassland and heath, after more frequent FTC in a controlled field experiment in Central Europe. Furthermore, we analyze the duration of the observed effects. Five FTC were induced by buried heating wires in addition to three naturally occurring FTC during winter 2005/06. More frequent FTC significantly increased aboveground production of experimental grassland early in the following growing season. However, no reaction was found for experimental heath within the first growing season. Biomass production of heath communities dropped significantly and C/N ratio increased in the freeze-thaw treated plots in the second year after the manipulation, whereas production in the grassland communities was no longer affected significantly, except for an increase in C/N ratio. This response can at least partly be explained by changes in nutrient availability, as plant available nitrate increased in the manipulated grassland plots and decreased in the manipulated heath plots. The results show the high ecological importance of climate changes during winter, with the outcomes differing strongly between contrasting vegetation types. Furthermore, we show that short term climatic events can cause long-lasting effects, sometimes emerging in the vegetation only after considerable time lags (here: one growing season).

The use of local provenances in restoration, agriculture and forestry has been identified as measure to sustain biological diversity and to improve local productivity. However, the delineation of regional provenances is challenging because it requires the identification of well-defined groups based on spatiogenetic differentiation and/or the evidence of local adaptation. In this study, we investigate genetic variation at 186 AFLP loci in 46 European accessions of the important grassland species Arrhenatherum elatius and ask (1) whether genetic variation within accessions differs between European geographical regions; (2) at which spatial scale populations are structured across Europe and (3) whether putatively adaptive markers contribute to this pattern and whether these markers can be related to climatic site conditions. Basic expectations of population genetics are likely to be altered in autotetraploid species, thus, we adopted a band-based approach to estimate genetic diversity and structuring. Compared to other grasses A. elatius showed high genetic diversity and considerable differentiation among accessions (FST = 0.24). Accessions separated in a Western European and a Central/Eastern European group, without further structure within groups. A genome scan approach identified four potentially adaptive loci, whose band frequencies correlated significantly with climatic parameters, suggesting that genetic differentiation in A. elatius is also the result of adaptive processes. Knowledge on adaptive loci might in the long run also help to adapt ecosystems to adverse climate change effects through assisted migration of ecotypes rather than introduction of new species.