Plant traits – the morphological, anatomical, physiological, biochemical and phenological characteristics of plants and their organs – determine how primary producers respond to environmental factors, affect other trophic levels, influence ecosystem processes and services and provide a link from species richness to ecosystem functional diversity. Trait data thus represent the raw material for a wide range of research from evolutionary biology, community and functional ecology to biogeography. Here we present the global database initiative named TRY, which has united a wide range of the plant trait research community worldwide and gained an unprecedented buy-in of trait data: so far 93 trait databases have been contributed. The data repository currently contains almost three million trait entries for 69 000 out of the world's 300 000 plant species, with a focus on 52 groups of traits characterizing the vegetative and regeneration stages of the plant life cycle, including growth, dispersal, establishment and persistence. A first data analysis shows that most plant traits are approximately log-normally distributed, with widely differing ranges of variation across traits. Most trait variation is between species (interspecific), but significant intraspecific variation is also documented, up to 40% of the overall variation. Plant functional types (PFTs), as commonly used in vegetation models, capture a substantial fraction of the observed variation – but for several traits most variation occurs within PFTs, up to 75% of the overall variation. In the context of vegetation models these traits would better be represented by state variables rather than fixed parameter values. The improved availability of plant trait data in the unified global database is expected to support a paradigm shift from species to trait-based ecology, offer new opportunities for synthetic plant trait research and enable a more realistic and empirically grounded representation of terrestrial vegetation in Earth system models.

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. Geosphere-Biosphere Program (IGBP) and DIVERSITAS, the TRY database (TRY-not an acronym, rather a statement of sentiment; https ://www.try-db.org; Kattge et al., 2011) was proposed with the explicit assignment to improve the availability and accessibility of plant trait data for ecology and earth system sciences. The Max Planck Institute for Biogeochemistry (MPI-BGC) offered to host the database and the different groups joined forces for this community-driven program. Two factors were key to the success of TRY: the support and trust of leaders in the field of functional plant ecology submitting large databases and the long-term funding by the Max Planck Society, the MPI-BGC and the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, which has enabled the continuous development of the TRY database.

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Questions Functional redundancy in assemblages may insure ecosystem processes after perturbation potentially causing temporary or permanent local species extinctions. Yet, functional redundancy has only been inferred by indirect evidence or measured by methods that may not be the most appropriate. Here, we apply an existing method to measure functional redundancy, which is the fraction of species diversity not expressed by functional diversity, to assess whether functional redundancy affects community resilience after disturbance. Location Subtropical grassland, south Brazil (30°05′46″S, 51°40′37″W). Method Species traits and community composition were assessed in quadrats before grazing and after community recovery. Grazing intensity (G) was measured in each quadrat. We used traits linked to grazing intensity to define functional redundancy (FR) as the difference of Gini–Simpson index of species diversity (D) and Rao's quadratic entropy (Q). Also, with the same traits, we defined community functional stability (S) as the similarity between trait‐based community composition before grazing and 47 and 180 d after grazing ending. Using path analysis we assessed different postulated causal models linking functional diversity (Q), functional redundancy (FR), grazing intensity (G) and community‐weighted mean traits to community stability (S) under grazing. Results Path analysis revealed the most valid causal model FR → S ← G, with a significant positive path coefficient for FR → S and a marginally significant negative one for S ← G. Since FR and G were independent in their covariation and in their effects on S, the model discriminated community resistance to grazing (the effect of G on S) from community resilience after grazing caused by functional redundancy (indicated by the effect of FR on S). Conclusion We show that expressing functional redundancy mathematically is a useful tool for testing causal models linking diversity to community stability. The results support the conclusion that functional redundancy enhanced community resilience, therefore corroborating the insurance hypothesis.

Questions What are the main short‐term changes in vegetation structure after fire and mowing in Campos grasslands? Are there differences in functional vegetation group responses between sites with diverse fire histories and different treatments (fire and mowing)? Location Subtropical grasslands in Porto Alegre, Brazil, 30 °03′ S, 51 °07′ W. Methods In two sites with different fire histories: FB – frequently burned grasslands and E – exclusion of fire for 6 yr, seven pairs of plots were examined. In each pair, fire and mowing treatments were established. Bare soil and litter cover were estimated. Vegetation relevés were conducted, plants identified, their cover estimated and stems counted (except for graminoids). Later, plants were grouped according to their functional group (graminoids, forbs and shrubs) for statistical analyses. Observations were conducted 30, 90 and 360 d after treatments. Results Burned plots always showed a higher percentage of bare soil, whilst mowed plots had higher litter cover. Fire enhanced graminoid and forb cover, but did not affect shrubs. Species turnover was very high, mainly in burned plots in site FB and in mowed plots in site E. Species diversity in burned plots was the same in sites FB and E 1 yr after treatments, contrary to our hypothesis. However, in mowed plots, the number of species tended to decrease 1 yr after treatments for both sites FB and E. Conclusions The most important short‐term effect was the removal of litter and consequent opening of gaps, mostly by fire. This stimulated vegetation regeneration and provided microsites for the establishment of new species. However, fire did not enhance plant diversity, as we had hypothesized. Moreover, the disturbance history of sites should be considered, since vegetation in these sites responded differently to fire and mowing.