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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<p>Vegetation affects water balance partitioning via effects on incoming precipitation, local radiation balance and hydrological dynamics of soil. The extent of these effects is determined by plant functional traits. Commonly, the role of plant species on hydrological regulation has been assessed considering vegetation as homogeneous cover, even more, that approach underestimates the importance of species in this process. Nevertheless, in recent years, new focus has been placed on species study based on their functional traits and their roles in ecosystem functions as hydrological regulation. Still new tendencies are considering vegetation cover consisting of different species, each of them having different effects on hydrological regulation because they have different functional traits. In an 8-year old ecosystem restoration project established in Medellín (Colombia), we explored the relations between plant functional traits of 10 dominant species and ecohydrological processes that determine precipitation partitioning in the canopy via stemflow and throughfall. Here we show that functional traits describing tree crowns are significantly related with stemflow and throughfall. Our species exhibit differences in their functional traits and ecohydrological processes, forming a gradient of variation of ecohydrological processes and crown functional traits: from wide and less dense crowns in <em>Alnus acuminata</em> to smaller but more dense crowns in <em>Quercus humboldtii</em>, related with less throughfall temporal variability, and less stemflow temporal variability, respectively; the other species are placed along this gradient. This result suggests a complementary effect of species on the hydrological processes and consequently on the hydrological function, highlighting the importance of considering species diversity on hydrological regulation assessment. More specifically, our results emphasize the need to include information about the effects of species planted in ecological restoration projects over ecohydrological processes, via ecological criteria such as plant functional traits. This approach permits a more objective and complete study of hydrological regulation that brings key information for an adequate ecosystem management and restoration based on ecological roles of species that, through biological diversity, optimize ecosystem functions and services.</p>