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.

Summary 1.Conceptual frameworks relating plant traits to ecosystem processes such as organic matter dynamics are progressively moving from a leaf-centred to a whole-plant perspective. Through the use of meta-analysis and global literature data, we quantified the relative roles of litters from above-and below-ground plant organs in ecosystem labile organic matter dynamics. 2.We found that decomposition rates of leaves, fine roots and fine stems were coordinated across species worldwide although less strongly within ecosystems. We also show that fine roots and stems had lower decomposition rates relative to leaves, with large differences between woody and herbaceous species. Further, we estimated that on average below-ground litter represents approximately 33 and 48% of annual litter inputs in grasslands and forests, respectively.3. These results suggest a major role for below-ground litter as a driver of ecosystem organic matter dynamics.We also suggest that, given that fine stem and fine root litters decompose approximately 1.5 and 2.8 times slower, respectively, than leaf litter derived from the same species, cycling of labile organic matter is likely to be much slower than predicted by data from leaf litter decomposition only. Synthesis.Our results provide evidence that within ecosystems, the relative inputs of above-versus belowground litter strongly control the overall quality of the litter entering the decomposition system. This in turn determines soil labile organic matter dynamics and associated nutrient release in the ecosystem, which potentially feeds back to the mineral nutrition of plants and therefore plant trait values and plant community composition.

Plant growth dynamics are shaped by the diversity of associating pathogenic, saprotrophic, and mutualistic soil fungi.

International audienceA broad and diversified group of compounds, secondary metabolites, are known to govern species interactions in ecosystems. Recent studies have shown that secondary metabolites can also play a major role in ecosystem processes, such as plant succession or in the process of litter decomposition, by governing the interplay between plant matter and soil organisms. We reviewed the ecological role of the three main classes of secondary metabolites and the methodological challenges and novel avenues for their study. We highlight emerging general patterns of the impacts of secondary metabolites on decomposer communities and litter decomposition and argue for the consideration of secondary compounds as key drivers of soil functioning and ecosystem functioning.Synthesis. Gaining a greater understanding of plant-soil organisms relationships and underlying mechanisms, including the role of secondary metabolites, could improve our ability to understand ecosystem processes. We outline some promising directions for future research that would stimulate studies aiming to understand the interactions of secondary metabolites across a range of spatio-temporal scales. Detailed mechanistic knowledge could help us to develop models for the process of litter decomposition and nutrient cycling in ecosystems and help us to predict future impacts of global changes on ecosystem functioning