Plant nutrient responses

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Plant tissue nutrient concentrations and ratios are important predictors of ecosystem processes and ecological interactions. The overall objective of this project is to study the effects of plant diversity on the temporal dynamics of plant nutrient responses, including their stability as temporal long-term invariability, resistance during and recovery after environmental perturbations. The project is organized in three work packages: (1) We will analyze the time-series data of community-level elemental concentrations, ratios and stocks of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) in plant aboveground biomass of the Main Experiment. We aim to identify the drivers underlying diversity effects on plant community nutrient responses and their temporal variability by incorporating data on changes in plant community composition, soil characteristics and environmental changes. (2) We will collect leaf material of all sown species in the plant communities of the Main Experiment to study specific-specific concentrations of C, N, P and K. Using these data, we intend to decompose the importance of plant community composition versus the importance of intraspecific variation in leaf nutrient concentrations for the community means and diversity of plant tissue elemental concentrations in the long-term biodiversity experiment, which cannot be disentangled alone with community-level data. (3) We will study the species-specific uptake of isotopic tracers (15N, 13C) and carbon and nitrogen concentrations in plant aboveground biomass during the drought and re-wetting phase of the ResCUE Experiment to assess how plant and functional trait diversity buffer against the decline in community-level C and N uptake during drought and promote increased community-level C and N uptake when plant communities recover during re-wetting. We will analyze how plant species assigned to different functional groups and distinguished by different functional traits related to drought resistance vary in their C and N uptake during the drought and re-wetting phase. At the community level, we will also measure concentrations of P and K in aboveground plant material in both phases of the ResCUE Experiment to directly evaluate how climate events influence plant diversity effects on community-level concentrations, ratios and pools of different nutrients.