Plant nutrient responses

植物组织养分浓度和比值是生态系统过程和生态相互作用的重要预测因子。该项目的总体目标是研究植物多样性对植物营养响应的时间动态的影响，包括它们的稳定性，即时间长期不变性，在环境扰动期间的抗性和在环境扰动后的恢复。本项目分为三个工作包：(1)分析主实验区植物地上生物量碳(C)、氮(N)、磷(P)和钾(K)元素浓度、比例和储量的时间序列数据。我们的目标是通过结合植物群落组成、土壤特征和环境变化的数据，确定多样性影响植物群落营养响应及其时间变异的驱动因素。(2)收集主实验中所有播种物种的叶片资料，研究C、N、P和k的特定浓度，利用这些数据，分解植物群落组成与种内叶片养分浓度变化对长期生物多样性实验中植物组织元素浓度的群落均值和多样性的重要性。仅靠社区层面的数据是无法解决的。(3)我们将研究干旱和再湿润阶段植物地上生物量对同位素示踪剂（15N、13C）和碳氮浓度的物种特异性吸收，以评估植物和功能性状多样性如何缓冲干旱期间群落C和N吸收量的下降，并在植物群落恢复过程中促进群落C和N吸收量的增加。我们将分析被划分为不同功能类群的植物物种在干旱和再湿润阶段对C和N的吸收是如何变化的。在群落水平上，我们还将在两个阶段测量地上植物材料中的P和K浓度，以直接评估气候事件如何影响植物多样性对群落水平上不同养分浓度、比例和池的影响。

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.