Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2009)

This data set contains aboveground community biomass in 2009 (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in 2009 just prior to mowing (during peak standing biomass in early June and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in three rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). All biomass was dried to constant weight (70°C, >= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The data for individual samples and the mean over samples for all biomass measures are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.本数据集包含2009年的地上群落生物量（包括播种植物群落、杂草植物群落、枯死植物残体以及未鉴定植物材料，所有生物量指标均以干重计），以及大型草地生物多样性实验（耶拿实验（Jena Experiment）；详见下文）主实验样地中播种物种的物种特异性生物量。 主实验共设置82个20米×20米的草地样地，所用物种库包含60个隶属于4个功能群的物种：禾草、豆科植物、高大草本与矮小草本。2002年5月，研究人员从该物种库中选取不同数量的植物物种播种至样地，以构建植物物种丰富度（1、2、4、8、16和60种）与功能群丰富度（1、2、3、4个功能群）的梯度样地。样地通过每年两次除草与刈割进行管护。 2009年，在主实验所有样地的刈割前（即植被地上生物量峰值期的6月初与8月末），共开展两次地上群落生物量采样。采样方法为：在每个大样地内的3个0.2米×0.5米的矩形区域内，于地面上方3厘米处剪割植被。每次采样前，通过在样地核心区域（即中央10米×15米范围内）随机选取坐标，确定这三个矩形区域的布设位置，且所有样地内矩形区域的布设位置保持一致。 研究人员将采集到的生物量划分为以下类别：播种植物物种的单种生物量、杂草植物物种（即对应样地未播种的物种）、脱落枯死植物残体（即数据文件中的dead plant material）、以及无法归类的剩余植物材料（即数据文件中的unidentified plant material）。所有生物量样品均置于70℃环境下烘干至恒重（烘干时长≥48小时）后称重。播种植物群落生物量通过累加各播种物种的生物量计算得到。 数据集同时提供了单个样品的生物量数据，以及所有生物量指标的样地平均数据。总体而言，针对该群落生物量数据的分析已证实，物种丰富度与功能群组成是驱动正生物多样性-生产力关系（biodiversity-productivity relationship）的关键调控因子。