Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2002)

This data set contains aboveground community biomass (Sown plant community, 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 in September 2002 just prior to mowing (during peak standing biomass) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in one rectangle of 0.2 x 0.5 m per large plot. The location of the rectangle was assigned prior to 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 rectangle within plots were identical for all plots. The harvested biomass was sorted into categories: in 2002 only individual species for the sown plant species were separated and processed. 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. 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.

本数据集包含大型草原生物多样性实验（耶拿实验（Jena Experiment），详见下文）主实验样地的地上群落生物量（播种植物群落，以干重生物量计）以及其中播种物种的物种特异性生物量。
在主实验中，研究人员从包含4个功能群（禾草类、豆科类、高大草本与矮小草本）的60个物种池中，建立了82块20×20米的草原样地。2002年5月，研究人员从该物种池中选取不同数量的植物物种进行播种，以此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。所有样地通过每年两次除草与刈割进行维护。
2002年9月，即在所有主实验样地首次刈割前（处于地上生物量峰值期），研究人员对全部主实验样地开展地上群落生物量采样。具体操作为：在每块大样地内选取0.2×0.5米的矩形区域，刈割该区域内地面3厘米以上的植被。该矩形区域的位置在采样前通过在样地核心区域（即中央10×15米范围内）随机选取坐标确定，且所有样地内矩形采样区域的位置布局保持一致。
采集得到的生物量被划分为不同类别：2002年仅对播种的植物物种进行单物种分离与处理。所有生物量样品均在70℃下烘干至恒重（时长≥48小时）后称重。播种植物群落的总生物量通过汇总各单播物种的生物量计算得到。
现有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均为驱动生物多样性-生产力正相关关系的重要影响因子。