Aboveground plant biomass from the Jena Experiment (Monocultures, year 2004)

This data set contains aboveground plant biomass in 2004 (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) of the monoculture plots of a large grassland biodiversity experiment (the Jena Experiment). In the monoculture plots the biomass of the sown plant community contains only a single species per plot and this species is a different one for each plot. Which species has been sown in which plot is stated in the plot information table for monocultures (see further details below). The monoculture plots of 3.5 x 3.5 m were established for all of the 60 plant species of the Jena Experiment species pool with two replicates per species. These 60 species comprising the species pool of the Jena Experiment belong to four functional groups (grasses, legumes, tall and small herbs). Plots were sown in May 2002 and are since maintained by bi-annual weeding and mowing. Aboveground plant biomass was harvested twice in 2004 just prior to mowing (during peak standing biomass in early June and in late August) on all experimental plots of the monocultures. This was done by clipping the vegetation at 3 cm above ground in 2 rectangles of 0.2 x 0.5 m per 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. excluding an outer edge of 0.5 m). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: 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. The data for individual subsamples (i.e. rectangles) and the mean over samples for all biomass measures are given.本数据集收录了大型草原生物多样性实验——耶拿实验（Jena Experiment）的单作样地2004年的地上植物生物量数据，涵盖播种植物群落、杂草植物群落、枯落植物材料与未鉴定植物材料四类，所有生物量指标均以干重计量。单作样地中，每个样地的播种植物群落仅包含单一物种，且不同样地的播种物种各不相同。各单作样地的播种物种信息详见单作样地信息表（详见下文更多细节）。耶拿实验共设置60个植物物种作为物种库，针对每个物种设置2个重复样地，样地规格为3.5×3.5米。该60个物种隶属于4个功能群：禾本科植物、豆科植物、高大草本与小型草本。样地于2002年5月播种，此后通过每年两次除草与刈割进行维护。 2004年，研究人员在所有单作实验样地的刈割前（即6月初与8月底的现存量峰值期）开展了两次地上生物量采样。采样流程为：在每个样地内的两个0.2×0.5米矩形样方中，于地面以上3厘米处剪切植被。每次采样前，均在样地核心区域（即排除0.5米宽外围边缘的区域）通过随机选取坐标的方式确定矩形样方的位置，且所有样地内的矩形样方位置保持一致。采集得到的生物量被划分为四类：目标播种植物物种、杂草植物物种（即该样地未播种的物种）、脱落的枯落植物材料（即数据文件中的枯落植物材料），以及无法归类的剩余植物材料（即数据文件中的未鉴定植物材料）。所有生物样本均经70℃烘干至恒重（时长≥48小时）后称重。数据集同时提供了各子样本（即各矩形样方）的单独数据，以及所有生物量指标的样本平均值。