Aboveground plant community and species-specific vegetation cover from the Jena Experiment (Main Experiment, year 2005)

This data set contains information on vegetation cover, i.e. the proportion of soil surface area that is covered by different categories of plants per estimated plot area. Data was collected on the plant community level (sown plant community, weed plant community, dead plant material, and bare ground) and on the level of individual plant species in case of the sown species. Data presented here is from 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.
In 2005, vegetation cover was estimated twice in May and August just prior to mowing (during peak standing biomass) on all experimental plots of the Main Experiment. Cover was visually estimated in a central area of each plot 3 by 3 m in size (approximately 9 m²) using a decimal scale (Londo). Cover estimates for the individual species (and for target species + weeds + bare ground) can add up to more than 100% because the estimated categories represented a structure with potentially overlapping multiple layers. In 2005, dead plant material was found only in a few plots. Therefore, cover of dead plant material is zero for most of the 82 plots.

本数据集包含植被覆盖度相关信息，即每块样地内不同植物类别覆盖的土壤表面积占比。数据采集涵盖两个水平：植物群落水平（播种植物群落、杂草植物群落、枯亡植物残体以及裸地），以及播种物种的单个植物物种水平。本数据集源自大型草地生物多样性实验——耶拿实验（Jena Experiment；详见下文）的主实验样地。

在主实验中，研究人员从包含4个功能群（禾本科植物、豆科植物、高大草本与矮小草本）共60个物种的物种库中，选取不同数量的植物物种，于2002年5月播种于82块20×20米的草地样地，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。样地通过每年两次的除草与刈割进行维护。

2005年，研究人员在所有主实验样地刈割前（即地上生物量峰值期）的5月与8月，分别开展两次植被覆盖度估算。采用十进制估算尺度——隆多尺度（Londo），在每块样地中央3×3米（约9平方米）的区域内进行目视估算。单个物种（以及目标物种+杂草+裸地）的覆盖度估算值之和可超过100%，因为所划分的覆盖类别存在多层重叠的可能。2005年仅在少量样地中发现枯亡植物残体，因此82块样地中的绝大多数样地的枯亡植物残体覆盖度均为0。