Aboveground plant community and species-specific vegetation cover from the Jena Experiment (Main Experiment, year 2008)

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 2008, 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.

本数据集收录植被覆盖度相关数据，即各估算样地内不同类别植物覆盖的土壤表面积占比。数据采集覆盖两个层面：植物群落层面（含播种植物群落、杂草植物群落、植物枯落物及裸地），若涉及播种物种，则进一步细化至单个植物物种层面。本次发布的数据源自大型草地生物多样性实验——耶拿实验（Jena Experiment）的主实验样地（详细信息见下文）。
该主实验共设立82块20×20米的草地样地，所用物种池包含隶属于4个功能群（禾本科植物、豆科植物、高大草本与小型草本）的60个物种。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播种至样地，以此构建植物物种丰富度（1、2、4、8、16和60个物种）与功能群丰富度（1、2、3、4个功能群）的梯度序列。所有样地通过每年两次除草与刈割进行管护。
2008年，研究人员在主实验所有样地的刈割前（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工作。估算区域为每块样地中央3×3米（约9平方米）的范围，采用十进制（Londo）目视估测法。由于所划分的覆盖类别可能存在多层重叠现象，单个物种（以及目标物种+杂草+裸地）的覆盖度估算值总和可能超过100%。