Standing belowground plant biomass from the Jena Experiment (Main Experiment, year 2014)

This data set contains measurements of standing belowground plant biomass. 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 in general by bi-annual weeding and mowing. Since 2010, plots were weeded three times per year. Plot size was reduced to 5 x 6 m since 2010.
In 2014, standing root biomass was sampled in June. Three soil cores with a 4.0 cm diameter per plot were taken to 40 cm depth and pooled plot-wise. The cores were immediately stored cool until further handling. For root washing, the bulk sample was soaked in water and then repeatedly rinsed with tap water over a 0.2 mm sieve. Remaining soil particles were removed by hand. Roots were dried at 60 - 70 °C and weighed subsequently. In 2014, soil cores were separated in depth increments of 0-5, 5-10, 10-20, 20-30 and 30 - 40 cm depth and the corresponding layers were pooled plot-wise. Roots were not seperated in coarse (diameter > 2 mm) and fine roots and only total root biomass is shown in this dataset.

本数据集包含现存地下植物生物量的实测数据。此处呈现的数据来自一项大型草原生物多样性实验——耶拿实验（Jena Experiment；详见下文）的主实验样地。主实验共设置82块20×20米的草原样地，其物种库涵盖隶属于4个功能群（禾草类、豆科植物、高大草本与矮小草本）的60个植物物种。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。样地日常维护采用每年两次除草与刈割的方式；自2010年起，样地除草频次调整为每年3次，同时样地面积缩减至5×6米。
2014年6月，研究人员对样地内的现存根系生物量开展采样工作。每块样地采集3个直径4.0厘米的土芯，采样深度达40厘米，随后将同一样地的所有土芯合并为混合样品。采集完成后立即将样品低温储存，以待后续处理。进行根系清洗时，先将混合样品浸泡于清水中，随后用自来水反复冲洗过0.2毫米孔径的筛网，再手工去除残留的土壤颗粒。将清洗后的根系置于60~70℃的环境中烘干，随后进行称重。2014年采集的土芯按0-5厘米、5-10厘米、10-20厘米、20-30厘米及30-40厘米的深度增量进行分层，同一样地的各层样品分别合并。本数据集未对根系进行粗根（直径>2毫米）与细根的区分，仅提供总根系生物量数据。