Morphological root parameters of standing roots from the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of diameter of standing roots. 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.
In September 2004, three soil cores with a 4.8 cm diameter per plot were taken to 30 cm depth. The bulk material of the pooled cores was cut with scissors to < 1 cm pieces. A subsample of 50 g was suspended in water and rinsed over a 0.5 mm screen. Roots collected in the screen were transferred into a water-filled clear acrylic tray and scanned. Mean diameter of the roots was determined by using WinRhizo (Regent Instruments, Quebec, Canada).

本数据集包含原位根系直径的测量数据。本次公开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（详细说明见下文）。
本主实验共设置82块20×20米的草地样地，所用植物均来自包含60个物种的物种库，这些物种分属4个功能群：禾草类、豆科类、高大草本与小型草本。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播种至各块样地，以构建植物物种丰富度（1、2、4、8、16及60种）与功能群丰富度（1、2、3、4个功能群）的梯度系列。
样地日常维护初期采用每年两次除草与刈割的方式；自2010年起，样地除草频率提升至每年三次。
2004年9月，对每块样地采集3个直径4.8厘米、深度30厘米的土芯。将合并后的土芯样品用剪刀剪至长度小于1厘米的碎段，称取50克子样品置于水中悬浮，随后过0.5毫米孔径的筛网冲洗。收集于筛网表面的根系被转移至盛有清水的透明亚克力托盘并进行扫描。最终通过WinRhizo（加拿大魁北克省Regent Instruments公司）软件测定根系的平均直径。