Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2006)

This data set contains measurements of dissolved organic carbon in samples of soil water collected 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 April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

本数据集包含源自大型草原生物多样性实验（耶拿实验，Jena Experiment；详见下文）主要样地的土壤水样溶解性有机碳（dissolved organic carbon）测定数据。该主实验共设置82块20 m × 20 m的草原样地，所用植物物种库包含隶属于4个功能群的60个物种：禾本科植物、豆科植物、高大草本与低矮草本。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）的梯度样地。所有样地通过每年两次的除草与刈割进行维护。
2002年4月，研究人员在10、20、30及60厘米深度处安装直径12 cm、厚度1 cm、孔径1~1.6 mm的玻璃吸力采样板（德国慕尼黑UMS GmbH公司）以采集土壤溶液。采样瓶持续抽至50~350 mbar的负压，使吸力压力较实际土壤水吸力高出约50 mbar，仅收集土壤渗滤液。每两周采集一次累积土壤溶液，采用高总有机碳（total organic carbon, TOC）元素分析仪（德国哈瑙Elementar Analysensysteme GmbH公司）测定其中溶解性有机碳浓度。样品需尽快完成分析，必要时于4℃冷藏保存。夏季时常无游离土壤溶液可采集，尤其在浅层土壤层中。本数据集提供了每两周测定的溶解性有机碳浓度的年均值。