Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2004)

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.本数据集包含大型草原生物多样性实验（耶拿实验，Jena Experiment；详见下文）主样地采集的土壤水样品中溶解性有机碳（dissolved organic carbon）的测定数据。该主实验共设置82个20×20米的草原样地，所用植物种源库包含60个物种，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。所有样地均通过每年两次除草与刈割进行抚育维护。 2002年4月，研究人员在10、20、30及60厘米的土壤深度处安装了直径12厘米、厚度1厘米、孔径1~1.6毫米的玻璃负压采样板（glass suction plate），设备产自德国慕尼黑UMS有限公司（UMS GmbH, Munich, Germany）。采样瓶持续抽至50~350毫巴的负压，使抽吸压力较实际土壤水张力高出约50毫巴，以此确保仅收集土壤渗滤液。研究人员每两周采集一次累计土壤溶液，并通过高总有机碳元素分析仪（high TOC elemental analyzer）测定样品的溶解性有机碳浓度，该仪器产自德国哈瑙Elementar分析系统有限公司（Elementar Analysensysteme GmbH, Hanau, Germany）。样品需尽快完成分析，必要时可于4℃条件下冷藏保存。夏季时常无法采集到游离土壤溶液，尤以表层土壤层为甚。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。