Collection of data on particulate and dissolved soil phosphorus in the Jena Experiment (Main Experiment, time series since 2002)

This data set contains two time series of measurements of dissolved phosphorus (organic, inorganic and total with a biweekly resolution) and dissolved inorganic phosphorus with a seasonal resolution. In addition, data on phosphorus from soil samples measured in 2007 and fractionated by different acid-extrations (Hedley fractions) are provided. All data measured at 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.
1. Dissolved phosphorus in soil solution: Suction plates installed on the field site in 10, 20, 30 and 60 cm depth were used to sample soil pore water. Cumulatively extracted soil solution was collected every two weeks from October 2002 to May 2006. The biweekly samples from 2002, 2003 and 2004 were analyzed for dissolved organic phosphorus (DOP), dissolved inorganic phosphorus (PO4P) and dissolved total phosphorus (TDP) by Continuous Flow Analyzer (CFA SAN ++, SKALAR [Breda, The Netherlands]).
2. Seasonal values of dissolved inorganic phosphorus in soil solution were calculated as volume-weighted mean values of the biweekly measurements (spring = March to May, summer = June to August, fall = September to November, winter = December to February).
3. Phosphorus fractions in soil: Five independent soil samples per plot were taken in a depth of 0-15 cm using a soil corer with an inner diameter of 1 cm. The five samples per plot were combined to one composite sample per plot. A four-step sequential P fractionation (Hedley fractions) was applied and concentrations of P fractions in soil were measured photometrically (molybdenum blue-reactive P) with a Continuous Flow Analyzer (Bran&Luebbe, Germany).

本数据集包含两套时间序列监测数据：其一为溶解态磷（有机态、无机态及总溶解态磷）的双周分辨率监测数据，其二为溶解态无机磷的季节分辨率监测数据。此外，本数据集还提供了2007年采集的土壤样品磷素数据，该类样品经不同酸浸提流程分级处理（即Hedley磷分级法（Hedley fractions））。所有监测数据均采自大型草原生物多样性实验——耶拿实验（Jena Experiment）的核心试验样地（详细信息见下文）。

在该核心实验中，研究团队基于包含4个功能群（禾本科植物、豆科植物、高大草本与小型草本）共60个物种的物种库，建立了82个20 m×20 m的草原样地。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样地，以构建植物物种丰富度（1、2、4、8、16及60个物种）与功能群丰富度（1、2、3、4个功能群）的梯度样地。所有样地均通过每年两次的除草与刈割进行管护。

1. 土壤溶液溶解态磷：研究人员在野外样地的10 cm、20 cm、30 cm及60 cm深度安装吸力采样板，用于采集土壤孔隙水。2002年10月至2006年5月期间，每两周采集一次累计提取的土壤孔隙水样品。2002、2003及2004年的每两周采集样品，采用连续流动分析仪（CFA SAN ++，SKALAR公司，荷兰布雷达）测定其中的溶解态有机磷（dissolved organic phosphorus，DOP）、溶解态无机磷（dissolved inorganic phosphorus，PO₄P）及总溶解态磷（dissolved total phosphorus，TDP）。
2. 土壤溶液溶解态无机磷季节均值：基于每两周的监测数据，通过体积加权平均法计算得到季节尺度的溶解态无机磷均值，其中春季为3月至5月，夏季为6月至8月，秋季为9月至11月，冬季为12月至次年2月。
3. 土壤磷素分级：研究人员采用内径1 cm的土壤钻，在0-15 cm深度每个样地采集5份独立土壤样品，将同一样地的5份样品混合为1份复合样品。随后采用四步连续磷分级法（Hedley fractions）对样品进行处理，并通过连续流动分析仪（Bran&Luebbe公司，德国）以光度法（钼蓝反应态磷）测定土壤各分级磷素的浓度。