SAFARI 2000 Plant and Soil C and N Isotopes, Southern Africa, 1995-2000

This data set contains measurements of the concentration and stable carbon (13C/12C) and nitrogen (15N/14N) isotope ratios of plant (leaves, roots and fungi) and soil samples from southern Africa. The study sites in Zambia, Botswana, Namibia, and South Africa are located along the Kalahari Transect precipitation gradient. Some of the sites were relatively undisturbed while others had different intensities of cultivation, domestic grazing, and fires. The data were collected to detect patterns of N cycling along precipitation and grazing gradients, including N2 fixation by legumes. Data from different multiple projects are included. The plants and soils were sampled mainly in the wet season of years 1995, 1999, and 2000, with most of the data collected during the SAFARI 2000 Kalahari Wet Season Field Campaign in February and March of 2000. Some grass samples were collected in the dry season of year 2000 (from Mongu-dambo and Sua Pan grassland sites). Soil and plant samples were analyzed in a laboratory for %C, %N, d13C, and d15N with an Optima isotope ratio mass spectrometer coupled to an elemental analyzer. The stable isotope ratios are expressed using standard delta notation in units per mil. The isotope ratios are expressed relative to the international standard PDB (Pee Dee Belemnite) for carbon and atmospheric N2 for nitrogen samples. The carbon and nitrogen contents are expressed in percentage weight of the dry sample.The data files contain numerical and character fields of varying length separated by commas (.csv format).

本数据集汇集了来自南非地区植物（叶片、根系和真菌）及土壤样本的浓度测量值，以及稳定碳同位素（13C/12C）和氮同位素（15N/14N）比率。研究地点分布于赞比亚、博茨瓦纳、纳米比亚和南非，并沿卡拉哈里降水梯度分布。部分区域相对未受干扰，而其他区域则经历了不同程度的耕作、家畜放牧和火灾。数据收集旨在探测降水梯度及放牧梯度下氮循环的模式，包括豆科植物固定氮气的过程。数据包含来自多个项目的数据。植物和土壤样本主要在1995年、1999年和2000年的雨季进行采集，其中大部分数据在2000年2月和3月的SAFARI 2000卡拉哈里雨季野外考察活动中收集。部分草样在2000年的干季采集（来自蒙古-达姆波和苏阿潘草原地点）。土壤和植物样本在实验室中通过Optima同位素比质谱仪（与元素分析仪耦合）分析了碳含量（%C）、氮含量（%N）、碳同位素比率（d13C）和氮同位素比率（d15N）。稳定同位素比率采用标准δ符号表示，单位为每千分之一。同位素比率以国际标准PDB（皮德迪贝勒姆石）为碳参考，以大气N2为氮参考。碳和氮含量以干样重量百分比表示。数据文件包含由逗号分隔的数值和字符字段，格式为.csv。