The vertical distribution of soil microbial biomass carbon: A global dataset

Soil microbial biomass carbon (SMBC) is important in regulating soil organic carbon (SOC) dynamics along soil profiles by mediating the decomposition and formation of SOC. The dataset is about the vertical distributions of SOC, SMBC, and soil microbial quotient (SMQ = SMBC/SOC) and their relations to environmental factors across five continents. Data are collected from literature, with a total of 289 soil profiles and 1040 observations in different soil layers compiled. The associated environment data were also collectd including climate, ecosystem types, and edaphic factors. More specifically, we develop this dataset by compiling data from 59 papers published in the Web of Sciene and the China National Knowledge Infrastructure from the year of 1970 to 2019. All the data included in this dataset meet two creteria: 1) there are at least three soil layers along a soil profile, and 2) soil MBC is measured using the fumigation extraction method. The data were obtained from tables and texts from literature directly, and the data in figures were extracted using GetData Graph digitizer software version 2.25. When climate and soil properties are not available from publications, we obtainted the data from the World Weather Information Service (https://worldweather.wmo.int/en/home.html) and SoilGrids at a spatial resolution of 250 meters (version 0.5.3, https://soilgrids.org). The units of all the variables are converted to the standard international units or commonly used ones and the values are converted correspondingly. For example, the value of soil organic matter (SOM) is converted to SOC using the equation (SOC = SOM × 0.58). Soil depth is calculated as the arithmetic mean value of the upper and lower boundaries for a given soil layer. This dataset can be used in predicting global SOC change along soil profiles using the multi-layer soil C models. It can also be used to analyse how soil microbial biomass changes with plant roots as well as the composition, structure, and functions of soil microbial communities along soil profiles at large spatial scales. This dataset offers opportunities to improve our prediction of SOC dynamics under global changes and to advance our understanding of the environmental controls.土壤微生物生物量碳（Soil Microbial Biomass Carbon, SMBC）通过介导土壤有机碳（Soil Organic Carbon, SOC）的分解与形成，在调控土壤剖面SOC动态过程中发挥着关键作用。本数据集聚焦五大洲范围内SOC、SMBC及土壤微生物熵（Soil Microbial Quotient, SMQ，定义为SMBC/SOC）的垂直分布特征及其与环境因子的关联关系。数据源自文献调研，共整合了来自不同土层的289个土壤剖面、1040组观测数据，并同步收集了配套环境数据，涵盖气候、生态系统类型以及土壤理化因子。具体而言，本数据集整合了1970年至2019年间Web of Science与中国知网（China National Knowledge Infrastructure, CNKI）收录的59篇文献中的数据。所有纳入本数据集的数据均满足两项筛选标准：其一，单条土壤剖面至少包含3个土层；其二，土壤微生物生物量碳（SMBC）采用熏蒸提取法进行测定。数据直接从文献的表格与文本中提取，图中数据则通过GetData Graph Digitizer软件（版本2.25）完成数字化提取。若文献未提供气候与土壤属性数据，则从世界气象组织世界天气信息服务平台（https://worldweather.wmo.int/en/home.html）以及空间分辨率为250米的SoilGrids数据库（版本0.5.3，https://soilgrids.org）获取补充数据。所有变量的单位均统一转换为国际标准单位或通用单位，并同步完成数值的相应换算；例如，通过公式SOC = SOM × 0.58，将土壤有机质（Soil Organic Matter, SOM）转换为SOC。指定土层的深度以其上下边界的算术平均值计算得到。本数据集可用于依托多层土壤碳模型预测全球土壤剖面SOC动态变化，亦可用于大空间尺度下探究土壤微生物生物量随植物根系的变化规律，以及土壤剖面微生物群落的组成、结构与功能特征。本数据集为提升全球变化背景下SOC动态的预测精度，以及深化对环境调控机制的认知提供了重要支撑。