Global Forest Ecosystem Structure and Function Data For Carbon Balance Research

A comprehensive global database has been assembled to quantify CO2 fluxes and pathways across different levels of integration (from photosynthesis up to net ecosystem production) in forest ecosystems. The database fills an important gap for model calibration, model validation, and hypothesis testing at global and regional scales.

The database archive includes: a Microsoft Office Access Database; data files for all tables in the database; query outputs from the database; and SQL script file for re-creating the database from the tables. The database is structured by site (i.e., a forest or stand of known geographical location, biome, species composition, and management regime). It contains carbon budget variables (fluxes and stocks), ecosystem traits (standing biomass, leaf area index, age), and ancillary information (management regime, climate, soil characteristics) for 529 sites from eight forest biomes. Data entries originated from peer-reviewed literature and personal communications with researchers involved in Fluxnet. Flux estimates were included in the database when they were based on direct measurements (e.g., tower-based eddy covariance system measurements), derived from single or multiple direct measurements, or modeled. Stand description was based on observed values, and climatic description was based on the CRU data set and ORCHIDEE model output. Uncertainty for each carbon balance component in the database was estimated in a uniformed way by expert judgment. Robustness of CO2 balances was tested, and closure terms were introduced as a numerical way to approach data quality and flux uncertainty at the biome level.

一项全面的全球数据库已构建，旨在量化森林生态系统中不同整合水平（从光合作用至净生态系统生产）的二氧化碳通量和途径。该数据库在全球及区域尺度上为模型的校准、验证和假设检验提供了重要的补充。数据库档案包括：Microsoft Office Access数据库；数据库中所有表的数据文件；数据库的查询输出；以及用于从表重新创建数据库的SQL脚本文件。数据库按照地点（即，已知地理位置、生物群落、物种组成和管理制度的森林或林分）进行结构化。它包含了529个地点来自八个森林生物群落的碳收支变量（通量和储量）、生态系统特征（现存生物量、叶面积指数、年龄）和辅助信息（管理制度、气候、土壤特征）。数据条目来源于同行评审的文献和个人与Fluxnet项目相关研究人员的交流。当二氧化碳估计值基于直接测量（例如，基于塔楼的涡度协方差系统测量）、单一或多个直接测量推导或模型化时，这些估计值被纳入数据库。林分描述基于观测值，气候描述基于CRU数据集和ORCHIDEE模型输出。数据库中每个碳平衡成分的不确定性通过专家判断以统一的方式进行估算。对二氧化碳平衡的稳健性进行了测试，并引入闭合项作为在生物群落水平上评估数据质量和通量不确定性的数值方法。