Global aboveground biomass carbon density of trees in the year 2010

This layer represents the aboveground biomass (AGB) carbon (C) density estimates for trees that were used to create the harmonized global AGB C density map of Spawn et al. (2020). It has been scaled by 10 to reduce file size and should by multiplied by 0.1 before analysis to attain units of megagrams C per hectare (MgC/ha). Since trees may coexist with other vegetation types within the extent of a given grid cell, estimates in this layer have been proportionally adjusted to account for the relative spatial extent that trees are assumed to occupy in each grid cell. Grid cells that do not contain trees report a value of zero. As such, taking the pixelwise sum of the accompanying layers for tree, grass, tundra and crop AGB C will produce the harmonized global AGB C density map of Spawn et al. (2020).

本图层呈现的是用于生成Spawn等人（2020）所提出的标准化全球地上生物量碳（aboveground biomass carbon, AGB C）密度图的树木碳密度估算值。为压缩文件体积，本图层已做10倍缩放处理，分析前需将其乘以0.1，方可转换为每公顷兆克碳（megagrams C per hectare, MgC/ha）的单位。由于在给定网格单元的范围内，树木可能与其他植被类型共存，因此本图层的估算值已按比例调整，以计入树木在各网格单元中假定占据的相对空间占比。不含树木的网格单元，其对应像素值为0。据此，将树木、草本、苔原与作物的地上生物量碳配套图层的逐像素求和结果，即可得到Spawn等人（2020）所提出的标准化全球地上生物量碳密度图。