Total C storage of forest ecosystems using three methods during 2004–2008 in Shaanxi Province.

The C density of ecosystems, estimated by field sampling only, was the sum of the mean C density in tree, shrub, herb, litter, and soil layers. The C density of trees was estimated through a forest inventory, and shrub-soil was the sum of the mean C density in the shrub, herb, litter, and soil layers based on field sampling measurements. Method 1: a combination of forest inventory data (tree layer) with field sampling measurements (estimates of storage in the shrub, herb, litter, and soil layers using the relationship between the tree layer and these layers). Method 2: a mean C density method, which calculated the C storage for each forest type by multiplying the mean ecosystem C density by the area obtained only from field sampling. Method 3: an integrated method that estimated C storage in the tree layer based on the forest inventory and estimated C storage in the understory, litter, and soil layers by multiplying the mean C density of these layers by the area based on field sampling.Total C storage of forest ecosystems using three methods during 2004–2008 in Shaanxi Province.