Abstract: We explored the importance of forest carbon density and its distribution pattern for forest and global carbon cycling. By using the forest inventory and allometric approaches, we measured carbon density and its distribution characteristics of young growth Pinus koraiensis plantations in different regions of Heilongjiang Province including southern slope of Xiaoxing’an Mountains, eastern slope of Zhangguangcai Mountains, western slope of Zhangguangcai Mountains, and Wanda Mountain). Among different regions, vegetation C pool and detritus C pool of P.koraiensis plantations varied significantly, but there was no significant differences in soil C pool and total C density. Vegetation, detritus, soil and total ecosystem C density were 35.95-76.36, 3.52-11.34, 101.96-173.37 and 154.54-256.78 tC·hm^-2, respectively. The distribution proportion of each ecosystem components were 18.78%-30.34%, 1.79%-5.24% and 65.58%-79.43%, respectively, and all differed significantly among regions. Overstory organs (except leaf) C density and its distributions were different significantly among regions. The C density of stem, branch, leaf and root were 22.47-47.11, 2.30-12.31, 2.90-5.80 and 7.02-17.16 tC·hm^-2, respectively. And the corresponding distribution proportion were 51.98%-64.80%, 6.68%-17.19%, 6.55%-834% and 20.23%-22.55 %, respectively. Root-shoot ratio (R/S) and ratio of soil C density (include detritus C density) to vegetation C density (SC/VC) were 0.26-0.29 and 2.31-4.69, respectively, with significant difference among regions. Basal area exhibited highly significant positive correlation with overstory C density, vegetation C density and forest ecosystem total C density (P<0.01), which can well reflect the dynamic of forest ecosystem C density.

Key words: Pinus koraiensis plantations, Heilongjiang Province, regions, carbon density, distribution proportion