Carbon Storage At Tree Layer Of Main Forest Types In Shaanxi Province

Carbon storage in forests of Chinese pine (Pinus tabulaeformis), black locust (Robiniapseudoacacia), oak (Quercus) and poplar (Populus) in Shaanxi province was studied. Basedon the tree species at different forest age, three replications of each forest was set and69plotswere investigated. Firstly, we surveyed the situation of sample site and measured the DBHand height of all the trees. Then the tree trunks, leaves, twigs, barks and roots were collectedand their carbon rates were measured. We estimated the carbon storage and the distributionpattern of the four tree species at different forest ages referring to the biomass equations. Theresults were as follows:1. The carbon rate of conifer was slightly higher than that of hardwood when they were atthe same forest age, and there were not significant differences among the hardwood at thesame forest age. Chinese pine had the highest mean carbon rate at the middle of itsdevelopment stages, while black locust and poplar had the highest mean carbon rate at theirmature periods. There were not differences among the mean carbon rates of oak during thethree development stages. The mean carbon rate of trunks and leaves was the highest, whilethat of roots was the lowest among the different organs of the species. Among the four treespecies, the proportion of carbon storage of trunks and leaves of Chinese pine was greatlyhigher than that of other species, but the proportion of carbon storage of twigs was the lowest.The proportion of carbon storage of roots of locust and oak was higher than that of other twospecies. There were no significant differences in the proportion of carbon storage of barksamong the four tree species.2. As the latitude decreased, the proportion of carbon storage of trunks of Chinese pineand black locust increased while that of roots reduced. The proportion of carbon storage oftwigs of black locust decreased, and the proportion of carbon storage of other organs ofChinese pine and black locust didn’t vary apparently. There were small changes among theproportion of carbon storage of all organs of oak as the latitude changed. From north to southof Shaanxi, the proportion of carbon storage of trunks and roots of poplar gradually decreased,while that of twigs gradually increased, and the proportion of carbon storage of leaves slightlychanged. 3. The carbon storage of Chinese pine, black locust, oak and poplar were24377.5kg/ha,25303.5kg/ha,46833.0kg/ha,27076.9kg/ha respectively. That of oak was the highest andthe others had no significant differences. The carbon storage of Chinese pine, black locust,and poplar gradually accumulated from the early growth stage to the middle growth stage, andthe carbon storage slightly increased. The carbon storage of oak significantly increasedthroughout the growing period.