Carbon storage and spatial distribution in Phyllostachy pubescens and Cunninghamia lanceolata plantation ecosystem

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) and Moso bamboo (Phyllostachy pubescens) are two native and major commercial tree species in South China. Because of their high quality in timber and value in economy, Chinese fir and Moso bamboo have been widely planted in the subtropical area of China. Their distribution area in China are more than 7×106 hm2 for Chinese fir plantation, approximately one fourth of total area of plantation forest in China, and more than 3×106 hm2 for Moso bamboo plantation, accounting for one fifth of the total bamboo forest area in the world. Moso bamboo and Chinese fir plantations are also important for high ecological value in soil preservation, water purification and carbon storage etc In order to estimate their carbon storage and its spatial distribution we compared the biomass, carbon concentration between the two plantation based on the survey in their permanent plots. The results showed that the mean carbon concentrations between the two tree species were significantly different, with higher total carbon concentration in Chinese fir than in Moso bamboo. The average carbon concentration in all organs changed in the order of trunk (50.43%) leaf (49.57%) bark (48.84%) branch (48.33%) root (47.89%) for Chinese fir, in the order of sheath (49.91%) branch (48.46%) leaf (46.92%) stem (46.68%) rhizome (44.78%) root (44.51%) for Moso bamboo. The average carbon concentration in Moso bamboo was not correlated to their age. The carbon concentration of soil to the depth of 60cm ranged from 0.746% to 2.390%, with higher carbon concentration and storage in the soil of 0—20 cm than in the other layer. The total carbon storage of Chinese fir and Moso bamboo plantation ecosystem were 150.19 tC·hm-2 and 166.34tC·hm-2 respectively. The spatial distribution pattern of carbon stocks was basically consistent in the order of soil layer trees layer shrub and herb and litter layer, with the order of soil (83.92%) trees (15.38%) standing litters (0.38%) shrub and herb (0.32%) in Moso bamboo plantation forest, and the order of soil (62.03%)trees (34.99%) standing litters (2.28%) shrub and herb (0.70%) in Chinese fir plantation. The carbon storage and its allocation among their organs in tree layer were found to be highly correlated with their biomass. Annual carbon fixation of tree layer in Moso bamboo was 9.94tC·hm-2·a-1, amounted to 36.44 tCO2·hm-2·a-1, about 1.39 times as that of Chinese fir plantation.