| Greenhouse effete is one of the most crucial global environment alissues presently. As the largest carbon pool of terrestrial ecosystem, the allocation dynamies of biomass and carbon density of forest ecosystem are important components of global carbon cycle. Based on the data of stem analysis from63Picea asperata trees in10sample plots, dynamies of biomass and carbon density for Picea asperata with5stand ages has been studied. For making a further thorough study on carbon cycling in forest ecosystems by region scale or nation scale, or even by globe scale, and provide some references for correctly estimating ecological benefits of forest. The main results as follows:With the inerease on stand age for14to60, biomass of the Picea asperata forest was in a range of7.68t/hm to106.50t/hm. Of which, tree layer was determined as6.11t/hm to99.30t/hm2, shrub layer determined as1.57t/hm2to7.20t/hm2, gass layer determined as7.68t/hm to106.50kg/hm, of which the tree layer consisted of the largest proportion, take more than79.53%of the system. With the growth of trees, the proportion of stem was increased from52.48%to54.28%, the bark was increased from11.24%to12.40%, the root was increased from13.56%to15.43%, while the proportion of branches was decreased from14.33%to9.98%and leaves was decreased from8.39%to6.24%。The carbon contents of different organs varied form50.49%to52.93%for the14-year-old plantation, form49.97%to53.44%for the23-year-old stands, form49.65%to52.17%for the32-year-old stands, form50.21%to52.74%for the45-year-old stands, and50.47%to52.48%for the60-year-old plantation. The carbon contents of different organs is not the same in the different age classes Picea asperata forest. Overall, the carbon content of the leaves and branches are higher than other organs. The carbon content changed not obvious with the Picea asperata aged. No obvious trends were detected for the carbon content in different groups of under-storey of plants as the forest aged. The carbon content in the whole canopy profile of a stand varied in the following order:tree layer> shrub layer>grass layer. The soil organic content inceeased along with the increase of age while decreased as the depth increased in the different age classes Picea asperata forest. The diversity of soil organic carbon content in different layers displayed as:the 0-15cm soil layer>the15-30cm soil layer>the30-45cm soil layer>the45-60cm soil layer in the different age and different assay fields Picea asperata forest.Carbon density of Picea asperata forest ecosystem mainly consisted of four sections, that was the trees, the shrub, the grass and the soil, and the order of whose carbon density could be ranked as follow:the soil>the trees>the shurb>the grass. Carbon density of the14-year-old、the23-year-old、the32-year-old、the45-year-old and the60-year-old Picea asperata forest was53.63、73.06、91.09、110.42、144.62t/hm2. Superiority of carbon density in the trees gradually strengthen with the forest stands age growth, carbon density of the trees had gone up from3.12t/hm2in the14-year-old to13.86t/hm2in the23-year-old to16.53t/hm2in the32-year-old to32.84t/hm2in the45-year-old to50.51t/hm2in the60-year-old.Carbon density in forestlands soil layer (0～60cm) was a considerable figure, soil carbon density in the14-year-old, the23-year-old, the32-year-old, the45-year-old and the60-year-old Picea asperata forestlands was up to49.86、58.06、72.50、74.81、and90.75t/hm2, respectively, accounting for more than62.75%of carbon density in the whole ecosystem. In the soil layer, carbon density of the surface soil (0-30cm) layer in the14-year-old, the23-year-old, the32-year-old, the45-year-old, the60-year-old Picea asperata forestlands held62.38%、60.19%、69.62%、65.41%and72.82%, respectively. The ratio of carbon density of aboveground to that of underground deceased as the Picea asperata forest age growth.The annual net primary production of the14-year-old, the23-year-old, the32-year-old, the45-year-old and the60-year-old Picea asperata forest was respectively0.50、1.52、1.49、2.40and3.01t/hm2·a, while their annual carbon amount was0.26、0.78、0.76、1.24和and1.55t/hm2-a, respectively. |
PDF Full Text Request