Study On Carbon Storage And Balance Of Chinese Main Forest Ecosystems

Forest ecosystems play important roles in terrestrial carbon cycle under global change. Forest Inventory Data is an important data sources in studying forest carbon cycle. In this study, forest inventory data (FID) were used to evaluate forest net primary productivity model (NPP), carbon storage, etc.. In terms of biotic-climatic NPP model and NPP model reflecting the influence of volume and stand age, NPP of Chinese P.tabulaeformis and five major planted forest species were estimated; carbon storages of Chinese main forest vegetation types were evaluated based on the Volume-Derived Biomass method; multiple linear regressive model was used to study the response of forest vegetation carbon storage to the changes of forest land use and climatic factors. The carbon budget of Chinese forest ecosystem was estimated based on CENTURY model. The main results include as follows:(1) The biotic-climatic NPP model of Chinese P.tabulaeforemis is developed: NPPa= (0.331n(V/A)+0.18) × 3000(l-e-0.00009695E). Its mean NPP was 7.82 Mg-ha-1·yr-1 and ranged from 3.32 to 11.87 Mgha-1· yr-1, Its spatial pattern decreased from the south to the north. The NPP in eastern and southern were more than 7.7 Mg·ha-1·yr-1, and the northern and western were lower than 5.5 Mgha-1·yr-1, while the NPP of the concentrated distributed regions (Shanxi and Shannxi provinces) were in the middle level, ranging from 5.5 to 7.7 Mg·ha-1·yr-1.(2) Based on FID and NPP model reflecting the influencing both volume and stand age, NPP values of five major planted forest species (Larix, Pinus tabulaeformis, Pinus massoniana, Cunninghamia lanceolata, Populus) were estimated, which were 8.43, 5.75, 4.42, 4.41, and 7.33 Mg·ha-1·yr-1, respectively. Those NPP values were lower than the mean NPP of the world, which showed that Chinese major planted forests had large potential toimprove sequestration carbon of forest ecosystem.(3) Chinese forest vegetation carbon storages were estimated based on the third and the fourth FID. The carbon storages were 3.48 and 3.78 Pg C (1 Pg=1015 g), respectively.The impact of the forest land use changes on forest carbon storage was studied based on multiple linear regressive model. The results showed that forest carbon storage increased with forest area and decreased with mean forest stand age. When the forest stand age increased by ten years and area increased by 104 ha, the carbon storage of Chinese forest vegetation would increase by 54.51Tg C (1 Tg=1012g).The responses of forest carbon storage to climatic factors were studied based on factor analyzing method. The results showed that temperature was the limiting factor. When the temperature increased, forest vegetation carbon storage decreased; while the precipitation increased, forest vegetation carbon storage increased. Furthermore, under three climate scenarios (under annual mean temperature increased by 4℃ and annual precipitation increased by 10%; annual mean temperature increased by 4℃ with no precipitation changes; annual mean temperature increased by 4℃ and annual precipitation decreased by 10%), Chinese forest vegetation carbon storage would increased by 9.19, 6.67, and 4.15Tg, respectively.(4) Chinese forest net ecosystem productivity (NEP) was evaluated based on Century model. The results showed Chinese forest ecosystem was a sink, and the forest NEP was 0.17Pg C. NEP in the southwest was larger (about 44%) than those in the east and the northwest (14%).