Vegetation carbon storage and carbon sequestration rates in northern Hebei Province

Forest resource is the largest carbon pool in terrestrial ecosystem, which contributes carbon to the global carbon cycle incomparably. The forest ecosystem in northern Hebei Province plays an important role in soil and water conservation, and carbon sink increase. In this study we took broadleaved forest, coniferous forest, mixed forest, economic forest and shrub in northern Hebei Province as objects to research the amount of carbon sequestration in this area by using Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) which referenced by IPCC as a platform. The data was based on original data of the 7th national forest continuous inventory and forest vegetation survey data of the area. Firstly, the literature-volume growth curve equations were created by comparing several growth functions based on the 7th national forest continuous inventory of continuous sample survey data for each forest type, as the driving force for model to simulate forest carbon storage. Secondly, volume-biomass transition equations, conversion parameters and forest biomass components (stem, bark, branch, foliage) proportion parameters of different forest types were estimated using the power function model, and further plotted by collecting a large number literature data in each forest types. And then, forest vegetation carbon storage, carbon density and carbon sequestration rate of different forest types in northern Hebei Province were calculated after the model running, debugging and simulating. The results showed that the fitting coefficients of different forest vegetation growth curve equations were exceeded 0.7. The parameters of fitting coefficient correlations of all volume-biomass transfer equations were exceeded 0.8, and there were significant differences among most proportion equations for biomass components (stem, bark, branch, foliage). By the comparison with estimated results by using measured data, the results of forest vegetation carbon storage, average carbon density and carbon sequestration rate simulated by using CBM-CFS3 were more reasonable. It could provide the basis to evaluate forest vegetation carbon sequestration potential in this area. The total forest vegetation carbon storage and average carbon density in northern Hebei Province in 2010 were 59.66 Tg(C) and 25.05 Mg(C)·hm^-2, respectively. The forest vegetation carbon sequestration rate ranged from 0.07 Mg(C)hm^-2a^-1 to 1.87 Mg(C)hm^-2a^-1. The carbon storages and average carbon densities of broadleaved forest, coniferous forest, mixed forest, economic forest in northern Hebei Province were 30.97 Tg(C), 12.36 Tg(C), 15.73 Tg(C), 0.60 Tg(C) and 26.09 Mg(C)·hm^-2, 26.14 Mg(C)·hm^-2, 24.50 Mg(C)·hm^-2, 7.53 Mg(C)·hm^-2, respectively. The spatial distribution of forest vegetation carbon density and carbon sequestration rate in northern Hebei Province showed an increase trend from northwest to southeast. After the forestation and afforestation, the area of forest increased by 6 400 km², and forest vegetation carbon storage increased 19.54 Tg(C) (not include shrub) in the study area. The potential ability of forest vegetation carbon sequestration in this area will increased quickly in future, because of its young-middle age forest structure. Therefore, afforestation played an important role in increasing forest vegetation carbon storage and carbon sequestration rate.