| Due to the fossil energy resources were widely used in various industries, which led to a gradual warming of the global climate and threat to the human survival, the climate change has become the common challenges faced by the countries of the world. The forest is known as the largest "carbon reservoir" and the most economical "carbon sinks", which plays an important role in adjustment and control to the global carbon cycle, so the forest carbon cycle has become a central issue of the global climate change researches. The estimation of regional forest ecosystem carbon stock has been one of the hotspots of the forest ecosystem carbon cycle researches.The present study is primarily focused on the forest ecosystems in Shanxi Procince, China. In this paper, the carbon content, biomass, carbon density and distribution pattern of the various layers (including arbor layer, shrub layer, grass layer, litter layer, soil layer) and the various organs were estimated and measured in the different origins and different age groups of the forest ecosystems, and the carbon pool of the forest ecosystem in Shanxi was calculated. In addition, the dynamics of carbon stock of the forest ecosystem in Shanxi was analyzed. The results were mainly concluded as follows:Firstly, the best fitting model form of biomass of Populus davidiana and Quercus wutaishanica was CAR(Constant Allometric Ratio) type, and Pinus tabulaeformis Carr and Platycladus orientalis (L.) Franco in the form od best fitting model were VAR(Variable Allometric Ratio) type. The model’s explanation of various organs of the four species reached or exceeded90%that based on DBH(diameter at breast height). The aboveground biomass of Populus davidiana, Pinus tabulaeformis Carr, Platycladus orientalis (L.) and Quercus wutaishanica accounted for79%,80.82%, 71.63%and69.91%of the total biomass respectively.Secondly, the carbon contents among the carious organs or the different forests were difference whether the origins or the age groups of forests. The carbon contents of the coniferous species (stands) were generally higher than the broadleaf species (stands), and which of the artificial forests generally higher than the natural forests. The average carbon content of coniferous forests was475.61g/kg and that of the broadleaf forests was468.72g/kg. The average carbon contents of Populus davidiana, Pinus tabulaeformis Carr, Platycladus orientalis (L.), Quercus liaotungensis, Larix principis-rupprechtii, Robinia pseudoacacia L., Betula platyphylla Suk and the forest stands were460.47g/kg,476.08g/kg,477.03g/kg,472.08g/kg,446.66g/kg,464.85g/kg,501.33g/kg and472.17g/kg respectively.Thirdly, the average biomass and carbon density of arbor layer of forest in Shanxi were81981.62kg/hm2and38849.91kg/hm2. The biomass and carbon density of tree trunk accounting for41.51%-58.64%and41.37%-58.79%of the tree layer respectively. The proportional allocation of the carbon of tree layer showed stem> root> branch> leaf, and the aboveground carbon accounted for77.57%of the arbor layer. The mean carbon densities of shrub layer, herb layer and litter layer accounted for0.09%,0.11%,1.54%of total of the forest ecosystem respectively. The carbons of the shrub mainly distributed in the branches, and the leaves and branches of the herb layer of carbon is evenly distributed. The average carbon density of the soil layer (0-100cm) was96229.96kg/hm2, which accounted for70.00%of forest ecosystems and was mainly concentrated in the0-50cm depth. The average biomass and carbon density of the forest ecosystem in Shanxi were91981.10kg/hm2and137472.14kg/hm2.Fourthly, the total carbon storage of the forest ecosystem showed linear growth law based on four forest continuous inventory data in Shanxi, which were197.13Tg(1995a),218.15Tg(2000a),238.73Tg(2005a),253.66Tg(2010a) and the average annual carbon sequestration3.77Tg with an average annual growth rate of1.61percent. The carbon storage of natural forest was189.92Tg that the average annual carbon sequestration2.69Tg, and which of artificial forests was63.74Tg that the average annual carbon sequestration1.08Tg. The ecosystem carbon storage of Quercus liaotungensis Koidz and Pinus tabulaeformis Carr accounted for54.78%of the forest ecosystems in Shanxi, which was the mainly forests in carbon sequestration. The carbon stocks of natural Quercus liaotungensis Koidz, natural Pinus tabulaeformis Carr and natural Betula platyphylla Suk accounted for79.69%of the natural forest ecosystems. The carbon stocks of artificial Pinus tabulaeformis Carr and artificial Populus davidiana accounted for69.99%of the artificial forest ecosystems.Fifth, the carbon stocks of tree layer, shrub layer, herb layer, litter layer and soil layer of the forest ecosystem were90.38Tg,0.24Tg,0.21Tg,5.80Tg and157.02Tg respectively, which of the natural forest ecosystem were68.86Tg,0.21Tg,0.15Tg,5.182Tg and115.52Tg respectively and the artificial forest ecosystem were21.52Tg,0.03Tg,0.07Tg,0.61Tg and41.50Tg respectively. The soil layer is the main layer of ecosystem carbon sequestration, followed by the arbor layer, litter layer, shrub layer and grass layer. If ignored the carbon stocks of litter layer, shrub layer and grass layer, the estimate of carbon stocks was imprecise.Sixth, the carbon storage of the forest ecosystem was distributed in near-mature forest(81.71Tg), middle-aged forest (78.38Tg) and young forest (53.54Tg) which accounted for84.23%of total carbon stocks of the forest ecosystem in Shanxi. The carbon storage of the natural forest ecosystem was distributed in near-mature forest(68.18Tg) and middle-aged forest (58.45Tg) which accounted for66.67%of total carbon stocks of the natural forest ecosystem in Shanxi. The carbon storage of the artificial forest ecosystem was distributed in near-mature forest(19.94Tg) and middle-aged forest (19.25Tg) which accounted for61.48%of total carbon stocks of the artificial forest ecosystem in Shanxi.Seventh, the total carbon stock of the forest ecosystem will reach274.47Tg in2015year, and the carbon stocks of the tree layr, shrub layer, grass layer, litter layer, soil layer will reach98.09Tg,0.262Tg,0.222Tg,6.287Tg,169.60Tg respectively.With the commencement of natural forest protection project in Shanxi, the natural forest was fully protected, growing better and natural succession updates. In recent years, with the plantation acreage had increasing and combined with tending treatments, the artificial forests was growing better and succession updates in Shanxi. Overall, the forests of Shanxi played an important role of carbon sink in China. |
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