| With the development of the society and economy of the human beings, the environmental problem has become increasingly severe. greenhouse effect, which caused by fossil fuel combustion, has become one of the serious global environment problems. As main part of the terrestrial ecosystem, forests play a decisive role in maintaining ecological balance, protecting ecological safety and preventing ecological crisis. Three Gorges Reservoir Area is an ecologically sensitive area, accurately predicting carbon storage is significant for researching regional carbon cycle and carbon sink. In this study, carbon storage and carbon density of forestry ecosystem in Three Gorges Reservoir Area had been estimated by researching carbon storage and carbon density in three layers of the forestry ecosystem. Masson pine forest, which was the widest in distribution in Three Gorges Reservoir Area, was taken for example, the main factors that influenced the system carbon density were studied. Our results indicated that:(1) Vegetation ecosystems in Three Gorges Reservoir Area were divided into 11 types, the biomass density in vegetation layer of diverse vegetation types showed an order : evergreen broad-leaved forest>coniferous-deciduous mixed forest> deciduous broad-leaved forest>Masson pine forest>coniferous mixed forest> Chinese-fir forest >bamboo forest>economic forest> temperate pine forest>Cypress forest>shrubbery. The sequence of NPP was that: bamboo forest>evergreen broad-leaved forest>Chinese-fir forest>Masson pine forest>coniferous-deciduous mixed forest>deciduous broad-leaved forest>coniferous mixed forest>economic forest>temperate pine forest>Cypress forest>shrubbery.(2) The mean vegetation layer carbon content rate of diverse vegetation types in Three Gorges Reservoir Area was 0.4903, and tissues carbon content rate were similar among of diverse tree species. The total carbon storage of vegetation layer was 58.70×10~6t, and Masson pine forest was 21.88×10~6t, Cypress forest was 2.11×10~6t, Chinese-fir forest was 1.54×10~6t, temperate pine forest was 0.91×10~6t, coniferous mixed forest was 5.83×10~6t, coniferous-deciduous mixed forest was 6.00×10~6t, evergreen broad-leaved forest was 2.71×10~6t, deciduous broad-leaved forest was 7.72×10~6t, shrubbery was 7.05×10~6t, economic forest was 2.18×10~6t, and bamboo forest was 0.60×10~6t, respectively.(3) The biomass density in litter of 11 vegetation types from high to low was that: Chinese-fir forest>temperate pine forest>deciduous broad-leaved forest>evergreen broad-leaved forest>Masson pine forest>coniferous mixed forest>bamboo forest> coniferous-deciduous mixed forest>Cypress forest>shrubbery>economic forest. The total litter biomass of vegetation types in Three Gorges Reservoir Area was 17.55×10~6t. The mean litter carbon content rate of diverse vegetation types was 0.3638, the sequence was that: Masson pine forest>Chinese-fir forest>bamboo forest >temperate pine forest>coniferous mixed forest>coniferous-deciduous mixed forest>Cypress forest>deciduous broad-leaved forest>evergreen broad-leaved forest >shrubbery>economic forest, and the carbon content rate of litter was significant for its organic carbon content. The total litter carbon storage of vegetation types in Three Gorges Reservoir Area was 667.28×10~4t, and Masson pine forest was 265.59×10~4t, Cypress forest was 18.50×10~4t, Chinese-fir forest was 24.92×10~4t, temperate pine forest was 19.60×10~4t, coniferous mixed forest was 64.00×10~4t, coniferous-deciduous mixed forest was 47.36×10~4t, evergreen broad-leaved forest was 20.10×10~4t, deciduous broad-leaved forest was 88.23×10~4t, shrubbery was 105.84×10~4t, economic forest was 4.76×10~4t, and bamboo forest was 8.40×10~4t, respectively. The mean litter carbon density of diverse vegetation types was 2.64 t/hm~2, and Chinese-fir forest(4.48t/hm~2)> temperate pine forest(4.02t/hm~2)>Masson pine forest(3.53t/hm~2)>coniferous mixed forest(3.02t/hm~2)>deciduous broad-leaved forest(2.99t/hm~2)>evergreen broad-leaved forest(2.94t/hm~2)>bamboo forest(2.55 t/hm~2)>coniferous-deciduous mixed forest(2.28t/hm~2)>cypress forest( 1.51 t/hm~2)>shrubbery( 1.30t/hm~2)>economicforest(0.42t/hm~2).(4) Carbon content in the soil at two levels(A and B) were various, the mean carbon content of layer A was 22.11g/Kg, and layer B was only 12.57 g/Kg. The mean layer A carbon density of diverse vegetation types was 56.3 t/hm~2, and the sequence of carbon density in layer A of diverse vegetation types was that: cypress forest>shrubbery>deciduous broad-leaved forest>temperate forest>Chinese-fir forest>coniferous mixed forest>coniferous-deciduous mixed forest>evergreen broad-leaved forest>Masson pine forest>bamboo forest>economic forest. The mean layer B carbon density of diverse vegetation types was 34.7 t/hm~2, and the sequence of carbon density in layer B of diverse vegetation types was that: cypress forest>Chinese-fir forest>temperate forest>deciduous broad-leaved forest>shrubbery>economic forest>bamboo forest>coniferous mixed forest>coniferous-deciduous mixed forest>Masson pine forest>evergreen broad-leaved forest. The total soil carbon storage of vegetation types in Three Gorges Reservoir Area was 2.21×10~8t, layer A was 1.48×10~8t and layer B was 0.73×10~8t, respectively.(5) The total forestry ecosystem carbon storage of Three Gorges Reservoir Area was 285.97×10~6 t.The mean carbon density of forestry ecosystems was 117.31 t/hm~2, the sequence of diverse vegetation types was that: cypress forest( 144.08 t/hm~2)> Chinese-fir forest(1 39.02 t/hm~2)>deciduous broad-leaved forest(125.89t/hm~2)>temperate pine forest(125.33 t/hm~2)>bamboo forest(117.85 t/hm~2)> coniferous mixed forest(113.28 t/hm~2)>economic forest(112.54 t/hm~2)> evergreen broad-leaved forest(110.25 t/hm~2)> Masson pine forest( 107.08 t/hm~2)>coniferous-deciduous mixed forest( 102.23 t/hm~2)> shrubbery(92.87 t/hm~2). The ratio of diverse layers to system carbon storage were various, vegetation layer ranged from 9.33% to 36.02%, litter layer ranged from 0.37% to 3.30%, and soil layer ranged from 61.32% to 89.27%, respectively.(6) Masson pine forest plots were studied, it suggested that system carbon density showed an obverse linear relationship with nutrient, an inverse linear relationship with slope angle, and a weak tendency to increase with altitude. Plot carbon density was similar from East to West, but variously from South to North in Three Gorges Reservoir Area.
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