The Research For Biomass And Carbon Stock Of Tree Layer Of Pure Forests And Mixed Forests Of Pinus Massoniana And Acacia Mangium

Global climate change has caused the people’s attention to the carbon balance and carbon stock in the terrestrial ecosystem. Terrestrial ecosystem carbon cycle plays an important role in global carbon balance, as the main body of land ecosystem, forest carbon sequestration function is increasingly significant. As an important economic tree species in southern China, Pinus massoniana is widely cultivated in Fujian province, Acacia mangium is afforestation tree species in coastal mountain. Pure forest and mixed forest of Pinus massoniana and Acacia mangium is the object of the research. The research contents mainly contain the diameter distribution of pure forest and mixed forest of Pinus massoniana and Acacia mangium, the influence of different slope positions on the biomass of pure forest and mixed forest of Pinus massoniana and Acacia mangium, the biomass models of Pinus massoniana and Acacia mangium,the carbon stock and value of pure forest and mixed forest of Pinus massoniana and Acacia mangium, the physical and chemical properties of the soil of pure forest and mixed forest of Pinus massoniana and Acacia mangium. The main results are as follows:1、The percentages that large and small diameter distribution of pure forest and mixed forest of Pinus massoniana and Acacia mangium account for are small,but the percentage that the middle diameter distribution accounts for is large,it accord with gaussian distribution,which is advantageous to the community stability and the growth of trees.2、The different organs’s and the total biomass above ground of tree layer of pure forest and mixed forest of Pinus massoniana and Acacia mangium increase with the rising of slope positions, the allocation proportion of different organs as the rise of slope positions show different patterns,which the allocation proportion of the trunk biomass reduce with rising of slope positions and the allocation proportion of the branches and leaves biomass increase with the rising of slope positions. 3、Through model fitting, selecte the superior biomass model of Pinus massoniana and Acacia mangium, the effect of power model is better.4、The distribution order of different organs of Pinus massoniana present the following displine:trunk>branch>leaf>bark, the distribution order of different organs of Acacia mangium present the following displine:trunk> branch>bark>leaf, the biomass of pure forest of Pinus massoniana and Acacia mangium is less than the mixed forest. The carbon density of pure forest of Pinusmassoniana is20.86t·hm-2, the value of carbon sequestration of pure forest of Pinusmassoniana is＄3652.22·hm-2, the carbon density of pure forest of Acacia mangium is40.93t-hm"2, the value of carbon sequestration of pure forest of Pinusmassoniana is＄6138.89·hm-2, The carbon density of mixed forest of Pinus massoniana and Acacia mangium is45.01t·hm-2, the value of carbon sequestration of mixed forest of Pinus massoniana and Acacia mangium is＄6751.88·hm-2. From the point of carbon density and the value of carbon sequestration, the capacity of carbon sequestration of mixed forest of Pinus massoniana and Acacia mangium is better than the pure forest.5、The volume weight of soil of pure forest and mixed forest of Pinus massoniana and Acacia mangium present the following displine:Increases with the increase of soil depth, the volume weight of soil of pure forest of Pinus massoniana and Acacia mangium is larger than the mixed forest.The field capacity、capillary moisture capacity and maximum water-holding capacity of pure forest of Pinus massoniana and Acacia mangium are less than the mixed forest; the capillary porosity and total porosity of pure forest of Pinus massoniana and Acacia mangium are less than the mixed forest, the noncapillary porosity of pure forest of Pinus massoniana and Acacia mangium are larger than the mixed forest.The content of soil organic matter、total nitrogen、total phosphorus、total potassium、hydrolyzable nitrogen、rapid available phosphorus and rapid available phosphorus of mixed forest of Pinus massoniana and Acacia mangium are higher than the pure forest,and present the following displine:reduces with the increase of soil depth.