Study On Biomass And Carbon Storage In The Mixed And Pure Stands

In this paper, five types of forest were researched, including26-year-old Pinus massoniana pure forest (PF26),50-year-old P. massoniana pure forest (PF50),26-year-old Castanopsis hystrix pure forest (CF26), mixed even-aged stand of P. massoniana and C. hystrix (PCME) and mixed uneven-aged stand of P. massoniana and C. hystrix (PCMU). By the method of sampling of neighboring grids, the sample plot to a total area of4000m2in each experi-mental stand was designed, which was devided to10parts, each area400m2. The biomass and carbon storage of different layers in the community was determined by the method of the standard tree on average diameter class and quadrat harvesting. And the otherness among them was analyzed through the canonical correlation analysis. The effects of different afforestation models on the community biomass and carbon storage in P. massoniana and C. hystrix plantations were attempted to find out, so as to provide the reference data for the reform of artifical pure stand and the construction of mixed stand. The research results show that:(1) Community biomass (t-hm-2) of5kinds of plantations orderd like this: PF50(337.520)>PCMU (270.991)>PF26(195.416)>PCME (143.934) >CF26(131.916). The variance analysis results indicated that the otherness among above forests reached extremely significant level(p<0.01). The vertical distribution pattern of community biomass for these plantations displayed an order of arbor layer>litter layer>lying vegetation; the distribution pattern of organ biomass both P. massoniana and C. hystrix all displayed that:trunk>root> branch> bark> foliage.(2) The average carbon content of P. massoniana (53.41～55.12%) was higher than C. hystrix (50.27～50.71%) under different afforestation models. The result of t-test (t=8.805>t0.01=2.690,p<0.01) indicated that the carbon content otherness among them was extremely significant, which reflected that the tree species assimilation efficiency on CO2was different because of varied biological characteristics. Whether in P. massoniana or C. hystrix, the otherness of carbon content in different organs all reached extremely significant level(p<0.01). Tree age and vegetation space acting as variable, the otherness of carbon content in the same organ of P. massoniana was extremely significant(p<0.01) under different afforestation models. Generally the average carbon content of lower arbor, shrub and herbaceous plant was less than the lord for the arbor layer.(3) The order of scosystem carbon storage (t-hm-2) for5kinds of plantations was that:PF50(292.828)>PCMU (236.772)>PF26(197.386)>PCME (181.936)>CF26(158.521), and any two of them existed significant (p<0.05) or extremely significant otherness(p<0.01). Affected by different forest types, the vertical distribution pattern of scosystem carbon storage of both CF26and PCME displayed an order that:soil layer>arbor layer>litter layer> lying vegetation, while PF26, PF50and PCMU ranked that:arbor layer>soil layer> litter layer> lying vegetation.(4)The order of soil carbon storage (t·hni-2) for5kinds of plantations was that: PF50(113.205)>PCME (109.074)>PCMU (93.868)>CF26(92.929)>PF26(90.432), the otherness among them was extremely significant(P<0.01). Among above forests, the soil carbon sequestration ability of PF50was the highest, and that of mixed stands was generally higher than the pure stands.