Study On Biomass And Spatial Structure Of Aerially-seeded Of Pinus Massoniana Mixed Forest

Biomass was an important indicator to measure and evaluate productivity of stands, and to a certain extent, it affected by the stand spatial structure. The paper selected mixed forest of aerially-seeded Pinus massoniana(middle-aged plantations)in Xingguo County as an object. It dicussed biomass distribution, spatial structure characteristics and their relationships through typical sample plots survey and sample determination. The main results were as follows:(1) Biomass of stand was 78.66 t/hm2. Biomass of arbor, shrub, herb and litter layer were 71.84 t/hm2, 1.21 t/hm2, 3.12 t/hm2 and 2.49 t/hm2. Biomass of different diameters arbor were mid-diameter tree > small diameter tree >big diameter tree, arbor different tree species were Pinus massonia> Schima superba> Liquidambar formosana > Cunninghamia lanceolata; undergrowth layers were overground biomass significantly higher than underground biomass, and litter layers were half-decomposed biomass significantly higher than undecomposed biomass.(2) The stand had nine kinds of structure units, the form of six adjacent tree and one object tree was common. The average aggregation index of stands was 0.87, The distribution pattern of wood was from aggregated distribution to uniform distribution with the increase of DBH. The distribution pattern of Pinus massoniana, Schima superba and Cunninghamia lanceolata were aggregated distribution, while the distribution pattern of Liquidambar formosana was uniform distribution. The average competition indexs of stands was 6.48, were along with the increase of DBH to decrease. The competition indexs of different tree species were Cunninghamia lanceolata > Schima superba > Liquidambar formosana > Pinus massoniana. The average mixed degree of stand was 0.47, which showed the tree species segregation of different tree species also had a low level. While the stand mixed degrees were along with the increase of DBH to increase, and the mixed degrees of different tree species were Liquidambar formosana > Cunninghamia lanceolata > Schima superba > Pinus massoniana.(3) Biomass of arbor, shrub, herb and litter were showed the random distribution was more than the aggregated distribution, and they were along with increases of competition and mixed degree to increase. The different mixed degree of arbor biomass, shrub biomass, herb biomass and litter biomass had significant difference(P< 0.05).