Studies On The Benefits Of Reconstruction Of Cunninghamia Lanceolata Forests In Xiaokeng Forest Farm, Shaoguan City

Construction of ecological forests is the major task in current ecological forestry in Guangdong, and forest reconstruction is the important measures to build high function and high benefit of ecological forests. Long-term continuous operation and the unreasonable managing methods of Cunninghamia lanceolata cause forest degradation,single structure in tree species of forests and poor ecological benefit, and that Cunninghamia lanceolata mixed with hardwood tree species significantly improves productivity. Therefore, it is extremely urgent to reconstruct Cunninghamia lanceolata stands. In this study, seedlings of Elaeocarpus sylvestris, Cinnamomum camphora,Castanopsis fissa, Castanopsis hystrix and Michelia macclurei were used to reconstruct Cunninghamia lanceolata stands, and the growth, leaf nutrient, understory plants diversity,soil physical and chemical properties and litter reserves and nutrient were studied in the five reconstruction stands. The results were as follows:(1) The difference in the growths of five arboreal used forest reconstructions was great.Comprehensively considing status in tree height, diameter at breast height and crown width,C. fissa was the fastest growing species and growth speed of C. hystrix, M. macclurei and C.camphora was medium, whereas E. sylvestris was the slowest growth species.(2) Leaf nitrogen content was 19.85, 20.20, 17.45, 15.49 and 14.87 g�kg-1, phosphorus content was 1.20, 1.22, 1.02, 0.73, and 0.91 g�kg-1, potassium content was 7.20, 7.52, 8.80,5.68 and 8.80 g�kg-1, and carbon content was 484.10, 507.87, 536.27, 482.11, 531.79 g�kg-1.in E. sylvestris, C. camphora, C. fissa, C. hystrix and M. macclurei trees.(3) There were 12 shrub species and 13 herb species in the E. sylvestris forest, 16 shrub species and 12 herb species in the C. fissa forest, 10 shrub species and 14 herb species in the C. hystrix forest, 9 shrub species and 20 herb species in herb layer in the M macclurei forest, respectively. Simpson and Shannon Wiener diversity index and evenness index(Jsw and Jsi) were 0.84, 2.51, 0.70 amd 0.84, respectively, in shrub layer under E. sylvestris stand, which were significantly higher than those of other forests.(4) The soil bulk density of E. sylvestris, C. camphora, C. fissa, C. hystrix and M. macclurei was 1.30, 1.19, 1.24, 1.29 and 1.16 g�cm-3, and the soil bulk density of E. sylvestris and C.hystrix was significantly greater than C. camphora and M. macclurei, whereas their soil capillary water holding capacity, total porosity, capillary porosity, non-capillary porosity and aeration porosity were smaller than the two both formers.(5) The p H value of soils under the five stands ranged from 4.3 to 5.1, belonging to strong acid soils. Soil organic matter and total N contents of was high in E. sylvestris and C camphora soils, medium in M. macclurei soil and low in C. fissa and C. hystrix soils was low. Total P content decreased in the order of M. macclurei > C. fissa > C. hystrix > E.sylvestris, Total K content decreased in the order of C. hystrix > E. sylvestris > C.camphora > M. macclurei > C. fissa. Availiable N,P and K contents decreased in the order of C. camphora > M. macclurei > E. sylvestris = C. fissa > C. hystrix, C. hystrix > C.camphora > E. sylvestris = C. fissa = M. macclurei and C. camphora > M. macclurei > C.fissa > C. hystrix > E. sylvestris, respectively.(6) The difference in of the five forests was relatively great, litter accumulation of C. fissa and C. hystrix forests was 2.22 kg/m2, which was significantly greater than other forests,litter accumulation of C. camphora forest was was 1.27 kg/m2 which was medium among the five forests, and that of E. sylvestris and M. macclurei was 0.60 kg/m2 and 0.71 kg/m2,which was smallest among the five forests. The litter nutrients of 5 samples were difference,most consistent with leaf nutrient content. The nitrogen conten of litter layer was 11.54,12.68, 10.33, 11.66 and 7.75 g�kg-1, phosphorus content was 0.54, 0.85, 0.43, 0.72, and 0.56g�kg-1, and potassium content was 2.26, 2.09, 2.64, 2.09 and 2.64 g�kg-1 in E. sylvestris, C.camphora, C. fissa, C. hystrix and M. macclurei forests, respectively. N and P contents of C.camphora litter were significantly greater than other forests, and K content of C. hystrix and M. macclurei was significantly greater than other forests.