| Natural forest is an important vegetation type, which plays an important and unsubstitutable role in environment protection, water and soil conservation, world carbon cycle balance maintenance and other ecological service functions. Lots of natural forests were destroyed due to human activities and continuously wood needs, and lead to natural forest changed to artificial plantations, this will has many deep effects on forest ecosystem functions. Soil physical properties and anti-erodibility were determined under natural forest (TRL) and artificial plantations of Phyllostachys heterocycla (MZL), Sassafras tzumu (CML), Cryptomeria fortunei (LSL), Cunninghamia Lanceolata (SML) and Metasequoia glyptostroboides (SSL) which were converted from TRL in Muchuan county. Sichuan Province. The methods of principal component analysis (ZCFM) was used to calculate the comprehensive value (KSX) to evaluate the impact of vegetation change on soil anti-erodibility. The results as follows:(1) Soil organic mater content decreased and soil bulk density increased after natural forest change to artificial forest. Soil organic matter content under different forests ranked as TRL> CML> SSL> LSL> MZL> SML, while soil bulk density under different forests ranked as TRL< CML< SSL< LSL< MZL< SML.(2) soil porosity and air permeability condition become worse after natural forest change to artificial forest. Soil capillary porosity, non-capillary porosity, total porosity, and air permeability under different forests all ranked as TRL> CML> SSL> LSL> MZL> SML.(3) Water holding capacity become worse after natural forest change to artificial forest. Soil natural water content, maximum water holding capacity, capillary water holding capacity and field water capacity under different forests ranked as TRL> CML > SSL> LSL> MZL> SML.(4)>0.25 mm and>0.5 mm particle-sized aggregate and water-stable aggregate contents and mean weight diameter of water stable aggregate were decreased, on the contrary, the ratio of soil structure deterioration and unstable aggregate index were increased after natural forest change to artificial forest.>0.25 mm and>0.5 mm particle-sized aggregate and water-stable aggregate contents and mean weight diameter of water stable aggregate under different forests ranked as TRL> CML> SSL> LSL > MZL> SML. while the ratio of soil structure deterioration and unstable aggregate index under different forests ranked as TRL< CML< SSL< LSL< MZL< SML.(5) Soil particle composition and micro-aggregate composition were changed after natural forest change to artificial forest, and lead to soil dispersion increase, structural granular index, aggregation state, aggregation rate and physical stability index decreased, while dispersion coefficient, erosion coefficient and index of erodibility increased.(6) Comprehensive value of soil anti-erodibility (KSX) decrease after natural forest change to artificial forest, it ranked as TRL< CML< SSL< LSL< MZL< SML. Significant (p< 0.05) correlations were observed between the indexes of soil anti-erodibility. The KSX was significant (p< 0.05) correlated with all indexes of soil anti-erodibility.The results suggest that protecting natural forest and choose appropriate afforestation trees were important for enhancing soil organic matter, increasing soil porosity, water holding capacity, soil aggregate and water-stable aggregate content and soil structure stability and decrease soil depersion, increase soil anti-erodibility. Among the artificial plantations. CML and SSL has best function for soil physical properties and anti-erodibility improvement, then both CML and SSL all can be selective trees as TRL's regenerative plantation. The results will lay a solid foundation for protecting natural forest, choosing appropriate trees, and soil management, also providing advice for trees choice in the process of converting farmland to forestland. |
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