川南山地林分变化对土壤物理性质和抗蚀性的影响

以川南天然林(TRL)及其转变成的毛竹林(MZL)、檫木林(CML)、柳杉林(LSL)、杉木林(SML)和水杉林(SSL)为对象,研究不同林分土壤物理性质和抗蚀性差异,以主成分分析法(ZCFM)和隶属函数法(LSHM)分别计算的土壤抗蚀性综合值Ⅰ(KSX-Ⅰ)和Ⅱ(KSX-Ⅱ)评价林分变化对土壤抗蚀性的影响,探索简便易行的土壤抗蚀性综合评价方法。结果表明,天然林转变为人工林后土壤物理性质和抗蚀性变差,呈现出有机质和0.25 mm水稳性团聚体含量、水稳性团聚体平均重量直径、团聚度、孔隙度及物理稳定性指数降低,而结构体破坏率、不稳定团粒指数、容重、分散率及侵蚀系数增加。各林分土壤KSX-Ⅰ和KSX-Ⅱ均呈现出TRLCMLSSLLSLMZLSML的规律变化。土壤抗蚀性指标间相关性均达到显著(p0.05)水平;土壤KSX-Ⅰ和KSX-Ⅱ之间呈显著相关关系(p0.05),且两者均与各抗蚀性指标间呈显著相关(p0.05)。说明天然林植被变化后会使土壤抗蚀性降低,影响原有植被水土保持功能,应该加强天然林及其生态功能保护;ZCFM和LSHM均可作为计算土壤抗蚀性综合值的有效方法,但考虑到计算过程的难易度,后者更简便易行。结果为土壤抗蚀性综合评价新方法的建立提供了参考。

EFFECTS OF FOREST CHANGE ON SOIL PHYSICAL PROPERTIES AND ANTI-ERODIBILITY IN SOUTHERN SICHUAN MOUNTAINS

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 southern Sichuan Province. The methods of principal component analysis (ZCFM) and membership function (LSHM) were used to calculate the comprehensive valueⅠ(KSX-Ⅰ) and Ⅱ(KSX-Ⅱ) of soil anti-erodibility, respectively, to evaluate the impact of forest change on soil anti-erodibility and explore a simple and feasible soil anti-erodibility evaluation method. The results showed that natural forest converted to artificial forests, leading to worse soil physical properties and anti-erodibility, and decreasing content of soil organic matter, >0.25 mm water stable aggregate, mean weight diameter of water stable aggregate, aggregate degrees, porosity and physical stability index; on the contrary, the ratio of soil structure deterioration, unstable aggregate index, bulk density, dispersion rate and erosion coefficient increased. The KSX-Ⅰ and KSX-Ⅱ of soil anti-erodibility under different forest types ranked as TRL > CML > SSL > LSL > MZL > SML. Significant (p<0.05) correlations were observed between the indices of soil anti-erodibility. The KSX-Ⅰwas significant (p<0.05) correlated with KSX-Ⅱ, and both were significant (p<0.05) correlated with all indices of soil anti-erodibility. Our results suggest that soil anti-erodibility and water and soil conservation will become worse after natural forest change, and the protection of natural forest and its ecosystem should be strengthened; both ZCFM and LSHM were effective methods to calculate comprehensive value of soil anti-erodibility, while the latter is more simple and convenient than the former when the difficulty degree of calculation process was took into consideration. The results could provide references for developing new methods for comprehensive evaluation of soil anti-erodibility.