庐山不同森林植被对土壤团聚体及其有机碳分布的影响

Effects of Different Types of Forest Vegetation on the Distribution of Soil Aggregate and Its Organic Carbon in Lushan Mountain

研究不同粒径团聚体有机碳含量与土壤团聚体分布的关系,对于认识森林土壤结构形成和碳氮稳定机制有一定的科学意义。以庐山6种森林植被类型土壤为研究对象,系统研究了不同森林植被对土壤团聚体及其有机碳分布的影响,结果表明:(1)不同土层的森林植被类型对粒径在>5mm和0.25~0.5mm范围内的土壤团聚体含量影响较明显,其中黄山松林下土壤团聚体含量最高;(2)6种森林植被在不同的土层下,水稳性团聚体百分含量(R0.25%)和平均重量直径(MWD)随着土层深度的增加而逐渐减小,其土壤团聚体的稳定性也随之减弱,在0—20cm土层下的土壤团聚体较稳定,黄山松林、马尾松林和玉山竹林下MWD值较大,在20—40,40—60cm土层差异则不明显;(3)在同一土层下黄山松林的土壤团聚体有机碳含量最大,常绿阔叶林最小,马尾松林、玉山竹林和黄山松林的土壤团聚体有机碳变化较明显,而其他3种差异不显著。

The formation mechanism and the stability of soil aggregate can be illustrated through the study on the relationship between organic carbon contents in different diameters of soil aggregates and the distribution of soil aggregate.Taking the soils in the six types of forest vegetation in Lushan as research samples,the effects of different types of forest vegetation on the distribution of soil aggregate and its organic carbon were systematically investigated.The results show that there is an obvious influence on the content of soil aggregate which diameter is greater than 5mm or the range of 0.25~0.5mm,caused by forest vegetation type in the different soil layers.Among them,the highest amount of soil aggregate content is detected in the Pinus taiwanensis forest.With the increase of soil depth,the percentage content and mean weight diameter of water stable aggregate in the six forest vegetation types under the different soil layers gradually decrease and so does the stability of soil aggregate.The soil aggregate is relatively stable in the 0—20cm soil layer and the mean weight diameters in Pinus taiwanensis forest,Pinus massonianaforest and Yushania chungii forest are larger,while the difference is not obvious in the 20—40,40—60cm soil layers.Compared with others,it is found that the Pinus taiwanensis forest′s organic carbon content in aggregate is the largest and the evergreen broad-leaved forest is the least.The changes of organic carbon contents have significantly taken place in Pinus taiwanensis forest,Pinus massonianaforest and Yushania chungii forest,while the changes of organic carbon contents are not evident in the other three types.