黄土丘陵区典型林地土壤团聚体稳定性评价

Evaluation of Soil Aggregates Stability with Typical Forest Lands in Gullied Rolling Loess Area

黄土丘陵沟壑区属黄土高原水土流失最严重的区域,为了对该区合理配置水土保持林提供依据与参考,笔者对兰州市西果园流域内油松、华北落叶松、侧柏3种典型林地土壤团聚体和土壤有机质含量进行测试,分析土壤有机质与土壤团聚体的关系,定量评价了3种林地的土壤团聚体稳定性。结果表明:油松、华北落叶松、侧柏这3种样地土壤团聚体以粒径>0.25 mm的大团聚体为主,土壤团聚体稳定性以华北落叶松样地的最好,油松次之,侧柏最差;土壤有机质含量随土层深度增加而减小,3种样地土壤有机质含量表现为华北落叶松>油松>侧柏,水稳性大团聚体含量、水稳性团聚体平均质量直径、水稳性团聚体几何平均直径与土壤有机质含量正相关,风干土大团聚体含量、团聚体破坏率、水稳性团聚体分形维数与土壤有机质含量负相关,土壤有机质含量对土壤大团聚体含量、团聚体破坏率和水稳性团聚体分形维数影响显著;研究区华北落叶松样地土壤团聚体稳定性高于油松和侧柏样地的,在水土保持林配置中可优先考虑华北落叶松。

The gullied rolling loess area is the most serious area of soil and water loss in the Loess Plateau.In order to provide basis and reference for the rational allocation of soil and water conservation forest in the gullied rolling loess area,by taking the Pinus tabulaeformis,Larix principisrupprechtii and Platycladus orientalis in Xiguoyuan watershed of Lanzhou as the research object,a systematic analysis of the relationship between soil aggregates and soil organic matter was made and the soil aggregates stability was evaluated.The results indicate that the>0.25 mm soil aggregates is the main aggregate size of Pinus tabulaeformis,Larix principisrupprechtii and Platycladus orientalis.The stability of soil aggregates is the best in Larix principisrupprechtii,then followed by Pinus tabulaeformis and Platycladus orientalis.The SOM of all stands is decreased with the increase of soil depth and which of the order is Larix principisrupprechtii>Pinus tabulaeformis>Platycladus orientalis.There is a positive correlation between Ww0.25,MWDw,GMDw and SOM,and there is a negative correlation between Wd0.25,PAD,Dw and SOM.SOM has a significant effect on the soil macroaggregate content,PAD and Dw.The stability of soil aggregate in Larix principisrupprechtii is higher than that in Pinus tabulaeformis and Platycladus orientalis and Larix principisrupprechtii can be given priority in the allocation of soil and water conservation forest in gullied rolling loess area.