滇中柏木林地枯落物去除对土壤水分物理性质的影响

Effects of Litter Removal on Physical Properties of Soil Moisture in Cypress Forest in Central Yunnan

柏木是云贵川三省常见的造林树种,对区域生态环境优化与水源涵养作用明显。为深入了解柏木林地枯落物层对土壤水分状况的影响,以近35年的人工柏木林为研究对象,在样地调查的基础上,对枯落物不同程度去除后土壤水分物理性质的变化进行了研究。结果表明:随地表枯落物的去除,枯落物层自然含水率呈降低趋势,其变化范围在66.95%~114.54%;表层土壤(0~10 cm)的土壤密度(1.11~1.15 g/cm~3)与亚表层(10~20 cm)土壤密度(1.18~1.27 g/cm~3)的变化不明显。随枯落物的去除,表层和亚表层土壤的总孔隙度和毛管孔隙度均有显著降低,非毛管孔隙度增大。表层土壤饱和持水量均值在353.07~458.96 g/kg,毛管持水量均值在233.27~357.17 g/kg,田间持水量均值在218.80~343.96 g/kg,大小顺序均为未去除>半去除>全去除,亚表层也一致。全去除枯落物对土壤各持水量影响最大,枯落物去除对表层和亚表层土壤水分状况均有明显影响。土壤是林分水源涵养功能的主体,但枯落物也有着减缓地表径流、改善土壤结构等重要作用。

Cypress is a common afforestation species in Yunnan,Guizhou and Sichuan provinces,which plays a significant role in regional ecological environment optimization and water conservation.In order to understand the effect of litter layer on soil water status in cypress forest,the change of soil water physical properties after litter removal was discussed on the basis of the investigation of artificial cypress forest in the past 35 years.The results show that the natural water content of litter layer decreases with the removal of surface litter,and its variation range is 66.95%~114.54%.There was no obvious change in soil density(1.11~1.15 g/cm~3) in surface soil(0~10 cm) and soil density(1.18~1.27 g/cm~3) in subsurface soil(10~20 cm).With the removal of litter,the total porosity and capillary porosity of surface and subsurface soil decreased significantly,while the non-capillary porosity increased.The average saturated water holdup of surface soil ranged from 353.07 g/kg to 458.96 g/kg;capillary water holdup ranged from 233.27~357.17 g/kg,and field water holdup ranged from 218.80~343.96 g/kg,with the order of unremoved > semi-removed > completely removed,and the sub-surface was the same.Total litter removal had the greatest effect on soil water capacity,and litter removal had a significant effect on surface and subsurface soil water status.Soil is the main body of water conservation,but litter also plays an important role in mitigating surface runoff and improving soil structures.