六盘山典型植被下土壤大孔隙特征

Soil macropore characteristics under typical vegetations in Liupan Mountains.

利用水分穿透曲线法和Poiseuille方程研究了六盘山8种典型植被类型下土壤大孔隙的半径与密度特征．结果表明：研究区典型植被下土壤大孔隙半径在0．4～2．3mm，加权平均半径为0．57～1．21mm，平均值为0．89mm；大孔隙密度变化范围为57～1117个·dm^-2，平均408个·dm^-2；半径〉1．4mm的大孔隙密度较小，其数量仅占大孔隙总数量的6．86％；大孔隙面积与土柱水分出流面积的百分比（简称土壤大孔隙面积比）介于0．76％～31．26％，平均为10．82％．研究区土壤大孔隙密度为阔叶林大于针叶林，亚高山草甸与阔叶林相当，灌丛与针叶林相当；土壤大孔隙面积比为阔叶林高于针叶林，灌丛与阔叶林相当，亚高山草甸与针叶林相当．

The radius and density of soil macropores under eight typical vegetations in Liupan Mountains of Northwest China were studied by using water breakthrough curves and Poiseuille equation. The results indicated that the radii of soil macropores ranged from 0.4 mm to 2. 3 mm, and the weighted mean radii ranged from 0. 57 mm to 1.21 mm, with a mean of 0. 89 mm. The density of soil macropores ranged from 57 individuals per dm^2 to 1 117 individuals per dm2, with a mean of 408 individuals per dm^2. The macropores with radii bigger than 1.4 mm had a lower density, accounting for only 6. 86% of the total. The area proportion of soil macropores ranged from 0. 76% to 31.26%, with a mean of 10. 82%. In study area, the density of soil macropores was higher in broadleaf forest than in coniferous forest, but basically the same in sub-alpine meadow and in broadleaf forest, as well as in shrubs and in coniferous forest. As for the area proportion of soil macropores, it was also higher in broadleaf forest than in coniferous forest, but basically the same in shrubs and in broadleaf forest soil, as well as in sub-alpine meadow and in coniferous forest.