沙地植被恢复过程土壤颗粒组成变化及其空间变异特征

Changes in Soil Particles Fraction and Its Spatial Variation Characteristics in Restoration Processes of Sandy Desertification Land

对不同沙漠化程度的6个群落样地的土壤取样,采用水洗法和吸管法分析了土壤颗粒组成。结果表明：在严重沙漠化的土地上,土壤颗粒组成以0.25～0.10 mm的细砂和0.50～0.25 mm的中砂等粗粒成分为主,分别为77.62%和19.02%,且细砂富集作用明显,富集系数达到了1.25;而0.10～0.05 mm的极细砂和〈0.05 mm的粘粉粒等细粒成分存在贫化作用,含量极低,分别为1.65%和1.67%。土壤颗粒组成的这种特征是沙漠化过程土壤各级颗粒受到强烈分选、土壤组成粗粒化的反映。沙地植被恢复过程土壤颗粒组成变化的主要表现是粘粉粒和极细砂富集作用强烈,富集系数达到了3.06和2.75,含量明显上升,分别为16.27%和27.38%,空间变异程度降低,细砂和中砂含量则显著降低。富集系数和变异系数能够指示和表征群落生态过程持续的强度和扩展的范围。

Soil on 6 communities in different restoration stage were sampled in a sandy desertified region, and the soil particles fraction were determined. The results showed that, soil in severely sandy desertified land is mainly constituted by 0. 25--0.10 mm fine sand and 0.50-0.25 mm middle sand, the contents of which are 77.62% and 19.02%, respectively, while the 0. 10-0.05 mm very fine sand and 〈0.05 mm silt and clay are low with contents of 1.65% and 1.67%, respectively. This characteristics indicated that soil particles were strongly divided and selected by wind in sandy desertification, making soil more and more coarse. Changes of soil particles fraction in restoration process are mainly that, the contents of very fine sand, silt and clay are increasing, while the fine sand and middle sand decreasing prominently, with the restoration degree increasing. With the effects that enhancing soil agglomeration, making the ability of soil to endure wind erosion strong, and making soil as substrate more stable, very fine sand , silt and clay are the indicator of favorable development of soil-vegetation system in restoration process of sandy desertification land.