科尔沁地区不同类型沙地土壤水分变化分析

Change Pattern of Soil Water Content in Different Dunes and Grassland in Horqin Sandy Land

于2005—2008年5—9月,利用中子水分仪对科尔沁沙地的流动沙丘、固定沙丘和沙质草地的不同深度(0—160cm)的土壤水分进行了为期4a的定期观测。采用方差分析和多重比较等方法,并采用变异系数对土壤水分的时空变异进行了分析。结果表明,可将土壤水分剖面的变化划分为3层:土壤水分剧变层(0—40cm),稳定层(41—130cm),活跃层(131—160cm)。在0—40cm土壤层,3种类型沙地土壤水分表现为随深度增加而增加,在41—130cm土壤层则随深度增加而减小,而在131—160cm土壤层流动沙丘表现为继续减小,但其它两种沙地的土壤水分则随深度增加而增加。同时土壤水分变异系数表现为:流动沙丘>固定沙丘>沙质草地。土壤水分在不同月份的变化表现为:7月>8月>6月>9月>5月,各月之间总体上差异性显著;各类型沙地土壤水分的年变化为:固定沙丘总体表现出逐年减小的趋势,沙质草地有变化但差异不大,而流动沙丘则随降雨的变化而变化。

Soil water content in 0—160 cm layers in mobile dune,fixed dune,and sandy grassland was monitored regularly in situ with neutron probe （CNC100,Beijing） from 2005 to 2008.The relationships between soil moisture and environmental factors were analyzed with multiple comparison and ANOVA.Results showed that three layers can be identified according to the vertical changes of soil water content in each site.They were drastic change layer （0—40 cm）,relative stable layer （41—130 cm）,and activity layer （131—160 cm）.Soil water content was increased with the increase of sample depth in layer of 0—40 cm,but decreased in layer of 41—130 cm in all sites.However,soil water content was decreased continuously with the increase of sample depth in layer of 131—160 cm in mobile dune only,but increased in other sites.By the coefficient variation of soil water content,landscape units presented the order of mobile dunefixed dunesandy grassland.There was a significant difference in soil water content in all sites in each month and by soil water content,months have the order of July August June May September.Variation of soil water content between years showed that there were a decreasing trend in fixed dune,a bit of difference in sandy grassland,and a complex pattern in mobile dune as affected directly by rainfall.