Soil water content in 0 —160 cm layers in mobile dune

fixed dune

and sandy grassland was monitored regularly in sit u 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 —160cm) . 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 dune > fixed dune > sandy 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 J uly > August > J une > 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.