Characteristics of stemflow for sand-fixed shrubs in Mu Us sandy land, Northwest China

Little work has been done on stemflow for desert shrubs in China. This study measured stemflow in two shrubs of Salix psammophila C. Wang et Chang Y. Yang and Artemisia sphaerocephala Krasch in Mu Us sandy land and established a relationship between stemflow and canopy characteristics, rainfall amount and intensity. During the experimental period, the amount of stemflow for S. psammophila and A. sphaerocephala accounted for 7.6% and 2.7% of the gross rainfall respectively. Statistical analysis showed that there was a significant positive linear correlation between rainfall and stemflow for the two shrubs; while the relationship between stemflow percentage and rainfall suggested that there existed a rainfall depth threshold of 3―5 mm for S. psammophila and 5―7 mm for A. sphaerocephala. Stemflow percentage positively increased with rainfall depth increasing before the rainfall depth threshold values had been reached but showed stability after the threshold. A stepwise regression analysis suggested that the shrubs with more branches, larger crown volume and smaller branch angle inclination tended to collect more volumes of stemflow. Moreover, stemflow amount and percentage increased with the maximum rain intensity increasing in 10 minutes (I10) and the stemflow percentage tended to increase quickly with I10 when it was less than 3.0 mm h-1 for S. psammophila and 2.0 mm h-1 for A. sphaero- cephala, and then showed stable trend with increasing of I10.