Temporal and spatial characteristics of soil moisture dynamics in fixed dune of the Horqin sandy land

Abstract

The spatio-temporal variability of soil moisture (SM) in the fixed dune was analyzed based on the long-term monitoring data of SM at a depth of 1.5m in the fixed dune of the Horqin Sandy Land from May to September (that is growing season) for the 6th consecutive year (2009~2014) and the synchronize rainfall data. The results indicated that: (1) The changes of SM with the month generally showed a “W-shaped” curve in 2009, 2010 and 2011, and higher SM appeared in July. In 2012, the SM was lower in May and higher in June, and decreased slightly in the following three months. In 2013 and 2014, the changes of SM with the month showed a continuous downward trend. (2) Except for 2013, the SM was lower in the surface layer (0~10 cm), and the SM increased first, then decreased, and finally increased with soil depth. (3) As the soil depth increases, both SD and CV of SM showed a decreasing trend. According to the SD and CV method, the vertical variation layers of SM in fixed dunes of the study area were initially divided into the fast changing layer of 0~50 cm, the active layer of 50~90 cm and the second active layer of 90~150 cm.