Spatial variability of soil moisture on aeolian sandy land in riparian ecotone of middle reaches of Yarlung Zangbo River valley

Soil moisture content is one of the restrictive factors of natural vegetation succession and artifical vegetation restoration in the alpine valley in Tibet. The purpose of this study is to characterize the distribution of soil moisture on different aeolian sandy land types, and to make inferences to guide the ongoing vegetation reconstruction. Taking aeolian sandy land in the riparian ecotone of the middle reaches of the Yarlung Zangbo River valley as a case study, geo-statistical and GIS methods were conducted to examine the spatial variability and vertical characteristics of soil moisture on. The results showed: 1) the mean soil moisture content at different depths on aeolian sandy land was from 6.14% to 14.20%, and decreased with the increasing depth of humid soil layer. The spatial variability of soil moisture was the strong variability; 2) Soil moisture content had a strong spatial correlation in the layer of 0-20 cm and a moderate spatial correlation in other layers. The spatial correlation decreased with the soil depth increased. The spatial distribution pattern of soil moisture between different soil depths had a significant similarity, and the highest was between 20-40 cm and 40-60 cm ; and 3) The soil moisture content varies with the micro-topograhpy, sandy land on flood plain > windward aspect > leeward aspect > sandy gravel land > top of sand dunes. The variations of water level, micro-topography and aeolian sand movement are the main factors to determine the differentiations of soil moisture content between different types of sandy land and parts of moving sand dunes.