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Summary: Soil moisture content is one of the limiting factors for natural vegetation succession in alpine river valleys on the Tibetan Plateau. However, its spatio-temporal variability and effect on artificial vegetation restoration has rarely been reported. In this paper, we conducted a case study to examine the spatio-temporal variability and vertical characteristics of soil moisture by setting up a 100×120m experimental plot on aeolian sandy land in a riparian ecotone and analyzing the result data using a geo-statistical approach. The soil moisture contents at different depths all showed strong temporal variability, with the mean soil moisture ranging from 4% to 6% in spring, from 6% to 14% in summer and from 9% to 12% in autumn. The Gaussian semi-variogram model was the best fitted theoretical model for the spatial structure of soil moisture contents in different seasons, and soil moisture at the field scale showed strong spatial dependence. The spatial patterns of soil moisture all demonstrated strong similarity between depths with the strongest between 0–20cm and 20–40cm depths in autumn. The soil moisture content over the upper 60cm was the key factor that restricted the seed germination and seedling growth, and it affected vegetation coverage and density. The precipitation, variations of river water level, elevation as well as landform types were the main factors determining the variations of soil moisture content in different seasons. The results have important implications for the ongoing vegetation restoration in the study area. [ABSTRACT FROM AUTHOR]

Abstract: Aeolian sandy land in the Yarlung Zangbo River basin has attracted the attention of many researchers. However, its dynamics as well as its relevance to various factors has rarely been reported with integrated studies. In this paper, spatio-temporal dynamics of the aeolian sandy land in the basin was studied by interpreting Landsat images acquired from 1975, 1990, 2000, and 2008 with the help of geographic information system (GIS) technology. Spatially, the results showed a decreasing trend from west to east, which is from the Maquanhe wide valley in the headwater area to the middle and lower reaches of the river basin. Temporally, aeolian sandy lands in the basin showed a slow increasing trend, with an increase of 10.5% during the 1975–2008 period, spreading most quickly during the period of 1990–1999. The factors related to dynamics of aeolian sandy land were analyzed from the perspectives of two driving factors, climate changes and human activities. The climate-dominated natural factors are the internal driving forces for the development of aeolian sandy lands, and the human factors are the external driving forces responsible for the increase of the aeolian sandy land area. [Copyright &y& Elsevier]