基于连续观测数据的毛乌素沙地生长季土壤水分动态及其对降雨的响应OA北大核心CSTPCD

Soil moisture is a crucial abiotic factor that limits the growth and development of plants and the ecolog-ical construction of sandy areas in semi-arid regions.In this study,continuous observations were performed on soil moisture at depths of 0-100 cm in shifting,semifixed,and fixed sandy land in the Mu Us Sandy Land during the growing seasons from 2008 to 2010 and from 2018 to 2021(April to October).The dynamic changes in soil moisture and its response to rainfall were systematically analyzed.The results are as follows:(1)Affected by sea-sonal changes in rainfall,the seasonal variation of soil moisture in shifting,semifixed,and fixed sandy land exhib-ited a generally"∽"-shaped or double-peaked pattern.The soil moisture in the 10-and 30-cm depth ranges exhib-ited greater fluctuations,whereas that in the 60-and 100-cm depth ranges showed smaller fluctuations.(2)The dynamic differences in soil moisture during the growing season were significant among the three degrees of fixa-tion.Overall,the shifting sandy land had the best soil moisture status with smooth changes,whereas the fixed san-dy land had the worst soil moisture status with the most drastic changes.The semifixed sandy land fell between the two.The soil moisture in the 10-30 cm depth range of the fixed sandy land was better than that of the semi-fixed and shifting sandy lands,whereas the situation was opposite at depths of 30-100 cm.(3)The pattern of rain-fall was the main factor determining the spatiotemporal distribution of soil moisture.As rainfall events occur and the amount of rain increases,the depth of rainwater infiltration gradually increases.However,deep replenishment of soil moisture in fixed sandy land requires higher rainfall amounts and longer periods.During the growing sea-son,small rainfall events were dominant,resulting in greater fluctuations in soil moisture in the surface layers.At the beginning of the growing season,soil moisture below 10 cm was not replenished because of low rainfall and small rainfall events,resulting in poor soil moisture conditions.The shifting and semifixed sandy lands had better soil moisture at depths of 10-30 cm than at depths of 30-100 cm,whereas the opposite was true for the fixed san-dy land.These results provide a scientific basis for the restoration of near-natural vegetation and the stable mainte-nance of sand-fixing vegetation on sandy decertified land in semi-arid regions.