水保所知识产出(1956---)知识库

In the arid and semi-arid regions of the Loess Plateau, seasonal freezing and thawing
influencesoilwatermovement,andwatermovementdirectlyinfluencesvegetationgrowth.
However, currently, research with regard to freezing and thawing processes under various
vegetation types and the mechanism of soil water movement is lacking. Therefore, the
present study explored soil water migration characteristics of two typical vegetation types
[arbor land (AL) and shrub land (SL)] on the Loess Plateau during seasonal freezing and
thawing processes using bare land (BL) as a control. We used field measured data for
hourly soil temperature (ST) and soil water content (SWC) at a depth of 100cm below the
soil surface from November 2017 to March 2018. Freezing and thawing process was
dividedintothree stagesbasedonSTchange (initialfreezingperiod, stablefreezingperiod,
and thawing period). Compared with previous studies in this area, ST is lower than
expected, and SWC migration characteristics are also different. The results revealed that:
1)themaximum freezingdepthofALandSLwas60cm,whichwas30cmlessthanthatof
BL. The freezing date of each soil layer in BL was the earliest and average ST value was the
lowest. BL had the highest degree of freezing. The freezing of all soil layers in AL occurred
at a later date than that of SL. ST and the minimum soil freezing temperatures were higher
than those of SL, and the capacity of AL to resist freezing was higher; 2) the SWCs in AL
and BL at depths of 0–10cm and 10–30 cm decreased, whereas SWCs of AL and BL at a
depth of 60 cm increased by 152 and 146%, respectively. The SWCs of SL at soil depths
of 0–10 cm, 10–30 cm, and 30–60 cm increased by 46.3, 78.4 and 205%, respectively.
The amount and distribution of soil moisture in SL were optimum when compared to those
ofALandBL.Theresultsofthepresentstudycouldprovideascientificbasisforvegetation
restoration in arid and semi-arid areas of the Loess Plateau.