Variation Characteristics of Soil Temperature and Moisture During the Freezing and Thawing Periods in Alpine Wetland in Qinghai-Tibetan Plateau
As the sources of some large rivers,the freeze-thaw process of alpine wetland in Qinghai-Tibetan Plateau is of great importance to regional and downstream ecosystem and climate regulation.Based on soil temperature and moisture observation data at Longbao test station of Yushu prefecture which is located in three rivers source area on Qinghai-Tibetan Plateau,the diurnal and seasonal variation characteristics of soil temperature and water content in the freezing and thawing processes were analyzed,especially during the freezing and thawing conversion period.The results indicate that the soil temperature and water content of alpine wetland had obvious seasonal variations in the freezing and thawing periods.The soil temperature was high in summer and low in winter.The profile values of soil temperature successively increased at 5 cm,40 cm,20 cm,30 cm,10 cm depth during the freezing period.On the contrary,it decreased in sequence at 5 cm,40 cm,20 cm,30 cm and 10 cm depth during the thawing period.The soil water content reduced gradually from top to bottom in the freezing period,while it increased from top to bottom during the thawing period.The soil temperature in surface layer (5 cm) and deep layer (40 cm) in alpine wetland had diurnal variation characteristics,the diurnal variation in surface layer was more significant than that in deep layer,and the variation range was biggest in summer.However,the soil water content was stable in a day except for a certain fluctuation in surface layer.The vertical distribution of soil temperature presented a three-layer structure due to the temperature differences between that at 10 cm,30 cm depth and their adjacent layers during the freeze -thaw transition period,while the soil water content appeared obvious regular changes,it decreased in the freezing period and increased in the thawing period with the increase of depth,and the change of soil water content in deep layer was later than that in shallow layer.
alpine wetlandsoil temperature and moisturecharacteristics of freezing and thawingfreezing and thawing conversion period
NETL
NSTL
万方数据
维普
