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根据岩溶生境特点设计表层岩溶水-岩石(灰岩)-土壤水分供应分层模拟柱,对青冈栎(Cyclobalanopsis glauca)进行水分控制试验;运用压力容积(P-V)技术,研究了在水分胁迫下青冈栎的日水势(P)、饱和含水量时的最大渗透势(ψssat)、初始质壁分离时的渗透势(ψstlp)、初始质壁分离时渗透水相对含量(ROWCtlp)、初始质壁分离时相对含水量(RWCtlp)、质外体水的相对含量(AWC),以及饱和含水量时最大渗透势与初始质壁分离时的渗透势之差(ΔP)的变化。结果表明,在无表层岩溶水-岩石-土壤处理中,随着土壤干旱胁迫程度的增加,ROWCtlp、RWCtlp、ψssat、ψtslp呈明显下降,而AWC值上升;在有表层岩溶水-岩石-土壤处理下,青冈栎受土壤水分胁迫不明显,水分参数变化不显著。表层岩溶缺水时,土壤水分含量是影响青冈栎水分参数变化的主要因素,在一定的干旱胁迫范围内,随着干旱程度的提高,青冈栎耐旱性不断增加。
According to the characteristics of karst habitat, the epidermis karst water-rock (limestone) -soil water supply stratified simulation column was designed to control the water cycle of Cyclobalanopsis glauca. By using the pressure-volume (PV) technique, (P) of oak, the maximum osmotic potential (ψssat) at saturated water content, the osmotic potential (ψstlp) at initial plasmolysis, the relative content of permeated water at initial plasmolysis (ROWCtlp), the initial plasmolysis RWCtlp, AWC, and the difference (ΔP) between the maximum osmotic potential at the saturated water content and the osmotic potential at the initial plasmolysis. The results showed that ROWCtlp, RWCtlp, ψssat and ψtslp decreased obviously and AWC increased with the increase of soil drought stress in surface-free karst water-rock-soil treatment. In the case of surface karst water-rock-soil treatment Under the soil water stress, the Quercus glauca was not obvious, and the change of water parameters was not significant. Soil moisture content is the main factor that affects the variation of the water parameter of Q.cv. oak in the case of superficial karst water deficit. Within a certain range of drought stress, the drought tolerance of Q. pungens increases with the increase of drought level.