黄土高原半干旱区沙棘林SPAC水势时空变异

Spatial and Temporal Variations on SPAC Water Potential of Seabuckthorn Stands in Semi-arid Region of the Loess Plateau

本文以黄土高原半干旱地区沙棘人工成林为研究对象,在SPAC系统中定位观测了沙棘林土壤水势、叶片水势和大气水势等。结果表明:天然降雨是研究区土壤水分的唯一补给来源,也是影响该区大气水势的主要环境因素,降雨量的分配具有明显的季节变化;沙棘林地土壤水势垂直分布基本呈现随土层的增加而上升的趋势;叶片水势变化趋势为早晨较高,随后下降,随着气温降低,水势又会波动回升。大气水势的日变化趋势基本相同,呈倒V字型。SPAC系统水势梯度明显,大气水势远高于树木叶片水势和土壤水势,树木叶片水势略高于土壤水势。

The paper studied the spatial and temporal change on water potential of seabuckthorn stands in SPAC system in semi-arid region of the Loess Plateau,which observed the soil water potential,leaf water potential and atmosphere water potential in the artificial seabuckthorn stands.The results show that rain is only source of water compensation to soil water,and is a main element which affects atmosphere water potential.Distribution of rainfall obviously varies according to seasons.The vertical distribution of soil water potential mainly presents an increasing trend with the increase of soil layers.The pattern of leaf water potential changes has little difference,leaf water potential is higher in the morning,then decline,and will fluctuate,recover with the decline of lapse rate.Diurnal variation trend of atmosphere water potential remains the same,which is inverse ＂V＂ shape.Water potential gradient in the SPAC system are significant,the atmosphere water potential was higher than those of leaf and soil,and the leaf water potential was a little higher than that of soil.