干旱荒漠区白刺灌丛沙堆土壤温度及水分养分变化特征

以民勤沙区不同变化阶段白刺灌丛沙堆为研究对象,测定白刺灌丛沙堆高度、长短轴、迎风坡与背风坡植被株高、盖度、枯枝和结实等形态特征，分析不同变化阶段土壤温度及水分养分变化特征。结果表明，1）土层0～10 cm处的土壤温度随着时间推移地面温度呈现出先逐渐升高而后缓慢下降的趋势，日变化规律为发育阶段＞雏形阶段＞稳定阶段＞衰退阶段。2）在不同发育阶段土壤含水率在40～60 cm土层中最高， 0～5 cm最低，随着土层深度增加水分含量呈现逐渐升高的趋势。3）不同变化阶段土层pH在5～10 cm最高，不同坡向pH均为迎风坡大于背风坡；衰退阶段背风坡中电导率最高，均大于其他发育阶段的坡向。4）土壤TN、速效磷平均含量发育阶段最高、有机质衰退阶段最高、稳定阶段均最低；土壤TN为雏形阶段、发育阶段和衰退阶段迎风坡中大于背风坡中，稳定阶段则相反；土壤有机质为雏形阶段和发育阶段背风坡中大于迎风坡中，稳定阶段和衰退阶段则相反；土壤速效磷为不同发育阶段迎风坡中大于背风坡中，土壤温度在0～10 cm处日动态呈现出先逐渐升高而后缓慢下降的趋势；土壤含水率在40～60 cm土层中最高，0～5 cm最低；pH在5～10 cm最高；电导率在衰退阶段背风坡中最高；土壤TN、有机质和速效磷在发育阶段表面养分含量达到最高，且显著高于其他几个阶段。研究结果为民勤荒漠区白刺群落植被恢复与保护提供科学理论依据。

Variation Characteristics of Soil Temperature,Water and Nutrient in Nitraria tangutorum Shrub-Growing Sand Pile in Arid Desert Area

Taking the Nitraria tangutorum shrub-growing sand piles at different developmental stages in Minqin sandy area as research objects,the pile height,length axis,plant height,coverage,dead branches and fruiting of sand pile were measured.The variation characteristics of soil temperature,moisture and nutrients in different changing stages were analyzed.The results showed that 1) the soil temperature at 0-10 cm soil layer increased gradually and then decreased slowly with time,the daily change rule was in the order of developmental stage>preliminary stage>stable stage>decline stage.2) The soil moisture content was the highest in 40-60 cm soil layer and the lowest in 0-5 cm soil layer at different development stages.3) The soil pH at 5-10 cm soil layer of all sand piles with different changing stages was the highest.The soil pH of windward slope was higher than that of leeward slope.The electrical conductivity of leeward slope of the piles at declining stage was higher than those of other developing stages.4) The average contents of total nitrogen and available phosphorus in soil were the highest in the developing stage; the contents of soil organic matter were the highest in the declining stage and the lowest in the stable stage; the contents of soil total nitrogen at preliminary stage,developmental stage,and decline stage were higher in windward slope than leeward slope,while in table stage,higher in leeward slope than windward slope; the contents of soil organic matter were higher in leeward slope than windward at preliminary stage and developmental stage,while they were opposite at stable stage; the contents of soil available phosphorus in windward slope were higher than leeward slope at all the developmental stages.The daily dynamic of soil temperature at 0-10 cm layer increased gradually at first and then decreased slowly.The soil water content was the highest in 40-60 cm soil layer,the lowest in 0-5 cm soil layer; the soil pH was the highest in 5-10 cm soil layer; the electrical conductivity was the highest in the leeward slope at decline stage; the contents of total soil nitrogen,organic matter and available phosphorus in surface soil were the highest at development stage,which were significantly higher than other stages.The results provide scientific and theoretical basis for the restoration and protection of N.tangutorum community in Minqin Desert area.