不同固定程度沙地油蒿叶水势的日动态及其环境影响因子的研究

用WP4露点水势仪观测不同固定程度沙地上油蒿叶水势日动态，同时分析各环境因子与油蒿叶水势的关系。结果表明，3种样地油蒿的叶水势均在5砄00最高，之后随着太阳辐射强度的增强，叶水势逐渐降低，直到中午13砄00左右达到最低值，此后随着太阳高度角的降低，叶水势又逐渐开始升高；相关性分析表明，油蒿叶水势变化主要受大气温度和光合有效辐射强度的影响，大气相对湿度及土壤水分对油蒿叶水势的影响并不显著；中午13砄00以前3种沙地油蒿叶水势的基本情况是流动沙地＞半固定沙地＞固定沙地，而15砄00～17砄00这段时间3种沙地油蒿叶水势与中午相反，这主要是由不同固定程度沙地上油蒿植株的年龄差异及浅层土壤水分自身的差异导致的。在大气温度和光合有效辐射强度较高的情况下，流动沙地上油蒿植株吸收水分的能力最强，而固定沙地上油蒿植株的吸水能力最弱，加之固定沙地自身匮乏的土壤水分条件，必将导致固定沙地上油蒿群落的衰退。

Study on the Leaf Water Potential of Artemisia ordosica in Different Fixation Stage of Sand Dunes and Its Influence Factors

The leaf water potential of Artemisia ordosica in different fixation stage of sand dunes was observed with WP4 water dew point meter , and the relationship between leaf water potential of Artemisia ordosica and environmen-tal factors were also analyzed .The results showed that：The leaf water potential of Artemisia ordosica in all of the three kinds of samples had the peak value at 5：00 , then decreasing with the augmentation of the solar radiation in-tensity, which reaching the lowest value around 13：00, after that, the leaf water potential gradually began to rise again with the decreasing angle of the sun;the correlation analysis showed that the leaf water potential of Artemisia ordosica had a negative correlation to the air temperature and the photosynthetic available radiation , but there were no significant correlation with atmospheric relative humidity and soil moisture;the basic trend of leaf water potential of Artemisia ordosica in the three kind of sample before 13：00 were in the following order： shifting sand dune 〉semi-fixed sand dune〉fixed sand dune , but the trend were opposite between 15：00~17：00 , which were mainly caused by age difference of Artemisia ordosica and the shallow soil moisture .Artemisia ordosica in the shifting sand dune had the strongest ability to absorb water with the increasing atmospheric temperature and photosynthetic effec -tive radiation, while in fixed dune ’ s had the weakest ability , the soil moisture in the fixed dune is also deficient , that would lead to the recession of Artemisia ordosica in the fixed dunes in a long time .