青海湖流域沙柳河湿地草地和具鳞水柏枝灌丛小气候特征研究

Microclimate features of grassland communities and Myricaria squamosa Desv.shrubs in Shaliu river wetland,Qinghai Lake basin

本文利用波文比系统和ECH2O土壤水分监测系统在青海湖流域沙柳河下游同一河道断面监测的两种典型湿地植被群落类型——草地和具鳞水柏枝灌丛的空气温度、相对湿度、净辐射、土壤热通量和土壤温度等数据,对流域内两种湿地植被群落的小气候特征进行了研究,研究发现:受大气候的变化影响,草地和具鳞水柏枝灌丛的空气温度日变化呈现出相同的变化趋势,在整个生长季具鳞水柏枝灌丛月平均值显著高于草地,具鳞水柏枝灌丛群落上层的空气温度高于群落下层,而草地上下层没有显著差异;具鳞水柏枝灌丛和草地空气相对湿度日变化规律相同,白天较低,晚上较高,在整个植物的生长季,草地和具鳞水柏枝灌丛空气相对湿度差异显著;草地和具鳞水柏枝灌丛群落冠层净辐射的日变化均呈单峰曲线,在7—9月份,具鳞水柏枝灌丛冠层与草地冠层的净辐射差异显著;草地和具鳞水柏枝灌丛地下5 cm土壤热通量的日变化呈单峰曲线,月变化趋势较为类似,具鳞水柏枝灌丛变化幅度显著大于草地;在整个植被生长季草地和具鳞水柏枝灌丛地下10 cm土壤温度日变化曲线呈相似的形状,月变化趋势基本一致,但是草地的月均值大于具鳞水柏枝灌丛;草地在白天和夜晚均由大气向地表输送热量,具鳞水柏枝灌丛在白天由大气向地表输送热量,而在晚上基本是由地表向大气输送热量;在两种湿地植被群落中,白天是水汽蒸发的过程,而夜晚是水汽凝结的过程,在地表与大气的能量交换中,潜热占主导。

Based on the microclimate data measured by Bowen-ratio system and soil water monitoring system （ECH2O）, the microclimate features of the grassland and Myricaria squamosa Desv. shrubs on the same cross-section of Shaliu river were studied. Affected by macroclimate, the air temperature of grassland and Myricaria squamosa Desv. shrubs showed the same daily change trend, the mean monthly air temperature of Myricaria squamosa Desv. shrubs was significantly larger than that of grassland during the growing season, the air temperature on the top of Myricaria squamosa Desv. shrubs was higher than the bottom, while grassland showed no difference. The air relative humidity of grassland and Myricaria squamosa Desv shrubs. which was higher during the daytime and lower during the night, also showed the same daily change trend, while it was significantly different between the two vegetation types during the growing season. The canopy net radiation daily change trend of the two vegetation types both showed the unimodal curve, but it was significantly different between the two vegetation types from July to September. The soil heat flux change trend of the two vegetation types both showed the unimodal curve, and their monthly change trades were similar, but the changing amplitude of grassland was larger than Myricaria squamosa Desv. shrubs. The soil temperature daily change trend of grassland was similar to Myricaria squamosa Desv. shrubs, so did the monthly change trend, but the mean monthly value of grassland is larger than Myricaria squamosa Desv. shrubs. Energy transferred from ground surface to air on grassland both at daytime and night, but in Myricaria squamosa Desv. shrubs, energy transferred from air to ground surface at daytime and from ground surface to air at night. In the two wetland vegetation communities, evapotranspiration occured at daytime and water condensation occured at night, latent heat was the dominant way in the energy exchange between ground surface and air.