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利用内蒙古额济纳旗1960—2010年逐日降水量观测资料,并连续监测了2012—2013年胡杨蒸腾速率和实时降水量,研究了小降雨事件对荒漠河岸林胡杨蒸腾耗水的影响。结果表明:50年来额济纳旗小降雨事件占总降雨事件的比例达90.63%。不同量级的小降雨事件对蒸腾速率的影响存在较大差异,小于1 mm的降雨发生前蒸腾速率处于下降趋势,降雨发生后蒸腾速率的下降幅度变小,2h后开始缓慢上升;1~4 mm降雨发生前蒸腾速率呈大幅下降趋势,降雨发生后1~2h蒸腾速率基本不变,降雨发生3~4h后蒸腾速率显著上升。小降雨事件对胡杨蒸腾耗水量的影响存在明显的时滞效应,0.2mm降水发生对其后各日蒸腾耗水量影响不大,降雨发生当日蒸腾耗水量的变化仍延续前几天蒸腾耗水量的变化趋势;0.4~0.8mm降雨量发生对其后2d内胡杨蒸腾耗水量有微弱影响,对2d后的蒸腾耗水量影响不大;1~4mm降雨发生后,第1天胡杨的蒸腾耗水量显著降低,但降雨后第2天胡杨蒸腾耗水量明显增加。降雨量和蒸腾速率的指数拟合关系表明小降雨事件对降雨后4h胡杨蒸腾速率的影响最大;对降雨后1h的蒸腾速率影响较小。
By using daily precipitation data from 1960-2010 in Ejina Banner, Inner Mongolia, continuous monitoring of the transpiration rate and real-time precipitation of Populus euphratica from 2012 to 2013, the effects of small rainfall events on the transpiration water consumption of desert Populus euphratica Populus were studied. The results show that over the past 50 years, the proportion of small rainfall events in Ejina Banner has reached 90.63% of the total rainfall events. The effects of rainfall events of different magnitudes on transpiration rate are quite different. The transpiration rate before the rainfall less than 1 mm is in a downward trend, the decrease rate of transpiration rate becomes smaller after 2 hours, The transpiration rate decreased sharply before rainfall occurred. The transpiration rate of 1 ~ 2 h after rainfall was basically unchanged, and the transpiration rate increased significantly after 3 ~ 4 h of rainfall. The effect of small rainfall on the transpiration water consumption of Populus euphratica has obvious time lag effect. The occurrence of 0.2mm rainfall has little effect on the transpiration water consumption of the following days. The transpiration water consumption on the day of rainfall also continues the transpiration water consumption The trend of 0.4-0.8 mm rainfall had a weak influence on the transpiration water consumption of Populus euphratica in the next 2 days, but had little effect on the transpiration water consumption after 2 days. After the rainfall of 1-4 mm, the transpiration water consumption of Populus euphratica on the first day was significant Decreased, but the transpiration of Populus euphratica increased obviously on the second day after rainfall. The exponential fitting relationship between rainfall and transpiration rate shows that the small rainfall event has the greatest effect on the transpiration rate of Populus euphratica 4 h after rainfall and has little effect on the transpiration rate at 1 h after rainfall.