风对极端干旱区胡杨蒸腾速率的影响

以2014年4-11月的胡杨蒸腾速率和风速的实测数据, 分析了风对极端干旱区胡杨蒸腾速率的影响. 结果表明: 不同风速对胡杨蒸腾速率的影响存在差异, 风速的瞬时变动并不一定都会促进蒸腾速率的升高. 0~2 m·s^-1风速作用对胡杨蒸腾速率的影响不大; 2~8 m·s^-1风速作用下, 胡杨蒸腾速率显著升高, 且随着风速的增大, 蒸腾速率上升幅度增加. 其中, 2~4 m·s^-1风速作用下, 其变化幅度较0~2 m·s^-1时增加了4.51%; 4~6 m·s^-1风速作用下, 其变化幅度较2~4 m·s^-1时增加了7.03%; 6~8 m·s^-1风速作用下, 其变化幅度较4~6 m·s^-1时增加了16.19%. 当风速大于8 m·s^-1时, 胡杨蒸腾速率不再上升而呈下降趋势, 且随着风速的增加, 蒸腾速率降低的幅度也越大, 其中, 8~10 m·s^-1风速作用下, 蒸腾速率下降了8.08%; 大于10 m·s^-1的风速作用下, 胡杨蒸腾速率的下降幅度高达32.91%. 胡杨蒸腾速率和风速的错位相关分析表明, 风速对胡杨蒸腾速率的影响多为实时性的, 在极少数的大风天气影响下, 蒸腾速率恢复的时间较慢, 形成了个别日期的滞后效应. 风速和胡杨蒸腾速率的指数拟合关系最显著, 且2~8 m·s^-1风速下, 蒸腾速率随着风速呈指数增加趋势; 8 m·s^-1以上风速作用下, 蒸腾速率随着风速的增加呈指数减少趋势. 在0~2 m·s^-1风速作用下, 蒸腾速率变化不大.

Effect of wind speed on transpiration rate of Populus euphratica in extreme arid deserts

The transpiration rate of Populus euphratica in relation to wind speed was measured simultaneously in an extreme arid region of Northwest China during 2014 by heat ratio method in an automatic meteorological station. Response of transpiration rate of Populus euphratica to wind speed in extreme arid desert region was analyzed. It is found that the effects of wind speed on transpiration rate of Populus euphratica exist differences. Wind speed not necessarily increase transpiration rate. When wind speed reaches 0-2 m·s^-1 wind speed has a little effect on transpiration rate. When wind speed reaches in between 2 m·s^-1 and 8 m·s^-1 the transpiration rate increases remarkably: compared with the wind speed of 0-2 m·s^-1, it will increasing 4.51% as the wind speed at 2-4 m·s^-1; compared with the wind speed of 2-4 m·s^-1, it will increasing 7.03% as the wind speed at 4-6 m·s^-1; compared with the wind speed of 4-6 m·s^-1, it will increasing 16.19% as the wind speed at 6-8 m·s^-1. Once the wind speed exceeds 8 m·s^-1, the transpiration rate does not increase but decrease and decrease with weed speed increasing. It will decrease 8.08% and 32.91% when the weed speed exceed 8-10 m·s^-1 and 10 m·s^-1, respectively. In addition, it is found that the transpiration rate of Populus euphratica decreases more quickly under strongly wind speed. A correlation analysis show that time lag effect does not existent in most of date. Only under strong wind time lag effect exists owing to a slow transpiration recovery. Moreover, it is found that transpiration rate has an exponential correlation to wind speed