樟子松在西北干旱沙区的蒸腾日变化

Diurnal Transpiration Variation of Pinus sylvestris var. mongolica in Arid and Desert Area of the Northwest China

在典型干旱沙区的甘肃省民勤治沙站分别测定人工栽植的4a、9a和20a樟子松8月份蒸腾强度的日进程。结果表明,9a以上樟子松的蒸腾强度在午前随光强和气温而上升,午后下降。以当天的日平均蒸腾强度计,20a(16.30mmol·m-2·s-1)>4a(14.14mmol·m-2·s-1)>9a(12.51mmol·m-2·s-1)。4a、9a和20a樟子松的日均水分利用效率分别为0.1681μmol·mol-1、0.3926μmol·mol-1、0.0929μmol·mol-1。20a以前的樟子松对水分的利用效率较高,而且,一天之中,9:00以前的水分利用效率提升速率比其它任何时候都高。

In typical arid desert area, diurnal variations of transpiration rate of Pinus sylvestris var. mongolica in August were measured by Li-6200 .The results showed that elder (≥9 years) Pine's transpiration rate increased with the illumination rate and the air temperature before noon, decreased after noon. The relationship of average day's transpiration rate between 4 a ,9 a and 20 a was 20 a(16.3 mmol·m-2·s-1) > 4 a (14.14 mmol·m-2.s-1) > 9 a (12.51 mmol·m-2·s-1), and their average day's water utilization ratio were 0.168 1 μmol·mol-1,0.392 6 μmol·mol-1 and 0.092 9 μmol·mol-1 respectively. The 9 a pine had the highest utilization ratio, and the highest time appeared before 9 o'clock in the morning.