毛乌素沙地樟子松蒸腾变化规律及其与微气象因子的关系

Transpiration Rule of Pinus sylvestris var. mongolica and Its Relation to the Canopy Micrometeorology in Mu Us Sandy Area

本研究采用由热扩散植物液流技术测算得到的时间步长10 min的樟子松蒸腾速率数据,结合同步观测得到的冠层微气象要素值,分析了毛乌素沙区20年生樟子松主要生长季节蒸腾耗水规律及其冠层微气象的关系。结果表明:(1)樟子松蒸腾速率具有明显的时间变化特征。多云天气日,蒸腾速率日内变化总体呈多峰曲线趋势,单株蒸腾速率(Tr)在4-9月各月白天(6:00-19:00)的平均值为0．36-0．85 L．h-1;晴天日,除9月蒸腾速率日内变化呈多峰曲线趋势外,其余各月总体趋势呈单峰曲线,9月时Tr在10:00左右、13:00左右、15:00左右出现峰值,在 14:00左右出现谷值。4-8月各月日内Tr在10:00左右出现峰值。4-9月各月Tr白天平均值为0．37-0．83 L· h-1;阴天天气日,蒸腾速率日内变化总体呈单峰曲线趋势,日内Tr最大值出现在10:00左右。4-9月各月Tr白天 (6:00-19:00)平均值为0．29-0．63 L·h-1。在日际变化或季节变化方面,从4月份起,樟子松蒸腾耗水量逐渐增加,月耗水量在7月达到最高值,此后有所减小。4-9月总耗水量为1 143．7 mm,日平均为6．25 mm,7月份月耗水总量相对最大。4、5、6、7、8及9月耗水量分别占主要生长季节总量的10．76％、13．62％、14．05％、24．56％、 19．47％、17．52％。(2)主要生长期内,Tr与冠层太阳总辐射(Ra),空气温度(Ta)、湿度(RH),风速(V)等气象要素有很好的复相关性,并通过显著性检验(a=0．01),且各月内影响樟子松蒸腾的最主要气象因子都是Ra。

The transpiration rule of Pinus sylvestris var. mongolica and its relation to the canopy micrometeorology were analyzed through the experimental data of the tree sap flow and the canopy micrometeorology, which were measured by thermal dissipation sap flow velocity probe and CR10X automated meteorology system at a 10-minute recording interval respectively. The trees were 20 years old. The experiment was conducted in Mu Us sandy area during the main growing season（ Apr. - Sep. ） of 2004. The main results are as follows ： The diurnal variations of the tree transpiration were demonstrated several-peak curve in cloudy day,but single-peak curve in the overcast day , and single-peak curve in clear day except Sep. The total transpiration of the main growing season was 1 143.7 mm , the average daily transpiration was 6. 25 mm and monthly transpiration accounted for 10. 76% , 13. 62% , 14. 05% , 24. 56% , 19.47% ,17.52% in Apr. ,May,Jun. ,Jul., Aug.,Sep. , respectively. The transpiration per tree was significantly （ a = 0.01 ） related to the canopy solar radiation （Ra） , air temperature, relative humidity, and wind velocity in the main growing period and Ra is the most important micrometeorological factor effecting transpiration in the main growing season of the tree by comparing the partial correlation coefficient.