长江三角洲地区麻栎和栓皮栎蒸腾规律及其对气候因子的响应

森林蒸腾在维系森林生态系统水量平衡上起着重要作用,研究麻栎和栓皮栎的蒸腾耗水规律,有助于了解栎林的水文过程和水量平衡。采用热扩散探针法,对江苏省句容市麻栎和栓皮栎林蒸腾速率进行连续观测,研究蒸腾速率在晴天、阴天和雨天的日变化特征,以及不同天气下气候因子对蒸腾速率的影响机制。结果表明,麻栎和栓皮栎蒸腾速率日变化在晴天、阴天均为单峰型,而雨天峰型波动较大。晴天峰值出现在11:30—12:30,阴天峰值出现在13:30—14:00。不同天气下,麻栎、栓皮栎日均蒸腾速率表现为麻栎>栓皮栎,晴天>阴天>雨天。总辐射、气温、饱和水汽压差与麻栎、栓皮栎蒸腾速率呈极显著正相关。总辐射对麻栎、栓皮栎蒸腾速率的贡献最大,在晴天其贡献度分别为91.7%和85.5%,而在阴天为71.0%和80.1%,在雨天为50.4%和57.9%。总辐射是影响麻栎和栓皮栎蒸腾速率最大的气候因子,其次是饱和水汽压差、气温和土壤含水量。

Transpiration Regulations and Responses to Climate Factors of Quercus acutissima and Quercus variabilis in the Changjiang River Delta Area

Forest transpiration plays an important role in maintaining the water balance of forest ecosystem.Studying transpiration regulations of Quercus acutissima and Quercus variabilis is helpful to understand the hydrology process and water balance of Quercus spp.forest.In this study,the transpirations of Q.acutissima and Q.variabilis were observed continually by the thermal diffusion probe method in Jurong City,Jiangsu Province.Meanwhile,the daily dynamic characters of transpiration and the impact mechanism of climatic factors on transpiration rate under different weather circumstances were studied.The results showed that the daily variation of transpiration rate showed single peak curve in sunny days and cloudy days,and fluctuate peak pattern in rainy days.The peak value was appeared in 11:30—12:30 in sunny days and 13:30—14:00 in cloudy days.The daily mean transpiration for Q.acutissima and Q.variabilis under different weathers were showed as follow:Q.acutissima>Q.variabilis,sunny day>cloudy day>rainy day.The transpiration rate of Q.acutissima and Q.variabilis were significantly positive correlated to the total solar radiation,the atmospheric temperature,and the vapor pressure deficiency.The total solar radiation had the greatest contribution to the transpiration rate of Q.acutissima and Q.variabilis.The contribution rate were 91.7%and 85.5%in sunny days,71.0%and 80.1%in cloudy days,50.4%and 57.9%in rainy days.The total solar radiation among climatic factors had the most important influence on the transpiration rate of Q.acutissima and Q.variabilis,followed by vapour pressure deficit,air temperature,and soil water content.