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| Relationship between transpiration of Pinus tabulaeformis and its influencing factors in a semi-arid region of the Loess Plateau |
| Zhang Weiqiang1,He Kangning2,Zhu Yanyan2,Zhou Yi1,Gong Yuxia2,Tang Daofeng2 |
| 1.Forest Resarch Institute of Guangdong Province,510520,Guangzhou;2.College of Soil and Water Conservation,Beijing Forestry University,100083,Beijing: China |
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Abstract Relationship between transpiration of forest tree and its influencing factors is closely.Through controlling soil moisture artificially,using portable steady porometer(Li-1600) and speedy weight method(BP-3400) etc.,Transpiration rate Tr of Pinus tabulaeformis and environmental factors were measured under the condition of representative fine day in growing season of 2004.The results indicated that the diurnal course of transpiration rate(Tr) and stomatal resistance(Rst) of Pinus tabulaeformis display a double-peak curve and a "W" curve respectively under different soil moisture.Under the condition of representative fine day,the transpiration rate presents a cubic relation with soil water content,the SWC which causing Tr of Pinus tabulaeformis highest was 17.7%,19.8% and 17.5% in July,August and October respectively.Tr was affected not only by its physiology characteristic but also by the SWC and meteorologic factors.Tr had significant correlation with meteorologic factors if the soil moisture was sufficient,but it will decrease in serious water stress condition;In serious water stress condition,air temperature is the mainly factor to affect Tr in July and August,and photo synthetically active radiation is the mainly factor in October.When the soil water is sufficient,the mainly factor to affect transpiration rate was relative humidity,air temperature and leaf temperature in July,August and October respectively.The result of this paper provided the scientific basis of increasing survival rate and managing soil water in forestland.
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Received: 04 April 2006
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