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| A Study on Mathematical Model of Chinese Arborvitae Leaf Transpiration in the Semi-arid Region of the Loess Plateau |
| Wang Baitiari,Guo Jianghong,Yang Xuesong |
| College of Soil and Water Conservation, Beijing Forestry University, Key Laboratory of Soil and Water Conservation and Combating Desertification, Ministry of Education, 100083, Beijing, China |
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Abstract Soil moisture gradations of single Chinese arborvitae tree were established through artificial control of water amount, then the transpiration rate of leaf was observed under the natural conditions with a steady-state porometer in a fixed time interval, and the environmental factors, such as E, temperature and atmosphere humidity in canopy layer, water potential of leaf, soil water moisture, were observed synchronously. After a correlation analysis, the relationships of transpiration rate of Chinese arborvitae in semi-arid regions of loess plateau with the factors of physiological absorbed radiation (E) , vapour pressure deficit (pv) , water potential of leaf (Ψ) , and air temperature (t) is respectively obtained as follows: ηt = aEb, ηt = apb, ηt =ab , ηt = at2 + bt + c . Meanwhile, the relationship of transpiration rate and stomatal resistance (Rs) with soil water content (W) is given as follows: ηt =α+bW+cW2+dW3, Rs = α+bW+cW2+dW3. Based on the above analysis on the relationship between transpiration rate and various factors, the leaf transpiration model of Chinese arborvitae is developed, reasonable forecast result has been achieved using three factors including air temperature and vapour pressure deficit as well as water potential of leaf. The model is as follows: ηt = 0.6950exp(0.03158t- 14.249 2/pv + 0.7606/Ψ).
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Received: 04 June 2003
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