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| Transpiration of Platycladus orientalis plantation and its relationship with environmental factors in limestone area, Taihang Mountains |
| Li Yongsheng |
| Shanxi Academy of Forestry Sciences, 030012, Taiyuan, China |
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Abstract In order to ascertain the transpiration variation of oriental arborvitae（Platycladus orientalis (L.) Franco）plantation and its relationship with environmental factors in limestone area of Taihang Mountains, flowbased transpiration was measured simultaneously with environmental variables, including soil volumetric water content(Wv)，photosynthetically active radiation（Par），relative humidity（Hr），air temperature（ta）, wind speed (vw) and rainfall (R). Transpiration rate showed unimodal diurnal variations with diurnal mean value 0.025-0.041mm/h and maximum value 0.078-0.150mm/h over the experiment period. Diurnal transpiration rate was significantly affected by Hr, ta, Par and Wv（P<0.05）,which could give 87.7% variation together. The descending order of correlation degree was Par, Hr, ta and Wv. Accumulative and mean daily transpiration of stand mean was 0.2-1.6mm and 0.7mm respectively. They were significantly affected by Hr, ta, Par and Wv, which could give 64.3% seasonal variation together. The descending order of correlation degree was Par, Hr, Wvand ta over the experiment period. Par had the most significant effects on daily transpiration, followed by ta in most of period intervals. Hr and Wvhad significant effects on daily transpiration only during the wetting and drying alternation intervals. Accumulative and mean monthly transpiration were 18.3-28.8mm and 21.8mm respectively. The seasonal variation of accumulative monthly transpiration occurred unimodal pattern with peak value observed in June. Accumulative monthly transpiration only greatly correlated with Par（P<0.05）.The seasonal（1 April to 30 September）total transpiration amounts to 130.5mm, representing 42.5% of rainfall over the period.
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Received: 28 March 2011
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