溪頭柳杉林的蒸發散特性之研究

Characteristics of the Evapotranspiration of a Japanese Cedar Forest in Xitou, Taiwan

羅明慧(Sophie Laplace)

《國立臺灣大學生物資源暨農學院實驗林研究報告》 30卷4期 (2016/12) Pp. 303-312

https://doi.org/10.6542/EFNTU.2016.30(4).5

摘要

由於氣候變遷對水文循環的影響日益加劇，導致依賴霧氣或低雲層的環境如雲霧林，其水文逐漸受到明顯的負面影響。蒸發散在水文循環當中扮演重要的角色，因此研究其特性有助於深入了解雲霧林的水文機制。本研究在溪頭區中海拔之進行，以柳杉林為對象，利用通量法與樹液流法分別推測蒸發散ET及蒸散T。通量法利用溪頭40 m高通量塔之開放路徑式氣體分析儀（LI 7500, LI-COR, Lincoln, NE） 搭配一台三維音波風速計 （3D sonic anemometer, CSAT3, Campbell Scientific, Logan, UT），來推算溪頭柳衫林一年的蒸發散量。另外利用Granier熱消散探針來觀測15棵柳衫的樹液流量，並推算林分一年的蒸散量。結果顯示溪頭柳衫的T/ET比例為18 %，比其他森林環境低將近三倍。由於雲霧林地區的相關研究較少，也因此需要進行更多的觀測（例如土壤蒸發或地被植物蒸散的觀測，或者T/ET比例的年間變化），才能更深入了解雲霧林水文循環的特性。

關鍵字

蒸發散 ； 蒸散 ； 資料補遺

並列摘要

As climate change has an increasing influence on hydrologic cycle, montane cloud forests may be under greater negative impacts. Evapotranspiration plays an important role in terrestrial hydrologic cycle, and related research may help to better understand hydrological characteristics of cloud forests. This research too k place in a Japanese cedar forest located at the Xitou National Taiwan University Experimental Forest. The annual evapotranspiration (ET) and transpiration (T) were estimated by eddy covariance and sap flow methods, respectively. For the eddy covariance measurement, a forty-meter-high eddy flux tower equipped with an open-path CO_2/H_2O gas analyzer (LI 7500, LI-COR, Lincoln, NE) and a 3D sonic anemometer (CSAT3, Campbell Scientific, Logan, UT) were used. In addition, Granier's thermal dissipation probe was used to measure the sap flow velocity of 15 Japanese cedars in order to deduce the stand-scale T. The results showed that the annual T/ET ratio at the Xitou site was about 18% (varying from 2 to 41 % according to different range of vapor pressure deficit), which was almost three times lower than that of other forest environment. Since studies related to TIET ratio in cloud forests are lacking, further research such as contribution of soil evaporation and understory transpiration to evapotranspiration, or annual variation of T/ET ratio are needed.

並列關鍵字

Evapotranspiration ； Transpiration ； Cloud forest