利用樹液流觀測探討臺灣孟宗竹林之蒸散特性

Study on Transpiration in a Taiwanese Moso Bamboo Forest using Sap Flow Measurement

羅明慧(Sophie Laplace)

指導教授 ： 久米朋宣

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.01366

摘要

近五十年亞洲竹林不斷地擴散。無論是天然或人為因素造成的，此現象導致原本的植被會被竹林替換。至今科學界缺乏足夠的相關研究，使得難以判斷竹林替換其他森林如何影響水文循環。「蒸散」為水文循環當中很重要的一環，因此本研究主要目的為多了解竹林之蒸散特性。我們便 (1) 由樹液流速的觀測而推測溪頭 (台灣) 一片孟宗竹林一年的蒸散速率、(2) 與另外二片森林的蒸散比較 (一為附近的柳杉林、二為日本福岡的孟宗竹林)、(3) 最後我們進一步探討環境因子與生理因素對竹林蒸散的影響的角色。本研究利用Granier熱消散探針法觀測二十二根竹子，再由個體觀測的結果放大尺度到整片林分的蒸散。並且我們最後利用一個冠層氣孔導度的模擬，來評估環境因子及竹子生理對蒸散的影響。結果顯示竹幹段面樹液流速的方向變異較小，但個體變異較明顯。另外，雖顯示同樣的季節趨勢，溪頭竹林一年的蒸散量比附近的柳杉林大快三倍。但我們亦發現溪頭竹林的蒸散量比日本福岡少，且二片林分由於不同氣候條件而顯示不同季節變化。最後，由二片竹林的冠層導度之比較，可推測VPD與植物生理為影響竹子蒸散的主要因素。

關鍵字

竹林 ； 蒸散 ； 樹液流速

並列摘要

Bamboo forests are expanding rapidly in Asian countries since the past 50 years. Whether natural or artificial, this expansion involves the replacement of other vegetation types by bamboos. Nevertheless, the impacts this will have on the water cycle are still not well understand. Transpiration being one of the most important part of the water cycle, we aimed to further understand the characteristics of the transpiration of a Moso bamboo forest located in the mountainous area of Xitou, Taiwan. To this end, (1) we estimated the annual transpiration rate of a Moso bamboo forest with assessing effects of variations in sap flow on individual and stand scale transpiration estimates, (2) compared our results with a coniferous forest and with a Japanese Moso bamboo stand, and (3) modeled the canopy conductance to deepen our understandings of the particularities of the Taiwanese and Japanese bamboo stands. We used Granier thermal dissipation probe method to measure the sap flow velocity of 22 culms, and then scale-up the results to obtain the transpiration rate of the whole stand. We used a canopy conductance model to evaluate the importance of meteorological and physiological parameters on the bamboos transpiration. The results showed small circumferential variations but relatively important individual variations in sap flow velocity. The annual transpiration of the bamboo stand we studied in Xitou was almost three times higher than the transpiration of the cedar stand, even if the seasonal variation trend was similar for the two stands. On the other hand, the transpiration of bamboos in Xitou was smaller than the Fukuoka bamboo stand, with in addition different seasonal trends. We concluded that VPD and physiological factors influenced significantly the transpiration behavior of bamboos from the same species.

並列關鍵字

bamboo forest ； transpiration ； sap flow

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