樹液流速之實驗研究; Laboratory Experiments on Transient Response of Sap Flow

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Title:	樹液流速之實驗研究;Laboratory Experiments on Transient Response of Sap Flow
Authors:	彭建穎;Chien-ying Peng
Contributors:	土木工程研究所
Keywords:	樹枝自主性;光合作用輻射;土壤含水量;風速;樹液流速;Branch autonomy;Photosynthetically active radiation;Soil moisture;Wind;Sap flow
Date:	2010-07-06
Issue Date:	2010-12-08 13:33:01 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究利用Granier熱消散探針探討環境參數（譬如風速、太陽輻射量、土壤含水量和蒸氣壓差）如何影響兩種植物：馬拉巴栗(Pachira macrocarpa)和白水木(Messerschmidia argentea)的樹液流速。風速實驗和輻射量實驗的結果顯示不同樹種樹液的動態反應皆可以使用Phillips et al. (2004)中電阻-電容模式來描述，且樹液流速的穩態值Vs和時間常數Tc與探針的量測位置有關，馬拉巴栗主幹上位置較低(10 cm)樹液的時間常數小於較高(47 cm)位置的時間常數，而探針位置較低的樹液流速穩態值會大於較高探針的穩態值。此外，在相同風速下，實驗結果顯示土壤含水量在未飽和狀態下的樹液流速會低於飽和土壤含水量的樹液流速，但是在未飽和土壤及飽和土壤中的樹液流速的時間常數大致相同。此外，樹枝自主性實驗發現枝幹的樹液流速對外界環境的改變各自獨立，但主幹的樹液流速一定會受到外界環境參數改變的影響。 It is well know that plant transpiration and sap flow are influenced by the environmental parameters, such as wind, solar radiation, soil moisture, vapor pressure deficit and temperature. This study used the Granier-type heat dissipation sensors to investigate the transient response of sap flow on two plant species: Pachira macrocarpa and Messerschmidia argentea (L.). The results of wind speed and blackout experiments revealed that the transient responses of sap flow of these two plants could be described by the resistance-capacitance model of Phillips et al. (2004). But the time constant and steady sap flow velocity were dependent on the location on the sensors. For Pachira macrocarpa, the time constant Tc of lower height on the stem is smaller than that of higher height, and the steady sap flow velocity Vs at lower height is larger than that of higher height. It was also found that under the same wind speed, the sap flow velocity of plant in under-saturated soil is smaller than that of in saturated soil, but the time constants of well-watered plant and plant in under-saturated soil are about the same. The experimental results of branch autonomy demonstrated that the branches react independently to the change of environmental parameter.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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