蒸發散不僅在水平衡收支裡扮演重要的角色，同時對陸氣交互作用之地表過程也有重大之影響。利用渦流相關系統觀測地表通量，以及所收集的微氣象變數，計算出空氣動力導度、植被導度與退耦係數，並以樹液探針量測樹液流速。
本研究目的為：(1)利用退耦係數的概念，了解乾濕季內蒸發散的驅動營力，並探討植被層與大氣間耦合的情形。(2)以樹液探針量測現地的樹液流變動情形，觀察流速變化與環境變數的相關性。
研究成果指出，乾濕季平均退耦係數分別為0.20與0.34，平均植被導度分別為0.0047 m/s和0.0075 m/s，平均空氣動力導度皆為0.06 m/s。乾季時的樹液流動較為規律，具有日循環特徵，且淨輻射量與飽和蒸氣壓差對蒸散作用的影響較為顯著。降雨時期的樹液流資料較為散亂，呈現的變化曲線較為不平整。

Evapotranspiration (ET) not only plays an important role of water budget, but also significantly affects surface hydrology processes. Surface fluxes were observed with an eddy covariance system in association with environmental factors measurements for computing aerodynamic conductance, canopy conductance and decoupling coefficient. Moreover, sap flow was measured by sap flow probes designed in this study.
The purpose of this study included: (1) to investigate seasonal characteristics of evapotranspiration in association with the decoupling coefficients for examining interactions between canopy and atmosphere. (2) to study the correlation between sap flow velocities and environmental variables by sap flow probes designed in this study.
For dry and wet seasons, the decoupling coefficients of 0.20 and 0.34, respectively, the canopy conductance were 0.0047 m/s and 0.0075 m/s, respectively; the aerodynamic conductances were equally 0.06 m/s. During dry season, sap flow data shows significant diurnal cycles; radiation and vapor pressure deficit are concluded as major driving factors of tree transpiration. However, the wet season sap flow data presents irregular patterns due to frequent rainfalls.

1. Baumgartner, A. and E. Reichel, 1975, ”The World Water Balance”, R.Oldenbourg-Verlag, pp.1-179.
2. Bowen, I.S., 1926, “The ratio of heat losses by conduction and by evaporation from any water surface”, Physical Review 27, pp.779-787.
3. Do, F. and A. Rocheteau, 2002, “Influence of natural temperature gradient on measurements of xylem sap flow with thermal dissipation probes.1.Field observations and possible remedies”, Tree Physiology 22, pp.641-648.
4. Edwards, W.R.N., 1986, “Precision weighing lysimetry for trees, using a simplified tared-balance design”, Tree physiology 1,pp.127-144.
5. Granier, A., 1987, “Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements”, Tree Physiology 3, pp.309-320.
6. Granier, A., 1994, “Axial and radial water flow in the trunks of oak tress : a quantitative and qualitative analysis”, Tree Physiology 14, pp.1383-1396.
7. Granier, A., P. Brown, B. ko ̈stner, L.W. Gay and G. Najjar, 1996, “Comparisons of xylem sap flow and water vapour flux at the stand level and derivation of canopy conductance for Scots pipe”, Theor. Appl. Climatol. 53, pp.115-112.
8. Granier, A., R. Huc and S.T. Barigah, 1996, “Transpiration of natural rain forest and its dependence on climatic factors”, Agricultural and Forest Meteorology 78, pp.19-29.
9. Hao, Y.B., W. Yanfen, H. Xiangzhong, C. Xiaoyong, Z. Xiaoqi, W. Shiping, N. Haishan and J. Gaoming, 2007, “Seasonal and interannual variation in water vapor and energy exchange over a typical steppe in Inner Mongolia, China”, Agricultural and Forest Meteorology 146, pp.57-69.
10. Jarvis, P.G., 1976, “The interpretation of the variations in leaf water potential and stomata conductance found in canopies in the field”, Philosophical Transactions of the Royal society of London 273, pp.593-610.
11. Jarvis, P.G. and K.G. McNauton, 1986, “Stomatal control of transpiration : scaling up from leaf to region”, Advances in Ecological Research 15, pp.1-45.
12. Khantun, R., T. Ohta, A. Kotoni, J. Asnauma, M. Gamo, S. Han, T. Hirano, Y. Nakai, N. Saigusa, K. Takagi, W. Huimin and N. Yoshifuji, 2011, “Spatial variation in evapotranspiration over East Asia forest sites. I. Evapotranspiration and decoupling coeffient”, Hydrological Research Letters 5, pp.83-87.
13. Khantun, R., T. Ohta, A. Kotoni, J. Asnauma, M. Gamo, S. Han, T. Hirano, Y. Nakai, N. Saigusa, K. Takagi, W. Huimin and N. Yoshifuji, 2011, “Spatial variation in evapotranspiration over East Asia forest sites. II. Surface conductance and aerodynamic conductance” , Hydrological Research Letters 5, pp.88-92.
14. Kumagai, T., T.M. Saitoh, Y. Sato, T. Morooka, O.J. Manfroi, K. Kuragi and M. Suzuki, 2004, “Transpiration, canopy conductance and decoupling coeffient of a lowland mixed dipterocarp forest in Sarawak Borneo: dry spell effects”, Jounal of Hydrology 287, pp.237-251.
15. Kumagai, T., S. Aoki, H. Nagasawa, T. Mabuchi, K. Kubuta, S. Inoue, Y. Utsumi and K. Otsuki, 2005, “Effects of tree-to-tree and radial variation on sap flow estimates of transpiration in Japanese cedar”, Agriculture and Meteorology 135, pp.110-116.
16. Kumagai, T., H. Nagasawa, T. Mabuchi, S. Ohsaki, K. Kubota, K. Kogi, Y. Utsumi, S. Koga and K. Otsuki, 2005, “Sources of error in estimating stand transpiration using allometric relationships between stem diameter and sapwood area for Cryptomeria japonica and Chamaecyparis obtuse”, Forest Ecology and Management 206, pp.191-195.
17. Kume, T., K. Tsuruta, H. Komatsu, T. Kumagai, N. Higashi, Y. Shinohara and K. Otsuki, 2009, “Effects of sample size on sap flux-based stand-scale transpiration estimates”, Tree Physiology 30, pp.129-138.
18. Matsumoto, K., T. Ohta , T. Nakai, K. Daikoku, S. Iida, H. Yabuki, A.V. Kononov, M.K. van der Molen, Y. Kodama, T.C. Maximov, A.J. Dolman and S. Hattori, 2008, “Responses of surface conductance to forest environments in the Far East”, Agricultural and Forest Meteorology 148, pp.1926-1940.
19. Meinzer, F.C., G. Goldstein, N.M. Holbrook, P. Jackson and J. Cavelier, 1993, “Stomata and environmental control of transpiration in a lowland tropical forest tree”, Plant, Cell and Environment 16, pp.429-436.
20. Monteith, J.L., 1981, “Evaporation and Surface Temperature”, Quarterly Journal of the Royal Meteorology Society 107, pp.1-27.
21. Monteith, J.L. and M.H. Unsworth, 2007, Principles of Environmental Physics, Edward Arnold, London.
22. Nakai, T., A. Sumida, K. Daikoku, K. Matsumoto, M.K. van der Molen, Y. Kodama, A.V. Kononov, T.C. Maximov, A.J. Dolman, H. Yabuki, T. Hara and T. Ohta, 2008, “Parameterisation of aerodynamic roughness over boreal, cool- and warm- temperate forests”, Agricultural and Forest Meteorology 148, pp1916-1925.
23. Oren, R., J.S. Sperry, G.G. Katul, D.E. Pataki, B.E. Ewers, N. Phillips and K.V.R. Schafer, 1999, “Survey and synthesis of intra- and interspecific variation in stomata sensitivity to vapor pressure deficit”, Plant, Cell and Environment 22, pp.1515-1526.
24. Phillips, N., A. Nagchaudhuri, R. Oren and G. Katul, 1997, “Time constant for water transport in loblolly pine trees estimated from time series of evaporative demand and stem sap flow”, Tree 11, pp.412-419.
25. Saugier, B., A. Granier, J.Y. Pontailler, E. Dufrene and D.D. Baldocchi, 1997, “Transpiration of a boreal pine forest measured by branch bag, sap flow and micrometeorological methods”, Tree Physiology 17, pp.511-519.
26. Sheng, D., W. Yi-Long, T. Kume, Z. Jian-Guo, K. Otsuki, N. Yamanaka and L. Guo-Bin, 2011, “Sap flow characteristics and climatic responses in three forest species in the semiarid Loess Plateau region of China”, Agricultural and Forest Meteorology 151, pp.1-10.
27. Takanashi S, Y. Kosugi, S. Ohkubo, N. Matsuo, M. Tani and AR. Nik, 2009, “Water and heat fluxes above a lowland dipterocarp forest in Peninsular Malaysia”, Hydrological Processes Published online in Wiley InterScience.
28. Wilson, K.B., A. Goldstein, E. Falge, M. Aubinet, D.Baldocchi, C. Berbigier, C. Bernhofer, R. Ceulemans, H. Dolman, C.Field, A.Grelle, A. Law, B.E. Ibrom, A.Kowalski, T. Meyers, J. Moncrieff, R. Monson, W. Oechel, J. Tenhunen, R. Valentini and S. Verma, 2002, “Energy balance closure at FLUXNET sites”, Agricultural and Forest Meteorology 113, pp223-243.
29. Wullschleger, S.D., F.C. Meinzer and R.A. Vertessy, 1998, “A review of whole-plant water use studies in trees”, Tree Physiology 18, pp.499-512.
30. 吳秉諭，2011，「應用路面過程模式模擬蓮華池試驗集水區地表通量」，國立中央大學，碩士論文。
31. 吳聲沅，2008，「利用樹液探針研究環境參數對植物蒸散之影響」，國立中央大學，碩士論文。
32. 林祐竹，2011，「棲蘭山樣區降水對台灣扁柏樹液流影響之探討」，國立東華大學，碩士論文。
33. 邱奕霖，2005，「地表過程蒸發散之觀測與分析」，國立中央大學，碩士論文。
34. 洪志凱，2004，「樹液探針之發展與應用」，國立台灣科技大學，碩士論文。
35. 袁一夫，2008，「應用通量變異法與渦流相關法推估地表通量」，國立中央大學，碩士論文。
36. 張志遠，2008，「台灣南仁山亞熱帶雨林三種樹種的樹液流通量與風速及其他環境因子之關係」，國立台灣大學，碩士論文。
37. 張雁婷，2008，「應用土壤水分變化推估常綠闊葉林蒸發散量」，國立中央大學，碩士論文。
38. 郭振民，2009，「整合衛星遙測與無線化樹汁流觀測推估區域蒸發散」，國立成功大學，博士論文。
39. 陳俐如，2005，「鴛鴦湖地區台灣扁柏樹液流動之探討」，國立東華大學，碩士論文。
40. 陳奕穎，2012，「應用渦流相關法調查地表水氣通量與熱通量之特徵：以亞熱帶季節性常綠闊葉林為例」，國立中央大學，博士論文。
41. 彭建穎，2010，「樹液流速之實驗研究」，國立中央大學，碩士論文。
42. 黃正良，2010，「蓮華池天然闊葉林及杉木人工林試驗集水區水文與水質特性之探討」，國立台灣大學，博士論文。
43. 褚侯森，2008，「複雜地形中的通量觀測—以棲蘭山台灣扁柏森林樣區為例」，國立東華大學，碩士論文。
44. 羅勻謙，2004，「鴛鴦湖地區台灣扁柏森林生態系蒸散作用之研究」，國立東華大學，碩士論文。