Theory and Practical Application of Heat Pulse to Measure Sap Flow

Agronomy Journal - Tập 95 Số 6 - Trang 1371-1379 - 2003
Steve Green1, Brent Clothier1, Bryan Jardine1
1Environ. and Risk Manage. Group HortResearch Inst. Private Bag 11‐030 Palmerston North New Zealand

Tóm tắt

Heat pulse methods can be used for accurate measurements of sap flow in plant stems provided a reliable calibration procedure is used to relate the measured heat pulse velocity to the actual sap flow. This paper reviews the theory underpinning both the compensation and T‐max heat pulse methods that use a linear heater and temperature probes inserted radially into the plant stem. These probes not only disrupt the sap stream, but they also alter the thermal homogeneity of the sapwood in the vicinity of the probes. The degree of disturbance depends on the size and geometry of the probes and the corresponding wound width of the nonconducting sapwood. A two‐dimensional model of heat and water flow was used here to derive appropriate correction factors to account for the influence of both probe thermal properties and flow blockage. Wound width has a large influence on the heat pulse measurements while sensor material appears to have little or no influence. A table of correction factors is presented for both the compensation and T‐max methods. These new correction factors are confirmed by comparing heat pulse measurements in the trunk of a willow (Salix alba L.) and a poplar (Populus deltoides W. Bartram ex Marsh), against actual rates of transpiration determined from measured weight loss of the trees growing in large lysimeters. On a daily basis, both heat pulse measurements were found to be within 5 to 10% of the actual transpiration. The compensation method accurately measured flows close to 2 cm/h. The T‐max method had difficulty resolving any flows slower than about 10 cm/h.

Từ khóa


Tài liệu tham khảo

10.1023/A:1026520111166

10.1111/j.1365-3040.1995.tb00381.x

10.1093/treephys/18.3.177

10.1093/treephys/19.11.767

10.1093/treephys/21.9.589

Carslaw H.S., 1959, Conduction of heat in solids

10.1016/0168-1923(93)90047-L

Cermak J., 1990, Scaling up transpiration data between trees, stands and watersheds, Silva Carelica, 15, 101

10.1016/0378-3774(94)90048-5

10.2134/agronj1988.00021962008000030004x

10.1111/j.1365-3040.1981.tb02117.x

Dunlap F., 1912, The specific heat of wood

10.1080/00288233.1984.10418016

10.1016/S0378-3774(01)00119-6

10.1016/S0098-8472(02)00044-8

10.1051/forest:19850204

Green S.R., 1992, Radiation balance, transpiration and photosynthesis of an isolated tree, Agric. For. Meteorol., 64, 201, 10.1016/0168-1923(93)90029-H

Green S.R., 1998, Flow by the heat‐pulse method

10.1093/jxb/39.1.115

Green S.R., 2002, Rootzone processes, tree water use and the equitable allocation of irrigation water to olives, Geophys. Monogr., 129, 337

Green S.R., 1998, The response of sap flow in apple roots to localised irrigation, Agric. Water Manage., 33, 63, 10.1016/S0378-3774(96)01277-2

10.1016/S0168-1923(96)02362-3

10.1016/0168-1923(89)90072-5

Green S.R., 2003, Modeling light interception and transpiration in apple tree canopies.: (this issue), Agron. J., 95, 10.2134/agronj2003.1380

Huber B., 1932, Beobachtung und Messung pflanzicher Saftstrome, Ber. Dtsch. Bot. Ges., 50, 89, 10.1111/j.1438-8677.1932.tb00039.x

10.1016/0168-1923(91)90103-W

10.1016/S0168-1923(96)02397-0

10.1104/pp.33.6.385

10.1007/BF00029277

10.2480/agrmet.37.9

Savitzky A., 1964, Smoothing and differentiation of data by simplified least squares procedures, Anal. Chem., 68, 1627, 10.1021/ac60214a047

Siau J.F., 1971, Water in wood

Swanson R.H., 1962, An instrument for detecting sap movement in woody plants, 10.5962/bhl.title.80872

10.1093/jxb/32.1.221

Von Rosenberg D.U., 1969, Methods for the numerical solution of partial differential equations

Thông tin
Thông tin xuất bản

Agronomy Journal

Tập 95 Số 6

1371-1379

Thông tin tác giả