| Autor: |
L.P. Simmonds, James I. L. Morison, Donald Payne, Heping Zhang |
| Rok vydání: |
1997 |
| Předmět: |
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| Zdroj: |
Agricultural and Forest Meteorology. 87:155-169 |
| ISSN: |
0168-1923 |
| DOI: |
10.1016/s0168-1923(97)00017-8 |
| Popis: |
Sap flow estimates for whole trees (scaled from measurements on selected branches using the heat balance method) were compared with estimates of transpiration based on porometry in a study of poplar trees in an agroforestry system in the south of the UK. Sap flow showed good agreement with the transpiration rate estimated using the Penman-Monteith equation with measured stomatal conductance (R2 = 0.886) on six selected days during the season. The dominant environmental variable influencing transpiration was the vapour pressure deficit, as the “aerodynamic term” in the Penman-Monteith equation accounted for more than 70% of daily total transpiration, with the rest due to the “radiation component”. Stomatal conductance, estimated by inverting the Penman-Monteith equation from continuous measurements of sap flow over 55 days, was used to determine the parameters for a multiplicative stomatal conductance model. For an independent data set there was better agreement between measured sap flow and transpiration predicted from the stomatal conductance (R2 = 0.90) than for calculated and predicted stomatal conductance (R2 = 0.51). |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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