The application of the widely used Penrnan-Monteith evapotranspiration
equation to hybrid poplar trees is impossible without a valid surface resistance.
The increase in applications of drip-irrigated hybrid poplar trees for wood chip
stock and veneer production, as well as bioremediation, constitutes a need for
estimating the evapotranspiration of these trees. To the author's knowledge, there
are no published estimates of surface resistance for poplar trees.
Six years of weekly soil moisture content for drip-irrigated, hybrid poplar
trees were used in a water balance to compute evapotranspiration. The weekly data
were adjusted with reference evapotranspiration data to compute a daily
evapotranspiration. Only data that represent fully leaved hybrid poplars are used in
this study and the data were screened for the effects of drainage. Additional
parameters applied in this study include solar radiation, temperature, wind speed
and relative humidity taken at a nearby AGRIMET Weather Station.
The results of this study indicate that surface resistance values cannot be
described as a function of meteorological data within the constraints of the current
experiment design. The graph of poplar evapotranspiration versus surface
resistance shows that for a given evapotranspiration there can be multiple rs values.
This scatter is the influence of parameters other than rs within the Penman-Monteith
model. The use of an instrument to directly measure the surface
resistance is recommended in further studies. / Graduation date: 2000
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33226 |
| Date | 21 April 2000 |
| Creators | Butler, Dana Anthony |
| Contributors | Cuenca, Richard H. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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