Potentials and limitations of modelling vertical distributions of root water uptake of an Austrian pine forest on a sandy soil
✍ Scribed by P. A. D. Musters; W. Bouten; J. M. Verstraten
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 339 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0885-6087
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✦ Synopsis
Root water uptake patterns are often studied with simulation models of the unsaturated soil water ¯ow, as they are dicult to measure directly. Calibration of these models is not straightforward and causes uncertainties in simulated uptake distributions. In this paper we study how uncertainties in the calibration of the SWIF model aect uncertainty intervals in simulated uptake patterns of an Austrian pine stand (Pinus nigra var. nigra) on a sandy soil. After calibrating and validating SWIF with a large data set of more than 125 000 measured soil water contents over a three year period, uncertainty ranges in simulated soil water dynamics and root water uptake distributions were estimated with a Monte Carlo analysis.
In general, uncertainties in root uptake patterns were small (typically 52 10 À4 m 3 m À3 day À1 ) and were higher for trees with a shallow rooting system (0 . 8 m) than for trees with a deep rooting system (2 . 5 m). Uncertainties arose mainly from uncertainties in simulated soil water ¯uxes and from variations in the reduction of uptake during periods of drought. Uncertainties in soil water contents were far higher (typically 0 . 01 m 3 m À3 ) than uncertainties in uptake, illustrating that uncertainties in uptake parameters and those in the distribution of water uptake hardly aect the modelling of soil water dynamics. Root water uptake models should therefore be validated against measured uptake distributions, which can be determined on sandy soils during dry periods with a high water use when soil ¯uxes are negligible to uptake.