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Comparison of water flux from Douglas-fir and Oregon white oak of varying age and stature

Comparison of water flux from Douglas-fir and Oregon white oak of varying age and stature. Nathan Phillips, Barbara Bond Nate McDowell, Andrew Schauer, Mike Ryan, Eric Watrud, Nate Gehres,. Temperate conifer Dry angiosperm Tropical angiosperm.

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Comparison of water flux from Douglas-fir and Oregon white oak of varying age and stature

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  1. Comparison of water flux from Douglas-fir and Oregon white oak of varying age and stature Nathan Phillips, Barbara Bond Nate McDowell, Andrew Schauer, Mike Ryan, Eric Watrud, Nate Gehres,

  2. Temperate coniferDry angiospermTropical angiosperm

  3. Landsat TM, Wind River Canopy Crane Research Facility

  4. Betts et al. 1997, Nature

  5. Field et al. 1999

  6. Yoder et al. 1994

  7. X X X

  8. Watson et al. 1999

  9. Objectives • Determine whether tall trees show • reduced transpiration compared to • smaller trees • Scale whole-tree water use estimates • to the ecosystem and compare age • classes • Compare transpiration estimates to • ecosystem latent heat fluxes estimated • using eddy covariance (Doug-fir only) • [thanks KT Paw U, Jiquan Chen, Mattias Falk, Tom King]

  10. Suite of tests: Parameter Predicted change w/ size sap flow decrease stomatal conductance decrease latent heat flux decrease (?)

  11. Methods • sap flux measurements: • constant thermal dissipation • technique (Granier-Type). • Sampling: 6-9 trees in 20, 40, • and 500 y old doug-fir stands; • 8 trees each in old/young oak • Sub-sampling: 2-5 points within trees • Study period: 1998,99 • summer months for Doug-fir; • 1999 summer for oak • eddy covariance: • 20 and 500 y old Doug-fir stands

  12. Douglas-fir Study Area • Douglas fir dominated • 3 age class sites within 10 km • 2.5 m annual precipitation • 9 oC mean annual temperature • 350 - 500 m elevation Southern Washington 500 y, 65 m tall 40 y, 35 m tall 20 y, 15 m tall

  13. Phillips et al., AGU 1999

  14. Oregon white oak

  15. Future Directions

  16. 3PG Model Structure

  17. Bogh et al. 1999 Remote Sens. Environ.

  18. 2 cm

  19. Phillips et al. (NSF in review) adapted from Liu 1985

  20. Acknowledgements Andy S. Heather M, Megan V.H. Nate M. Eric W. Seth M. Nate G. Hyun K.

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