Science Inventory

BOLE WATER CONTENT SHOWS LITTLE SEASONAL VARIATION IN CENTURY-OLD DOUGLAS-FIR TREES

Citation:

BEEDLOW, P. A., D. T. TINGEY, R. S. WASCHMANN, D. L. PHILLIPS, AND M. G. JOHNSON. BOLE WATER CONTENT SHOWS LITTLE SEASONAL VARIATION IN CENTURY-OLD DOUGLAS-FIR TREES. TREE PHYSIOLOGY. Heron Publishing, Victoria, B.C, Canada, 27:737-747, (2007).

Impact/Purpose:

To measure seasonal variation of phloem-sapwood water content in Douglas-fir trees over 4 years

Description:

Purportedly, large Douglas-fir trees in the American Pacific Northwest use water stored in bole tissues to ameliorate the effects of seasonal summer drought, the water content of bole tissues being drawn down over the summer months and replenished during the winter. Continuous monitoring of bole relative water content (RWC) in two 110-20 year-old Douglas-fir trees with ThetaProbe impedance devices provided an integrated measure of phloem-sapwood water content over 4 years. Seasonal changes in RWC closely tracked cambial activity and wood formation, but lagged changes in soil water content by 2-3 months. The RWC in the combined phloem and sapwood markedly increased during earlywood production in the late spring and early summer to maximum values of 64¿77% as plant available soil water (ASW) decreased by ~60%. With transition and latewood formation, RWC decreased to minimum values of 59¿72%, even as ASW increased in the fall. The difference between minimum RWC in the fall and maximum RWC in midsummer was only ~5%. Seasonal changes in bole RWC corresponded to cambial phenology, although decreasing AWS appeared to trigger the shift from earlywood to latewood formation.

Record Details:

Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Product Published Date: 05/01/2007
Record Last Revised: 08/22/2007
OMB Category: Other
Record ID: 147502

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY

WESTERN ECOLOGY DIVISION

RISK CHARACTERIZATION BRANCH