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Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy

Publication ,  Journal Article
Thomas, SC; Winner, WE
Published in: Canadian Journal of Forest Research
January 1, 2000

Leaf area index (LAI) in old-growth Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) forests exceeds that of any other forest ecosystem by some estimates; however, LAI determinations in coniferous forests have generally been indirect, involving extrapolations of patterns observed in younger stands. Aided by a 75-m construction crane for canopy access, we used a vertical line-intercept method to estimate LAI for a ≥450-year-old Douglas-fir western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in southwestern Washington state. LAI was calculated as the product of foliage contact frequency and an "extinction coefficient" accounting for foliage angular distribution, geometry, and the ratio of "interceptable" to total leaf area. LAI estimates were 9.3 ±2.1 (estimate ±95% confidence interval), 8.5 ±2.2, and 8.2 ±1.8 in 1997, 1998, and 1999, respectively, or 8.6 ±1.1 pooled across years. Understory vegetation, including foliage of woody stems <5 cm diameter, represented 20% of this total. Sample points in which Douglas-fir was dominant had a higher total LAI than points dominated by western hemlock, including a higher LAI of understory vegetation. Our results do not support the contention that old-growth Douglas-fir - western hemlock forests maintain an appreciably higher LAI than do other forest ecosystems. Moreover, LAI in very old stands may decline as western hemlock replaces Douglas-fir through the course of succession.

Duke Scholars

Published In

Canadian Journal of Forest Research

DOI

ISSN

0045-5067

Publication Date

January 1, 2000

Volume

30

Issue

12

Start / End Page

1922 / 1930

Related Subject Headings

  • Forestry
  • 07 Agricultural and Veterinary Sciences
  • 05 Environmental Sciences
  • 04 Earth Sciences
 

Citation

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Thomas, S. C., & Winner, W. E. (2000). Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy. Canadian Journal of Forest Research, 30(12), 1922–1930. https://doi.org/10.1139/x00-121
Thomas, S. C., and W. E. Winner. “Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy.” Canadian Journal of Forest Research 30, no. 12 (January 1, 2000): 1922–30. https://doi.org/10.1139/x00-121.
Thomas SC, Winner WE. Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy. Canadian Journal of Forest Research. 2000 Jan 1;30(12):1922–30.
Thomas, S. C., and W. E. Winner. “Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy.” Canadian Journal of Forest Research, vol. 30, no. 12, Jan. 2000, pp. 1922–30. Scopus, doi:10.1139/x00-121.
Thomas SC, Winner WE. Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy. Canadian Journal of Forest Research. 2000 Jan 1;30(12):1922–1930.

Published In

Canadian Journal of Forest Research

DOI

ISSN

0045-5067

Publication Date

January 1, 2000

Volume

30

Issue

12

Start / End Page

1922 / 1930

Related Subject Headings

  • Forestry
  • 07 Agricultural and Veterinary Sciences
  • 05 Environmental Sciences
  • 04 Earth Sciences