© 1998 Heron Publishing—Victoria, Canada
Conversion of total leaf area to projected leaf area in lodgepole pine and Douglas-fir
Hugh J. Barclay (1)
1. Pacific Forestry Centre, 506 West Burnside Road, Victoria, B.C. V8Z 1M5, Canada (hbarclay@pfc.forestry.ca) / Received January 28, 1997
Summary
Three definitions of leaf area index (LAI) in the literature have no predictable relationship with each other. Factors were
derived for converting total LAI to projected LAI of horizontal leaves and to projected LAI for inclined leaves of lodgepole
pine (Pinus contorta Dougl. var. latifolia Engelm.) and coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to allow comparison of results from different studies. An algorithm was derived to allow determination of
these factors based on twig angles and the angles that the foliage subtends with the twig. Allowances were made for both the
vertical and horizontal components of projection. The value of the factor for converting total LAI to projected LAI for inclined
leaves was 0.229 + 0.0032 for lodgepole pine and 0.230 + 0.0037 for Douglas-fir. Sensitivity analysis established that this
conversion factor was more sensitive to differences in vertical angles of the twigs than to twig rotation or foliar arrangement
on the twig.
Keywords:
leaf area index, Pinus contorta, Pseudotsuga menziesii, sensitivity analysis.
