Mitchell, R. G. 1974. Estimation of needle populations on young, open-grown Douglas-fir by regression and life table analysis. Res. Pap. PNW-181. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 14 p.
Needle populations of young, open-grown Douglas-fir(Pseudotsuga menziesii (Mirb. ) Franco) can be estimatedfrom regressions on tree height, stem diameter, crownwidth, number of limbs, number of branch tips, and foliatedbranch surface. A time-specific life table based on treeheight and age appeared to realistically describe needledistributions by ages throughout the crown. The model alsopermitted evaluation of needle recruitment and loss for eachtree age. In 13 years, the modeled tree recruited some 1.7million needles and lost about 0.5 million needles to old ageand the effects of extrinsic factors.
KEYWORDS: Douglas-fir, Pseudotsuga menziesii,foliage area.