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  • Variation in Douglas-fir ( Pseudotsuga menziesii var. menziesii ) and red alder ( Alnus rubra ) stem taper across varying stand conditions in the Pacific Northwest
Title: Variation in Douglas-fir ( Pseudotsuga menziesii var. menziesii ) and red alder ( Alnus rubra ) stem taper across varying stand conditions in the Pacific Northwest
Tree taper has been of interest for over a century, yet questions remain regarding the effects of silvicultural treatments and forest health on recoverable volume. This work utilizes data from Douglas-fir ( Pseudotsuga menziesii (Mirb.)) ( n = 608) and red alder ( Alnus rubra (Bong.)) ( n = 495) trees to assess the influences of fertilization, pruning, thinning, regeneration origin, and defoliation caused by Swiss Needle Cast (SNC; Nothophaeocryptopus gaeumannii), on stem taper in the Pacific Northwest. The Kozak (2004; For. Chor. 80: 507–515) variable-exponent equation was used to test the addition of treatment and crown variables as the model is widely regarded for its flexibility in application. Using a mixed effects framework, results reveal that thinning of Douglas-fir can result in a 3.5% increase in upper stem diameter inside bark, while pruning may lead to a 4.1% decrease. SNC-induced defoliation of Douglas-fir reduced mean diameter above-breast height by 11.5%. Total volume of artificially regenerated red alder was 16% greater than naturally regenerated stems. Overall, thinning of healthy Douglas-fir and planting red alder may increase recoverable volume and C captured in long-term timber products in the region, and the inclusion of crown variables can increase the predictive power of taper estimates for some species.  more » « less
Award ID(s):
1915078
PAR ID:
10651078
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
Canadian Journal of Forest Research
Date Published:
Journal Name:
Canadian Journal of Forest Research
Volume:
55
ISSN:
0045-5067
Page Range / eLocation ID:
1 to 10
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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