Ten-Year Douglas-Fir Stand Productivity Differs Among Contrasting Silvicultural Regimes in Western Washington, USA

2021 ◽  
Author(s):  
Timothy Brian Harrington ◽  
David H. Peter ◽  
David D. Marshall ◽  
Dean S. DeBell
Keyword(s):  
Douglas Fir ◽  
Stand Productivity ◽  
Western Washington

Crown structure in western hemlock, Douglas-fir, and grand fir in western Washington: trends in branch-level mass and leaf area

1995 ◽  
Vol 25 (12) ◽  
pp. 1897-1912 ◽  
Author(s):  
John A. Kershaw Jr. ◽  
Douglas A. Maguire
Keyword(s):  
Branch Length ◽  
Allometric Equation ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Crown Structure ◽  
Indicator Variables ◽  
Western Washington ◽  
Modified Likelihood ◽  
Individual Trees ◽  
Fertilization Effects

Extensions of a basic allometric equation applied in predicting total foliage of individual trees were developed to estimate foliage and woody components of individual branches in western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and grand fir (Abiesgrandis (Dougl. ex D. Don) Lindl.). Nine initial equations were fitted on both nonlinear and log-transformed scales to data collected in the western Cascade Mountains of Washington. In all cases, the logarithmic form of each equation provided the best fit to the data based on a modified likelihood criterion and residual patterns. Branch diameter was the overall best predictor of branch foliage and woody mass; however, significant (p = 0.05) improvements in fit were obtained when other structural and positional variables were included in the equations (e.g., foliated branch length and depth into crown). The effects of fertilization and site (locality) differences were explored using indicator variables for western hemlock branches. Significant site effects were observed for intercept terms for all three branch components (total foliage area, total foliage mass, and total woody mass), while fertilization effects were observed in interaction with relative height above crown base for both foliage components.

Twenty-Eight Years of Thinning at Several Intensities in a High-Site Douglas-Fir Stand in Western Washington

1990 ◽  
Vol 5 (2) ◽  
pp. 37-40 ◽  
Author(s):  
Kevin L. O'Hara
Keyword(s):  
Pseudotsuga Menziesii ◽  
Rapid Growth ◽  
Basal Area ◽  
Douglas Fir ◽  
Growth Potential ◽  
Control Treatment ◽  
High Site ◽  
Western Washington

Abstract A 28-year thinning study in a dense, natural, high-site coastal Douglas-fir (Pseudotsuga menziesii) stand compared three thinning treatments and an unthinned control. Gross, net, and total recoverable periodic cubic volume increments from the control treatment were not significantly different from the highest yielding thinned treatment. An increasing reserve basal area thinning treatment was the least severe thinning treatment and produced the highest gross, net, and total recoverable periodic increments of the thinning treatments. Commercial thinnings of dense or fully stocked plantations of Douglas-fir may produce similar results: vigorous stands with rapid growth potential. West. J. Appl. For. 5(2):37-40, April 1990.

Litter decomposition and nutrient release in Douglas-fir, red alder, western hemlock, and Pacific silver fir ecosystems in western Washington

1980 ◽  
Vol 10 (3) ◽  
pp. 327-337 ◽  
Author(s):  
Robert L. Edmonds
Keyword(s):  
Weight Loss ◽  
Nutrient Release ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Silver Fir ◽  
Rapid Weight Loss ◽  
Red Alder ◽  
Cellulose Decomposition ◽  
The Pacific ◽  
Western Washington

Decomposition rates and changes in the nutrient content of needle and leaf litter were examined in Douglas-fir (Pseudotsugamenziesii Mirb. Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), Pacific silver fir (Abiesamabilis (Dougl.) Forbes), and red alder (Alnusrubra Bong.) ecosystems in western Washington, U.S.A. Nylon litterbags (1-mm mesh) were placed in the stands in November and December 1974. Bags were collected after 3, 6, 12, and 24 months and weighed, except in the Pacific silver fir stand when bags were collected after 6, 9, 14, and 24 months. Litter was analyzed for C, N, P, K, Ca, Mg, Mn, lignin, and cellulose. Decomposition constants (k values) were determined. Fastest decomposition after 2 years occurred in red alder leaves, followed by Douglas-fir, western hemlock, and Pacific silver fir needles. There were significant differences in weight loss among species after 1 year, but no significant differences were evident after 2 years. Red alder leaves showed rapid weight loss in the 1st year but decomposed little in the 2nd year. Decomposition constants were highly positively correlated with minimum air temperatures and negatively correlated with C:N ratios. Low litter moisture tended to reduce decomposition in summer, particularly in the Pacific silver fir stand. Decomposition proceeded under snow in this ecosystem. The pattern of loss of elements from litterbags after 2 years varied from ecosystem to ecosystem, particularly for N. The following element mobility series resulted for the four ecosystems: red alder (K > Mg > Ca > P > N > Mn), Douglas-fir (K > P > Ca > Mg > Mn > N), western hemlock (K > Ca > Mg > N > Mn > P), and Pacific silver fir (K > Mg > Ca > Mn > P > N).

Old-Growth Douglas-Fir in Western Washington

1992 ◽  
pp. 333-364 ◽  
Author(s):  
L. B. Brubaker ◽  
S. Vega-Gonzalez ◽  
E. D. Ford ◽  
C. A. Ribic ◽  
C. J. Earle ◽  
...  
Keyword(s):  
Douglas Fir ◽  
Old Growth ◽  
Western Washington
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