Nitrogen Mineralization Following Fertilization of Douglas-fir Forests with Urea in Western Washington

2004 ◽  
Vol 68 (5) ◽  
pp. 1720-1728 ◽  
Author(s):  
Thomas R. Fox
Keyword(s):  
Nitrogen Mineralization ◽  
Douglas Fir ◽  
Western Washington

Nutrient concentrations and nitrogen mineralization in forest floors of single species conifer plantations in coastal British Columbia

2000 ◽  
Vol 30 (9) ◽  
pp. 1341-1352 ◽  
Author(s):  
C E Prescott ◽  
L Vesterdal ◽  
J Pratt ◽  
K H Venner ◽  
L M de Montigny ◽  
...  
Keyword(s):  
Nitrogen Mineralization ◽  
Tree Species ◽  
N Mineralization ◽  
Single Species ◽  
Douglas Fir ◽  
Picea Sitchensis ◽  
Slope Position ◽  
Nutrient Concentrations ◽  
Net N Mineralization ◽  
Forest Floors

We examined the extent to which nutrient concentrations and C and N mineralization rates in forests floors under different tree species are predictable from the chemistry of foliar litter and its rate of decomposition. We studied replicated single species plantations of western redcedar (Thuja plicata Donn ex D. Don), western hemlock (Tsuga heterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and Sitka spruce (Picea sitchensis (Bong.) Carr.) at four locations. Nutrient concentrations in forest floors correlated poorly with litter nutrient concentrations; the only significant relationships were for Ca and K. Nitrogen mineralization correlated weakly with forest floor C/N ratio, and differed more among sites than among species. None of the litter chemistry parameters were related to net N mineralization rates. Decomposition was fastest in hemlock litter, intermediate in Douglas-fir litter and lowest in cedar litter. Litter also decomposed more rapidly on hemlock forest floors than on cedar forest floors. Rates of N mineralization in the forest floors were not related to rates of decomposition of foliar litter. Differences among sites in N mineralization rates were related to the understory vegetation composition, particularly the amount of the ericaceous shrub salal, which in turn was related to slope position. These site factors appeared to override the effect of tree species on rates of N mineralization.

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

scholarly journals Biomass and dynamics of attached dead branches in the canopy of 450-year-old Douglas-fir trees

2006 ◽  
Vol 36 (2) ◽  
pp. 378-389 ◽  
Author(s):  
Hiroaki Ishii ◽  
Tomoko Kadotani
Keyword(s):  
Tree Height ◽  
Dry Mass ◽  
Tsuga Heterophylla ◽  
Important Variable ◽  
Douglas Fir ◽  
Dead Branch ◽  
Western Washington ◽  
Term Monitoring ◽  
Branch Death

The amount, physical characteristics, and spatial distribution of attached dead branches in the canopy of 450-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) trees were studied over a 5-year period (1998–2003) to quantify their contribution to the canopy woody detritus pool of an old-growth Douglas-fir – western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in the western Washington Cascades. We developed a five-class decay rating for attached dead branches. From the size distribution and relative amounts and vertical distribution of attached dead branches in the five decay classes, we inferred that death of large original branches had occurred in the recent past, followed by the production and death of epicormic branches. Tree height was an important variable for predicting branchwood dry mass per tree. We estimated that attached dead branches of Douglas-fir contributed 63.8% of the total canopy woody detritus pool of the stand. During the study period, 0.24%·year–1 of live branchwood mass died attached, and 0.37%·year–1 and 4.34%·year–1, respectively, of live- and dead-branch mass were lost due to branchfall and fragmentation. Because branch death and branchfall are stochastic processes, long-term monitoring in the canopy and on the ground is needed to understand the dynamics of canopy woody detritus.

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