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).

Canopy disturbances over the five-century lifetime of an old-growth Douglas-fir stand in the Pacific Northwest

2002 ◽  
Vol 32 (6) ◽  
pp. 1057-1070 ◽  
Author(s):  
Linda E Winter ◽  
Linda B Brubaker ◽  
Jerry F Franklin ◽  
Eric A Miller ◽  
Donald Q DeWitt
Keyword(s):  
Pacific Northwest ◽  
Variable Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
The Pacific ◽  
History Of ◽  
Horizontal Heterogeneity ◽  
Restoration Strategies

The history of canopy disturbances over the lifetime of an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand in the western Cascade Range of southern Washington was reconstructed using tree-ring records of cross-dated samples from a 3.3-ha mapped plot. The reconstruction detected pulses in which many western hemlock (Tsuga heterophylla (Raf.) Sarg.) synchronously experienced abrupt and sustained increases in ringwidth, i.e., "growth-increases", and focused on medium-sized or larger ([Formula: see text]0.8 ha) events. The results show that the stand experienced at least three canopy disturbances that each thinned, but did not clear, the canopy over areas [Formula: see text]0.8 ha, occurring approximately in the late 1500s, the 1760s, and the 1930s. None of these promoted regeneration of the shade-intolerant Douglas-fir, all of which established 1500–1521. The disturbances may have promoted regeneration of western hemlock, but their strongest effect on tree dynamics was to elicit western hemlock growth-increases. Canopy disturbances are known to create patchiness, or horizontal heterogeneity, an important characteristic of old-growth forests. This reconstructed history provides one model for restoration strategies to create horizontal heterogeneity in young Douglas-fir stands, for example, by suggesting sizes of areas to thin in variable-density thinnings.

Comparing productivity of pure and mixed Douglas-fir and western hemlock plantations in the Pacific Northwest

2006 ◽  
Vol 36 (6) ◽  
pp. 1484-1496 ◽  
Author(s):  
M M Amoroso ◽  
E C Turnblom
Keyword(s):  
Pacific Northwest ◽  
Stand Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Mixed Stand ◽  
Mixed Stands ◽  
Individual Tree ◽  
The Pacific ◽  
Increase In Productivity

We studied pure and 50/50 mixtures of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) plantations to compare attained total yields between mixed-species stands as opposed to monocultures of equal densities. Whether overall stand density influences this outcome has not been adequately investigated, and to address this we included three density levels (494, 1111, and 1729 trees/ha) in the analysis. At age 12, as components of the mixed stands, Douglas-fir exhibited greater height, diameter, and individual-tree volume than western hemlock at all densities. At 494 and 1111 trees/ha the monocultures had a higher volume per hectare than the mixed stand, but at 1729 trees/ha the mixed stand appeared to be just as productive as the pure stands. The increase in productivity by the mixture at high densities seems to have resulted from the partial stratification observed and most likely also from better use of the site resources. Because of this, less interspecific competition was probably experienced in the mixed stand than intraspecific competition in the pure stands. This study shows the important role density plays in the productivity of mixed stands and thus in comparing mixed and pure stands.

Use of growth curve derivatives to illustrate acceleration and deceleration of growth in young plantations under variable competition

2006 ◽  
Vol 36 (10) ◽  
pp. 2515-2522 ◽  
Author(s):  
Michael Newton ◽  
Elizabeth C Cole
Keyword(s):  
Growth Period ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Early Years ◽  
Western Hemlock ◽  
Richards Equation ◽  
Second Derivative ◽  
Red Alder ◽  
Vegetation Control ◽  
Second Derivatives

Deceleration of growth rates can give an indication of competition and the need for thinning in early years but can be difficult to detect. We computed the first and second derivatives of the von Bertalanffy – Richards equation to assess impacts of density and vegetation control in young plantations in western Oregon. The first derivative describes the response in growth and the second derivative describes the change in growth over time. Three sets of density experiments were used: (i) pure Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), (ii) mixed Douglas-fir and grand fir (Abies grandis (Dougl. ex D. Don) Lindl.), and (iii) mixed western hemlock (Tsuga heterophylla (Raf.) Sarg.) and red alder (Alnus rubra Bong.). Original planting densities ranged from 475 to 85 470 trees·ha–1 (4.6 m × 4.6 m to 0.34 m × 0.34 m spacing); western hemlock and red alder plots were weeded and unweeded. For the highest densities, the second derivative was rarely above zero for any of the time periods, indicating that the planting densities were too high for tree growth to enter an exponential phase. As expected, the lower the density, the greater and later the peak in growth for both the first and second derivatives. Weeding increased the growth peaks, and peaks were reached earlier in weeded than in unweeded plots. Calculations of this sort may help modelers identify when modifiers for competition and density are needed in growth equations. Specific applications help define onset of competition, precise determining of timing of peak growth, period of acceleration of growth, and interaction of spacing and age in determination of peaks of increment or acceleration or deceleration.

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.

Water stress and survival of three species of conifer seedlings planted on a high elevation south-facing clear-cut

1987 ◽  
Vol 17 (9) ◽  
pp. 1115-1123 ◽  
Author(s):  
N. J. Livingston ◽  
T. A. Black
Keyword(s):  
Survival Rates ◽  
High Elevation ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Silver Fir ◽  
High Survival ◽  
High Survival Rate ◽  
Poor Survival ◽  
Tolerance Mechanisms ◽  
Clear Cut

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabilis (Dougl.) Forbes) container-grown 1-0 seedlings were spring planted on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia. Treatments, which included inclining seedlings to the southwest, provision of shade cards, irrigation, and irrigation and shade cards combined, were applied to determine whether modification of seedling microclimate would increase survival. Highest survival rates, regardless of treatment, were shown by Douglas-fir. By April 1984, 72 and 82% of untreated Douglas-fir seedlings planted in 1981 and 1982, respectively, survived, whereas survival of treated seedlings ranged from 81 to 95%. The high survival rate in Douglas-fir appeared to be due to their high drought tolerance. The osmotic potential of unirrigated Douglas-fir seedlings declined by over 1.1 MPa during the course of the 1982 growing season in response to decreasing soil water potentials and consequently turgor was maintained in the foliage. Transpiration rates of these seedlings were never less than 50% of those that were irrigated. Western hemlock and Pacific silver fir seedlings exhibited very poor survival, possibly owing to the lack of stress avoidance and tolerance mechanisms. Survival rates of the two species were increased by shade cards and irrigation but never exceeded 64%.

THE INITIATION AND SPREAD OF PORIA WEIRII ROOT ROT OF DOUGLAS FIR

1965 ◽  
Vol 43 (1) ◽  
pp. 1-9 ◽  
Author(s):  
G. W. Wallis ◽  
G. Reynolds
Keyword(s):  
Root Rot ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Natural Soil ◽  
Limited Extent ◽  
Red Alder ◽  
Red Cedar ◽  
Considerable Resistance ◽  
Western Red Cedar ◽  
Living Tissues

Root rot caused by Poria weirii Murr. occurred when healthy roots of Douglas fir came into contact with inoculum in infected roots of the previous stand. Mycelium grew ectotrophically on the bark of the Douglas fir roots, frequently well in advance of growth in the wood, and penetrated to living tissues directly through sound as well as injured bark. Spread of the disease to adjacent trees took place where healthy and diseased roots were in contact, the mycelium apparently spreading to only a very limited extent through natural soil. It was shown that mycelium could invade roots of trees felled for at least 12 months and Douglas fir heartwood that had been buried in soil for at least 12 months. Viable Poria mycelium was isolated from infected roots as small as 2 cm in diameter 11 years after the trees had been cut. While Douglas fir and western hemlock appeared to be quite susceptible to infection, western red cedar, red alder, and bigleaf maple showed considerable resistance.

Quaternary Palynology of the Pacific Slope of Washington

1977 ◽  
Vol 8 (3) ◽  
pp. 282-306 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Pinus Contorta ◽  
Meteorological Data ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Olympic Peninsula ◽  
The Holocene ◽  
Pollen Stratigraphy ◽  
The Pacific ◽  
Pacific Slope

Quaternary deposits on the Pacific slope of Washington range in age from the earliest known interglaciation, the Alderton, through the Holocene. Pollen stratigraphy of these deposits is represented by 12 major pollen zones and is ostensibly continuous through Zone 8 over more than 47,000 radiocarbon yr. Before this, the stratigraphy is discontinuous and the chronology less certain. Environments over the time span of the deposits are reconstructed by the comparison of fossil and modern pollen assemblages and the use of relevant meteorological data. The Alderton Interglaciation is characterized by forests of Douglas fir (Pseudotsuga menziesii), alder (Alnus), and fir (Abies). During the next younger interglaciation, the Puyallup, forests were mostly of pine, apparently lodgepole (Pinus contorta), except midway in the interval when fir, western hemlock (Tsuga heterophylla), and Douglas fir temporarily replaced much of the pine. Vegetation outside the limits of Salmon Springs ice (>47,00034,000 yr BP) varied chiefly between park tundra and forests of western hemlock, spruce (Picea), and pine. The Salmon Springs nonglacial interval at the type locality records early park tundra followed by forests of pine and of fir. During the Olympia Interglaciation (34,000–28,000 yr BP), pine invaded the Puget Lowland, whereas western hemlock and spruce became manifest on the Olympic Peninsula. Park tundra was widespread during the Fraser Glaciation (28,000–10,000 yr BP) with pine becoming more important from about 15,000 to 10,000 yr BP. Holocene vegetation consisted first of open communities of Douglas fir and alder; later, closed forests succeeded, formed principally of western hemlock on the Olympic Peninsula and of western hemlock and Douglas fir in the Puget Lowland. Over the length of the reconstructed environmental record, climate shifted between cool and humid or relatively warm, semihumid forest types and cold, relatively dry tundra or park tundra types. During times of glaciation, average July temperatures are estimated to have been at least 7°C lower than today. Only during the Alderton Interglaciation and during the Holocene were temperatures higher for protracted periods than at present.

Forest fire history of Desolation Peak, Washington

1990 ◽  
Vol 20 (3) ◽  
pp. 350-356 ◽  
Author(s):  
James K. Agee ◽  
Mark Finney ◽  
Roland De Gouvenain
Keyword(s):  
Ponderosa Pine ◽  
Fire History ◽  
Forest Type ◽  
Douglas Fir ◽  
Forest Community ◽  
Western Hemlock ◽  
Silver Fir ◽  
Forest Types ◽  
Natural Fire ◽  
Interior Forest

Forests in the vicinity of Desolation Peak, Washington, are of special ecological interest because of their transitional nature between coastal and interior forest types. The area is west of the Cascade Mountain crest but in the rainshadow of mountains farther to the west. Fire return intervals were hypothesized to be shorter than typical for coastal forest types, such as those dominated by western hemlock and Pacific silver fir, and longer than typical for interior forest types, such as ponderosa pine, owing to the close juxtaposition of these types at Desolation Peak. Seven forest community types were defined, and a 400-year fire history was developed for this 3500-ha area. The average natural fire rotation was 100 years; this varied by a factor of two by century and by topographic aspect. Forest types typical of coastal regions, such as Douglas-fir, – western hemlock and mountain hemlock – Pacific silver fir, had mean fire return intervals (108–137 years) much lower than in other western Washington areas. The most interior forest type, ponderosa pine – Douglas-fir, had a higher mean fire return interval (52 years) than reported for similar forest types east of the Cascades. Historically, fire has created structural and landscape diversity on Desolation Peak and may be an important process in the maintenance of such diversity into the future.

Decomposition and nutrient release in Douglas-fir needle litter in relation to stand development

1979 ◽  
Vol 9 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Robert L. Edmonds
Keyword(s):  
Weight Loss ◽  
Nutrient Release ◽  
Nutrient Content ◽  
Douglas Fir ◽  
Strongly Correlated ◽  
Litter Bags ◽  
Net Productivity ◽  
Needle Litter ◽  
Weight Loss Data ◽  
Moisture Conditions

Decomposition rates and changes in the nutrient content of needle litter were examined in an age sequence of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands in western Washington. The stands at the initiation of the study were 11, 24, 44, 75, and 97 years old. Nylon litter bags (1 mm mesh) containing needles from the 44-year-old stand were placed in the stands in February 1975. Bags were collected after 3, 6, 12, and 24 months, weighed, and analyzed for N, P, K, Ca, Mg, Mn, and lignin. Decomposition constants (k values) were determined. After 2 years, maximum decomposition rate occurred in the 24-year-old stand, where temperature and moisture conditions were most favorable. Low litter moisture tended to inhibit decomposition in summer. Values of k determined from 1-year weight loss data and percent needle lignin after 2 years were significantly different between stands. Values of k determined from weight loss were greater than those determined from litter fall weight: forest floor weight ratios. Loss of elements from litter bags after 2 years was in the following sequence in all stands, N < Mn < Ca < Mg < P < K. Annual stand net productivity was strongly correlated to N + K loss from litter bags (r = 0.96).

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