Crown profile equations for stand-grown western hemlock trees in northwestern Oregon

2003 ◽  
Vol 33 (11) ◽  
pp. 2059-2066 ◽  
Author(s):  
David D Marshall ◽  
Gregory P Johnson ◽  
David W Hann
Keyword(s):  
Pseudotsuga Menziesii ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Lower Portion ◽  
Data Set ◽  
Profile Model ◽  
Crown Width ◽  
Crown Form

Crown profile equations were developed for stand-grown western hemlock (Tsuga heterophylla (Raf.) Sarg.) in northwest Oregon. The profile model uses a segmented approach, dividing the crown into an upper and lower portion at the point of the largest crown width (LCW). The model explains about 86% of the variation in crown width when LCW is known but only 66% when LCW is predicted using a model developed from a larger data set collected in the same area as the data for developing the crown profile models were collected. The model can be adjusted using measurements or predictions of LCW for western hemlock in other populations. Comparisons are made with the crown form of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco).

Survival dynamics of mechanically topped Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) snags in Douglas-fir plantations, Oregon, USA

2019 ◽  
Vol 433 ◽  
pp. 105-110
Author(s):  
Matthew E. Hane ◽  
Andrew J. Kroll ◽  
Aaron Springford ◽  
Jack Giovanini ◽  
Mike Rochelle ◽  
...  
Keyword(s):  
Pseudotsuga Menziesii ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock

Diaporthe lokoyae n. sp., the perfect state of Phomopsis lokoyae

1968 ◽  
Vol 46 (5) ◽  
pp. 601-603 ◽  
Author(s):  
A. Funk
Keyword(s):  
New Species ◽  
Pseudotsuga Menziesii ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Perfect State ◽  
Ascigerous State ◽  
A New Species

A new species of Diaporthe, for which the name D. lokoyae Funk is proposed, is described on the host Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and in culture. This Diaporthe is shown to be the ascigerous state of Phomopsis lokoyae Hahn. An outbreak of dieback in Douglas fir associated with this Diaporthe is described and discussed; a single occurrence on western hemlock (Tsuga heterophylla (Raf.) Sarg.) is reported.

Multi-decadal establishment for single-cohort Douglas-fir forests

2014 ◽  
Vol 44 (9) ◽  
pp. 1068-1078 ◽  
Author(s):  
James A. Freund ◽  
Jerry F. Franklin ◽  
Andrew J. Larson ◽  
James A. Lutz
Keyword(s):  
Pseudotsuga Menziesii ◽  
Temporal Patterns ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
Old Growth Forests ◽  
Western Washington ◽  
Century Development ◽  
Single Cohort

The rate at which trees regenerate following stand-replacing wildfire is an important but poorly understood process in the multi-century development of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) forests. Temporal patterns of Douglas-fir establishment reconstructed from old-growth forests (>450 year) have generated contradictory models of either rapid (<25 year) or prolonged (>100 year) periods of establishment, while patterns of tree establishment in mid-aged (100 to 350 year) forests remains largely unknown. To determine temporal patterns of Douglas-fir establishment following stand-replacing fire, increment cores were obtained from 1455 trees in 18 mature and early old-growth forests in western Washington and northwestern Oregon, USA. Each of the stands showed continuous regeneration of Douglas-fir for many decades following initiating fire. The establishment period averaged 60 years (range: 32–99 years). These results contrast both with the view of rapid (one- to two-decade) regeneration of Douglas-fir promoted in the early forestry literature and with reports of establishment periods exceeding 100 years in older (>400 year) Douglas-fir–western hemlock stands. These results have important implications for management designed to create and promote early-seral forest characteristics.

REPRODUCTION AND SURVIVAL OF THE AMBROSIA BEETLE TRYPODENDRON LINEATUM (OLIV.) (COLEOPTERA: SCOLYTIDAE) IN DOUGLAS-FIR AND WESTERN HEMLOCK LOGS

1987 ◽  
Vol 119 (2) ◽  
pp. 131-139 ◽  
Author(s):  
T.L. Shore ◽  
J.A. McLean ◽  
J.C. Zanuncio
Keyword(s):  
Sex Ratio ◽  
Pseudotsuga Menziesii ◽  
Pupal Stage ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Flight Period ◽  
Trypodendron Lineatum ◽  
Brood Production ◽  
Linear Relationships

AbstractSpring-felled logs of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and western hemlock, Tsuga heterophylla (Raf.) Sarg., were attacked by ambrosia beetles, Trypodendron lineatum (Oliv.), in the year after felling. By monitoring individual galleries it was determined that brood production was similar to that found in fall- and winter-felled logs. The sex ratio of the brood did not differ significantly from 1:1. Only beetles that had failed to establish successful galleries emerged during the "second" flight period. Significant linear relationships were found between frass weight and each of the following variables: number of egg niches, emerged adult progeny, and gallery length. Mortality in galleries in Douglas-fir and western hemlock logs, respectively, was found to be 9.4 and 12.4% between the egg and larval–pupal stage and 19.5 and 32.1% between the larval–pupal and adult stages.

A new Nitschkia on western conifers and its probable microconidial state

1979 ◽  
Vol 57 (20) ◽  
pp. 2113-2115 ◽  
Author(s):  
A. Funk
Keyword(s):  
British Columbia ◽  
New Species ◽  
Pseudotsuga Menziesii ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Coastal British Columbia ◽  
A New Species

A new species, Nitschkia molnarii (Ascomycetes: Nitschkiaceae), is described from Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) in coastal British Columbia, Canada. A microconidial state closely associated with the ascocarps is described, but not separately named.

Growth ofPseudotsuga menziesiiandTsuga heterophyllaseedlings along a light gradient: resource allocation and morphological acclimation

1997 ◽  
Vol 75 (9) ◽  
pp. 1424-1435 ◽  
Author(s):  
D. Mailly ◽  
J. P. Kimmins
Keyword(s):  
Leaf Morphology ◽  
Biomass Accumulation ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Low Light ◽  
Growing Seasons ◽  
Light Levels ◽  
Light Gradient ◽  
Relative Light Intensity

Silvicultural alternatives that differ in the degree of overstory removal may create shady environments that will be problematic for the regeneration of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Gradients of light in the field were used to compare mortality, growth, and leaf morphological acclimation of two conifer species of contrasting shade tolerances: Douglas-fir and western hemlock (Tsuga heterophylla (Raf.) Sarg.). Results after two growing seasons indicated that Douglas-fir mortality occurred mainly at relative light intensity (RLI) below 20%, while western hemlock mortality was evenly distributed along the light gradient. Height, diameter, and biomass of the planted seedlings increased with increasing light for both species but at different rates, and maximum biomass accumulation always occurred in the open. Douglas-fir allocated more resources to stem biomass than western hemlock, which accumulated more foliage biomass. Increases in specific leaf area for Douglas-fir seedlings occurred at RLI ≤ 0.4 and red/far red (R/FR) ratio ≤ 0.6, which appear to be the minimal optimum light levels for growth. Conversely, western hemlock seedlings adjusted their leaf morphology in a more regular pattern, and changes were less pronounced at low light levels. These results, along with early mortality results for Douglas-fir, suggest that the most successful way to artificially regenerate this species may be by allowing at least 20% of RLI for ensuring survival and at least 40% RLI for optimum growth. Key words: light, light quality, leaf morphology, acclimation.

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.

Palynology and paleoecology of postglacial sediments in an anoxic basin, Saanich Inlet, British Columbia

1983 ◽  
Vol 20 (5) ◽  
pp. 873-885 ◽  
Author(s):  
Linda E. Heusser
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Alnus Rubra ◽  
Red Cedar ◽  
Saanich Inlet ◽  
Anoxic Basin

Varved, black clayey silts deposited in the marine waters of Saanich Inlet yield unusually abundant and diverse pollen assemblages derived from the coastal Douglas-fir (Pseudotsuga) and western hemlock (Tsuga heterophylla) forests of southwestern British Columbia. The 12 000 year palynological record chronicles the development of vegetation since ice left Saanich Inlet: the succession of pine (Pinus contorta) and alder (Alnus rubra) woodlands by forests characterized by Douglas-fir and oak (Quercus) and later by western hemlock and red cedar (Thuja plicata). Rapid deposition of annual layers of pollen, charcoal, and other terrigenous particles provides detailed evidence of changes in land use during the past few hundred years: settlement, logging, farming, and urbanization. Vegetational and climatic changes inferred from pollen spectra in the marine sediments of Saanich Inlet compare favorably with changes inferred from correlative pollen assemblages previously described from adjacent parts of Vancouver Island and the Fraser River valley.

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.

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