Growth and foliar nutrition of juvenile western hemlock and western redcedar plantations on low- and medium-productivity sites on northern Vancouver Island: response to fertilization and planting density

2007 ◽  
Vol 37 (12) ◽  
pp. 2587-2599 ◽  
Author(s):  
R. W. Negrave ◽  
C. E. Prescott ◽  
J. E. Barker
Keyword(s):  
Volume Growth ◽  
Western Hemlock ◽  
Planting Density ◽  
Stem Volume ◽  
Thuja Plicata ◽  
Limiting Factor ◽  
Western Redcedar ◽  
Stand Volume ◽  
Reduced Height ◽  
Volume Increment

A factorial trial was established to examine the effects of planting density and fertilization on the growth of western redcedar ( Thuja plicata Donn ex D. Don) and western hemlock ( Tsuga heterophylla (Raf.) Sarg.) on nutrient-poor (CH) sites and nutrient-medium (HA) sites. Two levels of NPK fertilization were crossed with three levels of planting density (500, 1500, and 2500 stems/ha). Fifteen years after establishment and 10 years after the last fertilizer application, height, individual stem volume increment, stand volume, 5 year periodic annual increment (PAI), and 5 year periodic height increment were all increased by fertilization. Fertilization of CH sites increased annual stand volume increment by 753%–2552% and 122%–209% for hemlock and cedar, respectively; fertilization of HA sites increased PAI by 94%–264%. Volume growth response to fertilization was greater on HA than on CH sites. Increasing stand density reduced height growth on CH sites but not on HA sites. These results suggest that competition for nutrients can be a significant growth-limiting factor even before canopy closure occurs and that treatment of ericaceous sites may not be justified by productivity increases.

Old-Growth Douglas-Fir and Western Hemlock: A 36-Year Record of Growth and Mortality

1987 ◽  
Vol 2 (4) ◽  
pp. 111-114 ◽  
Author(s):  
Dean S. DeBell ◽  
Jerry F. Franklin
Keyword(s):  
Volume Growth ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Silver Fir ◽  
Pinus Monticola ◽  
White Pine ◽  
Old Growth ◽  
Stand Volume

Abstract Growth and mortality were measured at 6-year intervals in a 1,180-acre old-growth stand in southwestern Washington. Principal tree species were Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), Pacific silver fir (Abies amabilis), western redcedar (Thuja plicata), and western white pine (Pinus monticola). They composed 59, 27, 6, 6, and 1%, respectively, of the total cubic volume (13,290 ft³) in 1947. Gross volume growth averaged 94 ft³ per acre per year, and mortality averaged 86 ft³ per acre per year. Net growth was therefore minimal, and total stand volume remained nearly constant for 36 years. Douglas-fir, which accounted for only one-third of the gross growth and nearly one-half of the mortality, is losing dominance to western hemlock, which provided nearly one-half the gross growth and only 28% of the mortality. Pacific silver fir increased in importance in the lower canopy and composed 60% of the in-growth. Thus, although net gain in timber volume was nil, substantial changes occurred in stand characteristics during the 1947-1983 period. West. J. Appl. For. 2(4):111-114, October 1987.

Ectomycorrhizal mushroom response to partial cutting in a western hemlock - western redcedar forest

2001 ◽  
Vol 31 (6) ◽  
pp. 978-987 ◽  
Author(s):  
J M Kranabetter ◽  
P Kroeger
Keyword(s):  
Stand Structure ◽  
Basal Area ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Soil Conditions ◽  
Taxon Richness ◽  
Partial Cutting ◽  
Western Redcedar ◽  
Significant Block

We examined epigeous ectomycorrhizal mushroom richness and productivity after partial cutting in a western hemlock (Tsuga heterophylla (Raf.) Sarg.) - western redcedar (Thuja plicata Donn ex D. Don in Lamb.) forest of northwestern British Columbia. Mushrooms were collected throughout the fruiting season (July to October) for 3 years, starting 5 years after partial cutting, from plots with mesic soil conditions and residual basal areas ranging from 23 to 69 m2/ha for western hemlock and 0 to 26 m2/ha for western redcedar. Partial cutting had no apparent effect on mushroom phenology over the 3 years. Significant block interactions demonstrated that reductions in basal area of western hemlock could lead to positive, neutral, and negative responses in mushroom richness, biomass, and number of fruiting bodies. These responses were related to stand structure and the potential differences in tree vigour after partial cutting. In addition, there was weak evidence that western redcedar, a host for vesicular-arbuscular mycorrhiza, had a negative effect on average taxon richness. The study demonstrated that partial-cutting systems could allow some timber removal without necessarily reducing ectomycorrhizal mushroom communities.

Five-year growth responses of Douglas-fir, western hemlock, and western redcedar seedlings to manipulated levels of overstory and understory competition

2006 ◽  
Vol 36 (10) ◽  
pp. 2439-2453 ◽  
Author(s):  
Timothy B Harrington
Keyword(s):  
Growth Rate ◽  
Nitrogen Content ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Volume Index ◽  
Stem Volume ◽  
Western Redcedar ◽  
Foliar Nitrogen ◽  
Relative Growth ◽  
Vegetation Control

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western redcedar (Thuja plicata Donn ex D. Don) seedlings were planted in March 2001 within three clearcut-harvested, shelterwood, or thinned stands of mature Douglas-fir near Olympia, Washington. From 2002 to 2005, areas of vegetation control of 0, 4.5, or 9 m2 were maintained with herbicides around a total 162 seedlings per species. Photosynthetically active radiation (PAR) was 34%, 62%, and 100% of full sunlight in thinned stands, shelterwoods, and clearcuts, respectively. Effects of overstory level and vegetation control on seedling growth and resource availability generally were additive. Seedling stem volume index in clearcuts averaged four to eight times that observed in thinned stands, and with vegetation control, it averaged two to four times that observed without it. In thinned stands, relative growth rate of seedling stem volume index had a positive linear relationship with PAR (R2 = 0.38). Foliar nitrogen content of Douglas-fir explained 71% of the variation in relative growth rate. Factors explaining the most variation in foliar nitrogen content differed between thinned stands (PAR, R2 = 0.34) and clearcuts or shelterwoods (midday water potential, R2 = 0.63), suggesting that light and root competition, respectively, were the primary growth-limiting factors for these overstory levels.

Ionic balance and organic acids in western redcedar, western hemlock, and Douglas-fir seedlings grown in low- and high-N soils

1999 ◽  
Vol 29 (6) ◽  
pp. 669-678 ◽  
Author(s):  
J E Graff, Jr. ◽  
R K Hermann ◽  
J B Zaerr
Keyword(s):  
Organic Acids ◽  
Quinic Acid ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
N Availability ◽  
Ionic Balance ◽  
Total N ◽  
Western Redcedar

Seedlings of western redcedar (Thuja plicata Donn ex. D. Don), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were transplanted into soils with low and high levels of available NO3-(and total N). Current-year foliage was sampled after 10 weeks to determine the effect of N availability on foliar cation-anion balance (C-A) and the concentrations of low molecular weight organic acids of the three species. Carboxylate concentrations were estimated by using the difference between sums of cations and anions (C-A): 750 mequiv.·kg-1for western redcedar, 351 mequiv.·kg-1for western hemlock, and 266 mequiv.·kg-1for Douglas-fir. Quinic acid was a primary constituent, accounting for 40% of the total for western redcedar and 75% for western hemlock and Douglas-fir. Oxalic acid was present in greatest concentration in the foliage of western redcedar (65 mequiv.·kg-1) but was a minor constituent in western hemlock and Douglas-fir. The quantified acids accounted for only 15% of the C-A of western redcedar but >80% of the C-A of western hemlock and Douglas-fir. A considerable portion of the C-A balance not accounted for in redcedar may be associated with the accumulation of CaCO3. Litterfall deposition of CaCO3may lead to the consumption of H+ions and enrichment of exchangeable soil Ca in the rooting zone of long-lived western redcedar trees. No statistically significant differences among the soils were detected with regard to C-A or the concentration of organic acids.

Stand development following precommercial thinning and fertilization treatments in a western redcedar (Thuja plicata) dominated forest

2011 ◽  
Vol 41 (1) ◽  
pp. 151-164 ◽  
Author(s):  
Constance A. Harrington ◽  
Warren D. Devine
Keyword(s):  
Volume Growth ◽  
Basal Area ◽  
Site Quality ◽  
Thuja Plicata ◽  
Nitrogen And Phosphorus ◽  
Western Redcedar ◽  
Large Trees ◽  
Wide Range ◽  
Individual Trees ◽  
Area And Volume

Western redcedar (Thuja plicata Donn ex D. Don.) is an important North American tree species, but little information is available on its long-term responses to silvicultural treatments. Stand responses (mortality, ingrowth, basal area and volume growth, and distributions of trees by diameter and height classes) were followed for 25 years after thinning and fertilization treatments (alone and in combination) were applied to a naturally regenerated, low site quality western redcedar stand on the Olympic Peninsula in western Washington, USA. Mortality was low overall, but the densest stands experienced competition-related mortality. Thinning resulted in additional stem recruitment; after 25 years, the number of ingrowth trees exceeded the number of trees in the cohort left after thinning. Fertilization (with nitrogen and phosphorus) flattened size distributions and skewed them to larger size classes. Thinning plus fertilization resulted in the largest individual trees and the most large trees, but also many trees in a wide range of diameter classes. The recruitment of a second cohort did not result in a two-storied stand. Fertilization without thinning resulted in the greatest stand basal area and volume, as well as trees with fewer live lower branches.

scholarly journals Western redcedar population dynamics in old-growth forests: Contrasting ecological paradigms using tree rings

2003 ◽  
Vol 79 (3) ◽  
pp. 517-530 ◽  
Author(s):  
Lori D Daniels
Keyword(s):  
British Columbia ◽  
Population Dynamics ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Silver Fir ◽  
Old Growth ◽  
Western Redcedar ◽  
Old Growth Forests ◽  
Gap Phase ◽  
Coastal British Columbia

In coastal British Columbia, late-successional forests dominated by western redcedar (Thuja plicata Donn ex D. Don) are structurally complex, with deep multi-layered canopies, large trees that are > 250 years old, and abundant coarse woody debris (CWD). These forests are presumed to be "old-growth" forests in which fine-scale gaps are the dominant disturbance regime, accounting for their structural diversity. In this study, I have used tree-ring analyses to investigate western redcedar regeneration dynamics in these old-growth forests. Western redcedar dominates canopies of many stands, but is rare in the understorey although it tolerates shade. The traditional interpretation is that western redcedar depends on catastrophic disturbance to regenerate and that it is replaced through succession by western hemlock (Tsuga heterophylla (Raf.) Sarg.) and Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes), which are abundant in the understorey. Dominant trees are perceived to represent an even-aged, post-disturbance cohort and the lack of regeneration indicates a population decline in the absence of catastrophic disturbances. In this paper, I investigate four assumptions underlying this interpretation: (1) Tree size indicates age. (2) Populations establish as even-aged, post-disturbance cohorts. (3) Abundant CWD represents recent mortality. (4) Regeneration is insufficient to maintain canopy dominance. Using tree-ring evidence, I show that population dynamics of western redcedar are a combination of gap-phase establishment and a continuous mode of recruitment from the sub-canopy to the canopy. Specifically, size is a poor surrogate for tree age. Age distributions from 15 sites revealed uneven-aged populations, rather than single post-disturbance cohorts. Both logs and snags of western redcedar may persist more than 270 years; they do not represent recent mortality that is disproportionate to the number of live western redcedar in canopy. The regeneration niches of western redcedar and western hemlock overlap. For both species, gap-phase disturbances result in substrate suitable for successful seedling establishment. Preliminary results from dendroecological analysis of radial growth rates of trees in the subcanopy and canopy strata suggest that western hemlock and Pacific silver fir depend on gaps to recruit to the upper canopy, but recruitment of western redcedar may be independent of canopy gaps. I propose that differences in mode of recruitment to the canopy may explain the differences in population structures between western redcedar, western hemlock, and Pacific silver fir in the old-growth forest. These results provide an ecological precedent for use of a range of silvicultural systems, including clearcuts through single-tree harvesting and protection forests, when managing western redcedar in coastal British Columbia. Key words: Coastal British Columbia, disturbance regimes, regeneration dynamics, Thuja plicata, variable retention silviculture

Overturning resistance of western redcedar and western hemlock in mixed-species stands in coastal British Columbia

2007 ◽  
Vol 37 (5) ◽  
pp. 931-939 ◽  
Author(s):  
Kenneth E. Byrne ◽  
Stephen J. Mitchell
Keyword(s):  
British Columbia ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Specific Information ◽  
Mixed Species ◽  
Stem Form ◽  
Western Redcedar ◽  
Applied Forces ◽  
Coastal British Columbia

Specific information about the applied forces that cause trees to fail is required to validate mechanistic models of windthrow in different forest types. Static tree-pulling tests were conducted to examine the overturning resistance of western redcedar ( Thuja plicata Donn ex D. Don) and western hemlock ( Tsuga heterophylla (Raf.) Sarg.) in a mixed species second-growth stand in coastal British Columbia. Although widely used, tree-pulling techniques are not standardized. Data from three inclinometers were used to estimate stem deflection, which was found to increase with tree slenderness. Differing methods of fitting stem curvature had a small effect on estimates of self-loading at failure. The distance of the pivot point from the centre of the stem base increased with tree diameter. Accounting for the correct self-loading at failure produced a small difference in the overall turning moment regressions but did not improve the fit of these regressions. However, this difference increased with tree size and warrants consideration in future tree-pulling tests with large or plate-rooted trees. The stem mass – overturning resistance relationship had the best fit and was not significantly different for these species in spite of their differences in wood density and stem form.

Influence of millipedes on litter decomposition, N mineralization, and microbial communities in a coastal forest in British Columbia, Canada

2000 ◽  
Vol 30 (5) ◽  
pp. 817-826 ◽  
Author(s):  
H A Cárcamo ◽  
T A Abe ◽  
C E Prescott ◽  
F B Holl ◽  
C P Chanway
Keyword(s):  
Litter Decomposition ◽  
N Mineralization ◽  
Sitka Spruce ◽  
Douglas Fir ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Thuja Plicata ◽  
Coastal Forests ◽  
Western Redcedar ◽  
Litter Consumption

Laboratory experiments were conducted with the millipede Harpaphe haydeniana haydeniana Wood (Polydesmida: Xystodesmidae) to determine (i) its litter feeding preferences, (ii) rates of leaf litter consumption, (iii) feeding effects on available nitrogen, and (iv) functional microbial diversity. The millipede exhibited a preference for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and, to a lesser extent, Sitka spruce (Picea sitchensis (Bong.) Carrière) litter compared with western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata Donn ex D. Don) litter when given a choice. When only one litter type was provided, millipedes consumed considerably more western redcedar than Douglas-fir, Sitka spruce, or western hemlock. Among the six broadleaf species tested, paper birch (Betula papyrifera Marsh.), bigleaf maple (Acer macrophyllum Pursh), vine maple (Acer circinatum Pursh), and red alder (Alnus rubra Bong.) were consumed at much higher rates than swordfern (Polystichum munitum (Kaulf.) Presl.) or salal (Gaultheria shallon Pursh). Daily rates of conifer litter consumption ranged between 10 and 20% of the millipede's fresh biomass and may translate to 36% of the annual litter fall. Our results suggest that transformation of conifer litter into millipede frass can increase rates of litter decomposition and N mineralization, as well as influence microbial activity and diversity in coastal forests.

Spacing and provenance effects on the performance of shore pine (Pinus contorta var. contorta): 20-year test results

1995 ◽  
Vol 25 (4) ◽  
pp. 567-576 ◽  
Author(s):  
C.Y. Xie ◽  
C.C. Ying ◽  
W.D. Johnstone
Keyword(s):  
Pinus Contorta ◽  
Volume Growth ◽  
Height Growth ◽  
Planting Density ◽  
Stem Volume ◽  
Diameter Growth ◽  
Test Results ◽  
Seed Sources ◽  
Rate Of Increase ◽  
Shore Pine

Spacing and provenance effects on the performance of shore pine (Pinuscontorta var. contorta) at a frost-prone site in coastal British Columbia were investigated with respect to mortality, growth, stem defects, and disease and insect damages in a trial with six seed sources that were assigned to seven spacing regimes from 749 to 2990 stems per hectare. Twenty-year test results indicate that mortality was low (2.3% on average) and not significantly influenced by spacing. However, spacing effects on the other traits were significant. Increasing planting density reduced the proportion of stem defected and disease- and insect-damaged trees, slowed diameter and stem volume growth of individuals, and stimulated height growth. Height growth responded to planting density earlier than diameter growth, but diameter growth became more affected as trees grew. The total volume per hectare increases with planting density, but the rate of increase declined as the test proceeded. Response to planting density was homogeneous among provenances with respect to all the traits investigated. However, large and significant regional and provenance differences in mortality, growth, and disease and insect susceptibility were detected. Northern and outer coast provenances demonstrated higher mortality, slower growth, and larger proportions of disease- and insect-damaged trees. Clearly, determining appropriate spacing levels and selecting suitable seed sources are both important for the success of reforestation with shore pine at difficult sites.

Above-ground biomass predicts growth limitation in amabilis fir and western hemlock seedlings

2003 ◽  
Vol 79 (2) ◽  
pp. 285-290 ◽  
Author(s):  
Alan K Mitchell ◽  
B Glen Dunsworth ◽  
Tom Bown ◽  
Jonathan A Moran
Keyword(s):  
Nitrogen Concentration ◽  
Volume Growth ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Stem Volume ◽  
Above Ground Biomass ◽  
Growth Limitation ◽  
Foliar Nitrogen ◽  
Abies Amabilis ◽  
Ground Biomass

Conifer regeneration on clearcut montane sites is frequently affected by post-planting growth stagnation. The ability to predict such stagnation would be a valuable asset to forest managers. In this study, we tested the usefulness of above-ground biomass and photosynthetic efficiency (as estimated by foliar nitrogen concentration) in diagnosing growth limitations in western hemlock (Tsuga heterophylla) and amabilis fir (Abies amabilis). Seedlings were grown under different silvicultural systems (clearcut, patch cut, green tree retention and shelterwood) and post-planting treatments (fertilization, vegetation removal) at the Montane Alternative Silvicultural Systems (MASS) site on Vancouver Island, BC. Foliar nitrogen was found to be a poor predictor of height and stem volume growth. However, above-ground biomass predicted current height and stem volume (year 3 after planting), as well as future stem volume (year 7 after planting), in both species. Above-ground biomass therefore represents a useful measure of likely future growth performance, and may provide early warning of incipient growth stagnation in these species. Key words: amabilis fir, Abies amabilis, biomass, western hemlock, Tsuga heterophylla, growth limitation, photosynthetic capacity, biomass, seedling growth, regeneration

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