Measurement and simulation of dwarf mistletoe infection of second-growth western hemlock on southern Vancouver Island

1982 ◽  
Vol 12 (2) ◽  
pp. 280-291 ◽  
Author(s):  
W. J. Bloomberg ◽  
R. B. Smith
Keyword(s):  
Growth Rate ◽  
Vertical Distribution ◽  
Stand Density ◽  
Tree Height ◽  
Vancouver Island ◽  
Western Hemlock ◽  
Dwarf Mistletoe ◽  
Infection Level ◽  
Infection Age ◽  
Second Growth

Infection of western hemlock (Tsugaheterophylla (Raf.) Sarg.) residual overstory and second-growth understory by hemlock dwarf mistletoe (Arceuthobiumtsugense (Rosendahl) G.N. Jones) was analyzed in seven plots on southern Vancouver Island. The number of infections in residual trees ranged from 373 to 4058 and in second-growth trees from 3 to 455. The number in second-growth trees was significantly correlated positively with dbh and tree height and inversely with height/dbh ratio. The percentage of crown length infected varied significantly among plots and was significantly correlated with the number of infections. Vertical distribution of infections in tree crowns did not conform to test distributions; distribution by infection age approximated the Poisson. The range in infection age varied according to height in green crown and length of green crown infected. Mortality of infections varied significantly among plots and was greatest in lower slope sites and least in a drier upper slope site. Proportion of dead infections was a function of height in crown and total length of green crown infected. Data suggest that infection level in second-growth trees was proportional to the number of residuals and was inversely related to percent nonhost species, stand density, and growth rate. The number of infections predicted by a simulation model averaged 107% of the number recorded in residual trees and 128% in second-growth trees. Curves of predicted vertical distribution of infections in crowns were of the same shape as those recorded in plot sample trees. The predicted average age-class distribution of infections approximated Poisson distribution within the same probability range as recorded in plot sample trees. The predicted average dbh of residual and second-growth trees were 90 and 97%, respectively, of the recorded values; predicted average heights were 115 and 101%, respectively, of recorded values. Infection predicted by the model over a range of hypothetical stand, site, and infection conditions was used to elucidate major epidemiological factors that might bear on silvieultural control. Results confirmed the observed effects of number of residuals, stand composition, growth rate, and stand density on infections.

Wood density of young-growth western hemlock: relation to ring age, radial growth, stand density, and site quality

2004 ◽  
Vol 34 (12) ◽  
pp. 2433-2442 ◽  
Author(s):  
Dean S DeBell ◽  
Ryan Singleton ◽  
Barbara L Gartner ◽  
David D Marshall
Keyword(s):  
Growth Rate ◽  
Wood Density ◽  
Ring Width ◽  
Stand Density ◽  
Age And Growth ◽  
Western Hemlock ◽  
Site Class ◽  
Ring Density ◽  
Wide Range ◽  
Young Growth

Breast-high stem sections were sampled from 56 western hemlock (Tsuga heterophylla (Raf.) Sarg.) trees growing in 15 plots representing a wide range of tree and site conditions in northwestern Oregon. Growth and wood density traits of individual rings were measured via X-ray densitometry, and relationships of ring density and its components to age and growth rate were analyzed. Ring density was highest (0.49 g/cm3) near the pith, declined to 0.40 g/cm3 at age 10, remained stable to about age 25, and then increased gradually and remained between 0.43 and 0.44 g/cm3 from age 38 to 45 and beyond. A negative influence of rapid growth on whole ring density was greatest at young ages and diminished with time, becoming nonsignificant beyond age 30. Earlywood density, latewood density, and latewood proportion were all negatively related to ring width at young ages, but by age 21-25, latewood proportion was the only component of ring density that remained significantly diminished by increased growth rate. Residual differences in wood density (after age and growth rate were considered) did not appear to be related to either stand density or site class. Overall, young-growth hemlock trees are relatively uniform in wood density and likely to be more so if grown in intensively managed stands.

Young-growth western hemlock stand infection by Heterobasidionannosum 11 yearsm after precommercial thinning

1980 ◽  
Vol 10 (3) ◽  
pp. 389-394 ◽  
Author(s):  
T. D. Chavez Jr. ◽  
R. L. Edmonds ◽  
C. H. Driver
Keyword(s):  
Growth Rate ◽  
Radial Growth ◽  
Western Hemlock ◽  
Infection Level ◽  
Precommercial Thinning ◽  
Animal Damage ◽  
Significant Difference ◽  
Young Growth

Infection level and course of spread of Heterobasidionannosum (Fr.) Bref, in a 26-year-old western hemlock(Tsugaheterophylla (Raf.) Sarg.) stand, precommercially thinned 11 years previously, was determined. Impact of infection on height and radial growth of western hemlock was also examined. Tree infection increased from a mean of 8% initially, to an average of 90% in the residual trees. Stump colonization accounted for 61% of the tree infection by H.annosum, with stumps within 61 cm of the remaining trees providing most of the inoculum. The fungus also entered through animal damage wounds. Growth rate of H. annosum was estimated at 75 cm/year with a range of 23–128 cm/year. Although there was no significant difference between infected and uninfected trees in height or radial growth, infected trees had less height and slightly more radial growth than uninfected trees.

Modeling the incidence and severity of hemlock dwarf mistletoe in 110-year-old wind-disturbed forests in Southeast Alaska

1998 ◽  
Vol 28 (10) ◽  
pp. 1501-1508 ◽  
Author(s):  
L M Trummer ◽  
P E Hennon ◽  
E M Hansen ◽  
P S Muir
Keyword(s):  
Basal Area ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Managed Forests ◽  
Coastal Forests ◽  
Dwarf Mistletoe ◽  
Infection Level ◽  
Southeast Alaska ◽  
Preliminary Validation

Amodel was developed to predict the severity of dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones) in western hemlock trees (Tsuga heterophylla (Raf.) Sarg.) that developed within forests of Southeast Alaska that experienced near-catastrophic windthrow in the late 1800s. The model suggests that the degree of dwarf mistletoe severity on western hemlock trees was significantly and positively correlated with levels of dwarf mistletoe infection and basal area (m2/ha) in large and small residual trees that survived the wind disturbance. No significant relationships were found between severity level and any other factors, including site productivity, density of coexisting Sitka spruce (Picea sitchensis (Bong.) Carr.), or slope. The model demonstrates the overriding importance of infected residual trees to predict future severity of dwarf mistletoe; greater size and infection level of residual trees results in greater dwarf mistletoe levels on regenerating hemlock crop trees. The model, derived from 76 plots on Kuiu Island, was tested in 18 plots on Chichagof Island, providing a preliminary validation. Slower rates of dwarf mistletoe spread and intensification in forests of southeastern Alaska, as compared with similar coastal forests south of Alaska, provide an opportunity for managers to manipulate the parasite to desired levels in managed forests.

Western redcedar response to precommercial thinning and fertilization through 25 years posttreatment

2009 ◽  
Vol 39 (3) ◽  
pp. 619-628 ◽  
Author(s):  
Warren D. Devine ◽  
Constance A. Harrington
Keyword(s):  
Growth Rate ◽  
Basal Area ◽  
Tree Height ◽  
Thuja Plicata ◽  
Long Term Effects ◽  
Individual Tree ◽  
Western Redcedar ◽  
Precommercial Thinning ◽  
Second Growth ◽  
Poor Site

There is little information available on the long-term effects of managing western redcedar ( Thuja plicata Donn ex D. Don). In a 15- to 20-year-old naturally regenerated second-growth redcedar stand on a poor site on the Olympic Peninsula of Washington, we tested crop tree (largest 250 trees·ha–1) response to precommercial thinning and fertilization in a replicated study. Fertilization treatments were N or N+P applied at study installation and year 13; precommercial thinning occurred at installation. Precommercial thinning without fertilization produced a sustained increase in periodic individual-tree basal area (BA) growth rate from years 3 through 25 posttreatment. However, through year 12, higher BA growth rates resulted from fertilization. During years 13 through 25, when intraspecific competition increased, the highest BA growth rate resulted from the combination of fertilization and precommercial thinning. Compared with the unthinned–unfertilized control, fertilization without thinning increased year-25 crop-tree height by 34% and BA by 137%; thinning without fertilization increased height by 11% and BA by 91%. Height to live-crown base was decreased by thinning but increased by fertilization, while thinning significantly increased stem taper on the lower bole. Treatment responses and foliar analyses indicate crop tree growth was substantially limited by nutrient availability.

Impact of dwarf mistletoe on the growth of western hemlock trees having different patterns of suppression and release

1985 ◽  
Vol 15 (4) ◽  
pp. 665-668 ◽  
Author(s):  
A. J. Thomson ◽  
R. I. Alfaro ◽  
W. J. Bloomberg ◽  
R. B. Smith
Keyword(s):  
Volume Growth ◽  
Severe Infection ◽  
Vancouver Island ◽  
Western Hemlock ◽  
Dwarf Mistletoe ◽  
Area Sampling ◽  
The Impact ◽  
Site Variability

The impact of dwarf mistletoe on the volume growth of western hemlock was evaluated in trees from five locations on northeast Vancouver Island. Within each area, sampling was designed to minimize the effects of site variability. However, differences in age and in patterns of suppression and release between infection classes were observed in some stands. Growth was corrected for these differences by subtracting the suppression core and by making comparisons at equivalent ages. Volume losses associated with dwarf mistletoe infection were higher than reported in our previous studies in other areas, averaging 23 and 39% with moderate and severe infection levels, respectively.

Mass and nutrient content of woody debris and forest floor in western red cedar and western hemlock forests on northern Vancouver Island

1993 ◽  
Vol 23 (6) ◽  
pp. 1052-1059 ◽  
Author(s):  
Rodney J. Keenan ◽  
Cindy E. Prescott ◽  
J.P. Hamish Kimmins
Keyword(s):  
Forest Floor ◽  
Forest Type ◽  
Woody Debris ◽  
Nutrient Content ◽  
Vancouver Island ◽  
Western Hemlock ◽  
N Availability ◽  
Red Cedar ◽  
The Mean ◽  
Western Red Cedar

Biomass and C, N, P, and K contents of woody debris and the forest floor were surveyed in adjacent stands of old-growth western red cedar (Thujaplicata Donn)–western hemlock (Tsugaheterophylla (Raf.) Sarg.) (CH type), and 85-year-old, windstorm-derived, second-growth western hemlock–amabilis fir (Abiesamabilis (Dougl.) Forbes) (HA type) at three sites on northern Vancouver Island. Carbon concentrations were relatively constant across all detrital categories (mean = 556.8 mg/g); concentrations of N and P generally increased, and K generally decreased, with increasing degree of decomposition. The mean mass of woody debris was 363 Mg/ha in the CH and 226 Mg/ha in the HA type. The mean forest floor mass was 280 Mg/ha in the CH and 211 Mg/ha in the HA stands. Approximately 60% of the forest floor mass in each forest type was decaying wood. Dead woody material above and within the forest floor represented a significant store of biomass and nutrients in both forest types, containing 82% of the aboveground detrital biomass, 51–59% of the N, and 58–61% of the detrital P. Forest floors in the CH and HA types contained similar total quantities of N, suggesting that the lower N availability in CH forests is not caused by greater immobilization in detritus. The large accumulation of forest floor and woody debris in this region is attributed to slow decomposition in the cool, wet climate, high rates of detrital input following windstorms, and the large size and decay resistance of western red cedar boles.

Streamflow nitrogen loss following forest fertilization in a southern Vancouver Island watershed

1985 ◽  
Vol 15 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Eugene D. Hetherington
Keyword(s):  
Water Quality ◽  
Nitrogen Loss ◽  
Vancouver Island ◽  
Soil Permeability ◽  
Creek Watershed ◽  
Second Growth ◽  
Nitrogen Concentrations ◽  
Steep Slopes ◽  
Fall Application ◽  
Small Tributary

Water quality was monitored in the Lens Creek watershed on southern Vancouver Island to determine nitrogen loss following fall application of 224 kg N/ha urea fertilizer on a second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forest. Peak nitrogen concentrations measured in two small tributary streams were 14 mg/L as urea, 1.9 mg/L as ammonia, and 9.3 mg/L as nitrate. For the first 14 months, estimated nitrogen outputs in excess of background amounts were 5.9 and 14.5% of the total applied nitrogen for the two subsidiary watersheds with 46 and 80% of their drainage areas fertilized, respectively. These losses were considerably higher than amounts of less than 1% previously reported for western North America. Increased levels of urea N and ammonia N were short-lived, while nitrate N remained above background levels for the study duration. Reasons for the high nitrogen loss include nitrification of the urea during 7 weeks of mild, dry weather following fertilization, presence of alder and swampy areas adjacent to the streams, high soil permeability, steep slopes, and abundant, above average early winter rainfall. The watersheds had been previously fertilized, but any influence of this first fertilization on nitrogen loss during the present study is unknown. Lens Creek water quality was not adversely affected by the fertilization in terms of drinking water standards or toxicity to fish.

ECR Plasma Oxidation: Dependence on Energy of Argon Ion

1999 ◽  
Vol 585 ◽  
Author(s):  
S. Matsuo ◽  
M. Yamamoto ◽  
T. Sadoh ◽  
T. Tsurushima ◽  
D. W. Gao ◽  
...  
Keyword(s):  
Growth Rate ◽  
Flow Rate ◽  
Microwave Power ◽  
Electron Cyclotron Resonance ◽  
Ion Irradiation ◽  
Oxide Films ◽  
Ecr Plasma ◽  
Second Growth ◽  
Argon Ions ◽  
Argon Ion

AbstractEffects of ion-irradiation on oxidation of silicon at low temperatures (130°C) in an argon and oxygen mixed plasma excited by electron cyclotron resonance (ECR) interaction are investigated. First, dependence of energy and flux of incident ions on the flow rate and the microwave power is evaluated. It is shown that the flow rate and the microwave power are key parameters for controlling the energy and the flux of incident ions, respectively. Second, growth kinetics of the oxide films are studied. The growth rate depends on the energy and the flux of argon ions irradiated to the substrate, and the growth thickness increases proportionally to the root square of the oxidation time. Thus, the growth rate is limited by diffusion of oxidants enhanced by irradiation with argon ions. The effect of substrate bias on oxidation characteristics is also discussed. The electrical properties of the oxide films are improved by increasing the bias. The improvement is due to the reduction of damage at the surface of the substrate induced by the irradiation.

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