Douglas-fir height growth affected by western spruce budworm

1983 ◽  
Vol 13 (3) ◽  
pp. 445-450 ◽  
Author(s):  
G. A. Van Sickle ◽  
R.I. Alfaro ◽  
A.J. Thomson
Keyword(s):  
British Columbia ◽  
Recovery Period ◽  
Spruce Budworm ◽  
Site Index ◽  
Height Growth ◽  
Douglas Fir ◽  
Western Spruce Budworm ◽  
Total Height

Detailed dissections of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees repeatedly defoliated by the western spruce budworm (Choristoneuraoccidentalis (Freeman)) in two areas of British Columbia indicated that budworm severely affected height growth. Dissected trees lost an average 7.3 internodes in each infestation, of which 4.2 were destroyed or failed to grow during the budworm feeding and recovery periods, and 3.1 were existing internodes lost to dieback. An average of one internode of subnormal size, produced during the recovery period, was also present. Total height was reduced by 32% (11.4 m) and 19% (5.9 m) in areas that sustained four and two infestations respectively. Budworm infestations lead to an underestimation of the site index for Douglas-fir in the affected areas.

ESTIMATING NUMBER OF WESTERN SPRUCE BUDWORM EGGS FROM EGG MASS MEASUREMENTS IN BRITISH COLUMBIA

1982 ◽  
Vol 114 (7) ◽  
pp. 643-645 ◽  
Author(s):  
J. W. E. Harris ◽  
A. F. Dawson
Keyword(s):  
British Columbia ◽  
Extended Period ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Population Trends ◽  
Egg Mass ◽  
Western Spruce Budworm ◽  
Growth Loss ◽  
Insect Populations ◽  
The Relationship

Western spruce budworm, Choristoneura occidentalis Freeman, periodically attacks Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) in British Columbia, causing mortality, deformity, and growth loss. Insect populations are assessed annually by the Canadian Forestry Service's Forest Insect and Disease Survey, by branch sampling for egg mass densities; predictions of population trends and damage are based on these assessments. Eggs, laid in rows in masses affixed to needles, are a preferred stage to sample because they are easily collected, remain fixed in numbers for an extended period, and precede damage by sufficient time to plan suppression or other programs. Numbers of masses alone, however, may not show population trends accurately as egg numbers per mass varies. Thus it is sometimes necessary to count eggs (Miller 1957), which is a formidable task. Fortunately egg numbers can be estimated from the dimensions of egg masses (Washburn and Brickell 1973). In this study, we determined the relationship between egg numbers and egg mass length and number of rows for samples from Douglas-fir stands frequently affected by spruce budworm throughout British Columbia. Data were collected over 3 years, 1977-79, during which time budworm populations were in a period of decline.

scholarly journals RELATIVE QUALITY OF THE MAJOR FOREST ASSOCIATIONS OF THE SOUTHERN B.C. INTERIOR FOR GROWTH OF LODGEPOLE PINE, ENGELMANN SPRUCE, DOUGLAS-FIR AND ALPINE FIR

1966 ◽  
Vol 42 (3) ◽  
pp. 306-313 ◽  
Author(s):  
Walter Stanek
Keyword(s):  
British Columbia ◽  
Lodgepole Pine ◽  
Site Index ◽  
Height Growth ◽  
Douglas Fir ◽  
Regression Equations ◽  
Common Occurrence ◽  
Engelmann Spruce ◽  
Relative Quality

Height growth of lodgepole pine, Engelmann spruce, Douglas-fir and alpine fir was investigated in the Douglas-fir and Engelmann Spruce-Alpine Fir Zones of the Interior of British Columbia. In the same forest association each species has a characteristic site index at the age of 100 years (SI/100). Regression equations were calculated for predicting SI/100 of several species in different associations. Regression equations were also developed for estimating SI/100 of Engelmann spruce, Douglas-fir and alpine fir from known SI/100 of lodgepole pine. The latter species was selected because of its common occurrence in the two zones. In addition regression equation was calculated for predicting SI/100 of lodgepole pine from known SI/100 of Engelmann spruce. All regression equations apply to naturally established stands in the study area.

scholarly journals Characterization of western spruce budworm outbreak regions in the British Columbia Interior

2018 ◽  
Vol 48 (7) ◽  
pp. 783-802 ◽  
Author(s):  
Lorraine E. Maclauchlan ◽  
Lori D. Daniels ◽  
Janice C. Hodge ◽  
Julie E. Brooks
Keyword(s):  
British Columbia ◽  
Spruce Budworm ◽  
Growth Suppression ◽  
Douglas Fir ◽  
Western North America ◽  
Western Spruce Budworm ◽  
The North ◽  
South Central ◽  
Ecosystem Classification

The western spruce budworm (WSB; Choristoneura freemani Razowski) shapes Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests throughout western North America with periodic, severe landscape-level defoliation events. The largest and most continuous recorded defoliation occurred in the 2000s, largely centered in the Williams Lake and 100 Mile House WSB outbreak regions, peaking in 2007 at 847 000 ha defoliated in British Columbia (B.C.). Unique WSB outbreak regions in south-central B.C. are described using biogeoclimatic ecosystem classification, geography, 106 years of documented defoliation, and 46 stand-level Douglas-fir host tree-ring chronologies. Since the 1980s, recorded defoliation in B.C. has shifted from coastal ecosystems and become a dominant disturbance in drier, colder, interior Douglas-fir ecosystems. Defoliation records demarcate four outbreaks from 1950–2012 and up to three growth suppression events from 1937–2012. Outbreak duration was shorter in the north and far south of B.C., with recovery periods (no trees showing growth suppression) shorter over all WSB outbreak regions in the 2000s, suggesting that trees may be increasingly susceptible to each successive defoliation event. Knowing the regional outbreak periodicity may facilitate early detection of incipient WSB populations, which is critical for management as many of our low-elevation Douglas-fir forests become more stressed with changing and unpredictable climate regimes.

Multicentury history of western spruce budworm outbreaks in interior Douglas-fir forests near Kamloops, British Columbia

2006 ◽  
Vol 36 (7) ◽  
pp. 1758-1769 ◽  
Author(s):  
Rochelle Campbell ◽  
Dan J Smith ◽  
André Arsenault
Keyword(s):  
British Columbia ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Survival Rates ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Western Spruce Budworm ◽  
Air Temperatures ◽  
Forest Sites ◽  
History Of

Western spruce budworm (Choristoneura occidentalis Freeman) is a native defoliator of forests in the interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) forests of British Columbia, Canada. Dendrochronological techniques and the software program OUTBREAK were used to reconstruct a defoliation history of Douglas-fir for 19 forest sites near Kamloops in central British Columbia. By comparing the radial-growth response of ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) with that of Douglas-fir growing in nearby but separate stands, eight western spruce budworm outbreaks over the past 300 years were distinguished. Although there is considerable variation in the timing and duration of these western spruce budworm events at the stand level, synchronous outbreaks have occurred in approximately 30- to 43-year cycles. Spectral analyses of a composite time series from all stands showed similar and consistent intervals between outbreaks. Climatic variation appears to have been important to budworm outbreaks in the 20th century. Notable outbreaks tended to occur during years with average spring air temperatures following winters with less than average precipitation. Based on this finding, it is proposed that with high over-winter survival rates and a longer growing season, the duration of outbreaks may increase in the future.

Western Spruce Budworm Damage to Sprayed and Unsprayed Young Douglas-Fir

1988 ◽  
Vol 3 (2) ◽  
pp. 44-46 ◽  
Author(s):  
Rene I. Alfaro ◽  
Emil Wegwitz
Keyword(s):  
British Columbia ◽  
Regression Model ◽  
Pseudotsuga Menziesii ◽  
Tree Mortality ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Choristoneura Occidentalis ◽  
Western Spruce Budworm

Abstract Defoliation, mortality, and top-kill were measured in 40-year-old, open-grown Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) under attack by the western spruce budworm (Choristoneura occidentalis [Freeman]) in the interior of British Columbia, in control trees and trees treated with ground sprays of the insecticide Sevin. In untreated trees that sustained repeated defoliation of 50 to 90% of the total crown foliage, tree mortality began after four years and had reached 29% after eight years. Thirty-four percent of the survivors in this group suffered top-kill, which averaged 1.0 m at the end of eight years. No mortality and only negligible top-kill occurred in trees, sprayed or not, which sustained less than 50% defoliation. A regression model of the probability of tree mortality based on the defoliation is presented. West. J. Appl. For. 3(2):44-46, April 1988.

scholarly journals Development of Height-Age Models for Estimating Juvenile Height of Coastal Douglas-Fir in British Columbia

2003 ◽  
Vol 18 (3) ◽  
pp. 207-212 ◽  
Author(s):  
Gordon D. Nigh ◽  
Matthew G.E. Mitchell
Keyword(s):  
British Columbia ◽  
Nonlinear Least Squares ◽  
Site Index ◽  
Height Growth ◽  
Douglas Fir ◽  
Growth Patterns ◽  
Least Squares Regression ◽  
Data Set ◽  
Constant Variance ◽  
Power Models

Abstract Douglas-fir (Pseudotsuga menziesii var. menzeisii) is an important and abundant tree species in coastal British Columbia. Juvenile height estimates are important for management prescriptions and decisions involving regenerating stands. We used 100 plots to investigate the juvenile height growth of coastal Douglas-fir. The growth patterns of the sample trees were observed by felling and splitting them longitudinally and measuring the height of the annual nodes from the point of germination. Sixty-four plots were used to develop a height model as a function of total age and site index. The Chapman-Richards, Gompertz, and modified exponential and power models were fit using nonlinear least squares regression. The models were tested with the remaining 36 plots. The modified exponential and power equation was the best fitting of the three models. None of the models met the regression assumption of independently normally distributed residuals with a mean of zero and a constant variance. The modified exponential and power model was further analyzed using the complete data set by fitting height growth and incorporating a model for serial correlation in the error term to improve the statistical properties of the model. West. J. Appl. For. 18(3):207–212.

Estimating Dominant Height and Site Index of Even-Aged Interior Douglas-Fir in British Columbia

1992 ◽  
Vol 7 (1) ◽  
pp. 20-25 ◽  
Author(s):  
James S. Thrower ◽  
James W. Goudie
Keyword(s):  
British Columbia ◽  
Linear Model ◽  
Pseudotsuga Menziesii ◽  
Site Index ◽  
Logistic Function ◽  
Height Growth ◽  
Douglas Fir ◽  
Stem Analysis ◽  
Inland Empire ◽  
Dominant Height

Abstract Height-age and site-index curves were developed from stem analysis of 262 Douglas-fir trees (Pseudotsuga menziesii var. glauca) from 68 plots in the Interior Douglas-fir, Interior Cedar-Hemlock, and Sub-boreal Spruce Biogeoclimatic zones in the interior of British Columbia. Plots ranged in site index from about 8 to 30 m and in age from about 60 to 350 years; however, the analyses were limited to data up to 100 years of age. A conditioned logistic function was selected for predicting height, and a linear model was selected for predicting site index. The curves are similar to those developed in comparable studies in the Inland Empire, but differ substantially from curves developed in British Columbia from temporary sample plots. This study supports previous observations that the pattern of height growth for a given site index varies among ecologically different areas. West. J. Appl. For. 7(1):20-25.

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