Effects of stand and site characteristics on susceptibility and vulnerability of balsam fir and spruce to spruce budworm in New Brunswick

1997 ◽  
Vol 27 (11) ◽  
pp. 1859-1871 ◽  
Author(s):  
David A MacLean ◽  
Wayne E MacKinnon
Keyword(s):  
New Brunswick ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Site Characteristics

The influence of hardwood content on balsam fir defoliation by spruce budworm

1996 ◽  
Vol 26 (9) ◽  
pp. 1620-1628 ◽  
Author(s):  
Qiong Su ◽  
Ted D. Needham ◽  
David A. MacLean
Keyword(s):  
New Brunswick ◽  
Natural Enemies ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Generalized Model ◽  
Stand Management ◽  
Working Hypothesis ◽  
Model Combining

Changing stand composition by increasing hardwood content has been suggested as a long-term method for reducing susceptibility and vulnerability of balsam fir (Abiesbalsamea (L.) Mill.) to spruce budworm (Choristoneurafumiferana (Clem.)). Twenty-five mixed balsam fir–hardwood stands were selected in northern New Brunswick, with five stands in each 20% hardwood class (0–20, 21–40%, etc.). Defoliation each year from 1989 to 1993 was significantly (p < 0.0001) related to hardwood content, with r2 ranging from 0.57 to 0.81. As hardwood content increased, defoliation of balsam fir decreased. From 1989 to 1992, the years of moderate to severe defoliation, balsam fir stands with <40% hardwoods sustained 58–71% defoliation, on average, versus 12–15% defoliation in stands with >80% hardwood. A generalized model combining hardwood content and the estimated defoliation in pure softwood stands in a given year explained 77% of the variation in defoliation over stands and years. This study indicated that mixed balsam fir–hardwood stand management, with hardwood content >40%, could substantially reduce losses during spruce budworm outbreaks. Further research is warranted to elucidate the mechanism involved, but our working hypothesis is that greater hardwood content increased the diversity or populations of natural enemies such as birds and parasitoids.

Windthrow and growth response following a spruce budworm inspired, variable retention harvest in New Brunswick, Canada

2015 ◽  
Vol 45 (6) ◽  
pp. 659-666 ◽  
Author(s):  
Edward A. Wilson ◽  
David A. MacLean
Keyword(s):  
New Brunswick ◽  
Growth Response ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Natural Disturbance ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Growth Release ◽  
Variable Retention ◽  
Variable Retention Harvest

Forest management regimes increasingly focus on the emulation of natural disturbance events, e.g., fire or insect outbreaks, to help increase ecosystem sustainability. We determined the residual stand response to a variable retention harvest inspired by spruce budworm (Choristoneura fumiferana (Clemens)) outbreaks in New Brunswick, Canada. Our objectives were to analyze the differences between surviving residual trees and those that succumbed to windthrow and to quantify growth release. The treatment was based on harvesting the estimated spruce budworm outbreak mortality, i.e., 90% of mature balsam fir (Abies balsamea (L.) Mill., 60% of mature spruce (Picea spp.), and no hardwoods. Windthrow increased with the proportion of trees harvested and averaged 52% over 7–9 years in these stands with high balsam fir – spruce content. One-third of 42 harvested plots sustained >30% windthrow, whereas 73% of 11 similar unharvested plots had <10% windthrow. Balsam fir had higher windthrow than spruce at 53% and 41%, respectively. Windthrown balsam fir trees had significantly larger diameters at breast height (DBH, 1.3 m), larger heights, and smaller crown ratios than surviving residual trees. Substantial growth release occurred, with DBH increment of residual trees 48%–64% greater than trees in unharvested plots. Balsam fir and intolerant hardwoods exhibited the largest growth response. We suggest that future spruce budworm inspired harvests in stands with high balsam fir – spruce content use two or three entries about 5 years apart to reduce windthrow.

Accuracy of aerial sketch-mapping estimates of spruce budworm defoliation in New Brunswick

1996 ◽  
Vol 26 (12) ◽  
pp. 2099-2108 ◽  
Author(s):  
David A. MacLean ◽  
Wayne E. MacKinnon
Keyword(s):  
Decision Support ◽  
New Brunswick ◽  
Decision Support Systems ◽  
Tree Mortality ◽  
Support Systems ◽  
Spruce Budworm ◽  
Weather Conditions ◽  
Balsam Fir ◽  
Small Aircraft

The accuracy of aerial sketch-mapping estimates of spruce budworm (Choristoneurafumiferana (Clem.)) defoliation was evaluated from 1984 to 1993 in 222–325 sample plots in spruce (Picea sp.)–balsam fir (Abiesbalsamea (L.) Mill.) stands in New Brunswick. Operational aerial defoliation estimates were used, wherein all productive forest in known budworm infestation zones was surveyed each year from small aircraft with flight lines 2–5 km apart, and rated in classes of nil (0–10%), light (11–30%), moderate (31–70%), and severe (71–100%). Aerial defoliation estimates were compared with ground-based binocular estimates of current defoliation for an average of 10 trees/plot (range 5–20). Overall, 56% of plots were correctly rated by aerial sketch mapping in four classes (nil, light, moderate, and severe), with 37% of the plots underestimated and 7% overestimated. The predominant error (26% of plots) was rating defoliation as nil (0–10%) from the air when it was actually light (11–30%). This error was deemed not important in terms of predicting tree response, since data from the literature indicated that defoliation less than 30% did not cause tree mortality, although if continued, it would reduce growth. Using three defoliation classes (by combining nil and light, 0–30%), 82% of the plots were correctly classified by aerial sketch mapping. The probability of correct aerial classification of defoliation was significantly affected by defoliation class, weather conditions prior to and during observation flights, and the defoliation class × weather interaction. It was concluded that aerial sketch mapping of spruce budworm defoliation is a viable technique that can be used for both surveys and decision support systems that estimate forest response to budworm outbreaks and management activities.

Balsam fir mortality following the last spruce budworm outbreak in northwestern Quebec

1995 ◽  
Vol 25 (8) ◽  
pp. 1375-1384 ◽  
Author(s):  
Yves Bergeron ◽  
Alain Leduc ◽  
Claude Joyal ◽  
Hubert Morin
Keyword(s):  
Stand Structure ◽  
Management Strategies ◽  
Basal Area ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Forest Composition ◽  
Regression Analyses ◽  
Site Characteristics ◽  
Forest Mosaic ◽  
Independent Effects

Balsam fir (Abiesbalsamea (L.) Mill.) mortality caused by the last spruce budworm (Choristoneurafumiferana (Clem.)) outbreak (1970–1987) was studied in 624 sites belonging to a complex natural forest mosaic originating from different fires in northwestern Quebec. Multiple regression analyses were used to assess the respective effects of stand structure, species composition, site characteristics, and the forest composition surrounding the stand on observed stand mortality. Mortality was observed to increase in relation to diameter of the trees, basal area of balsam fir, and the number of stands dominated by conifers in the forest mosaic. All of these factors showed significant independent effects, but 60% of the variance remained unexplained. Site characteristics, however, did not show a significant relationship to stand mortality. The results suggest that forest composition at both the stand and the forest mosaic levels may be responsible for differing degrees of defoliation that result in differences in stand mortality. Forest management strategies that favor the presence of mixed compositions both at the stand level and at the mosaic level may contribute to decreased stand vulnerability.

MORTALITY IN IMMATURE BALSAM FIR FOLLOWING SEVERE BUDWORM DEFOLIATION

1960 ◽  
Vol 36 (4) ◽  
pp. 342-345 ◽  
Author(s):  
G. L. Baskerville
Keyword(s):  
New Brunswick ◽  
Spruce Budworm ◽  
Balsam Fir

In northwestern New Brunswick mortality is being followed in a 40- to 50-year-old stand of fir and spruce which was subjected to severe spruce budworm defoliation from 1951 to 1957. This paper reports some early findings by diameter and dominance classes.

scholarly journals FUNGOUS DETERIORATION OF BALSAM FIR KILLED BY SPRUCE BUDWORM IN NORTHWESTERN NEW BRUNSWICK

1964 ◽  
Vol 40 (4) ◽  
pp. 482-487 ◽  
Author(s):  
M. A. Stillwell ◽  
D. J. Kelly
Keyword(s):  
New Brunswick ◽  
Tree Mortality ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Dead Trees ◽  
One Year ◽  
Different Parts ◽  
Heavy Mortality

The rate of fungous deterioration was determined for 292 balsam fir (Abies balsamea (L.) Mill.) killed by the spruce budworm (Choristoneura fumiferana (Clem.) in an area of heavy tree mortality in northern New Brunswick. Trees dead less than one year and up to seven years were examined. Fifty fir trees dead 0 to 2 years in a light mortality area were also examined. Trees in the heavy mortality area deteriorated much more slowly than those examined by other workers in Ontario. Stereum chailletii (Pers.) Fr. and S. sanguinolentum (Alb. & Schw. ex Fr.) Fr. caused most of the incipient and advanced decay in New Brunswick, whereas S. chailletii caused all the incipient decay in trees dead less than one year in Ontario but was replaced after one year by Polyporus abietinus Dicks, ex Fr. which then caused most of the advanced decay. Advanced decay progressed faster in trees in the light mortality area in New Brunswick than in trees in the heavy mortality area. Nineteen species of basidiomycetes were associated with sapwood decay. Comments concerning the position and frequency of fungous occurrence in the different parts of the tree in relation to the number of years since death are made for eight of the more commonly isolated fungi. The introduction of S. chailletii into living trees by woodwasps and the differences observed in the development of P. abietinus in dead trees in the two regions are discussed.

scholarly journals BIOLOGICAL ASSESSMENT OF AERIAL FOREST SPRAYING AGAINST THE SPRUCE BUDWORM IN NEW BRUNSWICK: 1. TIMING OF OPERATIONS 1952-54

1955 ◽  
Vol 31 (4) ◽  
pp. 342-352 ◽  
Author(s):  
F. E. Webb
Keyword(s):  
New Brunswick ◽  
Field Data ◽  
Tree Mortality ◽  
Feeding Habits ◽  
Spruce Budworm ◽  
Area Coverage ◽  
Balsam Fir ◽  
Biological Assessment ◽  
Aerial Surveys ◽  
Working Out

The aerial spraying operations in New Brunswick against the spruce budworm have involved large areas in which tree mortality was imminent. In working out practical methods of timing applications, consideration has been given to the protection of foliage as well as to the immediate reduction of budworm populations. Modifications in operational techniques to lower spraying costs and increase area coverage have necessitated earlier spraying and lighter dosages. Factors considered in the timing include severity of infestation and defoliation, probable amount of spraying weather available, phenological differences between areas, the feeding habits of the budworm, and the tendency of spray to drift. The assessment of development was accomplished mainly by ground studies at representative locations and extended to the area at large by aerial surveys of balsam fir shoot growth.An analysis is made of spraying effectiveness in relation to timing from field data collected for studying the immediate results. From this, estimates are given of the average number of days during which various levels of rated effectiveness are attainable.

Patterns of balsam fir mortality caused by an uncontrolled spruce budworm outbreak

1989 ◽  
Vol 19 (9) ◽  
pp. 1087-1095 ◽  
Author(s):  
David A. MacLean ◽  
Donald P. Ostaff
Keyword(s):  
Tree Mortality ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Regression Equations ◽  
Cape Breton Island ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Cape Breton ◽  
Dead Trees ◽  
Site Characteristics

Tree mortality caused by spruce budworm (Choristoneurafumiferana (Clem.)) defoliation was assessed annually from 1976 to 1985 in 20 mature balsam fir (Abiesbalsamea (L.) Mill.) stands on Cape Breton Island, Nova Scotia, and was related to defoliation and to tree, stand, and site characteristics. Ten to 12 years after the start of the budworm outbreak, fir mortality averaged 87% of the merchantable volume (range 60–100%) among the stands. Timing of mortality was similar to that found in studies of previous outbreaks. In the first 4 years of the outbreak, virtually all the trees that died had more than 90% cumulative defoliation but, overall, 64, 21, and 14% of the dead trees had cumulative defoliation >90, 76 to 90, and 51 to 75%, respectively. Early in the outbreak, fir mortality was generally negatively correlated with tree vigor, relative crown position, or diameter at breast height, but in later years, trees were killed irrespective of these factors. Fir mortality was evenly distributed among different sized trees, and 73 to 86% of the trees in each 5 cm diameter at breast height class died. A linear regression equation between dead fir volume and total fir volume explained 89% of the variability in mortality among stands. Percent fir mortality was correlated (r = 0.84) with visual estimates of cumulative defoliation (including all age-classes of foliage) in 1981, but mortality was not correlated with cumulative current annual defoliation or with site characteristics. Using regression equations, fir mortality during this budworm outbreak was predicted to within ±6 m2/ha in 14 of 18 (78%) of the stands, with a relative accuracy of 17.7%.

Spruce Budworm Parasite Investigations in the Lower St. Lawrence and Gaspé Regions of Quebec

1960 ◽  
Vol 92 (5) ◽  
pp. 384-396 ◽  
Author(s):  
J. R. Blais
Keyword(s):  
New Brunswick ◽  
Large Scale ◽  
Spruce Budworm ◽  
Weather Conditions ◽  
Balsam Fir ◽  
Population Fluctuations ◽  
Factors Associated ◽  
Outbreak Area ◽  
Biological Studies ◽  
Unfavourable Weather

A spruce budworm outbreak started in Quebec and adjoining parts of New Brunswick in 1949 and spread each year until by 1955 most balsam fir stands within an area of 32,000 square miles were attacked. Approximately 45 per cent of this area was in the Lower St. Lawrence and Gaspe regions of Quebec. In Quebec, important population reductions took place in various sectors of the outbreak area as a result of unfavourable weather conditions in 1956 and 1957 (Blais, 1958a, 1958b), and the final collapse occurred in 1958 when populations returned to the endemic level throughout the area (Blais and Martineau, 1958). In New Brunswick, a relatively small outbreak area remained at the end of the summer in 1958 (Webb et al., 1959). The large-scale aerial applications of DDT begun in New Brunswick in 1952, and in Quebec in 1954, were continued until 1958. Biological studies in connection with the spraying were carried out in both provinces. In Quebec these studies consisted of assessing spruce budworm population fluctuations in both sprayed and unsprayed areas and in determining, where possible, the causes for these fluctuations. All factors associated with changes in population could not be adequately measured over such a large territory, but a real attempt was made to obtain information on parasitism. The present paper deals with this aspect of the studies.

Effectiveness of spruce budworm spraying in New Brunswick in protecting the spruce component of spruce–fir stands

1984 ◽  
Vol 14 (2) ◽  
pp. 163-176 ◽  
Author(s):  
David A. MacLean ◽  
A. Wayne Kline ◽  
Daniel R. Lavigne
Keyword(s):  
New Brunswick ◽  
Tree Mortality ◽  
Black Spruce ◽  
Minor Component ◽  
Spruce Budworm ◽  
Total Sample ◽  
Site Characteristics ◽  
Spruce Stands ◽  
Spruce Mortality ◽  
A Minor

Tree mortality and defoliation were examined in 45 spruce (Picea sp.) stands protected against damage by spruce budworm (Choristoneurafumiferana (Clem.)) and in 27 unprotected spruce stands in New Brunswick, and were related to tree, stand, and site characteristics. The "protected" and "unprotected" classes of stands were defined on the basis of any spraying in the last 5 years (1978–1982), but we also estimated the spray and budworm hazard history from 1973 to 1982 for each stand. Based on this total sample of about 17 000 trees, there was little difference in mortality levels of spruce or combined spruce–fir (Abiesbalsamea (L.) Mill.) between protected and unprotected stands. Spruce mortality was relatively low in both protected and unprotected stands, averaging about 13 and 20% of the total volume, respectively. Fir mortality was higher in unprotected than in protected stands, although fir formed only a minor component of most of the sampled stands. Both average mortality and range were similar among the four spruce types present in New Brunswick: black spruce (Piceamariana (Mill.) B.S.P.), red spruce (Picearubens Sarg.), hybrid red–black spruce, and white spruce (Piceaglauca (Moench) Voss). In examining the relation of tree mortality to stand and site characteristics, the strongest correlations were found between dead spruce–fir volume (cubic metres per hectare) and total stand volume (r = 0.85), and between dead fir volume and total fir volume (r = 0.75). No apparent relationships were observed between mortality levels and various indices of protection and budworm hazard. It should be emphasized in presenting these results that the spray program in New Brunswick has historically been designed to protect fir, so that any protection afforded to spruce would be entirely an incidental benefit from attention to the fir problem. Although our results do not reflect a failure of a clearly defined effort to protect spruce, we do recommend that further protection efforts for spruce in New Brunswick be reevaluated.

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