The impact of balsam woolly aphid damage on balsam fir stands in Newfoundland: discussion

1976 ◽  
Vol 6 (4) ◽  
pp. 557-558 ◽  
Author(s):  
D. G. Bryant
Keyword(s):  
1975 ◽  
Vol 5 (2) ◽  
pp. 195-209 ◽  
Author(s):  
G. Page

This paper presents data on the effects of balsam woolly aphid damage on the mensurational characteristics of balsam fir trees and stands, and quantitative estimates of changes in merchantable volumes that result from alterations in these characteristics. Average volume losses in damaged semi-mature and mature stands ranged from 2 to 6%, but were as high as 80% or more in a few highly susceptible stands. Strong and consistent relationships were recorded between the incidence and severity of aphid damage and a number of site and stand characteristics, including elevation, soil-moisture regime, stand height and age, balsam fir content and total balsam fir basal area of affected stands, and length of time damage had been present. These relationships were utilized to construct a hazard-rating system for use by forest managers in identifying sites and stands highly susceptible to severe damage, and in scheduling silvicultural control measures.


1990 ◽  
Vol 68 (11) ◽  
pp. 2235-2242 ◽  
Author(s):  
Rhonda L. Millikin

The impact of fenitrothion on the arthropod food of songbirds was measured using white birch (Betula papyrifera Marsh.) and balsam fir (Abies balsamea (L.) Mill.) branch sample and drop trays. Following ground application of fenitrothion at 293 g active ingredient/ha, there was a significant decrease in the biomass of arthropods as determined using branch samples from both tree species, but not until 5 days after the application (29% reduction for balsam fir, 35% for white birch). Samples from drop trays indicated an immediate kill of arthropods not associated with the tree. Most remaining arthropods on treated balsam fir trees were dead. These dead arthropods would not be suitable food for birds that require movement to detect their prey. There was no significant relationship between amount of deposit (treated trees only) and the reduction of arthropods for either tree species.


1998 ◽  
Vol 28 (5) ◽  
pp. 703-710 ◽  
Author(s):  
Erhard John Dobesberger

A stochastic simulation model was developed to derive a damage function for the spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), and balsam fir, Abies balsamea (L.) Mill., herbivore interaction at the stand level for open-grown trees. Both aggregated and uniform models of attack pattern by late-instar larvae based on k of the negative binomial were evaluated to determine the impact of larval density and attack pattern on the loss in stemwood volume increment of young, thinned balsam fir stands in Newfoundland. Percentage loss in stemwood increment was a nonlinear, negative exponential function of initial larval density. Implementation of control measures to prevent 50% defoliation that is caused by about 14 larvae/branch tip would result in saving 24% of the annual stemwood increment after 1 year of defoliation and about 32% after 2 years of cumulative defoliation. Aggregation of spruce budworm larvae among trees within a forest stand results in less growth loss compared with a uniform pattern of attack. The nonlinear damage function may suggest tolerance and possibly compensatory growth after herbivory by low population levels of the spruce budworm.


1976 ◽  
Vol 108 (10) ◽  
pp. 1097-1111 ◽  
Author(s):  
D. G. Bryant

AbstractOver 95% of feeding balsam woolly aphids occur in crevices on balsam fir branches and the highest density occurs within the 3-year tip of branches. The crevices occur under the bud scales at nodes, the base of each season’s growth, and among staminate flower buds or among and within flower bracts. The abundance and survival of aphids as well as mortality factors vary with the location of the nodes in a branch, the type of branch, and aphid generation. The significant differences show that there are 9 to 13 strata within the 3-year tip of a branch. For ecological studies and measuring population levels, the cluster of aphids within a defined crevice, for example under the bud scale at the base of a cluster of shoots, can be selected as a sample unit.


2000 ◽  
Vol 76 (4) ◽  
pp. 653-663 ◽  
Author(s):  
Vincent Laflèche ◽  
Jean-Claude Ruel ◽  
Louis Archambault

The effect of careful logging to preserve advance growth was studied in mixedwood stands of the balsam fir (Abies balsamea (L.) Mill.) - yellow birch (Betula alleghaniensis Britton) eco-climatic domain in eastern Quebec, Canada. The study is based on 19 sites harvested five years earlier. In each cutover, 50 sample plots have been established to quantify the abundance of regeneration five years after logging. This cutting method proved to be ineffective in limiting the invasion of competiting species such as mountain maple (Acer spicatum Lam.) and pin cherry (Prunus pensylvanica (L.), which fully occupied the sites with 25 092 and 5619 stems ha−1 respectively. Balsam fir was abundant after five years in the study area with 13 500 stems ha−1 but two thirds of the seedlings were smaller than 30 cm. Soil disturbance was minimal, probably limiting the establishment of yellow birch, which reached a density of 1416 stems ha−1 five years after logging. Height growth projection of regeneration over five years showed that competiting species should still dominate the sites. Commercial species should improve their position but would still account for only 40% of dominant stems. It is therefore unlikely that this regeneration method will be successful in bringing back the initial stand composition in a short period of time. The next stands will probably contain a high proportion of intolerant species with a dominance of paper birch (Betula papyrifera Marsh.) over yellow birch. In the near future, cleaning operations should be conducted to reduce the impact of competing vegetation and make sure that balsam fir will remain in the main canopy.


1976 ◽  
Vol 52 (3) ◽  
pp. 143-144 ◽  
Author(s):  
Hugh O. Schooley

After one period of balsam woolly aphid damage, young balsam fir trees resumed normal height growth by the reactivation of inhibited terminal buds on 60% of trees, and by re-orientation of primary internodal and nodal branches on 24% and 16% of trees, respectively. Permanent forks and crooks were formed only infrequently. Height growth loss on damaged trees was small, equalling one to four years growth.


2004 ◽  
Vol 34 (7) ◽  
pp. 1436-1443 ◽  
Author(s):  
Chantal Lemieux ◽  
Louise Filion

Most mature balsam fir trees (Abies balsamea (L.) Mill.) growing at the top of Mount Mégantic (Quebec) exhibit multiple leaders in the upper crown section, an indication of stressful conditions for tree development in this high-altitude stand. We report here on a detailed dendroecological analysis of windthrown trees showing that multiple stem development was linked to spruce budworm activity during the 1970s. In spite of severe defoliation, damaged trees temporarily restored their vegetative structure by forming reiterated axes. About 9% of all leaders sampled died during a 3-year period (1996-1998), which represents 60% of dead leaders sampled, with tree morbidity and mortality also peaking in 1996. Tree-ring dating of growth anomalies indicated the impact of major snow and (or) ice storms during the 1996 and 1998 winters, two events validated by field observations from the Mount Mégantic conservation area authorities. Biotic (defoliators) and extreme climatic events have a combined influence in the dynamics of high-altitude balsam fir forests.


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