Causality in mortality patterns of spruce trees during a spruce budworm outbreak

1989 ◽  
Vol 19 (5) ◽  
pp. 632-638 ◽  
Author(s):  
Akira Osawa
Keyword(s):  
Species Complex ◽  
Close Relationships ◽  
Tree Mortality ◽  
Black Spruce ◽  
Basal Area ◽  
Spruce Budworm ◽  
Red Spruce ◽  
Hybrid Index ◽  
The Mean ◽  
Spruce Mortality

Patterns of tree mortality in the species complex of red spruce (Picearubens Sarg.), black spruce (Piceamariana (Mill.) B.S.P.) and their possible hybrids that developed during a spruce budworm (Choristoneurafumiferana (Clem.)) outbreak in Maine, U.S.A., were analyzed in relation to five hypotheses of their causal mechanisms. The observed patterns of spruce mortality were primarily a result of the phenotypic variation among the spruces. Close relationships among the mean hybrid index of spruce trees in a plot and such stand variables as balsam fir (Abiesbalsamea (L.) Mill.) basal area and drainage index are likely to have created coincidental correlations between tree mortality and those variables that do not necessarily reflect causality.

Plot size and number of plots needed to assess spruce budworm impact

1982 ◽  
Vol 12 (2) ◽  
pp. 332-336 ◽  
Author(s):  
Chester Karpinski Jr. ◽  
J. A. Witter
Keyword(s):  
Coefficient Of Variation ◽  
Tree Mortality ◽  
Basal Area ◽  
Spruce Budworm ◽  
Dead Volume ◽  
Patchy Distribution ◽  
Plot Size ◽  
Percent Mortality ◽  
The Mean ◽  
Parameter Precision

This study investigated size and number of plots needed to precisely estimate tree mortality, mean dead basal area, mean dead volume, mean live basal area, and mean live volume in stands infested with the spruce budworm, Choristoneurafumiferana (Clemens).Depending on the parameter, precision of four different plot sizes (0.02, 0.04, 0.08, 0.40 ha) was examined. For most parameters the 0.04-ha plot appears to be approximately as precise as the larger plot sizes. Variables which affect the precision of the plot sizes are percent mortality, patchy distribution of the character of interest, and the variability associated with the population of interest. The precision of two, three, four, and five plots per stand was investigated. The coefficient of variation of the mean is reduced the greatest between two and three plots; subsequent reductions beyond three plots are not great. The number of plots needed based on sampling theory varied according to the parameter and the variability associated with the parameter. It was determined that the time involved in evaluating three 0.04-ha plots was approximately the same as needed to evaluate two 0.08-ha plots.

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.

Tree mortality and radial growth losses caused by the western spruce budworm in a Douglas-fir stand in British Columbia

1982 ◽  
Vol 12 (4) ◽  
pp. 780-787 ◽  
Author(s):  
R. I. Alfaro ◽  
G. A. Van Sickle ◽  
A. J. Thomson ◽  
E. Wegwitz
Keyword(s):  
Radial Growth ◽  
Tree Mortality ◽  
Small Diameter ◽  
Basal Area ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Radial Increment ◽  
Western Spruce Budworm ◽  
Number Of Stems ◽  
The Relationship

The effects of defoliation by western spruce budworm (Choristoneuraoccidentalis (Freeman)), on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) radial growth at breast height and tree mortality are given. Four hundred and twenty trees were marked in an 81-year-old stand, and their defoliation levels were recorded annually from 1970 to 1980 in an outbreak that lasted from 1970 to 1974, inclusive. Forty-one trees were felled and dissected in 1977, 3 years after recovery began. The number of stems per hectare was reduced by 39.3% and basal area by 11.6% through mortality, most occurring among the small diameter, suppressed, and intermediate trees. Relationships were established between mortality and defoliation. Radial increments were examined, and the presence of four outbreaks during the life of the stand was detected. The combined effect of these infestations amounted to a loss of about 12% of the estimated potential diameter had not the insects been active. The most recent outbreak (1970–1974) caused a total of 10 years of subnormal growth, including 5 years due to defoliation and 5 years of recovery. The relationship between radial increment losses and defoliation intensity and duration is studied and quantified.

Reduction of black spruce seed bank by spruce budworm infestation compromises postfire stand regeneration

2005 ◽  
Vol 35 (7) ◽  
pp. 1686-1696 ◽  
Author(s):  
Martin Simard ◽  
Serge Payette
Keyword(s):  
Seed Bank ◽  
Black Spruce ◽  
Reproductive Potential ◽  
Basal Area ◽  
Spruce Budworm ◽  
Stand Age ◽  
Viable Seed ◽  
Eastern Canada ◽  
Postfire Regeneration ◽  
Fire Disturbances

In the southern boreal forest of eastern Canada, black spruce (Picea mariana (Mill.) BSP) is subjected to both defoliating insect and fire disturbances. As black spruce depends on its aerial seed bank for postfire regeneration, reduction of cone crop during a spruce budworm (Choristoneura fumiferana (Clem.)) outbreak opens a vulnerability window during which stand regeneration could be hindered in the event of a fire. To assess the long-term effect of spruce budworm outbreak on black spruce reproductive potential, cone production and viable seed bank were estimated using cone crop surveys and germination trials in black spruce – lichen woodland stands that sustained different levels of defoliation during the 1980s. Black spruce cone crop was significantly related to the defoliation history of the stands (R2 = 0.89), but not to stand age, basal area, or tree density. Black spruce stands damaged by severe defoliation showed a smaller number of cones, a higher incidence of insect-damaged cones, and a viable seed bank 3 to 17 times smaller than a lightly defoliated stand. The vulnerability window for black spruce regeneration following a spruce budworm outbreak may be as long as 20 years in the study area because black spruce seed bank in heavily defoliated stands has not yet replenished. Our work supports conclusions from stand reconstruction studies that suggest closed-crown spruce–moss stands convert to open lichen woodlands as a result of weak postfire regeneration caused by successive insect and fire disturbances.

Genetic variation of red spruce in the Maritimes

1988 ◽  
Vol 18 (6) ◽  
pp. 703-709 ◽  
Author(s):  
D. P. Fowler ◽  
Y. S. Park ◽  
A. G. Gordon
Keyword(s):  
Genetic Variation ◽  
Black Spruce ◽  
Tree Improvement ◽  
Red Spruce ◽  
Hybrid Origin ◽  
Diameter Growth ◽  
Hybrid Index ◽  
Strongly Correlated ◽  
Variation Pattern ◽  
Breeding Zone

Red spruce, Picearubens Sarg., from 30 provenances was tested over a 23-year period at six locations in the Maritimes Region of Canada. Twenty-eight of the provenances were from the Maritimes Region and two were from West Virginia. Hybrid index was used to distinguish pure red spruce from red–black spruce derivatives. Trees from three of the Maritimes provenances were considered to be of hybrid origin. These three provenances produced the fastest-growing trees in the tests. The genetic variation pattern, at the provenance level, in pure red spruce of Maritimes origin is not well defined. Use of seed from provenances identified as superior for reforestation would result in about 10% greater height and diameter growth than would be obtained from average seed. The use of seed of poor provenances could result in a corresponding loss of growth. Height at ages 10, 15, and 23 years and diameter at age 23 years were all strongly correlated, suggesting that superior provenances of red spruce can be identified at age 10. The Maritimes Region can be considered as a single breeding zone for tree improvement efforts with red spruce.

The influence of forest composition and climate on outbreak characteristics of the spruce budworm in eastern Canada

2013 ◽  
Vol 43 (12) ◽  
pp. 1181-1195 ◽  
Author(s):  
David R. Gray
Keyword(s):  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Basal Area ◽  
Spruce Budworm ◽  
Climate Scenario ◽  
Forest Composition ◽  
Eastern Canada ◽  
The North ◽  
Average Change ◽  
Maximum Temperatures

The spruce budworm (Choristoneura fumiferana Clemens) is perhaps the single most important disturbance agent in Canada’s eastern forests. Climate and forest composition are dominant factors in spruce budworm outbreak dynamics through their direct influences on the pest, its natural enemies, and its hosts, and through their influence on the multitrophic interactions that are important in outbreak dynamics. A combination of four climate variables, three forest composition variables, and one location variable explained 60% of the multivariate variability in outbreak characteristics (duration and severity) in eastern Canada. Outbreak duration was most strongly influenced by April–May accumulation of degree-days; outbreak severity was most strongly influenced by the extreme maximum temperatures of April–May. The basal area of balsam fir had a stronger influence than that of black spruce on duration and on severity. Both outbreak characteristics declined in more northerly locations. Under a projected future (2011–2040) climate scenario the largest increases in outbreak duration and severity are predicted to occur on the Gaspé Peninsula and the north shore of the St. Lawrence River (Quebec). The largest decreases in duration and severity are predicted to occur in southern Ontario and along the Bay of Fundy in New Brunswick and Nova Scotia. The predicted average change in outbreak duration is around –1.3 years. The predicted average change in outbreak severity is only slightly different from zero (around –1.5% defoliation).

The Occurrence of Hybrid Swarms of Red and Black Spruces in Central New Brunswick

1972 ◽  
Vol 2 (4) ◽  
pp. 381-391 ◽  
Author(s):  
S. A. M. Manley
Keyword(s):  
New Brunswick ◽  
Selection Pressure ◽  
Parental Species ◽  
Black Spruce ◽  
Red Spruce ◽  
Hybrid Index ◽  
Site Preferences ◽  
Hybrid Swarms ◽  
Respective Characteristic ◽  
The Ideal

The data obtained by rating 50 plots in red × black spruce populations throughout central New Brunswick with a hybrid index indicate that red and black spruces have hybridized extensively. In the New Brunswick Lowland, gentle slopes and flat uplands form a continuum between characteristic habitats, permitting extensive contact between the two species. Where a considerable zone of contact was present, hybrid populations were established. Selection pressure is apparently strong, for despite the ideal opportunities for contact and the fertility of the hybrids, parental species remain phenotypically pure in their respective characteristic habitats (as far as these could be defined). The composition of hybrid populations was related to the extent of resemblance of 'intermediate' sites to parental site preferences. Introgressed black spruce predominated in hybrid populations, possibly due to the overriding influence of disturbances such as fire, logging, and damage to red spruce types by spruce budworm.

Densities of breeding birds and changes in vegetation in an Alaskan boreal forest following a massive disturbance by spruce beetles

2001 ◽  
Vol 79 (9) ◽  
pp. 1678-1690 ◽  
Author(s):  
Steven M Matsuoka ◽  
Colleen M Handel ◽  
Daniel R Ruthrauff
Keyword(s):  
Picea Glauca ◽  
Tree Mortality ◽  
Black Spruce ◽  
Bird Species ◽  
Tamiasciurus Hudsonicus ◽  
Forest Stands ◽  
Dendroctonus Rufipennis ◽  
Individual Bird ◽  
Large Outbreak ◽  
Spruce Mortality

We examined bird and plant communities among forest stands with different levels of spruce mortality following a large outbreak of spruce beetles (Dendroctonus rufipennis (Kirby)) in the Copper River Basin, Alaska. Spruce beetles avoided stands with black spruce (Picea mariana) and selectively killed larger diameter white spruce (Picea glauca), thereby altering forest structure and increasing the dominance of black spruce in the region. Alders (Alnus sp.) and crowberry (Empetrum nigrum) were more abundant in areas with heavy spruce mortality, possibly a response to the death of overstory spruce. Grasses and herbaceous plants did not proliferate as has been recorded following outbreaks in more coastal Alaskan forests. Two species closely tied to coniferous habitats, the tree-nesting Ruby-crowned Kinglet (Regulus calendula) and the red squirrel (Tamiasciurus hudsonicus), a major nest predator, were less abundant in forest stands with high spruce mortality than in low-mortality stands. Understory-nesting birds as a group were more abundant in forest stands with high levels of spruce mortality, although the response of individual bird species to tree mortality was variable. Birds breeding in stands with high spruce mortality likely benefited reproductively from lower squirrel densities and a greater abundance of shrubs to conceal nests from predators.

Interprovincial Forest Fertilization Trials 5-and 10-Year Results

1987 ◽  
Vol 63 (3) ◽  
pp. 184-192 ◽  
Author(s):  
G. F. Weetman ◽  
H. H. Krause ◽  
E. Koller ◽  
J. -M. Veilleux
Keyword(s):  
Tree Mortality ◽  
Black Spruce ◽  
White Spruce ◽  
Jack Pine ◽  
Red Spruce ◽  
Balsam Fir ◽  
Forest Fertilization ◽  
Fertilizer Response ◽  
Complete Report ◽  
Nitrogen Additions

Eighty one standard ferilizer trials were established in unmanaged. middle-aged stands of jack pine, black spruce, white spruce, red spruce and balsam fir in Nova Scotia, New Brunswick. Quebec, Ontario, Manitoba. Saskatchewan and Alberta. The 5-year and 10-year total volume responses, based on conventional plot remeasurements, are summarized for installations grouped by Forest Section. A complete report is being published separately. Jack pine stands were most consistently responsive to nitrogen additions; black spruce, red spruce and white spruce and balsam fir were much more variable in response. Spruce budworm defoliation and natural tree mortality resulted in very low or negative net increments for many installations. Where P or K was added with N additional response appeared small. Fertilizer efficiencies of 7 to 35 kg of applied nitrogen per cubic meter of additional response were indicated: recommendations are made for further work on fertilizer response.

Structural differences between forests regenerating following spruce budworm defoliation and clear-cut harvesting: implications for marten

2000 ◽  
Vol 30 (12) ◽  
pp. 1965-1972 ◽  
Author(s):  
David C Payer ◽  
Daniel J Harrison
Keyword(s):  
Habitat Quality ◽  
Coarse Woody Debris ◽  
Tree Mortality ◽  
Woody Debris ◽  
Choristoneura Fumiferana ◽  
Basal Area ◽  
Natural Disturbance ◽  
Spruce Budworm ◽  
Understory Vegetation ◽  
Clear Cut

American marten (Martes americana Turton) avoid recent clearcuts when establishing territories but do not avoid similarly aged stands with a history of extensive tree mortality caused by the eastern spruce budworm (Choristoneura fumiferana Clem.). We quantified differences in overstory vegetation, understory vegetation, and coarse woody debris between stands that were clear-cut or defoliated by spruce budworms 10-20 years prior to our study. Our objectives were to identify habitat features with functional significance for marten that were lacking in managed stands and to propose goals for silvicultural practices that more closely resemble a natural disturbance (insect defoliation), thus improving habitat quality for marten. In contrast to regenerating clearcuts, defoliated stands had greater volumes of snags, downed logs, and root masses and included taller trees. Although live-tree basal area was similar between stand types, our results suggest that vertical structure provided by large snags can offset limited availability of live trees for marten, particularly where coarse woody debris and understory vegetation are plentiful. In stands under even-aged management, habitat quality for marten may be enhanced by retention of >18 m2/ha cull trees and snags. Uneven-aged silvicultural systems, which more closely mimic natural disturbance by defoliating insects, may have particular promise for maintaining marten habitat.

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