Trembling aspen responses to drought and defoliation by forest tent caterpillar and reconstruction of recent outbreaks in Ontario

2007 ◽  
Vol 37 (9) ◽  
pp. 1586-1598 ◽  
Author(s):  
Barry J. Cooke ◽  
Jens Roland
Keyword(s):  
Radial Growth ◽  
Ring Width ◽  
Periodic Variation ◽  
Radial Increment ◽  
Forest Tent Caterpillar ◽  
Trembling Aspen ◽  
Long Term Effects ◽  
Moisture Index ◽  
Effects Of Drought ◽  
Tent Caterpillar

We investigated the long-term effects of drought and defoliation by forest tent caterpillars on trembling aspen radial growth in the province of Ontario using a dendroecological approach. Drought, as measured by Hogg’s climate moisture index (CMI), was found to have no discernible impact on aspen radial increment in either northeastern or northwestern Ontario during the study period 1930–2003. Forest tent caterpillar outbreaks were strongly decadal in periodicity in both regions and resulted in similar patterns of periodic variation in tree ring-width chronologies, indicating that, in humid environments prone to spatially synchronized tent caterpillar outbreaks, herbivory is the main factor limiting aspen radial growth. We show that the major decadal outbreak cycles of forest tent caterpillar can, by filtering with the computer program OUTBREAK, be reliably reconstructed from raw aspen ring-width chronologies. We determine the filtering parameters that give the most reliable reconstruction fit to observed patterns of outbreaks in each region. We show that the periodic outbreak signal is present even in areas where aerial surveyors frequently failed to detect significant levels of defoliation, and that the outbreak signal necessarily includes minor defoliation episodes that occur in between the major decadal outbreak cycles.

White tree rings formed in trembling aspen saplings following experimental defoliation

2002 ◽  
Vol 32 (11) ◽  
pp. 1929-1934 ◽  
Author(s):  
E H Hogg ◽  
M Hart ◽  
V J Lieffers
Keyword(s):  
Tree Rings ◽  
Populus Tremuloides ◽  
Ring Width ◽  
Malacosoma Disstria ◽  
Western Canada ◽  
Forest Tent Caterpillar ◽  
Trembling Aspen ◽  
Early Season ◽  
June July ◽  
Tent Caterpillar

Recent studies of trembling aspen (Populus tremuloides Michx.) in western Canada have shown a correlation between past insect defoliation events and the formation of narrow, abnormally pale-coloured ("white") tree rings. The objectives of this study were to test the hypothesis that defoliation causes the formation of white rings and to examine how defoliation affects ring width and density. We experimentally defoliated 7- to 18-year-old aspen in June, July, or August 1997 and subsequently found that white rings were formed the same year in all aspen that were severely defoliated in early June. These white rings were much narrower than in adjacent trees left as controls, and mean xylem density of the white rings (0.27 g·cm–3) was significantly reduced relative to normal rings (0.35–0.40 g·cm–3). In the year following defoliation, the tree rings remained narrow, but their appearance and density had returned to normal. Aspen defoliated later in the season formed relatively normal rings in 1997, but ring widths were reduced in 1998. The results confirm that white rings in aspen can be a useful retrospective indicator of the severe, early season defoliation that is typical during major outbreaks of forest tent caterpillar (Malacosoma disstria Hbn.) and other insects.

Long-Term Effects of Defoliation of Aspen by the Forest Tent Caterpillar

Ecology ◽  
1964 ◽  
Vol 45 (3) ◽  
pp. 630-633 ◽  
Author(s):  
G. B. Churchill ◽  
H. H. John ◽  
D. P. Duncan ◽  
A. C. Hodson
Keyword(s):  
Forest Tent Caterpillar ◽  
Long Term Effects ◽  
Tent Caterpillar

Tree-ring model interprets growth decline in natural stands of loblolly pine in the southeastern United States

1989 ◽  
Vol 19 (5) ◽  
pp. 612-621 ◽  
Author(s):  
Robert Zahner ◽  
Joseph R. Saucier ◽  
Richard K. Myers
Keyword(s):  
Tree Ring ◽  
Loblolly Pine ◽  
Radial Growth ◽  
Ring Width ◽  
Stand Density ◽  
Climatic Conditions ◽  
Radial Increment ◽  
Aggregate Model ◽  
Ring Model ◽  
Pine Stands

Annual ring widths and ring areas from 131 even-aged, natural, well-stocked stands of loblolly pine (Pinustaeda L.) in the Piedmont region were analyzed to reveal possible causes of a previously reported decline in radial growth. A linear aggregate model was used to separate independent factors that are known to contribute to radial growth variation in this species. Stand, site, and climatic conditions were reconstructed for each stand for the 36-year period 1949–1984 from previous inventories and from weather records at appropriately located stations. Within each of six 5-year age-classes, the model identified declines in both ring width and ring area associated with stand density, climate changes, and the passage of time. Regional climate first ameliorated this decline as pine stands passed from droughty conditions early in the 36-year period to a favorable climate during the middle of the period, and the decline accelerated later with the return of dry conditions toward the end of the period. The tree-ring model simulates a decline in radial increment in trees in natural pine stands between the ages of 20 and 45 years in the Piedmont which has averaged 1% per year since 1950. Part of the downward trend was attributed to increased competition, part to regional drought, and a considerable part to unidentified factors, possibly regional atmospheric deposition.

CONTROL OF FOREST TENT CATERPILLAR, MALACOSOMA DISSTRIA (LEPIDOPTERA: LASIOCAMPIDAE), WITH DIMILIN®

1979 ◽  
Vol 111 (7) ◽  
pp. 841-846 ◽  
Author(s):  
Arthur Retnakaran ◽  
Larry Smith ◽  
Bill Tomkins ◽  
Jeffrey Granett
Keyword(s):  
Populus Tremuloides ◽  
Rhodamine B ◽  
Malacosoma Disstria ◽  
Forest Tent Caterpillar ◽  
Trembling Aspen ◽  
Active Ingredients ◽  
Wettable Powder ◽  
Spray Deposit ◽  
Tent Caterpillar ◽  
Better Than

AbstractDimilin (25% wettable powder) was mixed in water and sprayed from a Grumman Agcat aircraft equipped with four micronair units at the rate of 70 g (active ingredients) / 4,67 L/ha (1 oz/0.5 U.S. gal per acre) on two stands of trembling aspen, Populus tremuloides Michx., heavily infested with forest tent caterpillar, Malacosoma disstria Hübner. The material was applied when the insects were in the first and second instars and the trees were starting to flush. Spray deposit analysis using a dye, Rhodamine-B, in the spray mix and spray plates in the plots indicated that conditions for spraying in the morning were better than those in the evening as expected. Total control of the forest tent caterpillar with very little defoliation of the trees was achieved.

Potential for combining sex pheromones for the forest tent caterpillar (Lepidoptera: Lasiocampidae) and the large aspen tortrix (Lepidoptera: Tortricidae) within monitoring traps targeting both species

2005 ◽  
Vol 137 (5) ◽  
pp. 615-619 ◽  
Author(s):  
Maya L. Evenden
Keyword(s):  
Populus Tremuloides ◽  
Economic Value ◽  
Malacosoma Disstria ◽  
Forest Tent Caterpillar ◽  
Trembling Aspen ◽  
Commercially Important ◽  
Monitoring Traps ◽  
The Impact ◽  
Tent Caterpillar ◽  
Choristoneura Conflictana

Trembling aspen, Populus tremuloides Michx. (Salicaceae), is the most widely distributed tree species in North America (Perala 1990) and is considered to be an ecologically (Hogg et al. 2002) and economically important (Brandt et al. 2003) component of the boreal forest. Due to the recently increased economic value of trembling aspen (Brandt et al. 2003), the impact of native insect defoliators on tree growth and mortality has become commercially important. Two of the most significant defoliators of trembling aspen throughout its range in Canada are the forest tent caterpillar (FTC), Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), and the large aspen tortrix (LAT), Choristoneura conflictana Walker (Lepidoptera: Tortricidae).

Weekly xylem production in trembling aspen (Populus tremuloides) in response to artificial defoliation

2004 ◽  
Vol 82 (5) ◽  
pp. 590-597 ◽  
Author(s):  
Brin Jones ◽  
Jacques Tardif ◽  
Richard Westwood
Keyword(s):  
Populus Tremuloides ◽  
Radial Growth ◽  
Regression Models ◽  
Wood Anatomy ◽  
Ring Width ◽  
Growing Season ◽  
Early Growth ◽  
Trembling Aspen ◽  
Forest Sites ◽  
Significant Difference

The present study investigated the effect of artificial defoliation on weekly radial xylem production in trembling aspen (Populus tremuloides Michx.). It was hypothesized that defoliated trees would show reduced xylem and vessel production and thinner secondary walls in fibres. Two adjacent natural forest sites were selected within Winnipeg, Manitoba. Microcores were extracted weekly from the stems of 30 aspen trees from May to October 2002. Ten aspen trees were defoliated using pole pruners between 22 June and 6 July. Measurements included weekly xylem increment, annual vessel characteristics, and late growing season fibre dimensions. No significant difference in overall ring width was observed; however, trees from both groups showed a significant reduction in ring width in 2002. The ratio of radial growth in 2002 / radial growth in 2001 was significantly less in defoliated trees, suggesting a higher reduction in radial growth due to defoliation. Sigmoidal regression models suggested early growth cessation in defoliated trees. No significant differences in vessel characteristics were observed between groups; however, the diameter and lumen width of fibres was significantly reduced in defoliated trees. It is speculated that a shorter radial growing season may have led to a reduced cell elongation period. An early cessation of the radial growing season associated with a reallocation of carbohydrates to produce a second flush of leaves could explain the reduced size of fibres from defoliated trees.Key words: wood anatomy, diffuse porous, image analysis, radial growth, cell dimension, dendrochronology.

Egg hatch of forest tent caterpillar (Lepidoptera: Lasiocampidae) on two preferred host species

2012 ◽  
Vol 144 (6) ◽  
pp. 756-763 ◽  
Author(s):  
David R. Gray ◽  
Don P. Ostaff
Keyword(s):  
Populus Tremuloides ◽  
Forest Tent Caterpillar ◽  
Trembling Aspen ◽  
Egg Hatch ◽  
Egg Masses ◽  
Temperature Regimes ◽  
Host Phenology ◽  
The Difference ◽  
And Performance ◽  
Tent Caterpillar

AbstractSynchrony between herbivore and host phenology can be an important factor in herbivore fitness. The survival of first-instar forest tent caterpillar (FTC) (Malacosoma disstria Hübner; Lepidoptera: Lasiocampidae) larvae and performance of surviving larvae are reduced when egg hatch and host budbreak are asynchronous. Budbreak in trembling aspen (Populus tremuloides Michaux; Salicaceae) and largetooth aspen (Populus grandidentata Michaux; Salicaceae), two preferred hosts of FTC, differ by ∼14 days. We examined the phenological requirements of FTC egg hatch to see if an inherent difference exists between FTC egg masses on the two hosts, and if the difference would promote synchrony with each host. Egg masses from a haphazard selection of clones of each host were collected in a mixed stand of trembling and largetooth aspen in New Brunswick, Canada. Egg masses were subjected to controlled temperature regimes in the laboratory, and hatch was monitored daily. Despite the differences in host phenologies and the obvious benefits of being synchronised with host phenology, egg masses collected from trembling aspen began hatching only 3 days earlier, and completed hatching only 2 days earlier, than egg masses collected from largetooth aspen. Bet hedging is discussed as a possible strategy to explain the absence of host-specific synchrony between egg hatch of FTC and the hosts it selects for oviposition.

Gap dynamics in aspen stands of the Clay Belt of northwestern Quebec following a forest tent caterpillar outbreak

2011 ◽  
Vol 41 (8) ◽  
pp. 1606-1617 ◽  
Author(s):  
Julien Moulinier ◽  
François Lorenzetti ◽  
Yves Bergeron
Keyword(s):  
Populus Tremuloides ◽  
Large Range ◽  
Natural Disturbance ◽  
Malacosoma Disstria ◽  
Forest Tent Caterpillar ◽  
Gap Dynamics ◽  
Trembling Aspen ◽  
Gap Formation ◽  
Canopy Opening ◽  
Tent Caterpillar

Forest tent caterpillar (FTC; Malacosoma disstria Hübner) outbreaks represent an important natural disturbance in broadleaf-dominated stands; however, their effects on forest gap dynamics are not well understood. To describe such effects on canopy gaps and tree recruitment patterns, we investigated 20 trembling aspen (Populus tremuloides Michx.) dominated stands defoliated severely over 0 to 3 years during the last outbreak (1998–2003) in the northwestern Clay Belt of Quebec. Results show that canopy opening more than tripled (12.3%–43.7%) from 0 to 3 years of severe defoliation, and mean gap size was more than 12 times greater (7.2–87.5 m2) over the same gradient. Regeneration patterns suggest that aspen recruitment is not sufficient to completely restore closed canopies in stands defoliated 0, 1, and 2 years, whereas it should be sufficient in stands defoliated 3 years, where large gaps allow trembling aspen establishment. Our results clearly indicate that FTC outbreaks represent an important factor of gap formation in trembling aspen stands. At the stand level, gaps create uneven stand structures, and at the landscape level, FTC defoliation duration creates a large range of even to uneven stand structures.

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