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

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.

EFFECTS OF CLIMATE AND FOREST STRUCTURE ON DURATION OF FOREST TENT CATERPILLAR OUTBREAKS ACROSS CENTRAL ONTARIO, CANADA

1998 ◽  
Vol 130 (5) ◽  
pp. 703-714 ◽  
Author(s):  
Jens Roland ◽  
Brendan G. Mackey ◽  
Barry Cooke
Keyword(s):  
Forest Structure ◽  
Large Scale ◽  
Climate Model ◽  
Malacosoma Disstria ◽  
Published Data ◽  
Climatic Data ◽  
Forest Tent Caterpillar ◽  
Forest Heterogeneity ◽  
Tent Caterpillar

AbstractWe examined the effect of forest structure and climate on large-scale and long-term patterns of outbreaks of forest tent caterpillar, Malacosoma disstria Hbn., across central Ontario. This was done using previously published data on outbreak duration and forest heterogeneity, combined with high-resolution climatic data simulated by the recently developed Ontario Climate Model. Our analysis, which eliminates some of the spatially confounding effects of forest structure and climate, suggests that both the predicted long-term temperature minimum for the coldest month and the predicted growing degree-days in the first 6 weeks of the growing season are important determinants of outbreak duration, with colder weather being associated with shorter outbreaks. Forest heterogeneity accounts for more variation in outbreak duration than either of the climatic variables.

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

Long-Term Effects of Head Lice Tx Unknown

2012 ◽  
Vol 43 (3) ◽  
pp. 42
Author(s):  
MITCHEL L. ZOLER
Keyword(s):  
Head Lice ◽  
Long Term Effects

The response of skin perfusion and of rheological and immunological variables to intravenous prostanoid administration in Raynaud’s phenomenon secondary to collagenosis

VASA ◽  
2005 ◽  
Vol 34 (4) ◽  
pp. 243-249 ◽  
Author(s):  
Drinda ◽  
Neumann ◽  
Pöhlmann ◽  
Vogelsang ◽  
Stein ◽  
...  
Keyword(s):  
Laser Doppler Flowmetry ◽  
Raynaud’S Phenomenon ◽  
Raynaud's Phenomenon ◽  
Plasma Viscosity ◽  
Laser Doppler ◽  
Erythrocyte Aggregation ◽  
Control Group ◽  
Long Term Effects ◽  
Doppler Flowmetry

Background: Prostanoids are used in the treatment of Raynaud’s phenomenon and acral perfusion disorders secondary to collagenosis. In subjective terms, intravenous administration of these agents produces success in more than 50% of patients. The therapeutic outcome of clinical administration of alprostadil or iloprost may vary from individual to individual. Patients and methods: The following variables were analysed in a cross-over study in 27 patients with collagenosis and Raynaud’s phenomenon: plasma viscosity and erythrocyte aggregation (rheological variables), partial pressure of oxygen and laser Doppler flowmetry in the finger region, and lymphocyte phenotyping and interleukin (IL) determinations (immunological variables). Results: Laser Doppler flowmetry revealed significant differences between patients with secondary Raynaud’s phenomenon and a control group of 25 healthy subjects. Laser Doppler readings did not change significantly as a result of the treatments. Therapy with iloprost produced a reduction in IL-1beta, L-selectin (CD 62 L) and IL-6. Conclusion: The change in immunological variables due to iloprost may explain the long-term effects of prostaglandins in the treatment of Raynaud’s phenomenon. From our results it is not possible to infer any preference for iloprost or alprostadil.

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