scholarly journals Long-term effects of precommercial thinning on the stem dimensions, form and branch characteristics of red spruce and balsam fir crop trees in Maine, USA

Silva Fennica ◽  
2009 ◽  
Vol 43 (3) ◽  
Author(s):  
Aaron Weiskittel ◽  
Laura Kenefic ◽  
Robert Seymour ◽  
Leah Phillips
Keyword(s):  
Red Spruce ◽  
Balsam Fir ◽  
Long Term Effects ◽  
Precommercial Thinning

Long-term outcome of precommercial thinning in northwestern New Brunswick: growth and yield of balsam fir and red spruce

2008 ◽  
Vol 38 (3) ◽  
pp. 592-610 ◽  
Author(s):  
Doug Pitt ◽  
Len Lanteigne
Keyword(s):  
Block Design ◽  
Abies Balsamea ◽  
Red Spruce ◽  
Balsam Fir ◽  
Growth And Yield ◽  
Stem Volume ◽  
Long Term Outcome ◽  
Precommercial Thinning ◽  
Minimum Requirement

A study was established between 1959 and 1961 to study the long-term responses of balsam fir ( Abies balsamea (L.) Mill.) and red spruce ( Picea rubens Sarg.) to precommercial thinning. Three nominal spacings of 4 ft (1.2 m), 6 ft (1.8 m), and 8 ft (2.4 m) were compared with an unthinned control in a randomized complete block design with five replicates. At the time of thinning, natural regeneration averaged 16 years of age, 8 years after harvest. Although thinning had minimal effect on gross total volume production over a 42 to 44 year observation period, actual spacings between 2.1 and 2.5 m produced an average of 360 m3·ha–1gross merchantable volume (GMV), representing a 21% gain over unthinned stands. The same spacings produced quadratic mean diameters of 21 and 23 cm, respectively, compared with 18 cm in the unthinned stands. These size increases translated to individual stem volume gains of 33% and 62%, significantly reducing the age at which thinned stands would meet a specified minimum requirement for merchantability or habitat. The mean annual increment of GMV ranged from 6 m3·ha–1·year–1in unthinned stands, to more than 7 m3·ha·–1·year–1in the thinned stands, and had not yet culminated an average of 50 years postharvest.

Forty years of spruce–fir stand development following herbicide application and precommercial thinning in central Maine, USA

2012 ◽  
Vol 42 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Matthew G. Olson ◽  
Robert G. Wagner ◽  
John C. Brissette
Keyword(s):  
Abies Balsamea ◽  
Balsam Fir ◽  
Stand Development ◽  
Long Term Effects ◽  
Herbicide Application ◽  
Precommercial Thinning ◽  
Clearcut Harvesting ◽  
Herbicide Treatments ◽  
Mixedwood Stands

We examined the development of a 33-year experiment in spruce–fir stands that received nine herbicide treatments (applied aerially in 1977), with and without precommercial thinning (PCT) (applied in 1986). We tested two commonly held assumptions about the long-term effects of herbicide and PCT in mixedwood stands managed for softwoods: (i) herbicide release produces stands dominated by softwoods and (ii) PCT promotes both softwood dominance and merchantable volume. All herbicides were effective at releasing balsam fir ( Abies balsamea (L.) Mill.) and spruce ( Picea spp.) from overtopping shrubs and hardwoods that had naturally regenerated following clearcut harvesting in 1970. Glyphosate (Roundup), triclopyr amine (Garlon 3A), 2,4,5-T, and a mixture of 2,4,5-T and 2,4-D herbicide treatments were all effective at shifting long-term species composition to softwood dominance after 30 years, irrespective of the rates applied. Herbicide-treated stands that did not receive PCT were overstocked with softwoods for at least 24 years and produced less than half of the merchantable softwood volume by 40 years than herbicide-treated stands that received PCT. Intolerant hardwoods dominated untreated stands for all 33 years of the experiment. When unsprayed plots received PCT, however, they produced stands at 40 years that were compositionally and structurally indistinguishable from those that had received both herbicide and PCT treatments. Results from this experiment clearly demonstrated that early herbicide application, regardless of type and rate of herbicide, created softwood-dominated mixedwood stands over the long term and that PCT more than doubled merchantable softwood volume within 25 years of application.

scholarly journals Stand Structure and Composition 32 Years after Precommercial Thinning Treatments in a Mixed Northern Conifer Stand in Central Maine

2011 ◽  
Vol 28 (2) ◽  
pp. 92-96 ◽  
Author(s):  
Aaron R. Weiskittel ◽  
Laura S. Kenefic ◽  
Rongxia Li ◽  
John Brissette
Keyword(s):  
Stand Structure ◽  
Abies Balsamea ◽  
Basal Area ◽  
Long Term Effects ◽  
Mixed Species ◽  
Precommercial Thinning ◽  
Large Trees ◽  
Stand Attributes ◽  
And Control

Abstract The effects of four precommercial thinning (PCT) treatments on an even-aged northern conifer stand in Maine were investigated by examining stand structure and composition 32 years after treatment. Replicated treatments applied in 1976 included: (1) control (no PCT), (2) row thinning (rowthin; 5-ft-wide row removal with 3-ft-wide residual strips), (3) row thinning with crop tree release (rowthin+CTR; 5-ft-wide row removal with crop tree release at 8-ft intervals in 3-ft-wide residual strips), and (4) crop tree release (CTR; release of selected crop trees at 8×8-ft intervals). PCT plots had more large trees and fewer small trees than the control in 2008. There were no other significant differences between the rowthin and control. The rowthin+CTR and CTR treatments had lower total and hardwood basal area (BA) and higher merchantable conifer BA than the control. CTR also resulted in more red spruce (Picea rubens [Sarg.]) and less balsam fir (Abies balsamea [L.]) than the other treatments. Although stand structures for rowthin+CTR and CTR were similar, the percentage of spruce in CTR was greater. Although the less-intensive rowthin+CTR treatment may provide many of the same benefits as CTR, the latter would be the preferred treatment if increasing the spruce component of a stand is an objective. Overall, early thinning treatments were found to have long-term effects on key stand attributes, even more than 30 years after treatment in areas with mixed species composition and moderate site potential.

Simulation of the long-term effects of different strategies for precommercial thinning in Pinus sylvestris

2017 ◽  
Vol 33 (4) ◽  
pp. 347-356 ◽  
Author(s):  
Nils Fahlvik ◽  
Mattias Berglund ◽  
Hampus Holmström ◽  
Urban Nilsson
Keyword(s):  
Pinus Sylvestris ◽  
Long Term Effects ◽  
Precommercial Thinning

Long-term effects of precommercial thinning on small mammals in northern Maine

2005 ◽  
Vol 205 (1-3) ◽  
pp. 43-57 ◽  
Author(s):  
Jessica A. Homyack ◽  
Daniel J. Harrison ◽  
William B. Krohn
Keyword(s):  
Small Mammals ◽  
Long Term Effects ◽  
Precommercial Thinning

scholarly journals Butt and Root Decay in Precommercially Thinned SpruceߝFir Stands

2007 ◽  
Vol 24 (2) ◽  
pp. 129-133 ◽  
Author(s):  
Suzhong Tian ◽  
William D. Ostrofsky
Keyword(s):  
Treatment Effect ◽  
Significant Relationship ◽  
Red Spruce ◽  
Balsam Fir ◽  
Precommercial Thinning ◽  
Commercial Thinning ◽  
Root Decay ◽  
Root Size ◽  
Decay Development

Abstract To test the effect of precommercial thinning (PCT) on butt decay development, 10 commercial thinning size spruceߝfir stands that were precommercially thinned 10ߝ24 years ago and seven unthinned (UT) control stands were assessed for butt decay incidence. The data indicate that PCT did not increase butt decay incidence for either red spruce or balsam fir compared with UT control stands. However, butt decay incidence increased with dbh, height, age, and years of PCT for balsam fir. These relationships were not found for red spruce. No significant PCT treatment effect was found for either species in root decay incidence (RDI) by examining all roots 1.0 cm or greater in diameter of 80 crop trees. RDI of balsam fir increased as root size increased. A significant relationship (r2 = 0.835) exists between RDI and butt decay proportion in the horizontal stump section for balsam fir. To evaluate whether the PCT operation resulted in the removal of butt-decayed stems preferentially, 55 10 × 10 m plots of precommercially thinned spruceߝfir stands were surveyed within 2 years after thinning. A total of 1,426 red spruce stumps; 2,471 balsam fir stumps; 441 retained red spruce trees; and 419 retained balsam fir trees were examined. The results showed that the practice of PCT tended to result in selecting a higher proportion of decayed trees as crop trees. Overall, 5.7% of retained trees and 1.6% of stumps were determined to have decay for red spruce, and 15.8% of retained trees and 5.6% of the stumps had decay for balsam fir.

LONG-TERM EFFECTS OF AERIAL APPLICATIONS OF VIRUS–FENITROTHION COMBINATIONS AGAINST THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

1977 ◽  
Vol 109 (1) ◽  
pp. 9-14 ◽  
Author(s):  
O. N. Morris
Keyword(s):  
Low Dose ◽  
Nuclear Polyhedrosis Virus ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Economic Damage ◽  
Long Term Effects ◽  
Chemical Insecticide ◽  
Nuclear Polyhedrosis

AbstractSpruce budworm infested stands of white spruce and balsam fir were aerially sprayed with an entomopox virus, a nuclear polyhedrosis virus (NPV), a low dose of fenitrothion, and the two virus–chemical insecticide combinations. Long-term assessment of the efficacy of the treatments showed that NPV + a low dose of fenitrothion suppressed the budworm population density particularly on balsam fir below that causing economic damage for 3 years due mainly to transmission of the virus from one generation to the next and maintenance of natural control agents in the population.

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.

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