USE OF THE RELATIVE TURGIDITY TECHNIQUE FOR MEASUREMENT OF WATER STRESSES IN GYMNOSPERM LEAVES

1965 ◽  
Vol 43 (2) ◽  
pp. 305-316 ◽  
Author(s):  
J. J. Clausen ◽  
T. T. Kozlowski

Adaptations of Weatherley's relative turgidity technique (Weatherley 1950), fitting it for use with red pine (Pinus resinosa Ait.), white pine (P. strobus L.), balsam fir (Abies balsamea (L.) Mill.), and eastern hemlock (Tsuga canadensis (L.) Carr.) are described. Results of preliminary investigations of sampling variation between trees, whorls, and needle ages in red pine are presented.

1982 ◽  
Vol 60 (11) ◽  
pp. 2295-2302 ◽  
Author(s):  
Joanna T. Tippett

Periderm formation across the base of short lateral roots facilitated their shedding in balsam fir (Abies balsamea (L.) Mill.), white pine (Pinus strobus L.), and hemlock (Tsuga canadensis (L.) Carr.). The periderm originated either from the pericycle, in line with normal subendodermal development, or after dedifferentiation and redifferentiation of cells across existing vascular tissues near the base of senescent short roots. Consequently the short roots were either shed neatly along with the cortex of the parent roots or they were isolated by a new layer of periderm linking existing parent-root periderm, analogous to protective tissue formation beneath petiole abscission zones. Short roots were not always isolated by periderm prior to detachment, but periderm still formed at the base of the root stubs and eventually became the superficial protective layer of the root scars.


2001 ◽  
Vol 10 (1) ◽  
pp. 91 ◽  
Author(s):  
David D. Neumann ◽  
Donald I. Dickmann

Beginning in 1991, periodic surface fires (frontal fire intensities <200 kW m–1) were introduced into a mixed red pine (Pinus resinosa Ait.) and white pine (P. strobus L.) plantation (dbh 16–60 cm). Replicated plots of 0.4–0.5 ha were either burned three times at biennial intervals (early May of 1991, 1993, and 1995), burned once (early May 1991), or not burned. Measurements were conducted during the 1994 and 1995 growing seasons. The pine overstory was largely unaffected by the fires. The understory on unburned plots contained 16 111 large seedlings (>1 m, ≤ 1.9 cm dbh) and 3944 saplings (2.0–5.9 cm dbh) per ha, consisting of 23 woody angiosperm taxa. Plots burned once contained 60% of the large seedlings, 7% of the saplings, and 6 fewer taxa than unburned plots. No large seedlings and few saplings were found in plots burned biennially. Cover of low (<1 m) woody and herbaceous vegetation in plots burned once or three times was twice that of unburned plots, even in the growing season immediately following the May 1995 re-burn. Recovery of low vegetative cover in the re-burned plots was rapid, exceeding that in once-burned or unburned plots by late summer following the burn. Species richness of low vegetation was 20–25% higher in burned than unburned plots, except in the year immediately following reburning. Taxa dominating this site following burning were Sassafras albidum (Nutt.) Nees, Rubus spp., Phytolacca americana L., and Dryopteris spinulosa (O.F. MÜll.) Watt. Restoration of low-intensity surface fires to ecosystems dominated by mature red pine or white pine is feasible, but major changes in understory structure and composition will occur.


1995 ◽  
Vol 71 (5) ◽  
pp. 621-626 ◽  
Author(s):  
Renée Tellier ◽  
Luc C. Duchesne ◽  
Robert S. McAlpine ◽  
Jean-Claude Ruel

In 1990, a jack pine forest was clear-cut on an 15 ha area and divided into 40 plots. In 1991, ten plots were burned-over under varying conditions to obtain different fire intensities and ten plots were scarified. Each plot was planted in 1992 with red pine (Pinus resinosa Ait.) and white pine (P. strobus L.) seedlings. Survival rate and health of the seedlings was evaluated for the first two years after planting and the non-crop vegetation was assessed using a competition index developed for conifer management in Ontario. Our results show seedling survival rate, health, biomass and height to be improved when planted on burned-over or scarified sites and that fire intensity influences certain of those characteristics. Key words: scarification, fire, Pinus resinosa, Pinus strobus, competition


1989 ◽  
Vol 121 (1) ◽  
pp. 55-63 ◽  
Author(s):  
R.J. West ◽  
A.G. Raske ◽  
A. Sundaram

AbstractOil-based formulations of Bacillus thuringiensis Berliner var. kurstaki, Dipel 132, Dipel 176, and Dipel 264, were aerially applied at rates of 1.18–2.36 L/ha over five 30-ha plots in a balsam fir, Abies balsamea (L.) Mill., forest in efficacy tests against the eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guen.), in Newfoundland. Double applications of 30 Billion International Units (BIU) per hectare of each formulation and single applications of 40 BIU per hectare of Dipel 176 and Dipel 264 were tested. Larval population reductions of more than 95% and no defoliation of old or new foliage were observed in the plots receiving double applications and in the plot treated with a single application of Dipel 264. Larval numbers were reduced by 85% and defoliation was 4% in the plot treated once with Dipel 176.These treatments were applied against low to moderate larval populations, and their success was attributed to excellent spray coverage and early application when 50% or more of the larvae were still in their first instar.


1959 ◽  
Vol 91 (10) ◽  
pp. 670-671 ◽  
Author(s):  
G. A. Bradley

While working at Cedar Lake in Northwestern Ontario in the summers of 1957 and 1958 the author was able to observe the feeding sites of various species of Cinara. Most of the observations were made within an area of a few square miles on either side of Highway 105, between Red Lake Road and Ear Falls, Ontario. This area is fairly typical of the Laurentian Shield, with numerous lakes, rocky ridges, sandy patches, and small bogs. The principal coniferous trees in this locality are black spruce, jack pine, and balsam fir. White spruce, white cedar, white pine, red pine, and common juniper are also present.


2000 ◽  
Vol 77 (10) ◽  
pp. 1529-1538 ◽  
Author(s):  
Tim Parshall

Stomata and pollen from forest hollow sediments in the Great Lakes were evaluated for their ability to document stand-scale forest invasion. In surface sediments of 19 forest hollows, stomate presence is related most closely to tree presence within 10-20 m for eastern hemlock (Tsuga canadensis (L.) Carr.), pine (Pinus spp. L.), balsam fir (Abies balsamea (L.) Mill.), and northern white cedar (Thuja occidentalis L.). Although the abundance of hemlock pollen in surface sediments is positively related to the abundance of hemlock trees within 100 m, it does not consistently reflect the presence of hemlock trees within this distance. Pollen and stomata preserved in forest hollow sediments from northwestern Wisconsin were used to document two stages of stand invasion by eastern hemlock. First, hemlock stomata initially appear approximately 2400 14C years BP, representing the initial colonization of the forest stand. Hemlock pollen also first appears at this time but in such low abundance that the presence of hemlock trees at the site cannot be known with certainty. Second, hemlock pollen percentages increase sharply around 350 14C years BP, approximately 2000 years following initial colonization, and represent an expansion of the local hemlock population not reflected by stomatal and needle abundance.


2001 ◽  
Vol 77 (4) ◽  
pp. 721-734 ◽  
Author(s):  
William C. Parker ◽  
Daniel C. Dey ◽  
Steven G. Newmaster ◽  
Ken A. Elliott ◽  
Eric Boysen

The effects of thinning on growth and survival of white pine (Pinus strobus L.), white ash (Fraxinus americana L.), and red oak (Quercus rubra L.), and understory plant diversity were examined in a young red pine (Pinus resinosa Ait.) plantation. Five years after thinning, seedling diameter, height, and stem volume were positively correlated with thinning intensity and the size of canopy openings. Percent survival did not differ among thinning treatments, but was significantly higher in white ash and white pine than red oak. Understory vegetation included 113 species, with species richness increasing with thinning intensity and proximity to neighbouring plant communities. Thinning to create relatively large canopy openings in combination with underplanting can promote the natural succession of young pine plantations to native forest species. Keywords: direct seeding, plant diversity, natural regeneration, red oak, restoration, white ash, white pine


2002 ◽  
Vol 134 (3) ◽  
pp. 391-401 ◽  
Author(s):  
G.G. Grant ◽  
P. de Groot ◽  
D. Langevin ◽  
S.A. Katovich ◽  
K.N. Slessor ◽  
...  

AbstractSex attractant blends were developed for monitoring three conifer-feeding species of Eucosma Hübner found in pine seed orchards and plantations in Wisconsin and Ontario. Eucosma monitorana Heinrich, which attacks developing cones of red pine, Pinus resinosa Aiton (Pinaceae), preferred lures containing 100:5:15 (μg blend) of (Z)-9-dodecenyl acetate (Z9-12:Ac), (E)-9-dodecenyl acetate (E9-12:Ac), and (Z)-9-dodecen-1-ol (Z9-12:OH), respectively, over lures without the alcohol or with higher levels of E9-12:Ac. This blend was unattractive to sympatric Eucosma gloriola Heinrich, a species that feeds inside shoots of red pine and eastern white pine, Pinus strobus L. Eucosma gloriola was attracted to a 100:30 blend of Z9-/E9-12:Ac, and adding Z9-12:OH had no significant effect. Eucosma tocullionana Heinrich, which attacks cones of eastern white pine, was attracted equally to 10:3 and 10:5 μg blends of Z9-/E9-12:Ac, and adding Z9-12:OH had no effect. A ratio as low as 1:0.3 was attractive to E. tocullionana but not to sympatric E. gloriola, which preferred a 100-fold higher dosage of the same blend. The seasonal flight periods of the three species overlapped in all study areas. The flight of E. gloriola usually peaked in late May slightly before that of E. monitorana while the flight of E. tocullionana peaked about 1–3 weeks later. The results indicate that sex pheromones, seasonal flight periods, and host preferences are isolating mechanisms for these closely related sympatric species.


2016 ◽  
Vol 39 (1) ◽  
pp. 165-188
Author(s):  
Greg Mitchell

From the 16th to 18th centuries, Labrador Inuit seem to have valued softwoods (from coniferous tree boles) for the manufacture of arrows and darts used in hunting and warfare. Microscopic examination of Inuit arrow shafts from the Twin Island 3 site (EkBc-07) in Red Bay shows that balsam fir (Abies balsamea) was the preferred species for these purposes in the 16th century. Balsam fir is found in abundance in the inner bays of southern Labrador and was easily accessible to Inuit. However, archival sources indicate that by the 18th century Labrador Inuit desired another species of softwood for arrow and dart shafts, one that grew only on the island of Newfoundland. I propose that the sought-after species was one, or both, of the two pine species growing in central Newfoundland (Pinus strobus or Pinus resinosa). Procurement of pine wood from Newfoundland would add another dimension to the established mobility and trading patterns of Inuit in southern Labrador. Conflicts with Europeans during the 16th through 18th centuries in the Strait of Belle Isle and the Petit Nord (on Newfoundland’s Great Northern Peninsula) may, in part, have been a result of the disruption in these travel and harvesting patterns. I suggest that iron products and wooden shallops (boats) from southern Labrador and northern Newfoundland were not the only “southern” commodities actively sought by Inuit during the early stages of European occupation; central Newfoundland’s pine wood was also important for manufacture of arrow shafts.


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