scholarly journals Conifer Recruitment in Trembling Aspen (Populus Tremuloides Michx.) Stands along an East-West Gradient in the Boreal Mixedwoods of Canada

Forests ◽  
2014 ◽  
Vol 5 (11) ◽  
pp. 2905-2928 ◽  
Author(s):  
Pierre Nlungu-Kweta ◽  
Alain Leduc ◽  
Yves Bergeron
Keyword(s):  
Populus Tremuloides ◽  
Trembling Aspen ◽  
Boreal Mixedwoods ◽  
East West

scholarly journals Spatial and temporal patterns of Populus tremuloides regeneration in small forest openings in northern Ontario

2009 ◽  
Vol 85 (4) ◽  
pp. 548-557 ◽  
Author(s):  
Arthur Groot ◽  
Rongzhou Man ◽  
Jim Wood
Keyword(s):  
Populus Tremuloides ◽  
Tree Height ◽  
Forest Harvesting ◽  
Trembling Aspen ◽  
Spatial And Temporal Patterns ◽  
Northern Ontario ◽  
Mixedwood Forests ◽  
Boreal Mixedwoods ◽  
Silvicultural System ◽  
Forest Openings

The density, height and diameter of trembling aspen sucker regeneration was assessed over a 10-year period in openings created by harvesting in a 40-year-old, 19-m-tall aspen stand in northeastern Ontario. The 5 types of opening comprised: circular openings of 9-m- and 18-m-diameter, 150-m-long east–west strips of 9-m and 18-m width, and a 1.5 ha (100 m × 150 m) clearcut. Density of aspen regeneration was significantly affected by opening type, location relative to the opening, time since harvest, and by all interactions of these factors. Aspen densities within the circular openings declined to low levels by year 10, despite considerable initial recruitment. Trembling aspen height and diameter were significantly influenced by opening type, location relative to the opening, time since harvest, and by opening × time and location × time interactions. Trembling aspen heights in the circular openings were substantially less than in the clearcut and strip openings by year 10. The results support the traditional view that aspen is best managed under the clearcut silvicultural system, and that trembling aspen regeneration following forest harvesting can be reduced by controlling the extent or intensity of overstory removal. Finally, the results suggest that disturbances that create gaps greater than 1 tree height in width in aspen or mixedwood forests may allow gap dynamics to function. Key words: trembling aspen, silviculture, boreal mixedwoods, regeneration, forest openings

Juvenile stand responses and potential outcomes of conifer release efforts on Alberta's spruce–aspen mixedwood sites

2004 ◽  
Vol 80 (5) ◽  
pp. 583-597 ◽  
Author(s):  
Douglas G Pitt ◽  
Milo Mihajlovich ◽  
Leslie M Proudfoot
Keyword(s):  
Growth Model ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Stand Structure ◽  
Landscape Management ◽  
Basal Area ◽  
White Spruce ◽  
Trembling Aspen ◽  
Management Objectives ◽  
Boreal Mixedwoods

Twelve Alberta forest regeneration blocks, situated on representative white spruce (Picea glauca (Moench) Voss) - trembling aspen (Populus tremuloides Michx.) boreal mixedwood sites, planted to white spruce, and operationally released with glyphosate herbicide, were surveyed in the fall of 2002. Stand structure and composition were quantified and compared for treated and untreated portions of each block. The Mixedwood Growth Model (MGM, Department of Renewable Resources, University of Alberta) was used to project these stands over a 100-year horizon and to model the outcomes of several additional silvicultural treatments that could be applied to these blocks. A single release treatment provided 17% and 43% gains in planted white spruce height and stem diameter, respectively, an average of five years after treatment. Treatment shifted stands from being deciduous-dominated, with only 12% conifer basal area, to more than 75% conifer basal area, increasing conifer volumes per hectare nearly three-fold, but retaining conifer-deciduous mixture. Model projections suggest that these stands will produce similar total volumes over an 80-year rotation and that conifer release essentially trades deciduous volume for conifer volume, the degree of release dictating the extent to which this trade-off takes place. A single conifer release treatment led to an average simulated mature stand that contains 21% deciduous basal area, likely meeting mixedwood rather than conifer regeneration criteria. Model simulations of additional silvicultural interventions in these stands suggested that a variety of options exist to satisfy a range of stand or landscape management objectives for spruce-aspen mixedwoods, all within a relatively fixed volume production envelope. A clearer understanding of how early stand conditions translate into stand and landscape management objectives seems prerequisite to solving management conflicts on boreal mixedwood sites. Key words: boreal mixedwoods, vegetation management, conifer release, Mixedwood Growth Model, white spruce, trembling aspen

scholarly journals Ethylene enhances root water transport and aquaporin expression in trembling aspen (Populus tremuloides) exposed to root hypoxia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiangfeng Tan ◽  
Mengmeng Liu ◽  
Ning Du ◽  
Janusz J. Zwiazek
Keyword(s):  
Gas Exchange ◽  
Water Transport ◽  
Populus Tremuloides ◽  
Leaf Gas Exchange ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Trembling Aspen ◽  
Expression Levels ◽  
Root Hypoxia ◽  
Exogenous Ethylene

Abstract Background Root hypoxia has detrimental effects on physiological processes and growth in most plants. The effects of hypoxia can be partly alleviated by ethylene. However, the tolerance mechanisms contributing to the ethylene-mediated hypoxia tolerance in plants remain poorly understood. Results In this study, we examined the effects of root hypoxia and exogenous ethylene treatments on leaf gas exchange, root hydraulic conductance, and the expression levels of several aquaporins of the plasma membrane intrinsic protein group (PIP) in trembling aspen (Populus tremuloides) seedlings. Ethylene enhanced net photosynthetic rates, transpiration rates, and root hydraulic conductance in hypoxic plants. Of the two subgroups of PIPs (PIP1 and PIP2), the protein abundance of PIP2s and the transcript abundance of PIP2;4 and PIP2;5 were higher in ethylene-treated trembling aspen roots compared with non-treated roots under hypoxia. The increases in the expression levels of these aquaporins could potentially facilitate root water transport. The enhanced root water transport by ethylene was likely responsible for the increase in leaf gas exchange of the hypoxic plants. Conclusions Exogenous ethylene enhanced root water transport and the expression levels of PIP2;4 and PIP2;5 in hypoxic roots of trembling aspen. The results suggest that ethylene facilitates the aquaporin-mediated water transport in plants exposed to root hypoxia.

The bacteria in sapwood, wetwood, and heartwood of trembling aspen (Populus tremuloides)

1973 ◽  
Vol 51 (2) ◽  
pp. 498-500 ◽  
Author(s):  
Donald M. Knutson
Keyword(s):  
Populus Tremuloides ◽  
Trembling Aspen ◽  
Indigenous Bacteria ◽  
Large Populations ◽  
Xylem Tissue

Bacteria (Erwinia, Bacillus) were consistently isolated from all samples of aspen sapwood and heartwood. In wetwood zones (water-soaked xylem tissue) or discolored heartwood, large populations often occur. No organisms unique to wetwood were isolated. Wetwood probably is formed by nonmicrobial means and, once formed, merely supports large populations of indigenous bacteria.

Wounding of aspen roots promotes suckering

2004 ◽  
Vol 82 (3) ◽  
pp. 310-315 ◽  
Author(s):  
Erin C Fraser ◽  
Victor J Lieffers ◽  
Simon M Landhäusser
Keyword(s):  
Populus Tremuloides ◽  
Growth Rates ◽  
Growing Season ◽  
Organic Layer ◽  
Trembling Aspen ◽  
Layer Depth ◽  
Injury Type ◽  
Organic Layers ◽  
Root Injury ◽  
Root Sucker

In early May, 1-m sections of trembling aspen (Populus tremuloides Michx.) roots in a forest cutblock were carefully exposed and examined for damage. Undamaged roots were subjected to one of three wounding treatments (scrape, sever, or uninjured control) and were then reburied to either the full normal organic layer depth or to one third of the normal depth. Following one growing season, the roots were reexposed and assessed for aspen sucker numbers and growth rates. Results indicate that injured roots produced suckers nearly twice as often as uninjured roots. Further, injured roots produced more suckers per root, and these suckers were taller and had greater leaf area. Roots buried under shallow organic layers also generated more suckers, regardless of injury type. The side of injury (distal or proximal) did not affect any of the measured variables. The present study suggests that moderate wounding of aspen roots increases initial sucker numbers and growth rates.Key words: trembling aspen, root sucker, root injury, regeneration.

THE BEHAVIOUR OF FIVE WOOD SPECIES IN COMPRESSION

IAWA Journal ◽  
2002 ◽  
Vol 23 (2) ◽  
pp. 201-211 ◽  
Author(s):  
Simon Ellis ◽  
Paul Steiner
Keyword(s):  
Young’S Modulus ◽  
Populus Tremuloides ◽  
Wood Species ◽  
Young's Modulus ◽  
Douglas Fir ◽  
Thuja Plicata ◽  
Trembling Aspen ◽  
Moisture Contents ◽  
Red Cedar ◽  
Western Red Cedar

Five wood species, Oregon ash (Fraxinus latifolia Benth.), Balau (Shorea spp.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Western red cedar (Thuja plicata Donn ex D. Don), and Trembling aspen (Populus tremuloides Michx.) were loaded in compression longitudinally, radially and tangentially. The wood cubes were conditioned to one of four moisture contents prior to loading. Small cubes were loaded until no void space remained after which samples were released and soaked in water. Stress /strain curves were recorded over the whole range of strain and cube thicknesses were recorded at the end of the compression, after release from the testing apparatus, and after soaking in water. Denser woods resulted in a greater Young’s modulus, higher levels of stress and shorter time to densification than did less dense woods. Higher initial moisture contents apparently increased the plasticity of the wood leading to a lower Young’s modulus and lower levels of stress during compression, greater springback after release of stress and greater recovery after swelling in water. Differences observed in the radial and tangential behaviours were believed to be due to the supporting action of the rays when the wood was compressed in the radial direction in balau and trembling aspen and to the relative difference between the lower density earlywood and higher density latewood regions in ash, Douglas-fir and western red cedar.

Annual differences in quality of leaf litter of aspen (Populus tremuloides) affecting rates of decomposition

1988 ◽  
Vol 66 (10) ◽  
pp. 1940-1947 ◽  
Author(s):  
Barry R. Taylor ◽  
Dennis Parkinson
Keyword(s):  
Water Absorption ◽  
Leaf Litter ◽  
Populus Tremuloides ◽  
Decomposition Rate ◽  
Rocky Mountains ◽  
Absorption Rate ◽  
Trembling Aspen ◽  
Leaching Loss ◽  
The Difference

Freshly fallen leaf litter was collected from a stand of trembling aspen (Populus tremuloides Michx.) in the Rocky Mountains of Alberta each autumn from 1981 through 1984. Leaves from 1981 and 1982 were yellow, waxy, and strong. Leaves from 1983 were pale brown and very brittle, and almost 1% of them suffered symmetrical deformities. Leaves from 1984 were composed of 80% yellow leaves and 20% green leaves, which apparently abscissed before senescence. Green and yellow 1984 leaves were distinctly different with respect to total (3 days) leaching loss, leachate conductivity, and proportions of ash, cellulose, and labile material. Green 1984 leaves contained twice as much nitrogen as yellow ones (13.1 vs. 6.5 mg∙g−1) and significantly more phosphorus (1.6 vs. 1.3 mg∙g−1). Leaves of different years varied widely with respect to leaf mass, water absorption rate, mass and conductivity of leachate, and proportions of cellulose, labiles, lignin, and ash, but there was no consistent ordering among years; leaves of different colouration (especially 1981 and 1983) were often physicochemically similar, while leaves identical in appearance were often chemically different. Small but significant differences in N and P concentrations among years were removed by 2 h leaching. Leaves of 1981 decomposing in laboratory microcosms at 26 °C lost less mass than either 1982 or 1983 leaves after 1 month, but not after 2 months. Ability of the cuticle to resist water absorption was probably responsible for the difference in initial decomposition rate.

scholarly journals Taper Equations for Five Major Commercial Tree Species in Manitoba, Canada

2007 ◽  
Vol 22 (3) ◽  
pp. 163-170 ◽  
Author(s):  
Ryan J. Klos ◽  
G. Geoff Wang ◽  
Qing-Lai Dang ◽  
Ed W. East
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
White Spruce ◽  
Jack Pine ◽  
Volume Estimation ◽  
Trembling Aspen ◽  
Stem Form ◽  
Taper Equation ◽  
Taper Equations

Abstract Kozak's variable exponent taper equation was fitted for balsam poplar (Populus balsamifera L.), trembling aspen (Populus tremuloides Michx.), white spruce (Picea glauca [Moench] Voss), black spruce (Picea mariana [Mill.] B.S.P.), and jack pine (Pinus banksiana Lamb.) in Manitoba. Stem taper variability between two ecozones (i.e., Boreal Shield and Boreal Plains) were tested using the F-test. Regional differences were observed for trembling aspen, white spruce, and jack pine, and for those species, separate ecozone-specific taper equations were developed. However, the gross total volume estimates using the ecozone-specific equations were different from those of the provincial equations by only 2 percent. Although the regional difference in stem form was marginal within a province, a difference of approximately 7 percent of gross total volume estimation was found when our provincial taper equations were compared with those developed in Alberta and Saskatchewan. These results suggest that stem form variation increases with spatial scale and that a single taper equation for each species may be sufficient for each province.

Within-tree patterns of wood stiffness for white spruce (Picea glauca) and trembling aspen (Populus tremuloides)

2014 ◽  
Vol 44 (2) ◽  
pp. 162-171 ◽  
Author(s):  
Derek F. Sattler ◽  
Philip G. Comeau ◽  
Alexis Achim
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Radial Growth ◽  
Tree Height ◽  
White Spruce ◽  
Vertical Position ◽  
Trembling Aspen ◽  
Mixed Effect ◽  
Cambial Age ◽  
Rate Of Increase

Radial patterns of modulus of elasticity (MOE) were examined for white spruce (Picea glauca (Moench) Voss) and trembling aspen (Populus tremuoides Michx.) from 19 mature, uneven-aged stands in the boreal mixedwood region of northern Alberta, Canada. The main objectives were to (1) evaluate the relationship between pith-to-bark changes in MOE and cambial age or distance from pith; (2) develop species-specific models to predict pith-to-bark changes in MOE; and (3) to test the influences of radial growth, relative vertical height, and tree slenderness (tree height/DBH) on MOE. For both species, cambial age was selected as the best explanatory variable with which to build pith-to-bark models of MOE. For white spruce and trembling aspen, the final nonlinear mixed-effect models indicated that an augmented rate of increase in MOE occurred with increasing vertical position within the tree. For white spruce trees, radial growth and slenderness were found to positively influence maximum estimated MOE. For trembling aspen, there was no apparent effect of vertical position or radial growth on maximum MOE. The results shed light on potential drivers of radial patterns of MOE and will be useful in guiding silvicultural prescriptions.

Sign in / Sign up

Export Citation Format

Share Document