Precommercial thinning of trembling aspen in northern Ontario: Part 1 – Growth responses

2001 ◽  
Vol 77 (5) ◽  
pp. 893-901 ◽  
Author(s):  
James A. Rice ◽  
G. Blake MacDonald ◽  
David H. Weingartner
Keyword(s):  
Populus Tremuloides ◽  
Trembling Aspen ◽  
Growth Responses ◽  
Northern Ontario ◽  
Individual Tree ◽  
Precommercial Thinning ◽  
Individual Tree Growth ◽  
Aspen Tree ◽  
Fibre Yield ◽  
Residual Tree

In Ontario, trembling aspen (Populus tremuloides Michx.) utilization has increased over the past 20 years and this trend is expected to continue. With this increased demand, questions are being raised about stand conditions required for optimum growth. In 1979, a study was initiated across the commercial range of aspen in northern Ontario to determine the optimum precommercial thinning intensities for aspen tree and stand growth. Six pure aspen stands between the ages of five and 22 years were thinned to residual spacings of 2 × 2 m, 3 × 3 m, 4 × 4 m, and 5 × 5 m. Unthinned and thinned plots were measured at regular intervals for up to 17 years after treatment. Diameter increased significantly with residual tree spacing over the range of site conditions, geographic locations, and tree ages. Precommercial thinning resulted in significantly increased height in three of the stands, and height generally increased with increased residual spacing. Fifteen to 17 years after treatment, gross total volume (GTV) was highest in the unthinned plots for all six stands and decreased as residual tree spacing increased. Gross merchantable volume (GMV) did not vary significantly with thinning in all but the oldest stand. The results of this study do not support the use of precommercial thinning to increase aspen fibre yield. However, if the management goal is maximizing individual tree growth, precommercial thinning of aspen should be considered. Key words: Trembling aspen, precommercial thinning, DBH response, height response, northern Ontario

Precommercial thinning of trembling aspen in northern Ontario: Part 2 – Interactions with Hypoxylon canker

2001 ◽  
Vol 77 (5) ◽  
pp. 902-910 ◽  
Author(s):  
Doug Pitt ◽  
David Weingartner ◽  
Sylvia Greifenhagen
Keyword(s):  
Populus Tremuloides ◽  
Planning Process ◽  
Block Design ◽  
Growth And Yield ◽  
Trembling Aspen ◽  
Northern Ontario ◽  
Precommercial Thinning ◽  
Crop Planning ◽  
Incidence And Mortality ◽  
Canopy Position

Hypoxylon canker [Entoleuca mammata (Wahlenberg:Fr) J.D. Rogers and Y.-M. Ju] incidence and mortality were monitored in six northern Ontario trembling aspen (Populus tremuloides Michx.) stands following precommercial thinning. At each of the six sites, a randomized complete block design experiment was established with four replicates of five thinning levels (none, 2-, 3-, 4-, and 5-m spacing). At the time of thinning, three stands were five years old; the remaining were ages 10, 15, and 22. Over the 15- to 17-year observation period, Hypoxylon-related mortality increased to 6–9% by the end of the period, regardless of thinning age or density. Hypoxylon infection incidence (excluding mortality) also increased, to 2–6% in unthinned stands and 8–11% in thinned stands by year 15. No differences among the thinning levels were observed. Prevalence, infection expressed as a percentage of surviving trees, did not differ among thinned and unthinned stands. Mortality attributed to factors other than Hypoxylon was 31–44% in unthinned stands and 7–23% in thinned stands, with no significant differences among thinning levels. Trees dying of other causes were typically small in diameter and of more subordinate crown classes than survivors. In contrast, Hypoxylon-caused mortality was independent of tree size and canopy position. Results suggest that log size and stand yield may be manipulated through density regulation, without concern for interacting impacts associated with Hypoxylon canker. Models are provided for estimating disease losses; predictions can then be factored into the crop-planning process. Key words: trembling aspen, precommercial thinning, Hypoxylon canker, growth and yield, crop planning

From tree to stand: Scaling relationships of water uptake and climate in a reclaimed boreal mixedwood stand.

2020 ◽  
Author(s):  
Morgane Merlin ◽  
Simon M. Landhäusser ◽  
Sean K. Carey
Keyword(s):  
Water Uptake ◽  
Populus Tremuloides ◽  
Sap Flow ◽  
White Spruce ◽  
Ratio Method ◽  
Water Fluxes ◽  
Trembling Aspen ◽  
Individual Tree ◽  
Flow Rates ◽  
The Relationship

<p>Soil water availability is a key factor in determining tree’s transpiration and sap flow rates, and varies with topography and soil depth. Reclaimed landscapes provide us with the unique opportunity to address the effects of those two variables independently on trees’ water uptake, and their relationship to climatic variation. We explored the relationship between individual tree water uptake and atmospheric variables for trembling aspen (<em>Populus tremuloides</em>) and white spruce (<em>Picea glauca</em>), and assessed how this relationship changed across different hillslope positions and rooting space. Growing season (May to September) sap and transpiration fluxes were monitored using heat ratio method sap flow sensors on trembling aspen and white spruce trees in 2014 and 2015 on a reclaimed hillslope in northern Alberta, Canada, with two different soil cover depths providing different rooting spaces. Both species’ sap flow rates and transpiration rates were strongly correlated to climatic variables such as vapor pressure deficit, precipitation events, air temperature, with slight differences in the relationship between topographical positions and soil depths. Site-level atmospheric water fluxes were obtained through eddy covariance measurements at the top of the hillslope. This allowed for a direct linkage of individual tree water uptake measurement to water flux measurements taken at the landscape-level. Understanding how distinct rooting and physiological characteristics of tree species and their growing conditions can be extrapolated to different scales, is crucial to our understanding of both atmospheric and edaphic water fluxes.</p>

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

Response of trembling aspen to partial cutting and subsequent forest tent caterpillar defoliation in a boreal mixedwood stand in northeastern Ontario, Canada

2008 ◽  
Vol 38 (6) ◽  
pp. 1349-1356 ◽  
Author(s):  
Rongzhou Man ◽  
Gordon J. Kayahara ◽  
James A. Rice ◽  
G. Blake MacDonald
Keyword(s):  
Populus Tremuloides ◽  
Malacosoma Disstria ◽  
Tree Level ◽  
Forest Tent Caterpillar ◽  
Trembling Aspen ◽  
Partial Cutting ◽  
Individual Tree ◽  
The Individual ◽  
Crown Dieback ◽  
Tent Caterpillar

The growth response and mortality of trembling aspen ( Populus tremuloides Michx.) were monitored 1, 3, 5, and 11 years after partially harvesting an aspen-dominated mature mixedwood stand in northeastern Ontario. Both diameter and height of aspen trees responded positively to harvesting. However, 3 years after harvest, the growth rates of residual aspen were severely suppressed by 3 years of moderate to severe defoliation by forest tent caterpillar ( Malacosoma disstria Hbn.). The diameter growth of surviving trees almost recovered, but due to continuous crown dieback in the 6 years after defoliation ceased, height growth did not. Over the 11 years after harvest, 70% of residual aspen died, with 80% of that mortality occurring in the 6 years after defoliation. Trees in the lower canopy and in the partial cut had higher mortality rates than those in the upper canopy and in the uncut control. Increased mortality at the individual tree level was generally associated with greater foliage loss. Aspen growth and mortality were associated with defoliation levels, particularly for trees in partial cut treatments. Partial cutting and crown class strongly influenced the response of aspen trees to insect defoliation and should be considered when selecting residual trees during harvesting.

scholarly journals Precommercial Thinning Increases Spruce Yields in Boreal Mixedwoods in Alberta, Canada

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 412
Author(s):  
Ivan Bjelanovic ◽  
Phil Comeau ◽  
Sharon Meredith ◽  
Brian Roth
Keyword(s):  
Growth Models ◽  
Growth And Yield ◽  
Diameter Growth ◽  
Growth Responses ◽  
Projection System ◽  
Precommercial Thinning ◽  
Thinning Intensity ◽  
Boreal Mixedwoods ◽  
Using Data ◽  
Mixedwood Stands

A few studies in young mixedwood stands demonstrate that precommercial thinning of aspen at early ages can improve the growth of spruce and increase stand resilience to drought. However, information on tree and stand responses to thinning in older mixedwood stands is lacking. To address this need, a study was initiated in 2008 in Alberta, Canada in 14 boreal mixedwood stands (seven each at ages 17 and 22). This study investigated growth responses following thinning of aspen to five densities (0, 1000, 2500, 5000 stems ha−1 and unthinned (control)). Measurements were collected in the year of establishment, and three and eight years later. Mortality of aspen in the unthinned plots was greater than in the thinned plots which were not significantly different amongst each other. Eight years following treatment, aspen diameter was positively influenced by thinning, while there was no effect on aspen height. The density of aspen had no significant effect on the survival of planted spruce. Spruce height and diameter growth increased with both aspen thinning intensity and time since treatment. Differentiation among treatments in spruce diameter growth was evident three years from treatment, while differentiation in height was not significant until eight years following treatment. Yield projections using two growth models (Mixedwood Growth Model (MGM) and Growth and Yield Projection System (GYPSY)) were initialized using data from the year eight re-measurements. Results indicate that heavy precommercial aspen thinning (to ~1000 aspen crop trees ha−1) can result in an increase in conifer merchantable volume without reducing aspen volume at the time of harvest. However, light to moderate thinning (to ~2500 aspen stems ha−1 or higher), is unlikely to result in gains in either deciduous or conifer merchantable harvest volume over those of unthinned stands.

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.

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