The response of good and poor aspen clones to thinning

2001 ◽  
Vol 77 (5) ◽  
pp. 874-884 ◽  
Author(s):  
M. Penner ◽  
C. Robinson ◽  
M. Woods
Keyword(s):  
Key Words ◽  
Populus Tremuloides ◽  
Basal Area ◽  
Trembling Aspen ◽  
Quadratic Mean ◽  
Piece Size ◽  
Area And Volume

The response of good and poor clones of trembling aspen (Populus tremuloides Michx) to thinning was assessed 16 years after treatment. Prior to the thinning treatment, the clones had been assessed as either poor or good using a rating matrix that considered height, diameter, quality and vigour of the clones. Results indicate that the 250 largest DBH stems∙ha−1 did not respond to thinning, irrespective of clone rating. The growth of these dominant trees was unaffected by smaller competitors. Considering all trees, the non-thinned (control) good clones were indistinguishable from the thinned good clones in terms of top height, basal area, quadratic mean DBH, volume∙ha−1, and trees∙ha−1 16 years after treatment. For the good clones, 16 years of self-thinning yielded the same result as a single manual thinning. Due to a slower rate of self-thinning, the non-thinned poor clones retained some of the small stems longer and thus had a higher basal area and volume than the thinned poor clones. Thinning did not increase the piece size of the dominant trees so there was no associated increase in value.Thinning good and poor clones of trembling aspen did not increase the standing volume or piece size. Therefore, thinning is recommended only for good clones and only if it is profitable on its own. The literature on the benefits of thinning of aspen is contradictory. This may be due, in part, to undocumented clonal differences. Key words: trembling aspen, clones, thinning response, poplar, clonal rating

scholarly journals Contrasting Release Approaches for a Mixed Paper Birch (Betula papyrifera)–Quaking Aspen (Populus tremuloides) Stand

2008 ◽  
Vol 25 (3) ◽  
pp. 124-132 ◽  
Author(s):  
Eric K. Zenner ◽  
Klaus J. Puettmann
Keyword(s):  
Populus Tremuloides ◽  
Basal Area ◽  
Complete Removal ◽  
Quaking Aspen ◽  
Betula Papyrifera ◽  
Mixed Stands ◽  
Early Release ◽  
Paper Birch ◽  
Area And Volume

Abstract Early release from competitors can be used to influence the species composition, quality, and rate of development of young stands. Release strategies can vary in intensity, ranging from complete removal of competitors and infrequent future entries (early, heavy, infrequent [EHI]) to lighter entries that are repeated more frequently (early, light, often [ELO]). It is unclear, however, which strategy is more successful for producing high-quality birch sawtimber (Betula papyrifera Marsh.) in mixed stands with aspen (Populus tremuloides Michx.). We evaluated the effects of various release intensities on the growth and mortality of a 16–18-ft-tall natural aspen–paper birch stand in Minnesota following density reductions from 1,500–3,000 trees ac−1 (trees per acre [TPA]) to 750 (ELO750), 500 (EHI500), and 250 (EHI250) TPA. After 6 years, paper birch was overtopped by aspen and contributed only 14% of basal area in control plots, but it occupied all diameter classes and contributed 77–87% of basal area in release plots. The basal area and volume of all paper birch and of only paper birch crop trees (100 largest TPA) were highest in lightly released ELO750 and lowest in control plots. Growth of mean quadratic diameter, basal area, and volume of paper birch was 2–3 times higher in release plots but independent of release intensity. Early release is necessary to maintain paper birch dominance, but there is no short-term advantage among treatment intensities. Long-term growth simulations using the Forest Vegetation Simulator suggest that merchantable timber production was unaffected by release strategy but that the EHI250 strategy produced the most birch sawtimber (40 times as much as in ELO750).

Growth and mortality following partial cutting in a trembling aspen – conifer stand: results after 10 years

2010 ◽  
Vol 40 (5) ◽  
pp. 894-903 ◽  
Author(s):  
Marcel Prévost ◽  
Daniel Dumais ◽  
David Pothier
Keyword(s):  
Populus Tremuloides ◽  
Growth Response ◽  
Effective Means ◽  
Basal Area ◽  
Trembling Aspen ◽  
Natural Conditions ◽  
Partial Cutting ◽  
Coniferous Species ◽  
Broad Leaved Species

We present the effects, 10 years after treatment, of different cutting intensities (removal of 0%, 35%, 50%, 65%, and 100% of basal area (BA)) on the response of residual trees in a 60-year-old mixed aspen–conifer stand in Quebec, Canada. While decennial mortality reached 170 stems·ha–1 under natural conditions (control, 24 m2·ha–1 BA), the removal of mature trembling aspen ( Populus tremuloides Michx.) trees reduced hardwood losses to 125, 105, and 0 stems·ha–1, respectively, in the 35%, 50%, and 65% cuttings, without affecting losses of coniferous species (≤25 stems·ha–1). The growth response of conifers was generally higher than that of broad-leaved species. For hardwoods, the decennial gains in merchantable BA decreased with respect to the control (3.2 m2·ha–1), to 1.2 m2·ha–1 in the 35% cut and to 0.9 m2·ha–1 in the 50% cut, but increased under the 65% cut (2.5 m2·ha–1). For conifers, gains were proportional to removal in partial cuts (2.6–4.9 m2·ha–1) and lower in the control (1.7 m2·ha–1). As a whole, our results suggest that partial cutting may be an effective means of increasing growth of the softwood proportion occupying the intermediate and suppressed strata in a mixed aspen-dominated stand.

scholarly journals Regeneration of aspen following partial and strip understory protection harvest in boreal mixedwood forests

2009 ◽  
Vol 85 (4) ◽  
pp. 631-638 ◽  
Author(s):  
Alison D Lennie ◽  
Simon M Landhäusser ◽  
Victor J Lieffers ◽  
Derek Sidders
Keyword(s):  
Forest Management ◽  
Key Words ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Basal Area ◽  
White Spruce ◽  
Mixedwood Forests ◽  
Partial Harvest ◽  
Second Year

Trembling aspen regeneration was studied in 2 types of partial harvest systems designed to harvest mature aspen but protect immature spruce and encourage natural aspen regeneration. Two partial harvest systems, where the residual aspen was either left in strips or was dispersed uniformly, were compared to traditional clearcuts. After the first and second year since harvest, aspen sucker density and growth was similar between the 2 partial harvests, but was much lower than in the clearcuts. However, in the partial cuts the regeneration density was very much dependent on the location relative to residual trees. The density of regeneration was inversely related to the basal area of residual aspen; however, sucker height was inversely related to the basal area of the residual spruce. Although there were adequate numbers of suckers after partial harvest, their viability and contribution to the long-term productivity of these mixedwood stands is not clear. Key words: silvicultural systems, forest management, residual canopy, white spruce, Populus tremuloides, Picea glauca, traffic

Partial cuts in a trembling aspen – conifer stand: effects on microenvironmental conditions and regeneration dynamics

2003 ◽  
Vol 33 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Marcel Prévost ◽  
David Pothier
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Abies Balsamea ◽  
Basal Area ◽  
Trembling Aspen ◽  
Limited Growth ◽  
Growth And Survival ◽  
Regeneration Dynamics ◽  
Canopy Opening ◽  
Light Soil

We present the 5-year combined effects of different cutting intensities (removal of 0, 35, 50, 65, and 100% of basal area) and scarification on available light, soil temperature, and regeneration dynamics in a mixed aspen– conifer stand in Quebec, Canada. Compared with the control, the 35% cut did not change transmitted light to the under story (<20% of full light), while the 50, 65, and 100% cuttings transmitted 30, 48, and 90% of full light, respectively, during the first summer. Trembling aspen (Populus tremuloides Michx.) suckering increased with percent basal area removal (p < 0.001). After 5 years, the 35 and 50% cuttings limited growth and survival of suckers (<1000 stems/ha, of which 5% are >1 m high), but the 65 and 100% cuttings favoured their development (8000 and 11 000 stems/ha, respectively, of which 29 and 38%, respectively, are >2 m high). Balsam fir (Abies balsamea (L.) Mill.) responded well to canopy opening alone with a maximal recruitment (31 000 seedlings/ha) in the 50% cut. Spruces (white spruce, Picea glauca (Moench) Voss, and red spruce, Picea rubens Sarg.) establish following scarification only, with a better response in the 65% cut (32 000 seedlings/ha) than in the 50 (15 000), 35 (10 000), and 0% (8000) cuttings.

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

Effects of density control and fertilization on growth and yield of young Douglas-fir plantations in the Pacific Northwest

2007 ◽  
Vol 37 (2) ◽  
pp. 449-461 ◽  
Author(s):  
Yuzhen Li ◽  
Eric C. Turnblom ◽  
David G. Briggs
Keyword(s):  
Basal Area ◽  
Douglas Fir ◽  
Growth And Yield ◽  
Quadratic Mean ◽  
Stand Growth ◽  
Density Control ◽  
Mean Diameter ◽  
Quadratic Mean Diameter ◽  
Area And Volume ◽  
Effects Of Density

To examine the effects of density control and fertilization on stand growth and yield of young Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plantations, seven treatment regimes were applied in sixty-three 9-year-old plots from nine installations across western Washington and Oregon. Fertilizer was applied at the rate of 220 kg N·ha–1 (as urea) at stand establishment and every 4 years thereafter. Results after 12 years showed that widely spaced stands exhibited significantly larger quadratic mean diameter than did narrowly spaced stands. The densest stands initially had the greatest overall stand basal area and volume, but accumulation rate in the dense stands had been declining with time. After 12 years, the less dense stands had met or exceeded the basal area periodic annual increment of dense stands. Across all densities, the periodic annual increments of quadratic mean diameter, basal area, and volume in fertilized plots were significantly greater than in unfertilized plots following the first and second urea applications. However, the first fertilization was insufficient to produce a significant increase in stand yield and the significant fertilization increases in yield were found following the second and the third urea applications. This study showed neither significant fertilization effect nor density effect on dominant height. In addition, no significant interactions were found for any stand growth and yield variables considered, but fertilization responses showed different trends among density treatments over time.

scholarly journals Twenty-six years of aspen regeneration under varying light conditions in a boreal mixedwood forest

2021 ◽  
pp. 1-13
Author(s):  
Holly D. Deighton ◽  
Arthur Groot ◽  
Nelson Thiffault ◽  
Mya Rice
Keyword(s):  
Populus Tremuloides ◽  
Basal Area ◽  
Light Conditions ◽  
Trembling Aspen ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Light Levels ◽  
Rate Of Increase ◽  
Silvicultural System ◽  
Understory Vegetation Cover

Density, height, and diameter at breast height of trembling aspen (Populus tremuloides Michx.) sucker regeneration were assessed over a 26-year period in openings created by harvesting in a 40-year-old aspen stand in northeastern Ontario (Canada). The opening types were 9- and 18-m diameter circles, 9- and 18- 150-m east-west strips, and a 100- 150-m clearcut, representing a range of light conditions. Density, height, and diameter at breast height of aspen regeneration were significantly affected by opening type, location relative to opening, and time since harvest. By year 26, aspen densities in circular openings declined to 0, despite high initial recruitment, and trembling aspen heights were significantly lower in the 9-m strips than in the 18-m strips or the clearcut. Year 26 aspen density, volume, and basal area increased with increasing initial light intensity, with the highest rate of increase between 80 and 100% light levels. Understory vegetation cover was largely unaffected by opening size; however, substantial understory aspen regeneration occurred in the smaller openings. Results support the traditional view that aspen is best managed under the clearcut silvicultural system, and >80% full light is recommended for adequate long-term aspen regeneration.

Building a dynamic growth model for trembling aspen in western Canada without age data

2013 ◽  
Vol 43 (3) ◽  
pp. 256-265 ◽  
Author(s):  
Oscar García
Keyword(s):  
Populus Tremuloides ◽  
Site Occupancy ◽  
Basal Area ◽  
Site Index ◽  
Growth And Yield ◽  
Site Quality ◽  
Diameter Distribution ◽  
Stand Age ◽  
Parameter Estimates ◽  
Trembling Aspen

A biologically inspired whole-stand growth and yield model was developed for even-aged thinned or unthinned stands dominated by trembling aspen (Populus tremuloides Michx.). The estimation used permanent sample plot data from British Columbia, Alberta, Saskatchewan, and Manitoba, supplemented by published site index and young stand information. An ingrowth imputation procedure was devised to facilitate the use of plot measurements where small trees are not measured. Two published site index models were closely approximated by a simple age-base invariant equation. Good parameter estimates for mortality and basal area growth were obtained without using age observations, which were unreliable or missing. Four differential equations describe the dynamics of top height, trees per hectare, basal area, and a site occupancy factor. Current values of these variables are used to estimate total and merchantable volumes up to any diameter limit and diameter distribution parameters. When an independent source of site quality estimates is available, the final model does not require stand age knowledge for making growth and yield predictions.

Partial cutting as an analogue to stem exclusion and dieback in trembling aspen (Populus tremuloides) dominated boreal mixedwoods: implications for deadwood dynamicsThis article is one of a selection of papers published in the Special Forum IUFRO 1.05 Uneven-Aged Silvicultural Research Group Conference on Natural Disturbance-Based Silviculture: Managing for Complexity.

2007 ◽  
Vol 37 (9) ◽  
pp. 1525-1533 ◽  
Author(s):  
B. D. Harvey ◽  
S. Brais
Keyword(s):  
Populus Tremuloides ◽  
Coarse Woody Debris ◽  
Tree Mortality ◽  
Woody Debris ◽  
Small Diameter ◽  
Basal Area ◽  
Trembling Aspen ◽  
White Birch ◽  
Partial Cutting ◽  
Downed Wood

In the winter of 1998–1999, two partial harvesting treatments that removed 33% (1/3) and 61% (2/3) of stand basal area were applied to even-aged trembling aspen ( Populus tremuloides Michx.) stands and compared with unharvested control stands. Stands in the 1/3 treatment were low thinned, while stands in the 2/3 removal were crown thinned. Coarse woody debris dynamics were assessed during the following 6 years by means of permanent sampling plots and downed wood inventories. Between 1999 and 2004, tree mortality was, respectively, 18%, 17%, and 32% in control stands and 1/3 and 2/3 harvesting treatments. Although total snag density was similar between controls and partial cutting treatments, total snag basal area was significantly higher in controls in 2004. Between 1999 and 2004, net change in aspen snag density was positive for controls and negative for both partial cutting treatments. Partial cutting also exacerbated mortality of small-diameter white birch ( Betula papyrifera Marsh.). Downed wood volume increased by 35 m3·ha–1 in controls and by 25 m3·ha–1 in the 2/3 harvesting treatment, while it decreased by 7 m3·ha–1 in the 1/3 harvesting treatment. Coarse woody debris goals can be established in silviculture prescriptions; type, timing, and intensity of partial cutting are crucial to the outcome.

scholarly journals Twenty-six years of aspen regeneration under varying light conditions in a boreal mixedwood forest

2021 ◽  
Vol 97 (3) ◽  
pp. 326-342
Author(s):  
Holly D. Deighton ◽  
Arthur Groot ◽  
Nelson Thiffault ◽  
Mya Rice
Keyword(s):  
Populus Tremuloides ◽  
Basal Area ◽  
Light Conditions ◽  
Trembling Aspen ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Light Levels ◽  
Rate Of Increase ◽  
Silvicultural System ◽  
Understory Vegetation Cover

Density, height, and diameter at breast height of trembling aspen (Populus tremuloides Michx.) sucker regeneration were assessed over a 26-year period in openings created by harvesting in a 40-year-old aspen stand in northeastern Ontario (Canada). The opening types were 9- and 18-m diameter circles, 9- and 18- _ 150-m east-west strips, and a 100- _ 150-m clearcut, representing a range of light conditions. Density, height, and diameter at breast height of aspen regeneration were significantly affected by opening type, location relative to opening, and time since harvest. By year 26, aspen densities in circular openings declined to 0, despite high initial recruitment, and trembling aspen heights were significantly lower in the 9-m strips than in the 18-m strips or the clearcut. Year 26 aspen density, volume, and basal area increased with increasing initial light intensity, with the highest rate of increase between 80 and 100% light levels. Understory vegetation cover was largely unaffected by opening size; however, substantial understory aspen regeneration occurred in the smaller openings. Results support the traditional view that aspen is best managed under the clearcut silvicultural system, and >80% full light is recommended for adequate long-term aspen regeneration.

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