scholarly journals Sprucing up the mixedwoods: growth response of white spruce (Picea glauca) to partial cutting in the eastern Canadian boreal forest

2016 ◽  
Vol 46 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
Jessica Smith ◽  
Brian D. Harvey ◽  
Ahmed Koubaa ◽  
Suzanne Brais ◽  
Marc J. Mazerolle
Keyword(s):  
Growth Rate ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Growth Response ◽  
Volume Growth ◽  
White Spruce ◽  
Growth Responses ◽  
Eastern Canada ◽  
Partial Cutting ◽  
Mixed Effect

Mixed-species stands present a number of opportunities for and challenges to forest managers. Boreal mixedwood stands in eastern Canada are often characterized by a dominant canopy of shade-intolerant aspen (Populus tremuloides Michx.) with more shade-tolerant conifers in the mid- to sub-canopy layers. Because the aspen and conifer components often attain optimal merchantable sizes at different moments in stand development, there is an interest in developing silvicultural practices that allow partial or total removal of aspen and favour accelerated growth of residual conifers. We tested four partial harvesting treatments in mixed aspen – white spruce (Picea glauca (Moench.) Voss) stands in which different proportions of aspen (0%, 50%, 65%, and 100% basal area) were removed. Ten years after treatments, 72 spruce stems representing dominant, co-dominant, and suppressed social classes were destructively sampled for stem analysis. Using linear mixed effect models, we analyzed growth as a function of treatment intensity, time since treatment, social status, pretreatment growth rate, and neighbourhood competition. Relative to control stands, radial and volume growth responses were detected only in the extreme treatment of 100% aspen removal. In relative terms, suppressed trees showed the greatest magnitude of cumulative growth increase. Compared with control trees, average annual radial and volume increments were, respectively, 23.5% and 7.1% higher for dominant trees, 67.7% and 24.1% higher for co-dominant trees, and 115.8% and 65.6% higher for suppressed trees over the 10 years after treatment. Growth response was proportional to pretreatment growth rate, and among neighbouring trees, only coniferous neighbours had a negative effect on white spruce growth. Our results suggest that in similar mixed-stand conditions, relatively heavy removal of overstory aspen accompanied by thinning of crowded conifers would result in greatest growth response of residual spruce stems.

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.

Stem- and stand-level growth and mortality following partial cutting in eastern boreal poplar – white spruce stands

2019 ◽  
Vol 49 (5) ◽  
pp. 463-470 ◽  
Author(s):  
Suzanne Brais ◽  
Brian D. Harvey ◽  
Arun K. Bose
Keyword(s):  
Growth Rates ◽  
Picea Glauca ◽  
Basal Area ◽  
Natural Disturbance ◽  
White Spruce ◽  
Primary Objective ◽  
Post Treatment ◽  
Tree Level ◽  
Growth Responses ◽  
Partial Cutting

Variable retention (VR) and partial cutting are both considered important silvicultural tools of natural disturbance or ecosystem based forest management approaches. Partial harvesting differs from VR in that post-treatment growth responses and stand regeneration are the primary objective rather than the maintenance of biodiversity. This partial cutting study is undertaken in mixed poplar (Populus spp.) – white spruce (Picea glauca (Moench) Voss) stands in the eastern Canadian boreal mixedwood forest. It compares, at the tree level, absolute growth rates (AGR) and relative growth rates (RGR) of basal area (BA) and stem survival; and at the stand level, it also compares absolute BA growth, mortality, and sapling density 10 years following treatment. The completely randomized experiment was established with four intensities of partial cutting (0, 50%, 65%, and 100% of poplar BA). All partial cutting intensities had a significant and similar positive effect on AGR of residual spruce stems. Complete poplar removal resulted not only in the highest increase in RGR of suppressed and intermediate spruce stems, but also in higher spruce mortality. Removal of 50% of the initial poplar stand BA provided the best trade-off between positive residual stem growth of spruce and poplar and limited post-treatment mortality.

Influences of paper birch competition on growth of understory white spruce and subalpine fir following spacing

2003 ◽  
Vol 33 (10) ◽  
pp. 1962-1973 ◽  
Author(s):  
Philip G Comeau ◽  
Jian R Wang ◽  
Tony Letchford
Keyword(s):  
Picea Glauca ◽  
Volume Growth ◽  
Basal Area ◽  
White Spruce ◽  
Light Transmittance ◽  
Height Increment ◽  
Growth Responses ◽  
Subalpine Fir ◽  
Volume Increment ◽  
Paper Birch

Five years after spacing a young, 11 m tall paper birch (Betula papyrifera Marsh.) stand, we examine relationships between growth of understory white spruce (Picea glauca (Moench) Voss), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and level of birch retention. Our objectives were to evaluate the effectiveness of selected measures of competition for estimating the effects of the residual birch and to evaluate the influence of residual birch densities on growth responses of naturally regenerated subalpine fir and white spruce. Basal area of Scouler willow (Salix scouler iana Barratt) and birch were found to effectively predict light transmittance (diffuse noninterceptance). The best models for predicting 4-year volume growth of subalpine fir and white spruce incorporate initial crown volume of the subject trees and transmittance as independent variables. Lorimer's index and Hegyi's index gave similar results to those obtained using basal area and transmittance, suggesting that there is little benefit in including measurements of proximity in a competition index. For both species, the correlation between basal area increment and light was substantially stronger than observed for volume increment. However, height increment of both subalpine fir and spruce was only weakly correlated with measured light levels. The ratio of height increment to volume increment decreased with both increasing initial height and transmittance for subalpine fir and white spruce.

Effects of overtopping on growth of white spruce in Alaska

2013 ◽  
Vol 43 (9) ◽  
pp. 861-871 ◽  
Author(s):  
E.C. Cole ◽  
M. Newton ◽  
A. Youngblood
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Boreal Forests ◽  
Plant Cover ◽  
Volume Growth ◽  
White Spruce ◽  
Maximum Growth ◽  
Hardwood Species ◽  
Stock Types ◽  
Bare Root

Early establishment of competing vegetation often presents an obstacle to the success of planted white spruce (Picea glauca (Moench) Voss) seedlings. We followed growth and development of white spruce and associated vegetation for up to 17 years in Alaska’s boreal forests to quantify roles of overtopping plant cover in suppressing conifers. The three study areas represented a range of site conditions of varying productivity and species of competing cover, different site preparation and release treatments, and different bare-root and container white spruce stock types. Herbaceous overtopping peaked early after planting and decreased as white spruce were able to outgrow competitors. Overtopping by shrubs and hardwoods, especially aspen (Populus tremuloides Michx.) and resin birch (Betula neoalaskana Sarg.) peaked somewhat later than herbaceous overtopping and decreased over time for most sites and treatments. In a model that combined all sites, vegetation management treatments, and years, overtopping and previous year’s volume explained approximately 85% of the variation in volume growth. Increasing the size of planting stock helped reduce overtopping, hence suppression, even in treatments dominated by hardwood species. Results suggested that control of overtopping was essential for maximum growth and long-term or increasing levels of overtopping severely suppressed white spruce seedling growth.

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.

Are mixtures of aspen and white spruce more productive than single species stands?

1999 ◽  
Vol 75 (3) ◽  
pp. 505-513 ◽  
Author(s):  
Rongzhou Man ◽  
Victor J. Lieffers
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Single Species ◽  
Physical Separation ◽  
Soil Resource ◽  
Mixedwood Forests ◽  
Environmental Extremes ◽  
Spruce Stands ◽  
Boreal Mixedwoods

In boreal mixedwood forests, aspen (Populus tremuloides) and white spruce (Picea glauca) commonly grow in mixture. These species may avoid competition through differential shade tolerance, physical separation of canopies, phenological differences, successional separation, and differences in soil resource utilization. Aspen may also be able to positively affect the growth of white spruce by improving litter decomposition and nutrient cycling rates, controlling grass and shrub competition, ameliorating environmental extremes, and reducing pest attack. These positive relationships likely make mixed-species stands more productive than pure stands of the same species. The evidence regarding the productivity of pure versus mixed aspen/white spruce stands in natural unmanaged forests is examined in this paper. Key words: Tree mixture; productivity; boreal mixedwoods; aspen; white spruce

scholarly journals GROWTH SUBSTANCE CURVATURES OF AVENA IN LIGHT AND DARK

1936 ◽  
Vol 20 (2) ◽  
pp. 283-309 ◽  
Author(s):  
J. Van Overbeek
Keyword(s):  
Growth Hormone ◽  
Growth Rate ◽  
Growth Response ◽  
Growth Substance ◽  
Continuous Exposure ◽  
Growth Responses ◽  
Section 8 ◽  
Oxidative Inactivation

An attempt has been made to analyze the base response, one of the light growth responses of Avena coleoptiles, by means of growth substance curvatures. The decrease in growth rate (first part of the base response) after exposure to light does not show if hetero-auxin is substituted for auxin-a (Sections 5, 6, and 10). This decreased growth after exposure very likely is due to an oxidative inactivation of auxin-a (Sections 8 and 9). Hetero-auxin can be inactivated too but in a much lesser degree than auxin-a (Section 9). The increase in growth rate following on the decreased growth (second part of the base response) is due to an increase in response of the plant to growth hormone which is independent of the type of hormone (Sections 1, 2, 7, 8, and 10). Under conditions of continuous exposure to light, however, the inactivation of the auxin-a under influence of the light is superimposed on this increased response to growth hormone. This inactivation can be eliminated from the light growth response by replacing the auxin-a by hetero-auxin. More detailed information on this subject can be found in Section 10. A review of the experiments and their results can be obtained from the scheme in Section 8. In Section 11 it is shown that light inhibits the formation of growth hormone in the decapitated coleoptile (regeneration). Very small amounts of light (25 m.c.s.) inhibit the regeneration markedly.

Dynamics of regeneration gaps following harvest of aspen stands

2006 ◽  
Vol 36 (7) ◽  
pp. 1818-1833 ◽  
Author(s):  
Daniel A MacIsaac ◽  
Philip G Comeau ◽  
S Ellen Macdonald
Keyword(s):  
Spatial Heterogeneity ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Natural Disturbance ◽  
White Spruce ◽  
Deciduous Trees ◽  
Trembling Aspen ◽  
Calamagrostis Canadensis ◽  
Edaphic Conditions ◽  
Over Time

This study assessed the dynamics of gap development in postharvest regeneration in five stands in northwestern Alberta dominated by trembling aspen (Populus tremuloides Michx.). The pattern of gap development over time was determined from analysis of air photographs taken preharvest and 1, 4, 10, and 12 years postharvest. The area of each stand covered by gaps increased after harvest because of the addition of harvest-related gaps over and above those that had been present prior to harvest. The blocks we studied had a combined gap area of up to 29% of stand area 12 years postharvest. We measured regeneration characteristics, microsite, soil, light, and browse conditions in 30 aspen regeneration gaps (gaps in regeneration that were not gaps preharvest and were not due to obvious harvest-related disturbance) 14 years following harvest. Although deciduous trees within postharvest regeneration gaps were the same age as those outside (i.e., in a fully stocked matrix of newly established even-aged aspen stems), they were often suppressed, with significantly lower density and growth. Within the 14-year-old postharvest regenerating aspen stands, aspen height varied from 1 to 11 m; this substantial variability appeared to be largely due to the influence of browsing. There was little evidence of ongoing regeneration within postharvest regeneration gaps, indicating that these gaps will probably persist over time. This may impact future deciduous stocking and volume. It is unknown what may have initiated the formation of these gaps, although results suggest that they are not due to edaphic conditions or disease in the preharvest stands. There is evidence that bluejoint (Calamagrostis canadensis (Michx.) Beauv.) cover and browsing are important factors in the maintenance of postharvest regeneration gaps. The spatial heterogeneity resulting from gaps could be advantageous, however, either as part of ecosystem-based management emulating natural disturbance or as a template for mixedwood management, where white spruce (Picea glauca (Moench) Voss) are established in gaps.

The utility of the two-pass harvesting system: an analysis using the ecosystem simulation model FORECAST

2002 ◽  
Vol 32 (6) ◽  
pp. 1071-1079 ◽  
Author(s):  
Clive Welham ◽  
Brad Seely ◽  
Hamish Kimmins
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Ecosystem Model ◽  
Yield Potential ◽  
Model Forecast ◽  
Pass System ◽  
System A ◽  
Ecosystem Simulation ◽  
Harvesting Systems

The ecosystem model FORECAST was used to simulate the yield potential in Saskatchewan mixedwoods of the two-pass harvesting system. The simulated two-pass stand consisted of an overstory population of pure trembling aspen (Populus tremuloides Michx.) with a white spruce (Picea glauca (Moench) Voss) understory. The aspen was removed at year 60, and yields of the understory spruce and resprouting aspen were simulated for 80 years thereafter. The two-pass simulations were compared with two simulated conventional harvesting systems. The first system consisted of a single final harvest at year 140. In the second system, a clearcut was conducted at year 60. White spruce was then planted in the subsequent year at 400, 600, or 800 stems/ha, and aspen also permitted to resprout. Growth was then simulated for a further 80 years. FORECAST projections indicated that the two-pass system might be effective for releasing the white spruce understory, achieving at least a twofold gain in spruce volume relative to conventional methods. Furthermore, total volumes exceeded those derived from the unmanaged stand, while second rotation yields of aspen declined with spruce understory density. These simulations suggest the two-pass harvesting system has strong potential as a tool for mixedwood management.

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