Natural regeneration of white spruce in aspen-dominated boreal mixedwoods following harvesting

2010 ◽  
Vol 40 (3) ◽  
pp. 585-594 ◽  
Author(s):  
Jonathan Martin-DeMoor ◽  
Victor J. Lieffers ◽  
S. Ellen Macdonald
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Natural Regeneration ◽  
Boreal Forests ◽  
Weather Conditions ◽  
White Spruce ◽  
Woody Vegetation ◽  
Silvicultural Treatments ◽  
Boreal Mixedwoods ◽  
Time Of Harvest

In some boreal forests sites, there are considerable amounts of natural regeneration of white spruce ( Picea glauca (Moench) Voss) after logging, even without silvicultural treatments to encourage establishment. We assessed the factors controlling the amount of this regeneration 8–15 years postharvest on previously aspen-dominated ( Populus tremuloides Michx.) boreal mixedwood sites. We surveyed 162 transects across 81 cutovers, exploring the effects of mast years, season of harvest, distribution of seed trees, weather conditions around the time of harvest, and abundance of grass or woody vegetation on white spruce regeneration. Substantial amounts of naturally regenerated white spruce were found; however, sites with no seed trees had virtually no spruce regeneration. Average stocking was 7% (percentage of 9 m2 plots along a transect across a cutover that had at least one seedling), ranging from 0% to 62%. Stocking levels were higher in cutblocks that had been harvested in the summer, prior to seedfall of a mast year, and where there was a seed source within 60 m. Stocking was lower when conditions were cool and wet the year before and 2 years after harvest and when the site contained extensive cover of grass or woody vegetation.

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 Implications of selected approaches for regenerating and managing western boreal mixedwoods

2005 ◽  
Vol 81 (4) ◽  
pp. 559-574 ◽  
Author(s):  
Philip G Comeau ◽  
Richard Kabzems ◽  
John McClarnon ◽  
Jean L Heineman
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Management Strategies ◽  
Structural Diversity ◽  
White Spruce ◽  
Forest Types ◽  
Successful Management ◽  
Flexible Planning ◽  
Boreal Mixedwoods ◽  
Stand Conditions

We describe a range of approaches for managing boreal mixedwood stands composed of trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) in British Columbia and Alberta. Successful management of these complex forests requires a combination of well-defined objectives at the landscape level and flexible planning at the stand level. A variety of management strategies must be applied concurrently across the landscape to ensure that the natural mix of forest types and structural diversity is maintained. Selected approaches are discussed with regard to their suitability to particular stand conditions and sets of objectives, the types of tending and harvesting activities required, expected outcomes, and costs. The three approaches discussed are: 1) creation and management of two-storied intimate mixtures; 2) creation of a single-storied mixture of aspen and white spruce; and, 3) creation of a mosaic of discrete patches of each species. Key words: boreal mixedwood management, mixedwood silvicultural systems, aspen, white spruce, planning

Juvenile response to conifer release alternatives on aspen-white spruce boreal mixedwood sites.Part I: Stand structure and composition

2005 ◽  
Vol 81 (4) ◽  
pp. 538-547 ◽  
Author(s):  
Douglas G Pitt ◽  
F. Wayne Bell
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Stand Structure ◽  
Foliar Application ◽  
White Spruce ◽  
Fibre Production ◽  
Stem Volume ◽  
Stem Quality ◽  
Commercial Species ◽  
Boreal Mixedwoods

Stand structure and composition for planted white spruce (Picea glauca (Moench) Voss) and other naturally regenerating commercial species were compared seven years after the testing of five conifer release alternatives on three boreal mixedwood sites. No release resulted in aspen (Populus tremuloides Michx.) -dominated stands with 89% stocking and the highest basal areas (BAs, 5.1 m2/ha) and stem volume indices (SVIs, 10.7 m3/ha) observed. Release by manual or machine cutting increased planted spruce BA and SVI by 67 and 38%, respectively. However, this treatment also caused significant root and stump suckering of aspen, more than doubling stem densities and increasing stocking by 12% over untreated areas. Although cutting reduced the height of aspen from 6 m (untreated) to 2–3 m, equal to or just taller than planted spruce, it is likely that future growth will result in deciduous-dominated mixedwoods. Broadcast foliar application with Release® herbicide temporarily reduced the size of aspen, without causing the increased regeneration observed following cutting. This produced a more varied stand structure that promoted the stature of planted spruce, doubling dominant spruce stocking, BAs, and SVIs, and leading to a more balanced mixedwood. Broadcast release with Vision® herbicide produced conifer-dominated stands with few deciduous stems; these areas contained the lowest observed BAs (1.7 m2/ha) and SVIs (1.9 m3/ha). Relatively low planting densities (1350 sph), coupled with near complete deciduous removal in these plots, created very open-grown conditions that threaten overall productivity and stem quality of the spruce. The five approaches tested are capable of producing a range of stand conditions found in a healthy boreal mixedwood landscape. Key words: boreal mixedwoods, white spruce, trembling aspen, vegetation management, fibre production

scholarly journals Creating boreal mixedwoods by planting spruce under aspen: successful establishment in uncertain future climates

2016 ◽  
Vol 46 (10) ◽  
pp. 1217-1223 ◽  
Author(s):  
Richard Kabzems ◽  
Philip G. Comeau ◽  
Cosmin N. Filipescu ◽  
Bruce Rogers ◽  
Amanda F. Linnell Nemec
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Basal Area ◽  
Cost Effective ◽  
White Spruce ◽  
Understory Vegetation ◽  
Severe Drought ◽  
Boreal Mixedwoods ◽  
Uncertain Future ◽  
Canadian Boreal Forest

Planting white spruce (Picea glauca (Moench) Voss) under established aspen (Populus tremuloides Michx.) stands has substantial potential for regenerating mixedwood ecosystems in the western Canadian boreal forest. The presence of an aspen overstory serves to ameliorate frost and winter injury problems and suppresses understory vegetation that may compete with white spruce. Under future climatic regimes with more frequent and severe drought episodes, underplanting may be a cost-effective strategy for lowering the risk of mortality in mixedwood regeneration. We examine the growth of white spruce during the first 18 years after being planted beneath a 39-year-old stand of trembling aspen. Treatments included thinning from over 6000 stems·ha−1 to 3000, 2000, and 1000 stems·ha−1 and fertilization. Initial stimulation of understory vegetation by fertilization had no measureable effect on spruce heights or diameters at year 18. Aspen thinning treatments did not have a significant effect on spruce height growth rates after spruce crowns had emerged above the understory shrub layer due to rapid aspen basal area increases after thinning. Small, but significant, increases for spruce height and diameter were present in the 1000 and 2000 stem·ha−1 aspen thinnings. A much wider range of aspen stand conditions may be suitable for planting spruce to create mixedwood ecosystems than has been previously considered.

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 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.

Elevated mortality of residual trees following structural retention harvesting in boreal mixedwoods

2008 ◽  
Vol 84 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Kevin D Bladon ◽  
Victor J Lieffers ◽  
Uldis Silins ◽  
Simon M Landhäusser ◽  
Peter V Blenis
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Boreal Forests ◽  
Sustainable Forest Management ◽  
Mortality Rates ◽  
Permanent Sample Plots ◽  
Mixedwood Forests ◽  
Boreal Mixedwoods ◽  
Structural Retention ◽  
Annual Mortality

In recent years boreal forests have been harvested to retain a portion of the original canopy, thereby providing forest structure, mostly for biodiversity reasons. Boreal mixedwood cutovers were surveyed at one and five years after harvesting with approximately 10% structural retention, to quantify the mean annual mortality rates of the residual trembling aspen, balsam poplar, paper birch and white spruce trees. For comparison, "natural" mortality rates by species were estimated from permanent sample plots in stands of similar composition. Species ranking of the annual mortality rates of residuals in areas harvested with structural retention were: poplar (10.2%) > birch (8.7%) > aspen (6.1%) > spruce (2.9%). Annual mortality rates were 2.5 to 4 times greater than in the reference stands. The majority of broadleaved species died as snags (~70%–90%), while most spruce died due to windthrow (80%). Mortality rates increased with slenderness coefficient for codominant and understory poplar and for understory birch. For aspen, codominants were most likely to die, while in spruce, dominant trees and trees with the greatest damage to the bole from harvesting operations had the highest mortality. Key words: Alberta, Betula papyrifera, dieback, harvesting damage, mixedwood forests, variable retention, Picea glauca, Populus balsamifera, Populus tremuloides, structural retention, sustainable forest management

Glyphosate Herbicide: An Assessment of Forestry Potential

1978 ◽  
Vol 54 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Roy F. Sutton
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Woody Species ◽  
Ground Level ◽  
White Spruce ◽  
Woody Vegetation ◽  
First Year ◽  
Height Increment ◽  
White Birch ◽  
Second Year

Environmentally safe, yet potent in controlling herbs, grasses, and woody species, with possibilities for selective use, glyphosate (Roundup®) has great potential usefulness in forestry.In the small study reported here, twelve.01 ha plots were established in August, 1973 in dense 6-year-old shrub and hardwood post-fire regrowth near Chapleau, Ontario. In each plot, 16 rising 3 + 0 white spruce (Picea glauca [Moench] Voss) were planted centrally at.9 m ×.9 m spacing. Six treatments with two replications were applied at random the next day: 1, control; 2, all woody vegetation cut off at ground level; 3, all woody vegetation cut off in central planted area of plot; 4, sprayed with 60 mL glyphosate in 1.892 L of water; 5, sprayed with double strength glyphosate; 6, sprayed with sextuple strength glyphosate. Eight trees in each plot were shielded during the spraying. Browsing affected 16% of the spruce after 2 weeks, 96% by spring. Half of each plot was replanted with eight white spruce (four of them caged against browsing) in May, 1974.The objectives were to observe the effect of glyphosate on hardwood and shrub competition, to assay this effect by white spruce outplantings, and to evaluate the resistance to glyphosate of newly planted white spruce. Glyphosate was highly effective in killing trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), and beaked hazel (Corylus cornuta Marsh.): pin cherry (Prunus pensylvanica L. f.) resprouted with moderate vigor. White spruce responded significantly (P.01) to first-year non-herbicide (i.e., immediate) weed control, but second-year height increment was significantly (P.001) less than that of the first year: second-year height increment in the glyphosate treatments was significantly (P.001) greater than in the non-herbicide treatments. Growth and survival were both affected by non-treatment disturbances, but shielding during spraying improved second-year survival significantly (P.001).

scholarly journals Effects of substrate availability and competing vegetation on natural regeneration of white spruce on logged boreal mixedwood sites

2018 ◽  
Vol 48 (4) ◽  
pp. 324-332 ◽  
Author(s):  
Nicola A. Kokkonen ◽  
S. Ellen Macdonald ◽  
Ian Curran ◽  
Simon M. Landhäusser ◽  
Victor J. Lieffers
Keyword(s):  
Picea Glauca ◽  
Natural Regeneration ◽  
Negative Impact ◽  
Mineral Soil ◽  
Soil Surface ◽  
White Spruce ◽  
Solid Wood ◽  
Seedling Mortality ◽  
Competing Vegetation ◽  
Survival And Growth

Given a seed source, the quality of available substrates is a key factor in determining the success of white spruce (Picea glauca (Moench) Voss) natural regeneration. We examined the influence of substrate and competing vegetation on survival and growth of natural regeneration of white spruce up to 4 years following harvesting in deciduous-dominated upland boreal mixedwood sites. Feather moss, thick soil surface organic layers, litter, and solid wood were poor substrates for establishment. Early successional mosses establishing on mineral soil, thin organics, and rotten wood were generally favourable microsites but were not highly available on postharvest sites. Mineral soil substrates were not as suitable as expected, likely because on a postlogged site, they are associated with unfavourable environmental characteristics (e.g., low nutrient availability, exposure). There was some evidence that survival and growth of seedlings were improved by surrounding vegetation in the first years, but heavy competing vegetation had a negative impact on older seedlings. Burial by aspen litter greatly increased seedling mortality, especially when combined with a brief period of submergence due to heavy spring snowmelt. The results provide insight into conditions under which natural regeneration could be an option for establishing white spruce following harvesting of deciduous-dominated boreal mixedwood forests.

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