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

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.

1999 ◽  
Vol 29 (7) ◽  
pp. 993-1001 ◽  
Author(s):  
E C Cole ◽  
M Newton ◽  
A Youngblood

The current spruce bark beetle (Dendroctonus rufipennis Kirby) epidemic in interior Alaska is leaving large expanses of dead spruce with little spruce regeneration. Many of these areas are habitat for moose (Alces alces). To establish spruce regeneration and improve browse production for moose, paper birch (Betula papyrifera Marsh), willow (Salix spp.), and three stocktypes (plug+1 bareroot, and 1+0 plugs from two nurseries) of white spruce (Picea glauca (Moench) Voss) were planted in freshly cutover areas on Fort Richardson, near Anchorage. Four vegetation-management treatments were compared: broadcast site preparation with herbicides, banded site preparation with herbicides, mechanical scarification, and untreated control. Spruce seedlings had the greatest growth in the broadcast site preparation treatment (p < 0.01). Stocktype was the most important factor in spruce growth, with bareroot transplant seedlings being the tallest and largest 5 years after planting (p < 0.001). In the first 3 years, relative stem volume growth was greater for plug seedlings than for bareroot seedlings (p < 0.001). By year 4, relative growth rates were similar among all stocktypes. Treatment effects for paper birch and willow were confounded by moose browsing. Results indicate spruce can be regenerated and moose browse enhanced simultaneously in forests in interior Alaska.


2019 ◽  
Vol 49 (5) ◽  
pp. 463-470 ◽  
Author(s):  
Suzanne Brais ◽  
Brian D. Harvey ◽  
Arun K. Bose

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.


1980 ◽  
Vol 56 (1) ◽  
pp. 21-27 ◽  
Author(s):  
W. M. Stiell

In 1958 a thinning experiment to examine the relation of stand growth of white spruce (Picea glauca (Moench) Voss) to density of residual growing stock was established at the Petawawa national Forestry Institute in a 33-year-old plantation growing on a sandy old-field site. A treatment series consisted of sample plots thinned from below to basal area levels of 18.4, 25.3 and 32.1 m2/ha, together with unthinned plots serving as controls. Two such replicates were established. The plots were remeasured and thinned again to the prescribed basal areas in 1968 and 1978. Diameter growth and form quotient were clearly related to degree of thinning. Volume growth was reduced at the lowest residual basal area. The untreated plots contained the highest volume in 1978 but mortality had reduced their total production of merchantable wood by about 10% compared with the thinnings plus standing crop of the two lighter treatments. Thinning to leave a basal area in the range of about 22 to 35 m2/ha should yield 11 to 60 m3/ha of merchantable wood, depending on plantation age and intensity of cut, without reducing stand growth.


2005 ◽  
Vol 35 (3) ◽  
pp. 511-520 ◽  
Author(s):  
Eddie Bevilacqua ◽  
David Puttock ◽  
Terence J Blake ◽  
Darwin Burgess

The magnitude and duration of the growth response in residual trees following silvicultural release treatments are measures used to assess the success of silvicultural practices. Eighty-eight eastern white pine (Pinus strobus L.) trees, representing three different dominance classes, were sampled destructively from stands from a single study site that included areas of both unharvested (control) and silvicultural release treatments. The study area consisted of several pine mixedwood stands with understory white pine growing in association with an overstory of predominantly intolerant hardwoods. Annual height, diameter, basal area, stem and sawtimber volume increment, pattern of stem increment allocation along the bole, stem form, and height–diameter ratio were reconstructed over a postrelease period of 23 years using detailed stem analysis. Within 3 years of release, white pine in all dominance classes showed significant increases in diameter, basal area, and volume increment compared with control trees. Differences in the volume increment between released and control trees varied with canopy position, with emergent trees showing the greatest increased volume growth, followed by dominant and intermediate classes, respectively. A temporary shift in the growth allocation pattern along the bole varied depending on crown class, suggesting a period of growth adjustment during which trees are acclimating to changes in resource availability and wind exposure. The shift in growth allocation contributed to increased stem taper, resulting in decreased form class and height–diameter ratios in the released trees.


2016 ◽  
Vol 46 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
Jessica Smith ◽  
Brian D. Harvey ◽  
Ahmed Koubaa ◽  
Suzanne Brais ◽  
Marc J. Mazerolle

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.


2013 ◽  
Vol 59 (No. 4) ◽  
pp. 137-149 ◽  
Author(s):  
Ch.D.B. Hawkins ◽  
A. Dhar

Current British Columbia forest regulations drive the regeneration management towards pure conifer stands rather than remaining in a mixed-species condition. This approach may result in unnecessary vegetation control. The main objective of this investigation was to study the impact of variable paper birch densities on white spruce growth in 15&ndash;20 years old stands for management implications. Regression analysis was used to examine the effect of birch density and two competition indices to predict spruce growth. A mixed model ANOVA showed that spruce mean annual DBH and basal area increment differed significantly among sites and density. From the regression analysis it appears that birch density up to 4,000 stems&middot;ha<sup>&ndash;1</sup> had no significant influence on spruce growth which is much higher than the current BC reforestation guideline (1,000 stems&middot;ha<sup>&ndash;1</sup> broadleaves). Similarly, birch relative density index (RDI) had to exceed 3 to affect spruce DBH growth significantly on all sites except one. On most sites, spruce had a larger DBH than birch. Our results also suggest that rather than following the current broadcast approach to vegetation management, a targeted approach could enhance forest productivity and stand diversity. &nbsp;


2000 ◽  
Vol 76 (4) ◽  
pp. 643-652 ◽  
Author(s):  
Patricia Raymond ◽  
Jean-Claude Ruel ◽  
Marius Pineau

Stand regeneration failures, sometimes observed in rich second growth balsam fir stands, prompted a study in 1991 to assess the effects of the shelterwood cutting system on regeneration of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss) and paper birch (Betula papyrifera Marsh). The factorial experiment design (split-plot) includes forest cover reduction (0% and 25% of basal area) in main plots and germination substrate (mineral soil, litter removed and control) in subplots. Results of five growing seasons showed that germination substrate was the main factor determining first-year seedling establishment, and that cover reduction became important for seedling survival and long-term establishment of the three species. A 25% canopy reduction combined with mineral seedbed treatment resulted in the best regeneration densities of the three species. Thus far, the results demonstrate the importance of combining humus disturbance to seed cutting in order to achieve regeneration goals set for the future stand. Key words: shelterwood cutting system, balsam fir, white spruce, paper birch, regeneration, seed cutting, germination substrate


1988 ◽  
Vol 12 (4) ◽  
pp. 252-256 ◽  
Author(s):  
Stephen G. Dicke ◽  
John R. Toliver

Abstract Crown thinning a 63-year-old stand of baldcypress (Taxodium distichum [L.] Rich.) averaging 220 ft²/ac of basal area to 180, 140, and 100 ft²/ac resulted in 5-year diameter growths of 0.44, 0.51, and 0.77 in., respectively. The unthinned control was significantly less at 0.31 in. Six-year height growth averaged 3.1 ft and was not influenced by treatment. Thinning to 140 and 100 ft²/ac stimulated epicormic branching on many trees, which may lower log quality. All crown thinning treatments appeared to increase sawtimber volume increment and sawtimber volume/ac over the control 5 years after thinning. South. J. Appl. For. 12(4):252-256.


2019 ◽  
Vol 49 (11) ◽  
pp. 1471-1482
Author(s):  
Woongsoon Jang ◽  
Bianca N.I. Eskelson ◽  
Louise de Montigny ◽  
Catherine A. Bealle Statland ◽  
Derek F. Sattler ◽  
...  

This study was conducted to quantify growth responses of three major commercial conifer species (lodgepole pine (Pinus contorta Douglas ex Loudon var. latifolia Engelm. ex S. Watson), interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco), and spruce (white spruce (Picea glauca (Moench) Voss) and hybrid spruce (Picea engelmannii Parry ex. Engelm. × Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carrière))) to various fertilizer blends in interior British Columbia, Canada. Over 25 years, growth-response data were repeatedly collected across 46 installations. The fertilizer blends were classified into three groups: nitrogen only; nitrogen and sulfur combined; and nitrogen, sulfur, and boron combined. The growth responses for stand volume, basal area, and top height were calculated through absolute and relative growth rate ratios relative to a controlled group. Fertilizer blend, inverse years since fertilization, site index, stand density at fertilization, and their interactions with the fertilizer blend were used as explanatory variables. The magnitude and significance of volume and basal area growth responses to fertilization differed by species, fertilizer-blend groups, and stand-condition variables (i.e., site index and stand density). In contrast, the response in top height growth did not differ among fertilization blends, with the exception of the nitrogen and sulfur fertilizer subgroup for lodgepole pine. The models developed in this study will be incorporated into the current growth and yield fertilization module (i.e., Table Interpolation Program for Stand Yields (TIPSY)), thereby supporting guidance of fertilization applications in interior forests in British Columbia.


1993 ◽  
Vol 17 (3) ◽  
pp. 135-138 ◽  
Author(s):  
Eric J. Jokela ◽  
Stephen C. Stearns-Smith

Abstract Data from six fertilizer trials established in semimature southern pine stands (five slash pine, Pinus elliottii Engelm. var. elliottii; one loblolly pine, Pinus taeda L.) were analyzed to determine the efficacy of single vs. split fertilizer treatments. Both fertilizer treatments supplied an elemental equivalent of 200 lb nitrogen (N)/ac and 50 lb phosphorus (P)/ac; however, the first treatment was delivered as a single dose, and the second treatment was a split N application (i.e., 50 lb N and 50 lb P/ac (initial); 150 lb N/ac (2 yr later). Cumulative responses of fertilized plots were still significantly greater than the controls in five trials after 8 yr and averaged 43% (15.7 ft²/ac) and 39% (607 ft³/ac) for basal area and stand volume growth, respectively. In general, no significant differences in either the magnitude or duration of response were detected between the single and split N fertilizer treatments. This suggests that delaying a portion of the N application for 2 yr will not diminish the level of growth responses attained. Therefore, land managers have flexibility in using either application method when implementing midrotation fertilizer prescriptions. South. J. Appl. For. 17(3):135-138.


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