Early growth of white spruce underplanted beneath spaced and unspaced aspen stands in northeastern British Columbia

2004 ◽  
Vol 34 (11) ◽  
pp. 2277-2283 ◽  
Author(s):  
Philip G Comeau ◽  
Cosmin N Filipescu ◽  
Richard Kabzems ◽  
Craig DeLong
Keyword(s):  
British Columbia ◽  
Growth Rates ◽  
White Spruce ◽  
Early Growth ◽  
Understory Vegetation ◽  
Diameter Growth ◽  
Seedling Height ◽  
Trembling Aspen ◽  
Growth Of Seedlings

We examined the growth of white spruce planted underneath a 33-year-old stand of trembling aspen following thinning and fertilization. Thinning the stand to 2000 stems·ha–1 resulted in increased light reaching spruce seedlings and significant increases in height and diameter growth of seedlings over that observed in either the unspaced or 3000 stems·ha–1 treatments. Fertilization (applied 3 years prior to planting) stimulated development of understory vegetation and did not benefit the planted spruce. While growth was improved by thinning, the benefits of the thinning treatment to establishment of white spruce appeared to be small, and amounted to increasing seedling height from 62 cm (unthinned) to 73 cm (thinned to 1000 or 2000 stems·ha–1) at the end of 5 years. Results indicated that when stands are thinned for the purpose of accelerating growth rates of underplanted spruce, residual basal areas above 25 m2·ha–1 should be retained to suppress growth of understory vegetation. Comparison of height at age 5 for seedlings planted under untended stands at Fort Nelson with three sites near Dawson Creek indicated no differences between locations, when height at the time of planting was included as a covariate.

The effects of overstory shading on white pine weevil damage to white spruce and its effects on spruce growth rates

1996 ◽  
Vol 26 (2) ◽  
pp. 306-312 ◽  
Author(s):  
S.P. Taylor ◽  
C. Delong ◽  
R.I. Alfaro ◽  
L. Rankin
Keyword(s):  
British Columbia ◽  
Retrospective Study ◽  
Growth Rates ◽  
White Spruce ◽  
Optimum Level ◽  
Volume Loss ◽  
White Pine ◽  
Pine Weevil ◽  
White Pine Weevil ◽  
Extensive Damage

A retrospective study was conducted in 1993 that quantified the effects of overstory shading on both spruce weevil (Pissodesstrobi (Peck)) and leader growth on white spruce (Piceaglauca (Moench) Voss × Piceaengelmannii Parry ex Engelm.). The study was undertaken in the interior of British Columbia, where the weevil is causing extensive damage to plantations of white spruce. Shading on the spruce trees was measured by calculating the light interception index and percent overstory cover on individual white spruce trees at the centre of a 2.52 m radius plot. Current weevil attacks decreased significantly with increasing overstory cover, and the rate of decrease was greater in heavily versus lightly attacked stands. Shading also decreased leader growth. These results indicate that the optimum level of overstory removal may be a compromise between volume loss due to overstory competition and volume gain due to decreased weevil attacks.

Structure and dynamics of trembling aspen – white spruce mixed stands near Fort Nelson, B.C.

2004 ◽  
Vol 34 (2) ◽  
pp. 384-395 ◽  
Author(s):  
Richard Kabzems ◽  
Oscar García
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Stand Structure ◽  
White Spruce ◽  
Structure Type ◽  
Growth Patterns ◽  
Site Quality ◽  
Diameter Growth ◽  
Trembling Aspen ◽  
Mixed Stands

The trembling aspen (Populus tremuloides Michx.) – white spruce (Picea glauca (Moench) Voss) mixed woods near Fort Nelson are distinguished by the large size of individual trees, longevity, and the low occurrence of internal decay in trembling aspen. The development of these forest ecosystems has had limited documentation and may be significantly different than those described in other portions of the boreal forest. At five study stands, stem analysis techniques were used to examine the patterns of height and radial growth over time according to species and structure type. There were two patterns of species establishment that were consistent with the stand structure. In codominant stands, recruitment periods for trembling aspen and white spruce overlapped. The stratified stands were consistently associated with a 29- to 58-year lag in white spruce recruitment. Spruce that were codominant with aspen at the time of sampling had sustained periods of rapid height and diameter growth. White spruce that were later to establish on site had slower rates of height and diameter growth. White spruce ages indicated that a dominant recruitment episode was more common than continuous recruitment. Height and diameter growth of trembling aspen were similar in both stand types. The differences in trembling aspen growth patterns between stands were due to site quality. The white spruce in codominant stands did not appear to go through a period of suppression and then release associated with stand-level trembling aspen mortality, as commonly described for other boreal mixedwoods. The vigor and longevity of trembling aspen in Fort Nelson appear to prolong the period of trembling aspen domination of mixed stands well beyond the time periods observed in other boreal ecosystems.

The Winter Flounder (Pseudopleuronectes americanus) in Long Pond, Conception Bay, Newfoundland

1971 ◽  
Vol 28 (8) ◽  
pp. 1153-1165 ◽  
Author(s):  
V. S. Kennedy ◽  
D. H. Steele
Keyword(s):  
Food Intake ◽  
Growth Rates ◽  
Plant Material ◽  
Early Growth ◽  
Winter Flounder ◽  
Pseudopleuronectes Americanus ◽  
Food Items ◽  
Fish Remains ◽  
Males And Females ◽  
Conception Bay

Monthly samples of winter flounder taken in Long Pond from November 1962 to October 1963 indicated that the flounder moved into deeper water (7–10 m) during the summer and returned to shallow water (1–2 m) from September to June. These movements corresponded to the end of the spawning season and the ripening of the gonads respectively. Spawning occurred from March until early June, most of it in May and early June. Most males were mature at age 6 and most females at age 7. Fifty percent of the males and females were mature at 21 and 25 cm respectively. The growth rates of the males and females were similar until the age of 8, after which the females apparently outgrew the males. Early growth and fecundity were similar to those reported for other areas. No feeding took place in December or January but the flounder fed in March and continued to feed throughout the summer; food intake decreased in the fall. They were omnivorous and the type of food eaten varied with the locality. Polychaetes, plant material, and molluscs were the most common food items throughout the year. Capelin eggs and fish remains were found only during a few months of the year but were eaten in great quantities.

scholarly journals Identifying and Characterizing Important Trembling Aspen Competitors with Juvenile Lodgepole Pine in Three South-Central British Columbia Ecosystems

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Teresa A. Newsome ◽  
Jean L. Heineman ◽  
Amanda F. Linnell Nemec
Keyword(s):  
British Columbia ◽  
Lodgepole Pine ◽  
Geographic Range ◽  
Regression Analyses ◽  
Relative Height ◽  
Trembling Aspen ◽  
Ecosystem Productivity ◽  
Height Ratio ◽  
Critical Height ◽  
South Central

Critical height ratios for predicting competition between trembling aspen and lodgepole pine were identified in six juvenile stands in three south-central British Columbia ecosystems. We used a series of regression analyses predicting pine stem diameter from the density of neighbouring aspen in successively shorter relative height classes to identify the aspen-pine height ratio that maximizedR2. Critical height ratios varied widely among sites when stands were 8–12 years old but, by age 14–19, had converged at 1.25–1.5. MaximumR2values at age 14–19 ranged from 13.4% to 69.8%, demonstrating that the importance of aspen competition varied widely across a relatively small geographic range. Logistic regression also indicated that the risk of poor pine vigour in the presence of aspen varied between sites. Generally, the degree of competition, risk to pine vigour, and size of individual aspen contributing to the models declined along a gradient of decreasing ecosystem productivity.

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.

Growth, morphology, and gas exchange in white spruce (Picea glauca) seedlings acclimated to different humidity conditions

2001 ◽  
Vol 31 (6) ◽  
pp. 1038-1045 ◽  
Author(s):  
Jessica J Roberts ◽  
Janusz J Zwiazek
Keyword(s):  
Relative Humidity ◽  
Growth Rates ◽  
Picea Glauca ◽  
White Spruce ◽  
Physiological Characteristics ◽  
Growth Morphology ◽  
Early Seedling Growth ◽  
Second Growth ◽  
Early Seedling ◽  
Net Assimilation

The study examined the effects of different relative humidity conditions at germination, early growth, and following cold storage on morphological and physiological characteristics of white spruce (Picea glauca (Moench) Voss) seedlings. Seedlings that were grown for 18 weeks following seed germination at the lower, 30% RH (RHinitial) treatments were shorter and had smaller stem diameters, shorter needles with more epicuticular wax, and a greater density of needles per centimetre stem, compared with the 80% RHinitial seedlings. After 18 weeks of growth under 30, 50, and 80% RH, the seedlings were hardened off, stored for 8 weeks at 3°C and planted in pots in growth chambers under 42 and 74% relative humidity (RHsubsequent). Under 74% RHsubsequent conditions, the lower RHinitial seedlings flushed sooner and had higher growth rates compared with the higher RHinitial seedlings. When the higher RHinitial seedlings were placed under 42% RHsubsequent conditions, their bud flush was delayed, and subsequent growth rates were lower compared with the lower RHinitial seedlings. When measured at 40% RH, seedlings subjected to lower RHinitial had higher net assimilation rates and stomatal conductance compared with the seedlings acclimated to higher RHinitial humidity. It was concluded that the humidity conditions present during early seedling growth following germination significantly affect their morphological and physiological characteristics during the second growth season.

Population studies of white spruce. II. Natural inbreeding and relatedness among neighboring trees

1984 ◽  
Vol 14 (6) ◽  
pp. 909-913 ◽  
Author(s):  
Y. S. Park ◽  
D. P. Fowler ◽  
J. F. Coles
Keyword(s):  
New Brunswick ◽  
Population Studies ◽  
White Spruce ◽  
Early Growth ◽  
Height Growth ◽  
The Self ◽  
Open Pollination ◽  
Early Seedling ◽  
Natural Stands ◽  
Lethal Genes

Natural inbreeding and relatedness among neighboring trees were studied in several central New Brunswick populations of white spruce (Piceaglauca (Moench) Voss). Coefficients of relationship (r) were estimated by comparing the self-, neighbor-, open-, and unrelated-pollination effects on percent full seed. The estimates were 0.29 and 0.28 for neighbor and open pollinations, respectively. The effects of natural inbreeding on juvenile traits, e.g., germination and early growth, were slight while the effect on height growth increased with age at least to age 7 years. Neighboring white spruce trees growing in natural stands appear to be related at about the half-sib level (r = 0.25). Based on percent full seed, open-pollination approximates a level of inbreeding expected from trees related at a level well above that of half-sibs. Differential selection at the pre-embryo to early seedling stages results in progenies again related at the half-sib level. It is suggested that an inbreeding equilibrium exists in natural stands of white spruce and that this equilibrium approximates that expected from half-sib matings (F = 0.125). The inbreeding equilibrium is controlled, at least in part, by the frequency of lethal genes in the populations.

scholarly journals Adjacency to a harvest trail increases drought resistance of interior Douglas-fir (Pseudotsuga menziesii var. glauca) in partially harvested stands in central British Columbia

2018 ◽  
Vol 48 (7) ◽  
pp. 809-820 ◽  
Author(s):  
Neil P. Thompson ◽  
Kathy J. Lewis ◽  
Lisa M. Poirier
Keyword(s):  
British Columbia ◽  
Drought Tolerance ◽  
Pseudotsuga Menziesii ◽  
Growth Rates ◽  
Habitat Management ◽  
Odocoileus Hemionus ◽  
Douglas Fir ◽  
Ring Analysis ◽  
The Relationship

Drought tolerance of trees may be affected by competition, but most studies quantifying the relationship do not consider the effect of stem clustering. Trees are often clustered in interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mayr) Franco) forests near the grassland interface in central British Columbia due to past harvesting practices or habitat management for mule deer (Odocoileus hemionus hemionus (Rafinesque, 1817)). Climate change projections indicate continued increases in temperature, an outcome that would stress trees growing in dry environments. Trees placed in different states of competition by mechanical harvesting in the 1970s were sampled to provide a 40-year comparison of three levels of competition during 1–2 year droughts. Tree-ring analysis was used to assess the reduction in growth during drought years and resumption of growth in subsequent years. A clear separation of growth rates was evident between open-growing trees, trees on the edge of harvesting trails, and trees within the unharvested interior. Edge trees had intermediate growth rates but no differences were found in the long-term climate–growth relationship compared with open-growing trees. Both Edge and Open classes showed less relative growth reduction during droughts than Interior trees growing between harvest trails. Precipitation throughfall rates and competition for resources are likely driving short-term drought tolerance in combination with other factors.

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