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.

The reduction of organic-layer depth by wildfire in the North American boreal forest and its effect on tree recruitment by seed

2007 ◽  
Vol 37 (6) ◽  
pp. 1012-1023 ◽  
Author(s):  
David F. Greene ◽  
S. Ellen Macdonald ◽  
Sybille Haeussler ◽  
Susy Domenicano ◽  
Josée Noël ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Inverse Function ◽  
Organic Layer ◽  
Layer Depth ◽  
Tree Recruitment ◽  
Organic Layers ◽  
Boreal Region ◽  
The North ◽  
Forest Species Composition

We compared prefire and postfire organic-layer depths in boreal forest types (14 fires) across Canada, and examined tree recruitment as a function of depth. There was extensive within-stand variation in depth, much of it due to clustering of thinner organic layers around boles. There were no significant differences in postfire organic-layer depth among sites with different prefire forest species composition, but sites in the eastern boreal region had thicker postfire organic layers than those in the western boreal region. Mean organic-layer depth was much greater in intact stands than after fires; overall, fire reduced organic-layer depth by 60%, largely because of increases in the area of thin (<3 cm) organic layers (1% in intact stands vs. 40% in postfire stands). There was more variation in organic-layer depth within postfire than within prefire stands; notably, some areas in postfire stands were deeply combusted, while adjacent parts were only lightly combusted. We speculate that the diminished role of energy loss to latent heat around tree boles increased organic-layer consumption around tree boles. Seedlings were clustered around burned tree bases, where organic layers were thinner, and the dependence of a species on thin organic layers was an inverse function of seed size.

Net nitrogen mineralization and nitrification in trembling aspen forest soils on the Boreal Plain

2003 ◽  
Vol 33 (11) ◽  
pp. 2262-2268 ◽  
Author(s):  
N Carmosini ◽  
K J Devito ◽  
E E Prepas
Keyword(s):  
Populus Tremuloides ◽  
N Mineralization ◽  
Growing Season ◽  
Large Contribution ◽  
Net N Mineralization ◽  
Trembling Aspen ◽  
Mineral Horizon ◽  
Net Nitrification ◽  
Winter Activity ◽  
Aspen Forest

In situ net N mineralization and net nitrification rates were measured in organic forest floor (LFH) and mineral horizons of mature and logged trembling aspen (Populus tremuloides Michx.) stands on the Boreal Plain in western Canada. Cumulative May to September mineralization for mature and logged plots was 1354 ± 534 and 1631 ± 1584 mg N·m–2, respectively, in the LFH horizon and 810 ± 394 and –305 ± 3957 mg N·m–2, respectively, in the mineral horizon. Net nitrification in mature and logged plots was 86 ± 142 and 658 ± 435 mg NO3-N·m–2, respectively, in the LFH horizon and 67 ± 50 and 409 ± 325 mg NO3-N·m–2, respectively, in the mineral horizon. Monthly mean NH4-N concentrations in the LFH tended to be higher in logged plots than in mature plots. Winter net N mineralization and nitrification rates in the LFH of mature plots were up to 7% and 11% of growing season net rates, respectively. In comparison, these rates in logged plots were up to 127% and 59% of the growing season net rates, respectively, indicating that winter activity may make a large contribution to annual net mineralization and nitrification after logging.

Weekly xylem production in trembling aspen (Populus tremuloides) in response to artificial defoliation

2004 ◽  
Vol 82 (5) ◽  
pp. 590-597 ◽  
Author(s):  
Brin Jones ◽  
Jacques Tardif ◽  
Richard Westwood
Keyword(s):  
Populus Tremuloides ◽  
Radial Growth ◽  
Regression Models ◽  
Wood Anatomy ◽  
Ring Width ◽  
Growing Season ◽  
Early Growth ◽  
Trembling Aspen ◽  
Forest Sites ◽  
Significant Difference

The present study investigated the effect of artificial defoliation on weekly radial xylem production in trembling aspen (Populus tremuloides Michx.). It was hypothesized that defoliated trees would show reduced xylem and vessel production and thinner secondary walls in fibres. Two adjacent natural forest sites were selected within Winnipeg, Manitoba. Microcores were extracted weekly from the stems of 30 aspen trees from May to October 2002. Ten aspen trees were defoliated using pole pruners between 22 June and 6 July. Measurements included weekly xylem increment, annual vessel characteristics, and late growing season fibre dimensions. No significant difference in overall ring width was observed; however, trees from both groups showed a significant reduction in ring width in 2002. The ratio of radial growth in 2002 / radial growth in 2001 was significantly less in defoliated trees, suggesting a higher reduction in radial growth due to defoliation. Sigmoidal regression models suggested early growth cessation in defoliated trees. No significant differences in vessel characteristics were observed between groups; however, the diameter and lumen width of fibres was significantly reduced in defoliated trees. It is speculated that a shorter radial growing season may have led to a reduced cell elongation period. An early cessation of the radial growing season associated with a reallocation of carbohydrates to produce a second flush of leaves could explain the reduced size of fibres from defoliated trees.Key words: wood anatomy, diffuse porous, image analysis, radial growth, cell dimension, dendrochronology.

Impact of simulated aspen shoot blight on trembling aspen

2007 ◽  
Vol 37 (4) ◽  
pp. 719-725 ◽  
Author(s):  
P.V. Blenis
Keyword(s):  
Populus Tremuloides ◽  
Tree Height ◽  
Growing Season ◽  
Common Disease ◽  
Trembling Aspen ◽  
Mechanical Wounding ◽  
Tree Form ◽  
Shoot Blight ◽  
The Difference ◽  
Intensively Managed

Although aspen shoot blight (ASB), caused by Pollaccia americana Ondrej, is a common disease of trembling aspen ( Populus tremuloides Michx.), its impact is uncertain. Mechanical wounding, previously shown to be a reliable surrogate for ASB infection, was used to assess ASB impact in two experiments. In the first experiment, the effect of date of wounding on impact was studied by wounding 1-year-old aspen on four dates between 29 June and 10 August 2001. Tree form at the end of the 2001 growing season varied with wounding date, and for each of the wounding dates, tree height was reduced relative to that of unwounded, control trees. After the 2005 growing season, only trees wounded on 17 July were shorter than unwounded trees and the difference in heights was only 62 cm. In the second experiment, trees spaced at 2.0 or 0.67 m were wounded in four successive seasons to determine the effect of multiple years of infection on trees growing at different densities. Simulated ASB reduced tree height by an average of 16 cm, whereas branchiness was not increased by ASB, even at the lower density. Although ASB should not be ignored, these results suggest that it is unlikely to be amongst the most destructive pests of intensively managed aspen.

Photosynthesis of black spruce, jack pine, and trembling aspen after artificially induced frost during the growing season

1998 ◽  
Vol 28 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Manuel Lamontagne ◽  
Hank Margolis ◽  
Francine Bigras
Keyword(s):  
Populus Tremuloides ◽  
Picea Mariana ◽  
Tree Species ◽  
Pinus Banksiana ◽  
Black Spruce ◽  
Recovery Period ◽  
Growing Season ◽  
Jack Pine ◽  
Trembling Aspen ◽  
Monitoring Period

Light-saturated photosynthesis following artificial frosts was monitored for black spruce (Picea mariana (Mill.) BSP), jack pine (Pinus banksiana Lamb.), and trembling aspen (Populus tremuloides Michx.). None of the species exposed to -9°C in May or to -6 and -9°C in August recovered within the 23- and 14-day monitoring periods, respectively. Black spruce and jack pine treated at -6°C in May recovered within 5 and 23 days, respectively. Black spruce treated at -3°C in August recovered within 10 days. Frosts were applied to the upper and lower canopies of mature black spruce and jack pine in June and to mature trembling aspen in July. For black spruce, the lower canopy did not recover whereas the upper canopy partially recovered over the 10-day monitoring period. For jack pine and trembling aspen, there were no differences in recovery between canopy levels. Jack pine treated at -5.5°C recovered within the 10-day monitoring period whereas at -8.5°C, it only partially recovered. Although recovery period varied with species, phenological state, and frost temperature, gradual recovery of photosynthesis over 5-21 days seems a reasonable modelling algorithm for boreal tree species when growing season frosts lower than -3°C occur. However, cooling rates in our experiments were greater than those that normally occur in nature.

scholarly journals Patterns of bryophyte succession in a 160-year chronosequence in deciduous and coniferous forests of boreal Alaska

2017 ◽  
Vol 47 (8) ◽  
pp. 1021-1032 ◽  
Author(s):  
Mélanie Jean ◽  
Heather D. Alexander ◽  
Michelle C. Mack ◽  
Jill F. Johnstone
Keyword(s):  
Leaf Litter ◽  
Populus Tremuloides ◽  
Boreal Forests ◽  
Coniferous Forests ◽  
Stand Age ◽  
Organic Layer ◽  
Layer Depth ◽  
Litter Cover ◽  
Canopy Composition ◽  
Compositional Patterns

Bryophytes are dominant components of boreal forest understories and play a large role in regulating soil microclimate and nutrient cycling. Therefore, shifts in bryophyte communities have the potential to affect boreal forests’ ecosystem processes. We investigated how bryophyte communities varied in 83 forest stands in interior Alaska that ranged in age (since fire) from 8 to 163 years and had canopies dominated by deciduous broadleaf (Populus tremuloides Michx. or Betula neoalaskana Sarg.) or coniferous trees (Picea mariana Mill B.S.P.). In each stand, we measured bryophyte community composition, along with environmental variables (e.g., organic layer depth, leaf litter cover, moisture). Bryophyte communities were initially similar in deciduous vs. coniferous forests but diverged in older stands in association with changes in organic layer depth and leaf litter cover. Our data suggest two tipping points in bryophyte succession: one at the disappearance of early colonizing taxa 20 years after fire and another at 40 years after fire, which corresponds to canopy closure and differential leaf litter inputs in mature deciduous and coniferous canopies. Our results enhance understanding of the processes that shape compositional patterns and ecosystem services of bryophytes in relation to stand age, canopy composition, and changing disturbances such as fire that may trigger changes in canopy composition.

Seasonal changes in the major ash constituents of leaves and some woody components of trembling aspen and red osier dogwood

1978 ◽  
Vol 56 (15) ◽  
pp. 1798-1803 ◽  
Author(s):  
T. D. W. James ◽  
D. W. Smith
Keyword(s):  
Populus Tremuloides ◽  
Seasonal Changes ◽  
Growing Season ◽  
Early Spring ◽  
Reverse Direction ◽  
Trembling Aspen ◽  
Southern Ontario ◽  
Cornus Stolonifera ◽  
Nutrient Changes ◽  
Nutrient Variability

Concentrations of N, P, K, Ca, and Mg were determined at monthly intervals over the growing season in the leaves, twig bark, and twig wood of Populus tremuloides Michx. (trembling aspen) and in the leaves and stems of Cornus stolonifera Michx. (red osier dogwood) in southern Ontario. Concentrations of N, P, and K in the leaves of both species decreased from May to August. Levels of Mg and Ca increased. Nutrient changes in aspen twigs during the May to September period, with the exception of magnesium, followed the reverse direction to those in the leaves. Seasonal changes in all of the nutrients in twigs were very small. Seasonal nutrient variability in red osier stems was also slight, but concentrations of Mg and Ca showed a July peak, and K showed a peak in June. N and P declined from early spring to midsummer but by September in dogwood the levels had returned to the April values.

scholarly journals Ethylene enhances root water transport and aquaporin expression in trembling aspen (Populus tremuloides) exposed to root hypoxia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiangfeng Tan ◽  
Mengmeng Liu ◽  
Ning Du ◽  
Janusz J. Zwiazek
Keyword(s):  
Gas Exchange ◽  
Water Transport ◽  
Populus Tremuloides ◽  
Leaf Gas Exchange ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Trembling Aspen ◽  
Expression Levels ◽  
Root Hypoxia ◽  
Exogenous Ethylene

Abstract Background Root hypoxia has detrimental effects on physiological processes and growth in most plants. The effects of hypoxia can be partly alleviated by ethylene. However, the tolerance mechanisms contributing to the ethylene-mediated hypoxia tolerance in plants remain poorly understood. Results In this study, we examined the effects of root hypoxia and exogenous ethylene treatments on leaf gas exchange, root hydraulic conductance, and the expression levels of several aquaporins of the plasma membrane intrinsic protein group (PIP) in trembling aspen (Populus tremuloides) seedlings. Ethylene enhanced net photosynthetic rates, transpiration rates, and root hydraulic conductance in hypoxic plants. Of the two subgroups of PIPs (PIP1 and PIP2), the protein abundance of PIP2s and the transcript abundance of PIP2;4 and PIP2;5 were higher in ethylene-treated trembling aspen roots compared with non-treated roots under hypoxia. The increases in the expression levels of these aquaporins could potentially facilitate root water transport. The enhanced root water transport by ethylene was likely responsible for the increase in leaf gas exchange of the hypoxic plants. Conclusions Exogenous ethylene enhanced root water transport and the expression levels of PIP2;4 and PIP2;5 in hypoxic roots of trembling aspen. The results suggest that ethylene facilitates the aquaporin-mediated water transport in plants exposed to root hypoxia.

The bacteria in sapwood, wetwood, and heartwood of trembling aspen (Populus tremuloides)

1973 ◽  
Vol 51 (2) ◽  
pp. 498-500 ◽  
Author(s):  
Donald M. Knutson
Keyword(s):  
Populus Tremuloides ◽  
Trembling Aspen ◽  
Indigenous Bacteria ◽  
Large Populations ◽  
Xylem Tissue

Bacteria (Erwinia, Bacillus) were consistently isolated from all samples of aspen sapwood and heartwood. In wetwood zones (water-soaked xylem tissue) or discolored heartwood, large populations often occur. No organisms unique to wetwood were isolated. Wetwood probably is formed by nonmicrobial means and, once formed, merely supports large populations of indigenous bacteria.

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