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

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.

2004 ◽  
Vol 82 (3) ◽  
pp. 310-315 ◽  
Author(s):  
Erin C Fraser ◽  
Victor J Lieffers ◽  
Simon M Landhäusser

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.


2014 ◽  
Vol 44 (2) ◽  
pp. 162-171 ◽  
Author(s):  
Derek F. Sattler ◽  
Philip G. Comeau ◽  
Alexis Achim

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.


2003 ◽  
Vol 33 (11) ◽  
pp. 2262-2268 ◽  
Author(s):  
N Carmosini ◽  
K J Devito ◽  
E E Prepas

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.


2007 ◽  
Vol 37 (4) ◽  
pp. 719-725 ◽  
Author(s):  
P.V. Blenis

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.


Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 250
Author(s):  
Kristine Vander Mijnsbrugge ◽  
Arion Turcsán ◽  
Éva Erdélyi ◽  
Hans Beeckman

Background and Objectives: Studying responses in woody plants upon water limitation is gaining importance due to the predicted increase in frequency and intensity of droughts in Europe. We studied the variation in radial growth and in wood anatomical traits caused by water limited growth conditions in offspring from Quercus petraea (Matt.) Liebl., Q. robur L. and their morphological intermediates grown in the same environment. Materials and Methods: Cross sections were prepared from the stems of 210 three-year-old potted seedlings, comprising control plants and seedlings that experienced from late spring until early autumn of the first growing season two sequential periods of water with-holding each followed by plentiful re-watering. Pith radius, ring width of the three growing seasons and latewood vessel diameter in second and third growing season were measured. Presence of intra-annual density fluctuations, dendritic patterns of latewood vessels and the level of ring closure of earlywood vessels were observed. The traits were modelled to examine the explanatory power of the taxon of the mother tree and the drought treatment. Results: Most of the traits displayed significant differences between offspring from Q. petraea and Q. robur and offspring from the morphological intermediates behaved inconsistent among the traits. Most of the traits were significantly affected by the drought stress in the first growing season. Apart from radial growth, also latewood vessel size was reduced in the two growing seasons following the year in which drought was imposed on the seedlings, suggesting an adaptation to improve the tolerance to drought stress. We also found an indication for a compensation growth mechanism, counteracting the lost growing time during the drought stress, as the level of ring closure of the earlywood vessels in the year following the drought treatment was further advanced in the treated seedlings, an effect that disappeared in the subsequent year. Conclusion: Oaks exposed to drought adapt their growth and xylem structure to improve drought resistance. While youth growth of Q. robur is more competition-oriented, with a faster juvenile growth, Q. petraea seems to invest more in a precautious growth, being more prepared for stressful conditions. It is therefore possible that Q. robur seedlings may suffer more from intensified droughts than Q. petraea seedlings.


IAWA Journal ◽  
2010 ◽  
Vol 31 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Balazs Horvath ◽  
Ilona Peszlen ◽  
Perry Peralta ◽  
Bohumil Kasal ◽  
Laigeng Li

The directed modification of specific traits of trees through genetic engineering provides opportunities for making significant genetic improvements to wood properties in matter of years instead of extended time frames required for traditional natural selection. An attractive target of forest- tree engineering is the modification of lignin content and lignin structure. While lower lignin content improves pulping efficiency, a decrease in lignin content could affect wood characteristics that are critical for solid wood use.After one year of growth in a greenhouse, a total of forty transgenic aspen (Populus tremuloides Michx.) with reduced lignin content and increased syringyl to guaiacyl ratio were harvested and diameter growth and cell morphology were investigated using quantitative wood anatomy and fiber quality analysis techniques. Comparing genetic groups to the wild-type as the control, similar radial growth and quantitative anatomical properties were observed for the genetic group with reduced lignin content. The genetic group with increased S/G ratio had lower diameter growth, lower vessel lumen diameter, but more numerous vessels. The combined effect of changes in lignin content and structure on radial growth and cell morphology seems to be more complex and gave inconsistent results.


2007 ◽  
Vol 37 (9) ◽  
pp. 1586-1598 ◽  
Author(s):  
Barry J. Cooke ◽  
Jens Roland

We investigated the long-term effects of drought and defoliation by forest tent caterpillars on trembling aspen radial growth in the province of Ontario using a dendroecological approach. Drought, as measured by Hogg’s climate moisture index (CMI), was found to have no discernible impact on aspen radial increment in either northeastern or northwestern Ontario during the study period 1930–2003. Forest tent caterpillar outbreaks were strongly decadal in periodicity in both regions and resulted in similar patterns of periodic variation in tree ring-width chronologies, indicating that, in humid environments prone to spatially synchronized tent caterpillar outbreaks, herbivory is the main factor limiting aspen radial growth. We show that the major decadal outbreak cycles of forest tent caterpillar can, by filtering with the computer program OUTBREAK, be reliably reconstructed from raw aspen ring-width chronologies. We determine the filtering parameters that give the most reliable reconstruction fit to observed patterns of outbreaks in each region. We show that the periodic outbreak signal is present even in areas where aerial surveyors frequently failed to detect significant levels of defoliation, and that the outbreak signal necessarily includes minor defoliation episodes that occur in between the major decadal outbreak cycles.


2009 ◽  
Vol 39 (9) ◽  
pp. 1722-1736 ◽  
Author(s):  
Melissa Hoffer ◽  
Jacques C. Tardif

False rings (FRs) are a tree-ring anomaly that can be used to better understand tree growth and potentially reconstruct past climatic events. The main objective of this study was to explore the association between FRs and climate, especially drought occurrence. Sampling was conducted in Nopiming Provincial Park. Wood cores were extracted from jack pine ( Pinus banksiana Lamb.) in five stands and from co-occurring black spruce ( Picea mariana (Mill.) BSP) in three of these stands. After cross-dating, earlywood, latewood, and total ring width were measured on all cores. All FRs were identified, and their position within a tree ring was determined. Both species showed similar radial growth and FR patterns. Jack pine and to a lesser extent black spruce both showed abundant FRs in the juvenile period. Springs with cool and snowy conditions and summers with severe drought were associated with a higher frequency of FRs. These anomalies could be formed partly in response to timing of the start of the growing season and to conditions during that growing season that lead to interruption and subsequent resumption of normal growth. Jack pine radial growth was found to be more sensitive to precipitation, whereas that of black spruce was more sensitive to temperature.


1984 ◽  
Vol 14 (6) ◽  
pp. 789-793 ◽  
Author(s):  
John C. Brissette ◽  
Burton V. Barnes

Populustremuloides Michaux progeny from 13 local clones and 12 clones from five locations in Alaska, Alberta, and Utah were grown in southeastern Michigan to compare phenology and early growth. The progeny of western clones broke bud as much as 2 weeks before, and stopped growth up to 2 months earlier than local clones. After 2 years the western progeny averaged only 26–38% the height of the Michigan progeny. Survival and growth of ramets from 49 clones collected from British Columbia to Colorado and planted in southeastern Michigan were studied after 7 years. Only 30% of the 116 ramets and 39% of the clones survived. The poor performance of western clones in both experiments is probably due to their adaptation to longer photoperiods and (or) lower growing season minimum temperatures than occur in southeastern Michigan.


2004 ◽  
Vol 34 (9) ◽  
pp. 1946-1954 ◽  
Author(s):  
Qi-Bin Zhang ◽  
Richard J Hebda

Radial growth of trees in mountainous areas is subject to conditions associated with changes in elevation. We present ring-width chronologies for Douglas-fir trees (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) at nine sites spanning low to high elevations in the Bella Coola area of the central coast of British Columbia, near the northern limits of the species distribution, and investigate the variation in tree-ring growth patterns in relation to different elevations, using principal component (PC) analysis. We find that the first PC, which represents 55.6% of the total variance, reflects a common growth response at sites of different elevation. Response function analysis indicates that growing season precipitation is the major factor in controlling tree-ring growth. This factor explains more of the variance in low-elevation sites than it does in high-elevation ones. Temperature in August of the preceding year shows a negative relationship to ring-width growth. The second PC represents 16.7% of the total variance and reveals a distinct difference in growth response between low- and high-elevation sites. The length and temperature of the growing season seem to play an important role in tree-ring growth at sites of high elevation. Comparison of the Bella Coola records with those from southern Vancouver Island suggests that growing season precipitation influences growth of Douglas-fir on a macroregional scale, but other factors such as temperature modify the growth response at the limits of the distribution of the species.


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