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Sault Ste. Marie, Canada

Warren G.,122 MacDonald Brown Dr. | Baines P.,26 University Dr | Plamondon J.,Pulp and Paper Research Institute of Canada | Pitt D.G.,Canadian Wood Fibre Center
Forestry Chronicle | Year: 2013

The Green River precommercial thinning (PCT) trials were established between 1959 and 1961 in naturally regenerating balÂsam fir (Abies balsamea [L.] Mill.)-dominated stands an average of eight years after overstory removal. Three nominal spacings of 4 ft (1.2 m), 6 ft (1.8 m) and 8 ft (2.4 m) were compared to an unthinned control in six replicate blocks. In the fall of 2008, following completion of the ninth sequential evaluation of the study's 48 permanent sample plots, three of the six replicates were clearcut harvested; butt rot data were collected immediately afterwards. To date, forest management research and goals have focused on the benefits of PCT, such as increased tree size and merchantable volume, shorter rotation ages, and better stem form and uniformity. Comparatively little attention has been placed on negative aspects of PCT, such as the incidence and development of root and butt rots, and their impact on fibre yields and wood product values. Results from the Green River study provide evidence that PCT may increase the incidence of butt rot in balsam fir, with incidence proportional to thinning intensity (p < 0.01). We also observed incidence and volume of butt rot to increase with stem diameter (p < 0.05). The experiÂment suggests that factors such as stand age at time of thinning, and age at the time of harvest are important considerations when it comes to mitigating the impacts of butt rot through forest management. Source


Plamondon J.,Pulp and Paper Research Institute of Canada | Pitt D.G.,Canadian Wood Fibre Center
Forestry Chronicle | Year: 2013

The Green River precommercial thinning trials were established between 1959 and 1961 in naturally regenerating balsam fir (Abies balsamea [L.] Mill.)-dominated stands an average of eight years after overstory removal. Three nominal spacings of 4 ft (1.2 m), 6 ft (1.8 m) and 8 ft (2.4 m) were compared to an unthinned control in six replicate blocks. In the fall of 2008, folÂlowing completion of the ninth sequential evaluation of the study's 48 permanent sample plots, three of the six replicates were clearcut harvested using a cut-to-length system; data were collected on harvesting, forwarding and loading efficiency. Largely due to increased average tree size, precommercially thinned stands were associated with improvements in both harvesting and forwarding productivity, proportional to thinning intensity. For example, the nominal 6-ft spacing yielded 30% to 35% gains in harvesting productivity, and 16% to 39% gains in forwarding productivity (p < 0.04), these ranges spanning the different levels of operator expertise and block conditions observed. In total, estimated harvesting costs were $12.58/m3 in the unthinned stands, compared to $9.10/m3 in the 6-ft spaced stands (p = 0.02). Such a difference represents a $3.48/m' savings, which transÂlates into just over $ 1000 per ha, based on the gross merchantable volume produced in the 6-ft spaced stands. Source


Arevalo C.B.M.,University of Alberta | Chang S.X.,University of Alberta | Bhatti J.S.,Natural Resources Canada | Sidders D.,Canadian Wood Fibre Center
Soil Science Society of America Journal | Year: 2012

The temperature sensitivity of soil organic C contained in different particlesize fractions is important in the context of global climate change but to date has been poorly studied. We compared the effects of temperature (7, 14, and 21°C) on C mineralization rates in fractionated soils from four land use systems [agriculture, AG; plantation; grassland, GRA; and native aspen (Populus tremuloides Michx.) stand, NAT] in the parkland region of Alberta, Canada, over a 370-d laboratory incubation. Carbon was largely held in the fine (<53 μm) fraction (59%), followed by the medium (53-250 μm, 31%) and coarse (250-2000 μm, 10%) fractions. Across land uses and incubation temperatures, the amount of C mineralized from bulk soil over 370 d ranged between 2 and 9% of initial total organic carbon (C i), with mineralization rates based on per unit of C i ranging from 0.4 to 5.8 × 10 -4 mg C mg -18 C i d -1 and mean residence times (MRTs) ranging from 15 to 65 yr. Of the total amount of C mineralized, 77, 14, and 9% came from the coarse, medium, and fine fractions, respectively. The temperature sensitivity (Q 10) of organic C under NAT increased with decreasing particle size, while plantation-and GRA-derived soil organic C showed significantly greater Q 10 in the medium and fine fractions only. We conclude that the mineralization potential and temperature sensitivity of soil organic C in the studied land use systems were controlled mainly by organic matter quality and physical protection provided through aggregation and adsorption. © Soil Science Society of America. Source


Prunier J.,Laval University | Pelgas B.,Laval University | Pelgas B.,Natural Resources Canada | Gagnon F.,Laval University | And 4 more authors.
BMC Genomics | Year: 2013

Background: The genomic architecture of adaptive traits remains poorly understood in non-model plants. Various approaches can be used to bridge this gap, including the mapping of quantitative trait loci (QTL) in pedigrees, and genetic association studies in non-structured populations. Here we present results on the genomic architecture of adaptive traits in black spruce, which is a widely distributed conifer of the North American boreal forest. As an alternative to the usual candidate gene approach, a candidate SNP approach was developed for association testing.Results: A genetic map containing 231 gene loci was used to identify QTL that were related to budset timing and to tree height assessed over multiple years and sites. Twenty-two unique genomic regions were identified, including 20 that were related to budset timing and 6 that were related to tree height. From results of outlier detection and bulk segregant analysis for adaptive traits using DNA pool sequencing of 434 genes, 52 candidate SNPs were identified and subsequently tested in genetic association studies for budset timing and tree height assessed over multiple years and sites. A total of 34 (65%) SNPs were significantly associated with budset timing, or tree height, or both. Although the percentages of explained variance (PVE) by individual SNPs were small, several significant SNPs were shared between sites and among years.Conclusions: The sharing of genomic regions and significant SNPs between budset timing and tree height indicates pleiotropic effects. Significant QTLs and SNPs differed quite greatly among years, suggesting that different sets of genes for the same characters are involved at different stages in the tree's life history. The functional diversity of genes carrying significant SNPs and low observed PVE further indicated that a large number of polymorphisms are involved in adaptive genetic variation. Accordingly, for undomesticated species such as black spruce with natural populations of large effective size and low linkage disequilibrium, efficient marker systems that are predictive of adaptation should require the survey of large numbers of SNPs. Candidate SNP approaches like the one developed in the present study could contribute to reducing these numbers. © 2013 Prunier et al.; licensee BioMed Central Ltd. Source


Parker W.C.,Ontario Ministry of Natural Resources | Pitt D.G.,Canadian Wood Fibre Center | Morneault A.E.,Ontario Ministry of Natural Resources
Forest Ecology and Management | Year: 2010

The influence of herbaceous and woody vegetation control, either singly or in combination, on leaf gas exchange, water status, and nutrient relations of planted eastern white pine (Pinus strobus L.) seedlings was examined in a central Ontario clearcut over four consecutive growing seasons (GSs). Net carbon assimilation (An), leaf conductance to water vapour (Gwv), water use efficiency (WUE), and midday leaf water potential (ψm) were measured periodically during the second to fourth GSs of vegetation control treatments, while leaf nutrient relations were examined in GS five. Leaf An and Gwv were reduced (p≤0.05) in the presence of herbaceous vegetation in GS two, by both herbaceous and woody vegetation in GS three, and only by woody vegetation (largely trembling aspen (Populus tremuloides Michx.)) in GS four. Leaf WUE was increased (p≤0.05) in all three GSs in which herbaceous vegetation control was applied and where woody vegetation provided partial shading of planted white pine. Leaf water status was comparatively less responsive to vegetation control treatments, but leaf ψm was increased (p≤0.05) in the presence of woody vegetation in GSs two and four, likely due to shading and reduced atmospheric evaporative demand of the white pine seedling environment. Within a given GS, the effects of vegetation control on An, Gwv, and ψm were strongly linked to treatment-induced changes in total vegetative cover, and light and soil moisture availability. Seedling height, diameter, and volume growth rates were positively correlated with An and WUE in GSs two and three, but less so in GS four. Vector analysis suggested that herbaceous competition induced foliar N, P, and K deficiencies in five-year-old white pine seedlings while competition from aspen resulted in foliar Ca deficiency. © 2010. Source

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