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Messaoud Y.,University of Quebec | Asselin H.,University of Quebec | Bergeron Y.,University of Quebec | Grondin P.,Ministere des Ressources naturelles du Quebec
Forest Science | Year: 2014

The boreal zone of northeastern North America is characterized by mixedwood forests dominated by balsam fir (Abies balsamea (L.) Mill.) in the south and by coniferous forests dominated by black spruce (Picea mariana (Mill) B.S.P.) in the north. Site index values of balsam fir and black spruce were compared in 364 sites spread across the boreal zone of northwestern Quebec to determine if the northward dominance shift from balsam fir to black spruce could be explained by a difference in height growth. Site index of both species decreased along a south-north gradient, although the trend was only significant for balsam fir on clay deposits. Site index values shifted from being significantly higher for balsam fir in the boreal mixedwood forest, to being slightly (but not significantly) higher for black spruce in the coniferous forest. Mean annual temperature had a significant positive effect on site index for both species, and precipitation of the growing season had a significant negative effect only for balsam fir. The competitive advantage of black spruce over balsam fir in coniferous forests is due to a greater tolerance to cooler temperatures and water-logged soils. © 2014 Society of American Foresters.

Krause C.,University of Quebec at Chicoutimi | Dery Bouchard C.-A.,University of Quebec at Chicoutimi | Plourde P.-Y.,University of Quebec at Chicoutimi | Mailly D.,Ministere des Ressources naturelles du Quebec
Forest Ecology and Management | Year: 2013

Black spruce and Jack pine are the tree species most often planted in the boreal forest of the province of Quebec. Higher radial growth is expected from these stands in comparison with naturally regenerated forests. The fast growth response of these tree species in plantation has been associated with stem displacement and compression wood formation. This study aims to examine these parameters and to relate them with dendrometric variables. Analysis were conducted in 10 black spruce and 10 Jack pine plantations over 20. years old. Stem horizontal displacement was evaluated at stand level within plots of at least 50 stems. A sub-dataset of five dominant trees per plantation was then sampled in order to quantify the occurrences of compression wood. Stem horizontal displacement was mostly sparse for black spruce. In agreement with this observation, compression wood ratio (0.6% of total tree volume) can be considered low for this species. For Jack pine, the measurements of compression wood (5.0% of total tree volume) were higher than black spruce. Compression wood ratio was negatively correlated to stem height and positively to maximum stem horizontal displacement and tree crown cover ratio. We think that the capacity of Jack pine to grow faster, in given conditions, than black spruce is the main reason for the higher occurrence of sinuosity and compression wood in Jack pine plantations. © 2013 Elsevier B.V.

Rapanoela R.,Laval University | Raulier F.,Laval University | Gauthier S.,Natural Resources Canada | Ouzennou H.,Laval University | And 2 more authors.
Canadian Journal of Forest Research | Year: 2015

The capacity of a forest stand to produce timber is related to the interactions that exist between its regeneration capacity, physical site characteristics (climate, surficial deposit, drainage), and disturbances. Minimally, to be sustainably managed, a forest needs to be sufficiently productive and able to regenerate after a disturbance so that its productive capacity is maintained or enhanced. To this effect, we evaluated timber productivity over a large area (175 000 km2) covering the latitudinal extent of closed-canopy black spruce (Picea mariana (Mill.) B.S.P) forest. Site index and relative density index were used to identify stands that cannot reach a minimum volume of trees of minimum size over one rotation. A nonparametric method was used to estimate their values for all stands within the study area. This imputation used either physical site attributes alone to assess potential productivity independent of stand history or physical and vegetation site attributes to assess current productivity. The proportion of productive stands was then estimated at the scale of landscapes ranging from 39 to 2491 km2. Physical site factors alone explain 84% of the variability in the percentage of potentially productive stands (78% for currently productive stands); their combination resulted in an abrupt transition in productivity over the study area. However, burn rate alone also explains 63% of variation in the proportion of currently productive stands and 41% of the relative difference between percentages of potentially or currently productive stands. These results have implications for strategic forest management planning at land classification stage, as timber production area is assumed to remain stable through time, whereas it is apparently related to the disturbance rate. © 2015, National Research Council of Canada. All right reserved.

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.

Hebert F.,Ministere des Ressources naturelles du Quebec | Roy V.,Natural Resources Canada | Auger I.,Ministere des Ressources naturelles du Quebec | Gauthier M.-M.,Ministere des Ressources naturelles du Quebec
Forestry Chronicle | Year: 2013

The use of gap-based silviculture and enrichment planting was tested in temperate mixedwood forests in eastern Canada. Four different sizes of canopy opening or patch cuts were applied to six stands in the maple-birch domain of Quebec: We evaluated the influence of opening size, cardinal quadrant within the opening, and distance from the forest edge of openings on white spruce height and ground-level diameter (GLD) five years after enrichment planting. At ≥5 m from the edge, initial canopy transmittance was generally >60% in all four canopy treatments. White spruce seedling height and GLD were lower within 10 m from the edge, and generally increased where understory light levels were higher. Seedling survival, height, and GLD in the smallest opening (0.05 ha) were comparable or higher than those found in relatively larger openings. The 0.05-ha opening that more closely emulates natural canopy gaps of temperate mixedwood forests provided satisfactory seedling development, and is therefore compatible with a gap-based stand dynamics approach to management of mixedwood stands in Quebec.

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