Time filter

Source Type

Thiffault N.,Ministere des Ressources naturelles du Quebec | Hebert F.,Ministere des Ressources naturelles du Quebec | Jobidon R.,Ministere des Ressources naturelles du Quebec
Silva Fennica | Year: 2012

We aimed at evaluating the interacting effects of silvicultural and nursery practices on planted black spruce (Picea mariana (Mill.) BSP) dimensions, growth, survival and nutrition, 8 years following planting on a carefully logged boreal stand heavily invaded by Kalmia angustifolia L. and Rhododendron groenlandicum (Oeder) Kron & Judd. We also evaluated functional traits related to light and nutrient acquisition and key environmental resource availability to interpret treatment impacts on spruce seedling leaf traits and growth. An experimental black spruce plantation, consisting in a randomized block split-split-split plot design with 13 replicates was established in northeastern Quebec (Canada). Scarification (single-pass, double-pass), fertilization at the time of planting (control; macronutrients only; macro + micronutrients), stock type (container-grown; bare-root), and initial foliar N concentration (4 increasing levels) treatments were applied, and measurements were performed 5 and 8 years following planting. Double-pass scarification significantly increased soil temperature and reduced the competition cover, compared to the single-pass treatment. As a result, double-pass scarification promoted seedling growth over the single-pass treatment, and influenced the expression of other treatment effects. However, the relative gains associated with the second scarification pass have to be balanced against the supplemental investment involved by the treatment before being recommended. Our results point to variable effects of fertilization at planting to stimulate seedling initial growth. In this ecosystem, it appears that the silvicultural gains of this treatment depend on the variable of interest. Bare-root seedlings grew faster than containerized seedlings in the most intense site preparation treatment, but the differences have limited silvicultural impacts.


Tremblay S.,Ministere des Ressources naturelles du Quebec | Ouimet R.,Ministere des Ressources naturelles du Quebec | Houle D.,Ministere des Ressources naturelles du Quebec | Duchesne L.,Ministere des Ressources naturelles du Quebec
Canadian Journal of Forest Research | Year: 2012

Base cations (Ca, Mg, and K) are essential nutrients for forest growth. Many studies have reported important decreases in the soils of several forests in eastern North America, partly because of atmospheric acid deposition and forest harvesting. To quantify the impacts of these perturbations on forest base cations, accurate estimation of tree biomass and nutrient content is needed. However, most of tree nutrient contents are calculated with general allometric equations, leading to inaccurate estimates. We thus calculated tree biomass and base cation content for three common forest types in eastern Canada using site-specific allometric equations and compared them with those calculated with general allometric equations and nutrient concentrations of tree compartments taken from the literature. General allometric equations resulted in aboveground tree biomass estimates in the same range as ours (±15%), but the use of nutrient concentrations taken from the literature resulted mainly in overestimation of above-ground tree nutrient content (-13% to +81%), leading to inaccurate wood requirement estimates (-63% to +86%). Therefore, the development of site-specific equations to estimate above-ground tree base cation content is recommended.


Laflamme G.,Natural Resources Canada | Broders K.,University of New Hampshire | Cote C.,Natural Resources Canada | Munck I.,U.S. Department of Agriculture | And 2 more authors.
Mycologia | Year: 2015

In 2009 unusual white pine needle discoloration was observed in eastern Canada and northeastern USA. While the symptoms were similar in most pine stands, the disease was diagnosed as Canavirgella banfieldii in several locations and Dooks needle blight caused by Lophophacidium dooksii in others. Because of the similarities in symptom development and morphological characters of the causal agents, it was suspected that C. banfieldii and L. dooksii are either the same or closely related species. To test this hypothesis we examined several collections representing C. banfieldii and L. dooksii, including the two type specimens. Phylogenetic analyses of nuc internal transcribed spacer rDNA sequences confirm the synonymy of C. banfieldii with the earlier described L. dooksii and provide the first evidence of the close evolutionary relationship of L. dooksii to other pine pathogens. © 2015 by The Mycological Society of America, Lawrence, KS 66044-8897.


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.


Prevost M.,Ministere des Ressources naturelles du Quebec | DeBlois J.,Ministere des Ressources naturelles du Quebec
Forest Ecology and Management | Year: 2014

Stratified mixtures of pioneer hardwoods sheltering shade-tolerant conifers are commonly encountered in the southern boreal forest. We used two-step shelterwood cutting to release conifer advance growth and limit trembling aspen ( Populus tremuloides Michx.) development in a stratified mixed aspen-conifer stand in Quebec, Canada. This paper presents 10-year regeneration dynamics after the establishment cut applied with different cutting intensities (0%, 35%, 50%, 65%, and 100% basal area removal). Aspen suckering was proportional to cutting intensity ( p<. 0.001) and its survival was limited under all four densities of residual cover. After 10. years, aspen density was ≤600 stems/ha in the 0%, 35%, and 50% cuts, 1600. stems/ha in the 65% cut and 4700. stems/ha in the clearcut. Adequate protection of balsam fir ( Abies balsamea (L.) Mill.) and spruce ( Picea glauca (Moench) Voss and Picea mariana (Mill.) BSP) advance regeneration strongly contributed to limiting aspen development. The release treatment affected conifer sapling height growth, stem diameter, crown length growth and live crown ratio. Generally, the growth reaction to canopy removal was better in the clearcut than in partial cuts. Balsam fir response was good in the two initial height classes studied (130-300 and 301-500. cm), but a significant spruce response occurred only in the smallest class. The final cut will be necessary to assess the overall effect of two-step shelterwood cutting on species composition and growth of the new cohort. © 2014 Elsevier B.V.


Girard F.,University of Montréal | Girard F.,University of Quebec at Montréal | Beaudet M.,Ministere des Ressources naturelles du Quebec | Beaudet M.,University of Quebec at Montréal | And 4 more authors.
Forest Ecology and Management | Year: 2014

With increased rates of climate change, it is imperative for forest managers to have access to models that can take into account the expected effects of climate change on tree growth. To this end, growth function are sometimes used that include climatic variables such as mean annual temperature or precipitation averaged over decades. Such growth models are usually relatively easy to develop but they do not take into account the fact that tree diameter growth on a given year is determined not by climatic conditions that prevailed up to 30. years before but mainly by climatic conditions that prevailed during the current and previous year. Our objective is determine if including climatic variables obtained from dendroclimatic response function will lead to growth models having a better fit to data than versions with 30-year average climatic conditions, or no climate at all. Growth models were developed for Betula alleghaniensis, Acer saccharum, Acer rubrum and Fagus grandifolia using data from south-eastern Quebec. Three types of growth function were compared. A first set of growth function was developed in which the potential growth of a tree was modeled as a function of tree size and site characteristics (vegetation type and drainage) to be further modified as a non-linear function of plot basal area. The effect of climate was not explicitly accounted for in this fort set of growth function, therefore they will be refered to as Climate-implicit models. A second set of growth function was developed in which we explicitly accounted for the effect of climate by incorporating 30-year mean annual temperature and precipitation in the growth function. In a third type of growth function, also climate-explicit, we incorporated the most significant recent climatic variables identified using climatic response function developed for each species based on dendrochronological and climatic data. The three types of models were compared based on the Akaike information criterion (AIC). Our results showed that Climate-explicit growth models with climatic variables obtained from response function analysis outperformed other growth models for three out of four species ( B. alleghaniensis, A. saccharum and F. grandifolia). Incorporating climate in the form of 30-year average climatic conditions brought some improvement over a non-climatic function for A. rubrum, but this was not the case for other species. Accounting for growth dependency on climate by including recent monthly climatic variables provided by response function could be a potentially useful approach for the development of a new lineage of tree growth models dealing with climate change. © 2014 Elsevier B.V.


Messaoud Y.,University of Québec | Asselin H.,University of Québec | Bergeron Y.,University of Québec | 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.


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.


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.


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.

Loading Ministere des Ressources naturelles du Quebec collaborators
Loading Ministere des Ressources naturelles du Quebec collaborators