Barrette M.,Ministere des Forets de la Faune et des Parcs |
Tremblay S.,Ministere des Forets de la Faune et des Parcs
Forestry Chronicle | Year: 2015
Self-thinning plays an important role in the development of forest stands. This ecological process does not operate effectively in certain very dense boreal balsam fir stands. In these stands, tree growth has slowed down, reducing ecosystem services such as timber production. Silvicultural principles of thinning from below are based on the self-thinning process. Hence, the objective of this study was to ascertain whether this treatment could replace the self-thinning process and restore growth in a very dense balsam fir stand that had reached the age of commercial maturity. We followed stand evolution after an experimental thinning from below at three different intensities. After 10 years, the heavily thinned plots recovered a level of merchantable volume similar to that of control plots. This volume was distributed on 43 % fewer trees, and the mean quadratic diameter grew twice as rapidly for the 1000 largest of these trees. This is one of the first studies to document a convergent reaction of merchantable volume after thinning. Ultimately, we demonstrated that thinning from below can replace self-thinning and restore growth in very dense fir stands.
Fabianek F.,Laval University |
Simard M.A.,Ministere des Forets de la Faune et des Parcs |
Simard M.A.,Laval University |
Racine E.B.,Laval University |
Desrochers A.,Laval University
Canadian Journal of Zoology | Year: 2015
Male little brown bats (Myotis lucifugus (Le Conte, 1831)) and northern long-eared bats (Myotis septentrionalis (Trouessart, 1897)) often roost under exfoliating bark, within trunks, and within cavities of trees during summer. Current lack of knowledge about the roosting ecology of these species in boreal forest limits our understanding of how they may be affected by logging. The main objective was to identify tree and forest stand features that were selected by bats for roosting within a balsam fir (Abies balsamea (L.) Mill.) – paper birch (Betula papyrifera Marshall) forest of Quebec, Canada. Over 3 years, we captured and fitted radio transmitters to 22 individual bats to locate their roost trees for 7–14 days following release. We measured tree and forest stand features in the field and using light detection and ranging (LiDAR) technology. Roost trees were compared with random trees using generalized linear mixed models. Male Myotis bats selected larger and taller snags, within stands containing a higher proportion of canopy gaps and a larger number of snags compared with random trees. Vegetation clumps of 0.1 ha containing a minimum of 10 snags with a diameter at breast height (DBH) ≥ 10 cm should be maintained to preserve roosting habitat that is used by male Myotis bats in balsam fir – paper birch forests.
Morneau F.,63 Champagne Street |
Tremblay J.A.,Environment Canada |
Todd C.,50 State Street |
Chubbs T.E.,5 Wing Goose Bay |
And 4 more authors.
Northeastern Naturalist | Year: 2015
Aquila chrysaetos (Golden Eagle) breeds in both eastern and western North America. However, the former population has received much less attention than the latter. The purpose of this paper is to document the known distribution and abundance of eastern Golden Eagles within their breeding range and to identify gaps in knowledge for future studies. Eastern Golden Eagles breed in Labrador, Québec, and Ontario, Canada. The species has been extirpated as a breeder from the eastern US. In 2013, 187 Golden Eagle territorial pairs were documented in eastern Canada. Most territorial pairs occur in Québec (65.8%) and Labrador (26.7%). However, probably less than 16% of the total area of these regions has been surveyed. Based on the number of pairs observed and the proportion of area surveyed, we estimate that the total number of territorial pairs of eastern Golden Eagles to be ∼1236. The large area of unsurveyed landscapes and the corresponding lack of precision of the estimate highlight an important next step for future research. © 2015, BioOne. All rights reserved.
Pavey S.A.,University Laval |
Gaudin J.,University Laval |
Normandeau E.,University Laval |
Dionne M.,Ministere des Forets de la Faune et des Parcs |
And 3 more authors.
Current Biology | Year: 2015
Summary The two primary ways that species respond to heterogeneous environments is through local adaptation and phenotypic plasticity. The American eel (Anguilla rostrata) presents a paradox; despite inhabiting drastically different environments , the species is panmictic [2, 3]. Spawning takes place only in the southern Sargasso Sea in the Atlantic Ocean . Then, the planktonic larvae (leptocephali) disperse to rearing locations from Cuba to Greenland, and juveniles colonize either freshwater or brackish/saltwater habitats, where they spend 3-25 years before returning to the Sargasso Sea to spawn as a panmictic species. Depending on rearing habitat, individuals exhibit drastically different ecotypes [4-6]. In particular, individuals rearing in freshwater tend to grow slowly and mature older and are more likely to be female in comparison to individuals that rear in brackish/saltwater [4, 6]. The hypothesis that phenotypic plasticity alone can account for all of the differences was not supported by three independent controlled experiments [7-10]. Here, we present a genome-wide association study that demonstrates a polygenic basis that discriminates these habitat-specific ecotypes belonging to the same panmictic population. We found that 331 co-varying loci out of 42,424 initially considered were associated with the divergent ecotypes, allowing a reclassification of 89.6%. These 331 SNPs are associated with 101 genes that represent vascular and morphological development, calcium ion regulation, growth and transcription factors, and olfactory receptors. Our results are consistent with divergent natural selection of phenotypes and/or genotype-dependent habitat choice by individuals that results in these genetic differences between habitats, occurring every generation anew in this panmictic species. © 2015 Elsevier Ltd.
Caron W.-O.,Laval University |
Lamhamedi M.S.,Ministere des Forets de la Faune et des Parcs |
Viens J.,Laval University |
Messaddeq Y.,Laval University |
Messaddeq Y.,JIRU Institute Quimica
Sensors (Switzerland) | Year: 2016
The reduction of nitrate leaching to ensure greater protection of groundwater quality has become a global issue. The development of new technologies for more accurate dosing of nitrates helps optimize fertilization programs. This paper presents the practical application of a newly developed electrochemical sensor designed for in situ quantification of nitrate. To our knowledge, this paper is the first to report the use of electrochemical impedance to determine nitrate concentrations in growing media under forest nursery conditions. Using impedance measurements, the sensor has been tested in laboratory and compared to colorimetric measurements of the nitrate. The developed sensor has been used in water-saturated growing medium and showed good correlation to certified methods, even in samples obtained over a multi-ion fertilisation season. A linear and significant relationship was observed between the resistance and the concentration of nitrates (R2 = 0.972), for a range of concentrations of nitrates. We also observed stability of the sensor after exposure of one month to the real environmental conditions of the forest nursery. © 2016 by the authors; licensee MDPI, Basel, Switzerland.
Dao M.C.E.,Institute Of Lenvironnement Et Of Recherches Agricoles |
Rossi S.,University of Quebec at Chicoutimi |
Walsh D.,University of Quebec at Chicoutimi |
Morin H.,University of Quebec at Chicoutimi |
Houle D.,Ministere des Forets de la Faune et des Parcs
Frontiers in Plant Science | Year: 2015
The predicted climate warming and increased atmospheric inorganic nitrogen deposition are expected to have dramatic impacts on plant growth. However, the extent of these effects and their interactions remains unclear for boreal forest trees. The aim of this experiment was to investigate the effects of increased soil temperature and nitrogen (N) depositions on stem intra-annual growth of two mature stands of black spruce [Picea mariana (Mill.) BSP] in Québec, QC, Canada. During 2008–2013, the soil around mature trees was warmed up by 4°C with heating cables during the growing season and precipitations containing three times the current inorganic N concentration were added by frequent canopy applications. Xylem phenology and cell production were monitored weekly from April to October. The 6-year-long experiment performed in two sites at different altitude showed no substantial effect of warming and N-depositions on xylem phenological phases of cell enlargement, wall thickening and lignification. Cell production, in terms of number of tracheids along the radius, also did not differ significantly and followed the same patterns in control and treated trees. These findings allowed the hypothesis of a medium-term effect of soil warming and N depositions on the growth of mature black spruce to be rejected. © 2015 Dao, Rossi, Walsh, Morin and Houle.