Momenipour2013

Référence

Momenipour, S. (2013) Aspen Dynamics after harvesting in boreal coniferous forest of northwestern Quebec. Mémoire de maîtrise, Université du Québec en Abitibi-Témiscamingue.

Résumé

Previous studies have shown that aspen (Populw; tremuloides Michx) trees were gradually expanding into previously conifer-dominated stands after harvesting. Harvesting practices create disturbances on a wide range of spatial scales and intensities, and it is not known how different practices favour aspen invasion into black spruce (Picea mariana) forests. A clear understanding of how silvicultural treatrnents affect recruitment of aspen into coniferous stands is required to be able to modify forest practices in order to avoid conversion of previously coniferous stands into mixed or deciduous stands. The main objective of this work was to study the relationship between different levels of harvesting intensity ( clear cutting with scarification [CPRS-S], clear cutting [CPRS], and partial cutting [PC]), the mode of aspen recruitment, post-harvest aspen density, and aspen genetic diversity. A field study was established to test whether aspen regeneration density and its mode of regeneration (sexual or vegetative) could be affected by different levels of harvesting disturbance. It was further tested how organic matter (LFH) thickness, drainage class, percentage cover of woody debris, and shrubs affected aspen density and its mode of regeneration into previously coniferous forests. The mode of aspen recruitment was determined through dendrochronological analysis and five microsatellite DNA loci analyses were used for clone and genetic structure identification. Aspen regeneration density significantly varied between the three harvesting treatments, but it was however unrelated to the gradient of disturbance intensity. The vast majority of regeneration was of seedling origin in two harvesting methods (CPRS-S and CPRS), while it originated from root suckering in the PC treatrnent. Even though, the environmental variables (LFH thickness, drainage class and percentage cover of shrubs) significantly affected the density and mode of regeneration of as pen, they were inefficient in predicting aspen density and of recruitrnent mode. High levels of genetic and genotypic variability were observed that did not differ between the harvesting treatments and between the modes of aspen recruitrnent, sexual or vegetative. We concluded that differences in aspen modes of recruitment and density were more related to pre-harvest conditions rather than to the harvesting intensity.

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@MASTERSTHESIS { Momenipour2013,
    AUTHOR = { Momenipour, S. },
    TITLE = { Aspen Dynamics after harvesting in boreal coniferous forest of northwestern Quebec. },
    SCHOOL = { Université du Québec en Abitibi-Témiscamingue },
    YEAR = { 2013 },
    NOTE = { CEFTMS, DesRochers, A. and Tremblay, M.F. },
    ABSTRACT = { Previous studies have shown that aspen (Populw; tremuloides Michx) trees were gradually expanding into previously conifer-dominated stands after harvesting. Harvesting practices create disturbances on a wide range of spatial scales and intensities, and it is not known how different practices favour aspen invasion into black spruce (Picea mariana) forests. A clear understanding of how silvicultural treatrnents affect recruitment of aspen into coniferous stands is required to be able to modify forest practices in order to avoid conversion of previously coniferous stands into mixed or deciduous stands. The main objective of this work was to study the relationship between different levels of harvesting intensity ( clear cutting with scarification [CPRS-S], clear cutting [CPRS], and partial cutting [PC]), the mode of aspen recruitment, post-harvest aspen density, and aspen genetic diversity. A field study was established to test whether aspen regeneration density and its mode of regeneration (sexual or vegetative) could be affected by different levels of harvesting disturbance. It was further tested how organic matter (LFH) thickness, drainage class, percentage cover of woody debris, and shrubs affected aspen density and its mode of regeneration into previously coniferous forests. The mode of aspen recruitment was determined through dendrochronological analysis and five microsatellite DNA loci analyses were used for clone and genetic structure identification. Aspen regeneration density significantly varied between the three harvesting treatments, but it was however unrelated to the gradient of disturbance intensity. The vast majority of regeneration was of seedling origin in two harvesting methods (CPRS-S and CPRS), while it originated from root suckering in the PC treatrnent. Even though, the environmental variables (LFH thickness, drainage class and percentage cover of shrubs) significantly affected the density and mode of regeneration of as pen, they were inefficient in predicting aspen density and of recruitrnent mode. High levels of genetic and genotypic variability were observed that did not differ between the harvesting treatments and between the modes of aspen recruitrnent, sexual or vegetative. We concluded that differences in aspen modes of recruitment and density were more related to pre-harvest conditions rather than to the harvesting intensity. },
    OWNER = { Daniel Lesieur },
    TIMESTAMP = { 2014.10.31 },
}

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