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Full-Text Articles in Life Sciences
Interspecific Gene Flow Potentiates Adaptive Evolution In A Hybrid Zone Formed Between Pinus Strobiformis And Pinus Flexilis, Mitra Menon
Theses and Dissertations
Species range margins are often characterised by high degrees of habitat fragmentation resulting in low genetic diversity and higher gene flow from populations at the core of the species range. Interspecific gene flow from a closely related species with abutting range margins can increase standing genetic diversity and generate novel allelic combinations thereby alleviating limits to adaptive evolution in range margin populations. Hybridization driven interspecific gene flow has played a key role in the demographic history of several conifer due to their life history characteristics such as weak crossability barriers and long generation times. Nevertheless, demonstrating whether introgression is adaptive …
Substrate Availability And Regeneration Microsites Of Tolerant Conifers In Mixed-Species Stands In Maine, Jamie K. Weaver
Substrate Availability And Regeneration Microsites Of Tolerant Conifers In Mixed-Species Stands In Maine, Jamie K. Weaver
Electronic Theses and Dissertations
This study investigates regeneration in mixed-species stands in the Acadian Forest of Maine. We examined the effect of silvicultural intensity on available regeneration substrates and how seedling-substrate relationships may be impacted by management activities. Silvicultural treatments studied include two replicates each of 5-year selection, 20-year selection, commercial clearcutting (unregulated harvesting), and three replicates of no management (defined as no harvesting for at least 50 years). We focused on red spruce (Picea rubens Sarg.), eastern hemlock (Tsuga canadensis (L.) Carr.), balsam fir (Abies balsamea L. Mill), and red maple (Acer rubrum L.); all four species are common within the Acadian region. …
Early Life Stage Characteristics Of Six Acadian Conifer Species: Germination And Seedling Development In A Changing Climate, Jason D. Schatz
Early Life Stage Characteristics Of Six Acadian Conifer Species: Germination And Seedling Development In A Changing Climate, Jason D. Schatz
Electronic Theses and Dissertations
Global climate change will drastically alter regional climates. The influence of these changes on the distribution and relative abundance of forest trees is both critically important and subject to substantial uncertainty. It will be particularly important to understand the effects of different climate scenarios on the early life stages of major tree species, because: 1) Early life stage performance and survival strongly influence the abundance of mature trees of a given species, 2) Trees are most sensitive to environmental variation during their early life stages, and 3) Our knowledge of the response of Acadian Forest tree species to environmental variation …
Understory Growth Dynamics And Mensuration Techniques In Uneven-Aged, Mixed-Species Northern Conifer Stands, Andrew R. Moores
Understory Growth Dynamics And Mensuration Techniques In Uneven-Aged, Mixed-Species Northern Conifer Stands, Andrew R. Moores
Electronic Theses and Dissertations
Managing uneven-aged, mixed-species stands requires balancing the need for high leaf area allocation in the overstory where it is most efficient versus the need to allow for sufficient growth of younger cohorts in the understory. To help forest managers make informed decisions to maintain this balance, the understory growth dynamics of northern conifer species in stands managed under uneven-aged silvicultural systems were studied. Sapling height growth of Picea rubens Sarg., Abies balsamea (L.) Mill, and Tsuga canadensis (L.) Carr. were modeled as a function of overstory canopy openness (gap fraction) using regression analysis. Research was conducted in four uneven-aged northern …
Crop Tree Growth And Quality Twenty-Five Years After Precommercial Thinning In A Northern Conifer Stand, Leah M. Phillips
Crop Tree Growth And Quality Twenty-Five Years After Precommercial Thinning In A Northern Conifer Stand, Leah M. Phillips
Electronic Theses and Dissertations
Growth characteristics of selected Picea rubens Sarg. (red spruce) and Abies balsamea (L.) Mill. (balsam fir) crop trees were studied in a northern conifer forest to determine the effects of precommercial thinning (PCT) 25 years after initial treatment. Two measures of growth efficiency (GE, growth per unit of growing space) were examined: stemwood increment (dm3) per unit of projected leaf area (PLA) (m2) and stemwood increment (dm3) per unit of crown projection area (CPA) (m2). Stem form differences were evaluated by comparing stem taper between species and treatments. Branch diameters were measured between 1 .O - 2.0 meters above breast …
A Biosystematic Survey Of Sierra Lodgepole Pine (Pinus Contorta Var. Murrayana [Critchfield]) Populations In The Transverse And Peninsular Ranges Of Southern California, Richard Gobin Everett
A Biosystematic Survey Of Sierra Lodgepole Pine (Pinus Contorta Var. Murrayana [Critchfield]) Populations In The Transverse And Peninsular Ranges Of Southern California, Richard Gobin Everett
Theses Digitization Project
No abstract provided.