scholarly journals Végétation tardiglaciaire et postglaciaire au sud-est du parc des Laurentides, Québec

2011 ◽  
Vol 35 (3) ◽  
pp. 345-359 ◽  
Author(s):  
Claude Labelle ◽  
Pierre J.H. Richard
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Abies Balsamea ◽  
Pinus Strobus ◽  
Larix Laricina ◽  
Betula Papyrifera ◽  
Betula Glandulosa

L’analyse pollinique des sédiments de trois lacs situés au sud-est du parc des Laurentides a permis de retracer les étapes de la recolonisation végétale post-wisconsinienne. Celle-ci s’est effectuée selon un schéma assez constant à travers le secteur à l’étude. Au début, la végétation était très ouverte, mais tout de même relativement riche en taxons herbacés et arbustifs. Cette phase initiale de végétation (sous-zone la) fut suivie, après une période de transition (sous-zone 1b), par une végétation luxuriante de type toundra (sous-zone 1c). Celle-ci fut à son tour remplacée par une végétation de type toundra arbustive (sous-zone 1d) où l’on voit s’accroître l’importance de Betula glandulosa et d’autres éléments arbustifs. Avec un certain métachronisme entre les sites, l’afforestation s’est amorcée par l’installation du Populus cf. tremuloïdes (sous-zone 2a) et s’est poursuivie par l’arrivée de Picea mariana (fin de la sous-zone 2a) puis, par celle d’une série d’arbres tels Betula papyrifera, Pinus cf. divaricata, Abies balsamea, Picea glauca et Larix laricina (sous-zone 2b). Pendant cette dernière phase de l’afforestation, l’abondance du pollen d’Alnus cf. crispa dans les spectres est maximale. Il semble qu’au moins mille ans se soient écoulés avant l’arrivée des arbres autres que le Populus cf. tremuloïdes. Par la suite, l’histoire de la végétation forestière (zone 3) a été plutôt monotone. Bien que les diagrammes révèlent des périodes de plus grande abondance de certains taxons (Pinus strobus, Picea mariana, Pinus et. divaricata), la majorité des arbres, présents actuellement dans la région, ont migré très tôt à l’Holocène.

scholarly journals Histoire Postglaciaire de la Végétation dans la Région de Mont-Saint-Pierre, Gaspésie, Québec

2007 ◽  
Vol 38 (3) ◽  
pp. 257-274 ◽  
Author(s):  
Claude Labelle ◽  
Pierre J. H. Richard
Keyword(s):  
Acer Saccharum ◽  
Abies Balsamea ◽  
Pinus Strobus ◽  
Larix Laricina ◽  
Betula Alleghaniensis ◽  
Betula Papyrifera ◽  
Fraxinus Nigra

RÉSUMÉLes analyses pollinique et macrofossile de sédiments de deux lacs des environs de Mont-Saint-Pierre (Gaspésie), l'un dans la vallée côtière, l'autre sur le plateau, permettent de reconstituer l'histoire postglaciaire de la végétation dans deux situations physiographiques contrastées. Seul le plateau a été colonisé par une végétation initiale de type toundra (> 10 400 ans BP), pendant que la vallée était encore en partie ennoyée par la mer de Goldthwait. L'afforestation du plateau fut caractérisée d'abord par des populations de Picea sp., accompagné de Populus sp. et Larix laricina, puis par un envahissement progressif par Abies balsamea et Betula papyrifera. La baisse de la représentation pollinique de l'aulne vert (Alnus cf. crispa), maximale durant l'afforestation, paraît être un indicateur assez fidèle de la fermeture de la couverture forestière. Cette phase se termine vers 9000 ans BP sur le plateau. Le rythme de l'afforestation a été différent dans la vallée. Des taxons héliophiles s'y sont maintenus plus longtemps, ce qui peut être relié à l'activité des versants abrupts qui flanquent la vallée. Malgré des variations de l'abondance relative des arbres, la sapinière à bouleau blanc a sans doute occupé le plateau depuis 9000 ans BP environ. Par contre, la végétation de la vallée s'est passablement modifiée jusque vers 5000 à 4500 ans BP, par la migration successive de Betula alleghaniensis, de Pinus strobus, de Fraxinus nigra, dAcer saccharum et d'Ulmus americana. L'implantation progressive de ces arbres relativement thermophiles est à l'origine de la diversité du paysage actuel de la vallée. Ces reconstitutions permettent d'écarter l'hypothèse de Dansereau (1944) selon laquelle les érablières à Acer saccharum de la Gaspésie seraient des groupements hérités de l'optimum climatique de l'Holocène moyen, au cours duquel les érablières auraient été largement répandues sur le territoire. Les données montrent que ces érablières datent de l'Holocène Supérieur, la migration d'Acer saccharum ayant sans doute été freinée par des barrières topo-climatiques entraînant une discontinuité prononcée des habitats pouvant accueillir cette espèce.

Short-term effects of cut-to-length versus full-tree harvesting on conifer regeneration in jack pine, mixedwood, and black spruce forests in Manitoba

2004 ◽  
Vol 34 (9) ◽  
pp. 1938-1945 ◽  
Author(s):  
Isobel Waters ◽  
Steven W Kembel ◽  
Jean-François Gingras ◽  
Jennifer M Shay
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Jack Pine ◽  
Tree Regeneration ◽  
Understorey Vegetation ◽  
Advance Regeneration ◽  
The Impact

This study compares the effects of full-tree versus cut-to-length forest harvesting methods on tree regeneration in jack pine (Pinus banksiana Lamb.), mixedwood (Picea glauca (Moench) Voss – Populus tremuloides Michx. – Abies balsamea (L.) Mill.), and black spruce (Picea mariana (Mill.) BSP) sites in southeastern Manitoba, Canada. We surveyed tree regeneration densities, disturbance characteristics, and understorey vegetation in replicated control and harvested plots in each site type preharvest (1993) and 1 and 3 years postharvest (1994, 1996). In jack pine sites, the full-tree harvest method promoted regeneration of Pinus banksiana through increased disturbance of soil and the moss layer, and decreased slash deposition relative to the cut-to-length method. Conversely, in mixedwood sites the cut-to-length method resulted in less damage to advance regeneration and proved better at promoting postharvest regeneration of Abies balsamea and Picea glauca relative to the full-tree method. In black spruce sites, there were few differences in the impact of the two harvesting methods on regeneration of Picea mariana, which increased in frequency and density after both types of harvesting.

Gradient analysis of Larix laricina dominated wetlands in Canada's southeastern boreal forest

2001 ◽  
Vol 79 (4) ◽  
pp. 444-456 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques Tardif ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Abies Balsamea ◽  
Hierarchical Classification ◽  
Canopy Cover ◽  
Larix Laricina ◽  
Betula Papyrifera ◽  
Kalmia Angustifolia ◽  
Fraxinus Nigra ◽  
Hierarchical Classification Analysis ◽  
Substrate Ph

With the objective of understanding how vegetation was structured in four Larix laricina (Du Roi) K. Koch dominated wetlands in north-western Quebec, 186 point-centred quarters were sampled in four stands. For each point, both biotic and abiotic variables were collected and species cover was recorded. Divisive hierarchical classification analysis (Twinspan) identified nine vegetation clusters: i) Larix laricina & Spiraea alba, ii) Larix laricina & Kalmia angustifolia, iii) Larix laricina, Picea mariana & Alnus rugosa, iv) Larix laricina & Betula pumila, v) Thuja occidentalis & Trientalis borealis, vi) Abies balsamea & Betula papyrifera, vii) Fraxinus nigra & Onoclea sensibilis, viii) Alnus rugosa, and ix) Eleocharis smallii. Results of the canonical correspondence analyses indicated that the distribution of these clusters was mainly related to (i) distance from shore, (ii) shade (canopy cover), (iii) substrate nitrate concentration (in relation to the abundance of Kalmia angustifolia and Alnus rugosa), (iv) substrate pH (in relation to the abundance of Sphagnum spp.), and (v) substrate conductivity. Several characteristics of the water table also affected species distribution, including pH, depth, and carbon concentration. Further studies should address the effect of the presence of Kalmia angustifolia and Alnus rugosa on larch growth.Key words: larch, wetland, vegetation analysis, flooding, boreal forest.

Fungi that cause sapstain in Canadian softwoods

1999 ◽  
Vol 45 (11) ◽  
pp. 914-922 ◽  
Author(s):  
A Uzunovic ◽  
D -Q Yang ◽  
P Gagné ◽  
C Breuil ◽  
L Bernier ◽  
...  
Keyword(s):  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Pinus Contorta ◽  
Abies Balsamea ◽  
Forest Products ◽  
Fungal Species ◽  
Forest Products Industry ◽  
Diverse Range ◽  
Commercially Important

The Canadian forest products industry suffers considerable losses due to discoloration caused by sapstain fungi. Although studied for a number of years, the identity, biology, and ecology of these fungi are still only partly understood. To determine which fungi caused stain problems, a detailed survey was conducted at seven selected sawmills across Canada. In summer 1997, fresh logs and lumber were set aside in the mills 1 month prior to sampling for fungi. We excluded bark-beetle-attacked wood and our logs remained free from their attack during storage. Five commercially important softwood species, Abies balsamea (L.) Mill., Picea mariana (Mill.) B.S.P., Picea glauca (Moench) Voss, Pinus contorta Dougl., and Pinus banksiana Lamb., were included in the studies. A total of 1863 isolates were isolated from stained and adjacent areas on test wood, and were identified based on their morphological and physiological characteristics and mating compatibility to 13 different species representing five genera. The most commonly encountered genus, Ophiostoma (97%), was represented by nine species. A more diverse range of fungi was found in logs than in lumber; some species were more frequently isolated from one type of substrate and rarely (or not at all) from the other. No fungal species occurred exclusively in a particular region or wood substrate.Key words: bluestain, lumber, logs, Ophiostoma, Ceratocystis.

scholarly journals Habitat Segregation Among Songbirds in Old-Growth Boreal Mixedwood Forest

2004 ◽  
Vol 118 (1) ◽  
pp. 45 ◽  
Author(s):  
Enid E. Cumming
Keyword(s):  
Picea Glauca ◽  
Foraging Behaviour ◽  
Abies Balsamea ◽  
Deciduous Trees ◽  
Betula Papyrifera ◽  
White Birch ◽  
Bottom Part ◽  
Boreal Mixedwood Forest ◽  
Prince Albert National Park ◽  
Vireo Solitarius

The foraging behaviour of ten species of insectivorous songbirds — Boreal Chickadee (Poecille hudsonicus), Golden-crowned Kinglet (Regulus satrapa), Ruby-crowned Kinglet (R. calendula), Blue-headed Vireo (Vireo solitarius), Tennessee (Vermivora peregrina), Blackburnian (Dendroica fusca), Magnolia (D. magnolia), Yellow-rumped [Myrtle] (D. coronata), Black-throated Green (D. virens), and Bay-breasted (D. castanea) warblers — was observed in the boreal mixedwood forest of Prince Albert National Park in central Saskatchewan. Birds segregated their habitat use by preferentially foraging in different tree species, and through preferential use of different foraging locations (height and position) within trees.White Spruce (Picea glauca) was used more than expected by Yellow-rumped Warblers, and Golden-crowned and Ruby-crowned kinglets. Tennessee and Magnolia warblers used White Birch (Betula papyrifera), more than expected and Boreal Chickadees and Blue-headed Vireos used Balsam Fir (Abies balsamea) more than expected. Boreal Chickadees, Ruby-crowned Kinglets, and Tennessee, Blackburnian and Yellow-rumped warblers all used the bottom part of trees less than expected, while Blueheaded Vireos foraged near the top of trees less than expected. Large inner branches were avoided by Tennessee, Blackburnian and Yellow-rumped warblers, while Bay-breasted Warblers and Blue-headed Vireos avoided small outer twigs. In conifers, Blackburnian Warblers foraged significantly higher in the trees than all other species except Black-throated Green and Baybreasted warblers. Blackburnian Warblers also foraged significantly higher than Blue-headed Vireos and Magnolia Warblers in deciduous trees.

Cree antidiabetic plant extracts display mechanism-based inactivation of CYP3A4

2011 ◽  
Vol 89 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Teresa W. Tam ◽  
Rui Liu ◽  
John T. Arnason ◽  
Anthony Krantis ◽  
William A. Staines ◽  
...  
Keyword(s):  
Medicinal Plants ◽  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Abies Balsamea ◽  
Cytochrome P450 3A4 ◽  
Cyp3a4 Inhibition ◽  
Kalmia Angustifolia ◽  
Lycopodium Clavatum ◽  
Rhododendron Tomentosum

Seventeen Cree antidiabetic medicinal plants were studied to determine their potential to inhibit cytochrome P450 3A4 (CYP3A4) through mechanism-based inactivation (MBI). The ethanolic extracts of the medicinal plants were studied for their inhibition of CYP3A4 using the substrates testosterone and dibenzylfluorescein (DBF) in high pressure liquid chromatography (HPLC) and microtiter fluorometric assays, respectively. Using testosterone as a substrate, extracts of Alnus incana , Sarracenia purpurea , and Lycopodium clavatum were identified as potent CYP3A4 MBIs, while those from Abies balsamea , Picea mariana , Pinus banksiana , Rhododendron tomentosum , Kalmia angustifolia , and Picea glauca were identified as less potent inactivators. Not unexpectedly, the other substrate, DBF, showed a different profile of inhibition. Only A. balsamea was identified as a CYP3A4 MBI using DBF. Abies balsamea displayed both NADPH- and time-dependence of CYP3A4 inhibition using both substrates. Overall, several of the medicinal plants may markedly deplete CYP3A4 through MBI and, consequently, decrease the metabolism of CYP3A4 substrates including numerous medications used by diabetics.

THE VEGETATION OF NORTHERN MANITOBA: I. STUDIES IN THE SOUTHERN SPRUCE FOREST ZONE

1956 ◽  
Vol 34 (4) ◽  
pp. 523-561 ◽  
Author(s):  
J. C. Ritchie
Keyword(s):  
North America ◽  
Picea Mariana ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Local Community ◽  
Ground Vegetation ◽  
Spruce Forest ◽  
Betula Papyrifera ◽  
Eastern Canada ◽  
Forest Zone

It is pointed out that there are available no ecological accounts of the vegetation of Northern Manitoba and the surrounding regions. After brief accounts of the topography, geology, and climate, the communities which were met with in two areas of study are described. It is shown that the predominant and stable forest of mesic sites is dominated by Picea mariana, with a ground vegetation composed chiefly of weft-form mosses. In areas which have been burned various subseral variants of this forest are present. Pinus banksiana, as well as being a seral dominant of mesic sites, dominates various forests of outcrop ridges, sand plains, and eskers. Picea glauca is rare in the area, occurring only on those sites which show exceptionally favourable conditions of habitat. The vegetation of this region conforms with descriptions of the Southern Spruce Forest Zone of Eastern Canada, which classification might well be extended westwards at least as far as northwest Manitoba. There is some evidence that the dry climate which prevails west of the region, and for which there is slight evidence here, has influenced the flora and vegetation of the region. A description is given of a highly local community of Betula papyrifera var. neoalaskana on organic ridges which appears never to have been recorded previously for North America.

Tree recruitment from burn edges

2000 ◽  
Vol 30 (8) ◽  
pp. 1264-1274 ◽  
Author(s):  
D F Greene ◽  
E A Johnson
Keyword(s):  
Picea Glauca ◽  
Pinus Banksiana ◽  
Abies Balsamea ◽  
Basal Area ◽  
White Spruce ◽  
Picea Engelmannii ◽  
Larix Laricina ◽  
Tree Recruitment ◽  
Engelmann Spruce ◽  
Large Fires

We developed and tested a wind-dispersal model of tree recruitment into burns from living sources at the fire edge or from small unburned residual stands. The model was also tested on recruitment of serotinous Pinus banksiana Lamb. within a burn. The model assumed that source strength is proportional to basal area density and that an individual (point source) recruitment curve can be expressed as a lognormal distribution. The model made significant predictions of the recruitment curves of Engelmann spruce (Picea engelmannii Parry ex Engelm.), white spruce (Picea glauca (Moench) Voss), and balsam fir (Abies balsamea (L.) Mill.) to distances as great as 2.0 km, although it tended to underpredict Abies and overpredict Picea. The model gave significant prediction of recruitment for jack pine (Pinus banksiana) within burns with seeds derived from aerial seed banks, and of white spruce and tamarck (Larix laricina (Du Roi) K. Koch) up to 100 m from residual stands. By forestry standards, burns are poorly stocked by those species that must obligately recruit from edges. In large fires, adequate stocking by a species such as white spruce that had 5 m2/ha of basal area would be limited to about 70 m from the edge. Small residual stands are expected to supply about half of all the recruits of white spruce or fir at distances exceeding about 800 m from a nominal burn edge.

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