Variations, selon la progression de l'hiver, dans le choix de l'habitat et du régime alimentaire chez trois groupes d'orignaux (Alces alces) en milieu agro-forestier

1986 ◽  
Vol 64 (7) ◽  
pp. 1475-1481 ◽  
Author(s):  
Robert Joyal ◽  
Claude Bourque
Keyword(s):  
Populus Tremuloides ◽  
Snow Depth ◽  
Alces Alces ◽  
Abies Balsamea ◽  
Balsam Fir ◽  
Régime Alimentaire ◽  
Trembling Aspen ◽  
Plant Composition ◽  
Core Areas ◽  
Settlement Areas

Three distinct groups of moose (Alces alces) were followed for one winter in settlement areas of northwestern Quebec to investigate changes in their choice of diet and habitat over the winter. No trend was observed in structure and plant composition of winter yards over the season. From December to March, each group used at least three different core areas intensively, these areas totalling 1.02 (first group), 1.28 (second group), and 2.48 km2 (third group). The size of the winter yards diminished in March but this decrease was not due to an increase in snow depth, which reached its maximum of 88 cm in February. The total areas used by the three groups were 1.7, 2.6, and 6.6 km2, respectively. No trend was found in the diet during the winter, except that trembling aspen (Populus tremuloides) was most heavily used by the three groups in March. Twenty-three species of browse were used but 6 species formed nearly 95% of the diet; balsam fir (Abies balsamea) and mountain maple (Acer spicatum) were almost completely absent from the diet.

Mineralization rates and factors influencing snag decay in four North American boreal tree species

2012 ◽  
Vol 42 (1) ◽  
pp. 157-166 ◽  
Author(s):  
Virginie A. Angers ◽  
P. Drapeau ◽  
Y. Bergeron
Keyword(s):  
Wood Density ◽  
Populus Tremuloides ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Jack Pine ◽  
Decay Rates ◽  
Balsam Fir ◽  
Time Since Death ◽  
Trembling Aspen ◽  
Boreal Species

The rate at which the wood of dead trees decays has numerous ecological implications. Decay rates of fallen tree boles have been extensively documented. However, decay rates of snags and the factors that influence decay in snags have received much less attention, especially in boreal species of eastern North America. In this study, mineralization rates (measured as wood density loss) were assessed in snags of four boreal species: trembling aspen (Populus tremuloides Michx.), balsam fir (Abies balsamea (L.) Mill.), jack pine (Pinus banksiana Lamb.), and black spruce (Picea mariana (Mill.) BSP). Wood density and variables potentially influencing decay rates (time since death, age, average radial growth, diameter at breast height, cerambycid larvae activity, and scolytid larvae activity) were measured on discs of 207 snags in northwestern Quebec, Canada. Mineralization rates varied significantly among species. Trembling aspen exhibited a more rapid rate of loss than conifers (k = 0.0274). Jack pine was the second most rapid species to lose wood density (k = 0.0152), followed by balsam fir (k = 0.0123). Black spruce was particularly resistant to mineralization (k = 0.0058), and its wood density was not significantly influenced by time elapsed since death for the time period sampled in this study. Time since death coupled with cerambycid larvae activity was associated with lower wood densities in trembling aspen, balsam fir, and jack pine, whereas slower growth was associated with a decreased mineralization rate in black spruce.

Insect–host relationships influencing disturbance by the spruce budworm in a boreal mixedwood forest

2004 ◽  
Vol 34 (9) ◽  
pp. 1870-1882 ◽  
Author(s):  
V G Nealis ◽  
J Régnière
Keyword(s):  
Life Cycle ◽  
Populus Tremuloides ◽  
Black Spruce ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
White Spruce ◽  
Host Tree ◽  
Balsam Fir ◽  
Insect Host ◽  
Boreal Mixedwood Forest

Demographic data from a 15-year outbreak of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae), in a boreal mixedwood forest in Ontario, Canada, are used to interpret stand-level ecological disturbance in terms of susceptibility and vulnerability (mortality) of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) BSP). All three host-tree species are highly susceptible for oviposition by the spruce budworm and all are suitable for completion of the budworm life cycle. Host-related differences in susceptibility arise from the degree of synchrony between spruce budworm phenology during the feeding stages and host-tree phenology. Spruce budworm density was highest on white spruce throughout the budworm's life cycle and over the course of the outbreak, but more rapid flushing and growth of current-year buds in white spruce reduced damage relative to that on balsam fir. Conversely, later flushing of current-year buds on black spruce led to a reduction in budworm density early in the season and a corresponding reduction in defoliation. The combination of high budworm densities and severe defoliation caused mortality first on balsam fir. By the end of the outbreak, 89% of the balsam fir component >10 cm DBH was eliminated compared with 49% of the white spruce in the same size class. The lower susceptibility of black spruce resulted in survival of all but the smallest size classes of that species. Nonhost species such as trembling aspen (Populus tremuloides Michx.) nearly doubled their basal area during the outbreak. The results link processes inherent in the insect–host relationship with the population ecology of the insect and the disturbance ecology of the forest.

Canopy gap disturbance and succession in trembling aspen dominated boreal forests in northeastern Ontario

2005 ◽  
Vol 35 (8) ◽  
pp. 1942-1951 ◽  
Author(s):  
Steven B Hill ◽  
Azim U Mallik ◽  
Han YH Chen
Keyword(s):  
Populus Tremuloides ◽  
Boreal Forests ◽  
Abies Balsamea ◽  
Stand Development ◽  
Gap Size ◽  
Trembling Aspen ◽  
Gap Fraction ◽  
Gap Disturbance ◽  
The Impact ◽  
Development Proceeds

Canopy gaps play an important role in forest vegetation dynamics when fire return intervals are long. However, there is little known about the role of gaps in the development of forest stands that initially dominate following stand-replacing disturbance. We investigated gap disturbance during the breakup of trembling aspen (Populus tremuloides Michx.) stands at two scales: at the stand level we quantified gap fraction and gap size as stand development proceeds; at the gap level we determined causes of gap-maker mortality and evaluated resulting gap-maker structure and decay as stand development proceeds. We also evaluated the impact that gaps have on stand transition by quantifying the abundance and growth of juvenile trees in gaps of different sizes and ages. Ten stands between 60 and 120 years since fire in northeastern Ontario were sampled using line intersect transects. Gap fraction doubled (∼18%–36%) and mean gap size was more than four times greater (∼45–200 m2) over the time period. Standing dead gap makers in early states of decay were most frequent in young stands, whereas snapped gap makers in various states of decay were most frequent in old stands. Infection by fungal pathogens was the most frequent cause of mortality (56%) and was not related to time since fire. Balsam fir (Abies balsamea (L.) Mill.) was the most abundant juvenile recruit. However, transition probabilities for tree species were independent of gap type. These results indicate that gap creation is frequent during early stages of stand development in boreal forests; however, it is unlikely that successional trajectory is affected by their formation.

Partial cuts in a trembling aspen – conifer stand: effects on microenvironmental conditions and regeneration dynamics

2003 ◽  
Vol 33 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Marcel Prévost ◽  
David Pothier
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Abies Balsamea ◽  
Basal Area ◽  
Trembling Aspen ◽  
Limited Growth ◽  
Growth And Survival ◽  
Regeneration Dynamics ◽  
Canopy Opening ◽  
Light Soil

We present the 5-year combined effects of different cutting intensities (removal of 0, 35, 50, 65, and 100% of basal area) and scarification on available light, soil temperature, and regeneration dynamics in a mixed aspen– conifer stand in Quebec, Canada. Compared with the control, the 35% cut did not change transmitted light to the under story (<20% of full light), while the 50, 65, and 100% cuttings transmitted 30, 48, and 90% of full light, respectively, during the first summer. Trembling aspen (Populus tremuloides Michx.) suckering increased with percent basal area removal (p < 0.001). After 5 years, the 35 and 50% cuttings limited growth and survival of suckers (<1000 stems/ha, of which 5% are >1 m high), but the 65 and 100% cuttings favoured their development (8000 and 11 000 stems/ha, respectively, of which 29 and 38%, respectively, are >2 m high). Balsam fir (Abies balsamea (L.) Mill.) responded well to canopy opening alone with a maximal recruitment (31 000 seedlings/ha) in the 50% cut. Spruces (white spruce, Picea glauca (Moench) Voss, and red spruce, Picea rubens Sarg.) establish following scarification only, with a better response in the 65% cut (32 000 seedlings/ha) than in the 50 (15 000), 35 (10 000), and 0% (8000) cuttings.

Balsam fir and white spruce seedling recruitment in response to understory release, seedbed type, and litter exclusion in trembling aspen stands

2005 ◽  
Vol 35 (3) ◽  
pp. 667-673 ◽  
Author(s):  
G. Geoff Wang ◽  
Kevin J Kemball
Keyword(s):  
Forest Floor ◽  
Seedling Recruitment ◽  
Mineral Soil ◽  
Abies Balsamea ◽  
White Spruce ◽  
Balsam Fir ◽  
Trembling Aspen ◽  
Light Competition ◽  
Seedling Mortality ◽  
Undisturbed Forest

Experimental seeding of balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca (Moench) Voss) was implemented in three mature trembling aspen (Populus tremuloides Michx.) stands in southeastern Manitoba to test (i) the effect of vegetation (light) competition and seedbed type (undisturbed forest floor, exposed mineral soil, and rotten logs) on seedling recruitment over the first 2 years and (ii) the effect of broadleaf litter exclusion on seedling mortality during the first winter. The study indicated that, with adequate seed supply, seedbed type was the most important factor limiting seedling recruitment, especially the recruitment of white spruce, in trembling aspen stands. Seedling recruitment on the best and the worst seedbeds differed by 1.8 times for balsam fir but by 19 times for white spruce. Significant differences in soil moisture and temperature were found between seedbed types. Broadleaf litter exclusion also facilitated the recruitment of balsam fir and white spruce, but only on undisturbed forest floor. Vegetation (light) competition, however, did not limit seedling recruitment. On the contrary, the presence of understory vegetation benefited seedling recruitment on rotten logs. Compared with white spruce, balsam fir is better adapted to regenerate in trembling aspen stands. Balsam fir was about 4, 12, and 36 times better than white spruce when regenerating on exposed mineral soil, rotten log, and undisturbed forest floor, respectively.

Recent impact of fire on high-altitude balsam fir forests in south-central Quebec1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1289-1305 ◽  
Author(s):  
Pierre-Luc Couillard ◽  
Serge Payette ◽  
Pierre Grondin
Keyword(s):  
High Altitude ◽  
Fire Regime ◽  
Abies Balsamea ◽  
Balsam Fir ◽  
Stand Age ◽  
Forest Types ◽  
Plant Composition ◽  
White Birch ◽  
South Central

The dynamics of high-altitude balsam fir ( Abies balsamea (L.) Mill.) forests is mainly driven by insect outbreaks and windthrows. However, very little work has been done on the role of fire on the development and maintenance of this ecosystem. In this study, we document the role of fire in the high-altitude balsam fir forests of the Réserve Faunique des Laurentides (RFL), southern Quebec. Sixteen sites were sampled among six different forest types described according to plant composition and fire evidence. At each site, the diameter structure was recorded and stand age was calculated based on tree-ring dating of individual trees and radiocarbon-dated surficial charcoal samples. Fire played a major role in the recent dynamics of high-altitude fir forests in the RFL. Over the last 250 years, nearly 50% of the study area burned during two fire conflagrations, i.e., around 1815 and in 1878. The fires triggered gradual changes in plant composition and forest structure, as shown by a succession of forest types ranging from white birch ( Betula papyrifera Marsh.) to spruce–fir types. Absence of surficial charcoal older than 300 years suggests that high-altitude forests of the RFL area were not subjected to a constant fire regime. It is possible that recent fires were caused by human activity.

The effect of light availability and basal area on cone production in Abies balsamea and Picea glauca

2002 ◽  
Vol 80 (4) ◽  
pp. 370-377 ◽  
Author(s):  
David F Greene ◽  
Christian Messier ◽  
Hugo Asselin ◽  
Marie-Josée Fortin
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Light Availability ◽  
Abies Balsamea ◽  
Basal Area ◽  
White Spruce ◽  
Balsam Fir ◽  
Forest Edges ◽  
Cone Production ◽  
Effect Of Light

Mean annual seed production is assumed to be proportional to basal area for canopy trees, but it is not known if subcanopy trees produce fewer seeds than expected (given their size) because of low light availability. Ovulate cone production was examined for balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca (Moench) Voss) in 1998 and for balsam fir in 2000 in western Quebec using subcanopy stems, near or far from forest edges, or (at one site) planted white spruce trees in fully open conditions. A very simple light model for transmission through mature trembling aspen (Populus tremuloides Michx.) crowns and through boles near forest edges was developed to account for the effect of light receipt on cone production. The enhanced light near forest edges (e.g., recent clearcuts) leads to about a doubling of cone production for subcanopy stems. The minimum subcanopy height for cone production far from an edge is about 10 m for balsam fir and 14 m for white spruce, with these minima decreasing near edges. By contrast, the minimum height for white spruce in a plantation (full light) is about 3 m. Accounting for light receipt leads to an increase in the explained variance.Key words: balsam fir, cone production, light model, regressions, subcanopy stems, white spruce.

Influence de quelques défauts externes sur la stabilité des arbres face à une simulation mécanique de l'action du vent

1998 ◽  
Vol 28 (1) ◽  
pp. 123-131
Author(s):  
G Silva ◽  
J -C Ruel ◽  
M Samson ◽  
D Pin
Keyword(s):  
Populus Tremuloides ◽  
Maximum Stress ◽  
No Reduction ◽  
Abies Balsamea ◽  
The Other ◽  
Balsam Fir ◽  
Betula Alleghaniensis ◽  
Wind Action ◽  
Significant Difference ◽  
Standing Trees

A simulation of wind action was achieved to test the influence of some external defects on the resistance of standing trees of balsam fir (Abies balsamea (L.) Mill.), yellow birch (Betula alleghaniensis Britton), and trembling aspen (Populus tremuloides Michx.). The methodology used consisted of applying a force on the tree with a winch. Every tree was filmed during winching, and the geometrically corrected images were used to compute displacement. Balsam fir trees tended to break more than uproot, and in most cases, breakage occurred at the crack level. Even though maximum turning moment did not differ between control and defective balsam fir trees, a significant difference was found for maximum stress, showing a reduction in resistance associated with cracks. No reduction in resistance could be seen for the other species, but trees were relatively young and care should be taken before extending these results to older trees.

FOREST COMMUNITIES IN NORTHWESTERN ALBERTA

1953 ◽  
Vol 31 (2) ◽  
pp. 212-252 ◽  
Author(s):  
E. H. Moss
Keyword(s):  
Populus Tremuloides ◽  
Black Spruce ◽  
Abies Balsamea ◽  
White Spruce ◽  
Balsam Fir ◽  
Peat Moss ◽  
Mixed Stands ◽  
Natural Succession ◽  
Balsam Poplar ◽  
Feather Moss

Spruce, tamarack (larch), balsam fir, pine, and poplar communities of the region are described in terms of floristic composition and ecological relationships. The white spruce (Picea glauca) association is regarded as the climax type of the region. Of four phases or faciations presented by the white spruce association, the feather moss faciation appears to be the climax to which the other faciations tend to develop. Two black spruce (Picea mariana) communities are recognized, the black spruce – feather moss association and the black spruce–peat moss association. Of these, the former is characterized by "feather mosses" such as Hylocomium splendens and has developed on relatively level terrain without much peat formation, whereas the latter has a Sphagnum floor and has arisen in definite depressions through acid bog stages with the production of considerable peat. The black spruce – bog moss community is interpreted as subclimax, with natural succession to the black spruce – feather moss association. The tamarack (Larix laricina) community has many features in common with the black spruce – peat moss association but differs markedly, not only in its dominant species, but because of its development from a Drepano-cladus–Carex–Betula bog under persisting wet conditions. Succession to black spruce commonly occurs. Balsam fir (Abies balsamea) is relatively rare in the region and usually grows in mixed stands with white spruce, paper birch, aspen, and balsam poplar. Two divisions of the pine association are recognized, the jack pine (Pinus banksiana) and the lodgepole pine (P. contorta var. latifolia) consociations. For each of these, two phases are described, the pine – feather moss faciation on the more shaded sites and the pine–heath faciation on the more open and drier areas. Knowledge of the ranges of these two pines in northern Alberta and concerning hybrids between the species is extended. The poplar association, classified as aspen (Populus tremuloides) and balsam poplar (P. balsamifera) consociations, is considered in relation to other vegetation, especially prairie grassland and white spruce. Encroachment of aspen poplar upon native grassland is counteracted by various factors, notably burning. Natural succession of poplar and pine to white spruce is impeded chiefly by forest fires. Some attention is given to phytogeographical problems of this transition region.

Winter foods of moose in La Vérendrye Park, Québec: an evaluation of two browse survey methods

1976 ◽  
Vol 54 (10) ◽  
pp. 1765-1770 ◽  
Author(s):  
Robert Joyal
Keyword(s):  
Populus Tremuloides ◽  
Survey Methods ◽  
Abies Balsamea ◽  
Dry Weight ◽  
Balsam Fir ◽  
White Birch ◽  
Eastern Canada ◽  
Mixed Stands ◽  
Corylus Cornuta ◽  
Key Species

The winter foods of moose (Alces alces) were determined in three winter yards in representative mixed forests of western Quebec. Browse use was measured by estimation of browse units and by twig counts. The first method enabled identification of key species in the diet while the second gave, in weight, the proportion of each. Both methods are compared. A total of 21 species offered available food, but only 12 were browsed. More than 75% of the diet in dry weight came from mountain maple (Acer spicatum), balsam fir (Abies balsamea), and willows (Salix spp.), with 53, 13, and 9.5% respectively. The mean weight of browsed twigs of different species varied. widely. Balsam fir twigs weighed about seven times more than white birch (Betula papyrifera) and 10 times more than beaked hazel twigs (Corylus cornuta). Moose preferred willows and trembling aspen (Populus tremuloides), which showed the highest availability:utilization ratio. Mountain maple was eaten proportionally to its availability. Results can be used in carrying-capacity studies in other mixed stands of eastern Canada.

Sign in / Sign up

Export Citation Format

Share Document