La végétation des contreforts des Laurentides : une analyse des gradients écologiques et du niveau successionnel des communautés

1990 ◽  
Vol 68 (2) ◽  
pp. 391-401 ◽  
Author(s):  
Sylvie Gauthier ◽  
Daniel Gagnon
Keyword(s):  
Acer Saccharum ◽  
Acer Rubrum ◽  
Ecological Factors ◽  
High Elevation ◽  
Fagus Grandifolia ◽  
Community Type ◽  
Two Factors ◽  
Community Types ◽  
Topographic Positions ◽  
Vegetation Variation

The forest vegetation of the foothills of the Laurentians was studied to determine which ecological factors are most strongly correlated with vegetation variation. Vegetation and ecological factors were sampled within 78 plots distributed systematically on 19 transects. Ordination and classification analyses show that soil moisture and richness, two factors strongly associated to topographical variations, are the ecological factors that best explain vegetation distribution. Eleven community types were identified. Oligotrophic–xeric community types, characterized by Pinus strobus and Quercus rubra, are generally found in sites at high elevation, where soils are thin, well drained and nutrient poor. The Acer saccharum community types, of the mesotrophic–mesic group, are situated at the base of slopes with deep, rich soils. Fagus grandifolia, Acer rubrum, and Tsuga canadensis characterize a third group of oligotrophic–mesic community types, found on sites with relatively poorly drained and nutrient-poor soils, in topographic positions intermediate to the first two groups. A community type successionnal status index, based on the homogeneity and similarity of the tree and sapling strata, shows that natural and anthropogenic disturbances are also responsible for part of the vegetation variation. Hemlock and beech forests are the most successionnally advanced community types of the oligotrophic–mesic group. On richer soils fed by seepage, the maple–hickory community type is also relatively stable. These results contribute to the ongoing discussion about the eventual outcome of succession on mesic sites in northeastern North America.

La végétation forestière du secteur nord-ouest de la vallée du Saint-Laurent, Québec

1988 ◽  
Vol 66 (4) ◽  
pp. 793-804 ◽  
Author(s):  
Claude St-Jacques ◽  
Daniel Gagnon
Keyword(s):  
Acer Saccharum ◽  
Acer Rubrum ◽  
Ecological Factors ◽  
Detrended Correspondence Analysis ◽  
Forest Community ◽  
North West ◽  
The North ◽  
Two Factors ◽  
Community Types ◽  
And Cluster Analysis

The forest vegetation of the north-west section of the St. Lawrence Valley in Quebec was sampled within 68 quadrats. The location of the quadrats was selected by means of a stratified random sampling plan. Ordination (detrended correspondence analysis) and cluster analysis (TWINSPAN) allowed the identification of 11 forest community types. The ecological factors most closely associated with the distribution of these communities are soil drainage and richness. These two factors are strongly related to the types of surface deposits. Communities dominated by Acer saccharum are found on well drained and nutrient-rich moraines. On the contrary, communities dominated by Acer rubrum and the majority of coniferous forests are found on poorly drained and nutrient-poor soils. Two floristically distinct community types, the Fraxinus – Tilia americana forests and the Tsuga canadensis – Acer saccharum forests, are found on poorly drained marine deposits with edaphically identical lower horizons. However, the pH and major cation concentrations of the upper soil horizons are much lower under the cover of the hemlock forests than under the cover of the ash – basswood forests.

Physical and historical determinants of the pre- and post-settlement forests of northwestern Pennsylvania

2003 ◽  
Vol 33 (9) ◽  
pp. 1683-1697 ◽  
Author(s):  
Gordon G Whitney ◽  
Joseph P DeCant
Keyword(s):  
19Th Century ◽  
Acer Saccharum ◽  
Petroleum Industry ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Quercus Alba ◽  
Old Field ◽  
European Settlement ◽  
Northern Portion ◽  
The 19Th Century

Our analysis of the early land survey records and more recent U.S. Forest Service inventory data documents the changing nature of northwestern Pennsylvania's forests following European settlement. Initially, the northern portion of the four-county study area was dominated by forests of Fagus grandifolia Ehrh. and Acer saccharum Marsh. associated with the richer, finer-textured soils of the rolling Glaciated Appalachian Plateau. Up to 80% of the region was cleared for farming in the 19th century. Marginal farmland was abandoned and reverted to forests in the 20th century. Fires and leached, nutrient-poor soils favored the dominance of Quercus spp. and Castanea dentata (Marsh.) Borkh. in the presettlement forests of the rugged Unglaciated Appalachian Plateaus to the south. The rough nature of the terrain discouraged the early clearance of the plateaus' forests. The advent of the petroleum industry and its insatiable demand for barrels in the 19th century, however, assured the selective removal of the larger (>20 in. (50 cm) DBH) Quercus alba L. from the region's woods. The increasing homogeneity of northwestern Pennsylvania's forests today is due to the sharp decline of the more distinctive indicator species and the rise of a number of opportunistic old-field or gap species, notably Prunus serotina Ehrh. and Acer rubrum L.

La végétation forestière du delta de Lanoraie, Québec

1991 ◽  
Vol 69 (8) ◽  
pp. 1839-1852 ◽  
Author(s):  
L. Lamontagne ◽  
C. Camiré ◽  
C. Ansseau
Keyword(s):  
Populus Tremuloides ◽  
Acer Saccharum ◽  
Abies Balsamea ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
The Other ◽  
Moisture Regime ◽  
Acidic Ph ◽  
Mature Trees ◽  
Forest Sites

The vegetation and the soil characteristics of the sandy terraces of the Lanoraie Delta, Quebec, were sampled at 84 forest sites using the methods of Whittaker and Canada Soil Information System. The ordination results show that the soil moisture regime (xeric–hydric) and the pH (3.5–5.0) are the main factors responsible for the spatial distribution of the vegetation. When these results (ordination analysis) and those of the cluster analysis are superimposed, the relationship between the five vegetation groups studied and particular ecological conditions can be seen. Thus, two groups of vegetation dominated by conifers are found in the middle of the terraces. One of these is dominated by Tsuga canadensis and the other by Abies balsamea and Picea rubens. These two groups are found on podzolic, gleyed soils with a mounded microrelief, which are strongly acidic (pH < 3.5) and have a hydric–mesic moisture regime. The remaining three vegetation groups are dominated by deciduous species. Among these, two groups arise from human activities such as logging or farming. One of these is dominated by Fagus grandifolia, Acer saccharum, Acer rubrum, and Quercus rubra and is composed of mature trees. The other is dominated by Pinus strobus, Polulus grandidentata, Populus tremuloides, or Betula papyrifera and is composed of young trees. These two types occupy the edge of the terraces where the topography is flat and the soil podzolic with a moderately to slightly acidic pH (4.0–5.0) and a xeric–mesic moisture regime. Finally the third group, dominated by Acer rubrum, is found on medium acidic (pH = 4.0), gleyed soils with a hydric–mesic moisture regime. This study shows that Acer rubrum is the best suited species for sandy, acidic, and nutrient-poor sites of the Lanoraie Delta. Key words: Lanoraie Delta, multivariate analysis, vegetation classification, Acer rubrum.

Using witness trees to assess forest change in southeastern Ohio

2001 ◽  
Vol 31 (10) ◽  
pp. 1708-1718 ◽  
Author(s):  
James M Dyer
Keyword(s):  
Acer Saccharum ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Forest Composition ◽  
Significant Shift ◽  
Quercus Alba ◽  
Forest Change ◽  
Composition And Structure ◽  
Successional Species ◽  
Witness Trees

In 1787, the U.S. Congress authorized the sale of the "Ohio Company Purchase", ca. 5000 km2 in Appalachian Ohio. The land was surveyed using a township and range system shortly thereafter. Data on >5600 witness trees were transcribed from the survey records, and witness tree locations were plotted on a digital map. This information was used to evaluate presettlement forest composition and structure and to investigate vegetation-site relationships before widespread alteration of the forests had taken place. Presettlement conditions were compared with present conditions using forest inventory and analysis (FIA) data. Two hundred years ago, the forests of southeastern Ohio were dominated by large individuals of Quercus alba L., Carya Nutt. spp., Quercus velutina Lam., and Fagus grandifolia Ehrh. These four taxa accounted for 74% of all witness trees. Although almost 70% of the region is forested today, the second-growth forest has witnessed a decrease in Quercus and Carya and an increase in Acer saccharum Marsh., Acer rubrum L., and many early successional species in smaller size classes. Despite the significant shift in forest composition and structure, species in general seem to be occupying similar positions in the present-day landscape compared with the presettlement forest; topographic variables most strongly control species occurrence in this landscape.

Direct and indirect effects of a dense understory on tree seedling recruitment in temperate forests: habitat-mediated predation versus competition

2008 ◽  
Vol 38 (6) ◽  
pp. 1634-1645 ◽  
Author(s):  
Alejandro A. Royo ◽  
Walter P. Carson
Keyword(s):  
Indirect Effects ◽  
Vegetation Cover ◽  
Acer Saccharum ◽  
Resource Competition ◽  
Seedling Recruitment ◽  
Plant Cover ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Tree Seedling ◽  
The Impact

In forests characterized by a dense woody and herbaceous understory layer, seedling recruitment is often directly suppressed via interspecific competition. Alternatively, these dense layers may indirectly lower tree recruitment by providing a haven for seed and seedling predators that prey on neighboring plant species. To simultaneously test for resource competition and indirect, habitat-mediated effects, we factorially manipulated understory plant cover (removed versus intact) and predation (exclosures versus controls) at three forested sites. We found that vegetation cover created privileged foraging areas that increased seed removal and seedling predation rates. Predator preference was directly related to seed size with larger seeded species including Prunus serotina Ehrh. and Fagus grandifolia Ehrh. removed more readily than smaller seeded species such as Fraxinus americana L. We found strong species-specific evidence for habitat-mediated indirect effects; establishment of P. serotina and Acer saccharum Marsh.was significantly lower under an intact hay-scented fern ( Dennstaedtia punctilobula (Michx.) T. Moore) canopy when small mammals were present. Competition also played a strong role; both P. serotina and Acer rubrum L. survival as well as A. rubrum emergence were reduced under a fern canopy with or without seed predators. The impact of habitat-mediated indirect effects and resource competition appear to vary predictably based upon predator preferences and differences in the timing of woody seed dispersal and germination relative to vegetation cover phenology. Overall, our results suggest that habitat-mediated indirect effects may be common and occur wherever vegetation provides the potential for creating privileged foraging areas.

scholarly journals Forest Disturbance Types and Current Analogs for Historical Disturbance-Independent Forests

Land ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 136
Author(s):  
Brice B. Hanberry
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Forest Disturbance ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Eastern United States ◽  
Red Maple ◽  
Disturbance Regimes ◽  
Historical Distribution ◽  
Lower Peninsula

Forest classifications by disturbance permit designation of multiple types of both old growth forests and shorter-lived forests, which auto-replace under severe disturbance, and also identification of loss of the disturbance type and associated forest. Historically, fire and flooding disturbance regimes, or conversely, infrequent disturbance, produced unique forests such as disturbance-independent forests of American beech (Fagus grandifolia), eastern hemlock (Tsuga canadensis), and sugar maple (Acer saccharum) in the Eastern United States. However, disturbance has changed to primarily frequent mechanical overstory disturbance, resulting in novel forests. To demonstrate the transition to no-analog forests after disturbance change, I compared historical tree surveys (ca. 1837 to 1857) to current surveys in the Northern Lower Peninsula of Michigan. To establish widespread disturbance change effects, I also located where beech and hemlock are currently most abundant throughout the Eastern US compared to historical distribution of beech–hemlock forests. In the Northern Lower Peninsula of Michigan, beech and hemlock historically were about 30% of all trees, but currently, beech and hemlock are 2% of all trees. Red maple (Acer rubrum) increased from 1% to 11% of all trees and aspen (Populus) increased from 2% to 13% of all trees. The squared-chord difference between historical and current surveys was 0.40, or dissimilar forests. Areas with ≥20% beech and hemlock or ≥15% of either species decreased from about 52 million to 6 million hectares, with current distribution restricted to the Northeastern US. Current forests are dissimilar to historical forests, and this transition appears to be driven by disturbance regimes without historical analogs. Disturbance change may provide perspective in forest management for climate change.

The 8200-year vegetation history of an urban woodland as reconstructed from pollen and plant remains

Botany ◽  
2017 ◽  
Vol 95 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Martin Lavoie ◽  
Pierre J.H. Richard
Keyword(s):  
Spatial Scale ◽  
Acer Saccharum ◽  
Vegetation History ◽  
Acer Rubrum ◽  
Fagus Grandifolia ◽  
Small Scale ◽  
Plant Remains ◽  
Local Plant ◽  
History Of ◽  
Urban Woodland

Data on the long term evolution of urban forests are rare. Using pollen and macrofossil analyses of a sediment core collected in a swampy forest hollow on Île aux Chats, an island in Bois-de-Saraguay woodland park in Montreal (Quebec), the postglacial history of a maple forest was reconstructed at a local spatial scale for the last 8200 years. Results show that after Île aux Chats emerged from the waters of Lake Lampsilis, it was rapidly colonized by a maple forest that was already diversified 8000 years ago. More than half of the vascular species identified in the macrofossil assemblages are absent from the local plant community today, notably coniferous species (Pinus resinosa, Larix laricina, Picea mariana). Other plants have multiplied their populations over time (Tilia americana, Tsuga canadensis, Acer rubrum). The maple forest was probably sustained by a small-scale gap dynamic caused by windthrow, fires having apparently been very rare. Fagus grandifolia, never abundant locally in the past, is observed to be currently expanding, and could eventually compete with Acer saccharum. This study constitutes not only a rare plurimillenial study of an urban woodland in eastern North America, but also of a maple forest at a local spatial scale.

Decay of birdseye sugar maple (Acer Saccharum) and curly red maple (Acer Rubrum)

2020 ◽  
Vol 52 (3) ◽  
pp. 292-297
Author(s):  
Tara Lee Bal ◽  
Katherine Elizabeth Schneider ◽  
Dana L. Richter
Keyword(s):  
Acer Saccharum ◽  
Sugar Maple ◽  
Acer Rubrum ◽  
Red Maple

American beech and sugar maple sapling relative abundance and growth are not modified by light availability following partial and total canopy disturbances

2015 ◽  
Vol 45 (6) ◽  
pp. 632-638 ◽  
Author(s):  
Kim Bannon ◽  
Sylvain Delagrange ◽  
Nicolas Bélanger ◽  
Christian Messier
Keyword(s):  
Soil Fertility ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Light Availability ◽  
Soil Nutrient ◽  
Fagus Grandifolia ◽  
American Beech ◽  
Clear Cutting ◽  
Canopy Opening ◽  
Unmanaged Forest

Studies have reported divergent results on the effect of soil fertility and canopy opening on understory density and growth of sugar maple (AS; Acer saccharum Marsh.) and American beech (FG; Fagus grandifolia Ehrh.). The main objective of this study was to evaluate the effect of a gradient of canopy opening and soil fertility on the density and growth of AS and FG saplings in southwestern Quebec, Canada. We investigated 56 stands containing both AS and FG that were subjected to different disturbance history types (DHTs) (UF, unmanaged forest; PC, partial cut; and CC, clearcut) on various soil types. AS and FG absolute and relative sapling density varied greatly among the 56 stands; however, no significant effects of DHT, soil nutrient availability, or their interaction were found. Both species responded positively in terms of radial growth to canopy openings, with FG growth being slightly better than AS growth in PC stands compared with other canopy treatments. Contrary to our hypothesis, AS did not show significantly higher growth than FG following clear-cutting. These results do not support the idea that AS abundance and growth could be promoted by increasing the intensity of the canopy opening during harvest, at least on the generally acidic and base-poor soils that were investigated.

Exploring the Relationship Between Social Interaction, Cognitive Processing and Learning Achievements in a MOOC Discussion Forum

2021 ◽  
pp. 073563312110273
Author(s):  
Zhi Liu ◽  
Ning Zhang ◽  
Xian Peng ◽  
Sannyuya Liu ◽  
Zongkai Yang ◽  
...  
Keyword(s):  
Social Network ◽  
Social Interaction ◽  
Network Analysis ◽  
Cognitive Processing ◽  
Learning Analytics ◽  
Discussion Forum ◽  
Community Type ◽  
Eigenvector Centrality ◽  
Community Types ◽  
The Relationship

In the field of learning analytics, mining the regularities of social interaction and cognitive processing have drawn increasing attention. Nevertheless, in MOOCs, there is a lack of investigations on the combination of social and cognitive behavioral patterns. To fill in this gap, this study aimed to uncover the relationship between social interaction, cognitive processing, and learning achievements in a MOOC discussion forum. Specifically, we collected the 3925 participants’ forum data throughout 16 weeks. Social network analysis and epistemic network analysis were jointly adopted to investigate differences in social interaction, cognitive processing between two achievement groups, and the differences in cognitive processing networks between two types of communities. Finally, moderation analysis was employed to examine the moderating effect of community types between cognitive processing and learning achievements. Results indicated that: (1) the high- and low-achieving groups presented significant differences in terms of degree, betweenness, and eigenvector centrality; (2) the stronger cognitive connections were found within the high-achieving group and the instructor-led community; (3) the cognitive processing indicators including insight, discrepancy, and tentative were significantly negative predictors of learning achievements, whereas inhibition and exclusive were significantly positive predictors; (4) the community type moderated the relationship between cognitive processing and learning achievements.

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