La végétation de deux tourbières de la municipalité régionale de comté du Haut-Saint-Laurent (Québec)

1987 ◽  
Vol 65 (10) ◽  
pp. 1969-1988 ◽  
Author(s):  
Martin Jean ◽  
André Bouchard

Within a multidisciplinary study of terrestrial ecosystems of the Haut-Saint-Laurent Regional County Municipality, the vegetation of "Large Teafield" and "Small Teafield" peatlands is described from 127 stands. Detrended correspondence analysis and correlations between data indicate that the greatest vegetational variation is expressed by variables related to trophic regime (e.g., pH of peat) and moisture regime (e.g., organic content). In addition to gradient analysis, hierarchical clustering combined with reference to contingency tables is used to characterize the typology along gradients. Mapping of the community types partially relates the distribution analysis to a circular spatial pattern of the vegetation. Highly oligotrophic sites are colonized by low shrubs. Chamaedaphne calyculata is found at the centre of the peatlands, where the peat deposit is thick and fire does not play an important role. Low shrubs dominated by Betula populifolia surround the Chamaedaphne calyculata vegetation and are more affected by burning towards the perimeter. Heavily burned sites are dominated by Epilobium angustifolium. The perimeters of the peatlands are colonized by Betula populifolia or Populus tremuloides open forests, while the most stable forests are dominated by Acer rubrum. Some marshes and swamps are present where the peat deposit is thin. Sixteen community types are described for the study area.


1988 ◽  
Vol 66 (4) ◽  
pp. 793-804 ◽  
Author(s):  
Claude St-Jacques ◽  
Daniel Gagnon

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.



1997 ◽  
Vol 75 (8) ◽  
pp. 1363-1370 ◽  
Author(s):  
A. G. Schwarz ◽  
Ross W. Wein

Dry grasslands in Wood Buffalo National Park are unique biological features at 60°N latitude, since they contain plant species normally found in more southern grasslands at 50–55°N latitude. The objectives of this study were to inventory dry grasslands, classify them according to similarity of species cover, and establish relationships with understory species in Populus tremuloides and shrub communities. Dry grasslands were studied at nine sites; most were clustered in the Salt River and Peace Point areas. The largest unit of grassland was about 3.0 ha, and most units were less than 0.5 ha. This contrasts with the hundreds of hectares recorded earlier in the century. Of the 128 vascular plant species identified, 29 are considered as southern, and of these, 15 are regionally rare. Sixty-four plots were classified into nine community types, using two-way indicator species analysis. A group of six communities were dominated by grass and shrub species with a component of southern grassland species. Three communities, strongly dominated by Populus and shrubs, represent community types that invade dry grasslands. Ordination of plots using detrended correspondence analysis showed relationships among the community types and a clear separation of southern grassland species from those found in forest communities. Vascular plant diversity, as represented by mean species richness, ranged from about 15 to 28, and Shannon diversity indices ranged from 1.883 to 2.615. The cover of southern grassland species was negatively correlated (correlation coefficient of −0.524) with cover of tall shrubs and trees, suggesting that the dry grasslands of Wood Buffalo National Park are threatened by tree and shrub invasion, which is due, in part, to a lack of recent fires at these sites. Key words: northern grasslands, biodiversity, endangered species, endangered spaces.



1991 ◽  
Vol 69 (8) ◽  
pp. 1839-1852 ◽  
Author(s):  
L. Lamontagne ◽  
C. Camiré ◽  
C. Ansseau

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.



2017 ◽  
Vol 35 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Darby McGrath ◽  
Jason Henry ◽  
Ryan Munroe ◽  
Erin Agro

Abstract This experiment investigated the effect of different plug-tray cell designs on root development of red maple (Acer rubrum), red oak (Quercus rubra), and quaking aspen (Populus tremuloides) seedlings. In April of 2015, seeds of each species were sown into three plug trays with different substrate volumes and grown for 17 weeks. Two trays had permeable walls for air-pruning, one with vertical ribs and one without. The third tray had impermeable plastic cell walls. Harvested seedlings were analyzed for root dry weight, length, volume, surface area and number of deflected roots. Root length per volume was highest in the impermeable-walled tray for red maple and quaking aspen. The total numbers of deflected root systems were higher for all species in the impermeable-walled tray. Seedlings grown in the air-pruning trays had smaller proportions of deflected root masses. Greater substrate volume did not influence root deflection development. The air-pruning tray without vertical ribs had the lowest total number of root masses with misdirected roots and lower proportions of root masses with misdirected roots for all species. These results indicate that improved root architecture in root-air pruning tray designs is achievable in tree propagation; however, vertical plastic structures in air-pruning trays can still cause root deflections. Index words: Deflected roots, air-pruning, seedling, propagation, plugs, root architecture. Species used in the study: red maple (Acer rubrum L.); red oak (Quercus rubra L.); quaking aspen (Populus tremuloides Michx.).



1989 ◽  
Vol 67 (10) ◽  
pp. 2967-2974 ◽  
Author(s):  
J. C. Earle ◽  
K. A. Kershaw

Plant zonations and selected environmental variables were studied in a subarctic coastal marsh at Ekwan Point, James Bay, Ont. Eight distinct community types were identified using two-way indicator species analysis classification (TWINSPAN). These were interpreted as a primary successional sequence. The eight communities were found to conform closely to the classical marsh zonations based on elevation and tidal influence: (1) lower salt marsh, (2) middle salt marsh, (3) upper salt marsh, (4) saline meadow, (5) freshwater meadow, and (6) freshwater fen. Environmental data collected along the vegetation transects indicated that changes in elevation and soil-water salinity probably influence species distributions. A species ordination using detrended correspondence analysis (DECORANA) revealed several trends in plant distribution patterns. Consideration of the environmental affinities of species separated along three ordination axes suggested that salinity and elevation, water content, and soil texture were probably important factors influencing successional processes in the marsh during at least the last century. An inverse salinity gradient, which has been reported at many sites along the west coast of Hudson and James bays, was not found at Ekwan Point.



1997 ◽  
Vol 129 (6) ◽  
pp. 991-999 ◽  
Author(s):  
R.W. Nicol ◽  
J.T. Arnason ◽  
B. Helson ◽  
M.M. Abou-Zaid

AbstractLarval growth and pupal parameters of the forest tent caterpillar (Malacosoma disstria Hübner) reared on the foliage of two host trees (Populus tremuloides Michx. and Acer saccharum Marsh.) and one nonhost tree (Acer rubrum L.) were quantified. This was achieved by undertaking a larval development bioassay under controlled laboratory conditions, but using fresh leaves collected in two field seasons. Larvae fed foliage of P. tremuloides grew exponentially and began to pupate after 3 weeks. Larvae fed with A. saccharum gained significantly less weight and had a reduced number of larvae pupate, and the pupae weighed significantly less than their counterparts fed on P. tremuloides. All larvae that were fed the foliage of A. rubrum died within 2 weeks. A nutritional utilization bioassay with fourth-instar larvae revealed that the foliage of A. saccharum has a growth-inhibitory component, whereas that of A. rubrum is antifeedant. Reasons are discussed for the discrepancy between the many reports of A. saccharum being a food host for M. disstria in the field and the laboratory results.



1986 ◽  
Vol 64 (1) ◽  
pp. 217-226 ◽  
Author(s):  
Kern Ewing ◽  
K. A. Kershaw

Coastal wetlands of the Hudson Bay Lowlands along southern James Bay are generated by a positive water balance, low relief, and a rising land surface. Marshes, dominated by sedges and grasses, and separated by beach ridges, occur between unvegetated intertidal flats and the inland boreal forest. Bay waters, affected by currents, shallow depths, and large freshwater inputs from major rivers in the Hudson Bay drainage, are brackish. Off the coast at the Harricanaw River, surface salinity in the bay is <4 ppt while soil water salinities in the adjacent marsh are higher. Standing water and tidal water in contact with vegetation often measure 0 ppt salinity. Plant communities adapted to brackish water have developed. Using two-way indicator species analysis classification, twelve widespread community types were recognized. Ordination using detrended correspondence analysis revealed gradients of salinity, elevation, drainage, vegetation development, complexity, and peat formation, and separated coastal from estuarine communities. An inverse salinity gradient, which has been reported elsewhere in James Bay, was not found; explanations are proposed for isolated areas of high salinity.



1989 ◽  
Vol 67 (2) ◽  
pp. 491-504 ◽  
Author(s):  
Catherine LaFarge-England

A quantitative analysis of contemporary moss assemblages is presented for a fault block at the southern end of Piper Pass, northern Ellesmere Island, N.W.T. (82°12′N, 68°31′W). Twenty-eight stands are analyzed using the two-way indicator species analysis, resulting in seven major species groups and five major stand groups. Physical parameters correlated with the stand data show soil moisture and slope to be the most important factors influencing the distribution of moss assemblages. Sodium, organic content, and specific conductivity are also correlated with the vegetation data. Detrended correspondence analysis confirms these stand relationships. The interdependence of physical, chemical, and vegetation data is also discussed. Distribution patterns of the species groups within the stand groups are analyzed by means of a percent frequency diagram. A direct gradient analysis of the vegetation below a late-lying snowbank also demonstrates the selective distribution of species in terms of environmental gradients.



2011 ◽  
Vol 32 (1) ◽  
pp. 81-93 ◽  
Author(s):  
Pierre Richard

L’analyse pollinique d’une cuvette tourbeuse au mont Shefford, Québec, révèle une première phase lacustre de 11400 à 4 200 ans environ avant l’actuel. Le site fut par la suite occupé par une tourbière à Ericacées et Myrique baumier (Myrica gale), puis par une aulnaie à Alnus rugosa et enfin, par une forêt dominée par l'érable rouge (Acer rubrum). La végétation régionale, après la déglaciation, fut d’abord représentée par un désert de type périglaciaire 11400 ans avant l’actuel (AA), puis par une toundra herbacée d'abord, arbustive ensuite, de 11 400 à 11 100 ans AA. L’afforestation s’est effectuée par des peuplements ouverts d’épinette (Picea mariana) et de peuplier faux-tremble (Populus tremuloides), donnant lieu à une pessière ouverte jusque vers 10 100 ans AA. Le domaine de la sapinière à bouleau blanc peut être proposé pour la végétation couvrant la période de 10 100 à 7500 ans AA, après quoi le domaine de l’érablière à tilleul s’est constitué et a dominé jusqu’à nos jours. Le diagramme du mont Shefford est proposé comme diagramme standard en raison du caractère particulièrement complet des séquences polliniques, les plus anciennes étant contemporaines de l’épisode de Saint-Narcisse (moraine frontale). Des aspects méthodologiques portant sur l’interprétation en termes de végétation sont discutés, et les principales zones d’assemblage pollinique du Québec méridional central sont présentées.



1989 ◽  
Vol 67 (4) ◽  
pp. 1126-1136 ◽  
Author(s):  
M. Muc ◽  
B. Freedman ◽  
J. Svoboda

A cluster analysis was used to apportion 136 stands in a High Arctic lowland among six vascular plant community types. These communities are described on the basis of the average prominence values of vascular species and the total cover of macroalgae, bryophytes, lichens, and vascular plants within the designated clusters of stands. The relationships among the community types was explored by a detrended correspondence analysis. The ordination of stands showed considerable floristic overlap among the most widespread plant communities on the lowland. This largely reflects the microtopographic heterogeneity of the sites, the relatively depauperate flora of the High Arctic, and the considerable ecological amplitude of the most prominent vascular plant species.



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