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.

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.

scholarly journals Etude Eco-Dendrométrique Du Dépérissement Du Cèdre De l’Atlas Dans Le Parc National De Theniet El Had “Algérie”

2016 ◽  
Vol 12 (29) ◽  
pp. 112
Author(s):  
Taleb Mohamed Lamine ◽  
Maatoug M’hamed ◽  
Azouzi Blel ◽  
Zedek Mohamed ◽  
Hellal Benchabane
Keyword(s):  
Analysis Of Variance ◽  
National Park ◽  
Ecological Factors ◽  
Management Plan ◽  
Ecological Data ◽  
Descriptive Data ◽  
North West ◽  
The North ◽  
The Relationship

This study aims to search the relationship between the decline of the Atlas cedar and the eco-dendrometrique factors in the National Park of Theniet El Had located in the north-west of Algeria. This study takes place throughout 30 circular plots of 1.000m2 area in which, a dendrometric measures and ecological data are taken in addition to descriptive data for Atlas cedar trees. The descriptive data shows that 34% of inventoried Atlas cedar have damaged leaves and 30% have more then 25% of their crowns damaged. The analysis of variance shows that there is no relationship between the rate of the Atlas cedar decline ant the ecological factors, components of the soil and dendrometric parameters except for the average circumference witch is influenced by the competition between trees. Therefor, a particular management plan for the regulation of competition is a necessity for this park.

scholarly journals An ecological study of the plant communities in the proposed Highveld National Park, in the peri-urban area of Potchefstroom, South Africa

Koedoe ◽  
2010 ◽  
Vol 52 (1) ◽  
Author(s):  
Mahlomola E. Daemane ◽  
Sarel S. Cilliers ◽  
Hugo Bezuidenhout
Keyword(s):  
South Africa ◽  
Plant Communities ◽  
National Park ◽  
Environmental Planning ◽  
Detrended Correspondence Analysis ◽  
Floristic Composition ◽  
North West ◽  
The North ◽  
High Conservation ◽  
Grassland Biome

The proposed Highveld National Park (HNP) is an area of high conservation value in South Africa, covering approximately 0.03% of the endangered Grassland Biome. The park is situated immediately adjacent to the town of Potchefstroom in the North-West Province. The objective of this study was to identify, classify, describe and map the plant communities in this park. Vegetation sampling was done by means of the Braun-Blanquet method and a total of 88 stratified random relevés were sampled. A numerical classification technique (TWINSPAN) was used and the results were refined by Braun-Blanquet procedures. The final results of the classification procedure were presented in the form of phytosociological tables and, thereafter, nine plant communities were described and mapped. A detrended correspondence analysis confirmed the presence of three structural vegetation units, namely woodland, shrubland and grassland. Differences in floristic composition in the three vegetation units were found to be influenced by environmental factors, such as surface rockiness and altitude. Incidences of harvesting trees for fuel, uncontrolled fires and overgrazing were found to have a significant effect on floristic and structural composition in the HNP. The ecological interpretation derived from this study can therefore be used as a tool for environmental planning and management of this grassland area.Conservation implications: Grasslands are amongst the most threatened and least conserved vegetation biomes in South Africa, with less than 1.3% currently being conserved. The HNP has significant value for biodiversity conservation and the protection of this area will contribute to the preservation of the highly threatened Highveld vegetation types. 

A Biogeographical Analysis of the Tasmanian Endemic Ptunarra Brown Butterfly, Oreixenica ptunarra Couchman (Lepidoptera : Nymphalidae : Satyrinae)

1997 ◽  
Vol 45 (1) ◽  
pp. 21 ◽  
Author(s):  
P. B. McQuillan ◽  
C. J. Ek
Keyword(s):  
Male Genitalia ◽  
Species Conservation ◽  
Ecological Factors ◽  
Morphological Characters ◽  
Climatic Conditions ◽  
Conservation Strategies ◽  
North West ◽  
Phenotypic Characters ◽  
The North ◽  
Tasmanian Endemic

Considerable geographic variation occurs in the Tasmanian endemic butterfly, Oreixenica ptunarra, and there is a high correlation between clusters of morphological characters and ecological factors, especially climate and elevation. Evidence is presented for the existence of a longitudinal cline in phenotypic characters of wing pattern and size, which is unrelated to the modest amount of variation in the male genitalia (a possible surrogate for genetic variability). Butterflies from warmer, less cloudy eastern Tasmania are larger and less dark in colour than those from the west, culminating in the small dark populations of the north-west. This suggests selection for efficiency in thermoregulation as climatic conditions become more marginal for adult activity from east to west. The prevailing subspecies classification does not fully reflect the range of variation in this species. Conservation strategies that aim to guarantee the survival of the collective phenotype of O. ptunarra based on this taxonomy are therefore misinformed. The north-west populations are disjunct geographically and in features of phenotype, but are not especially discrete in the morphology of the male genitalia. We propose that the subspecies angeli Couchman and roonina Couchman be reduced to synonymy with nominotypical ptunarra Couchman, and a new subspecies should be recognised to incorporate populations from the montane grasslands of north-western Tasmania.

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
Keyword(s):  
Populus Tremuloides ◽  
Acer Rubrum ◽  
Detrended Correspondence Analysis ◽  
Terrestrial Ecosystems ◽  
Organic Content ◽  
Peat Deposit ◽  
Moisture Regime ◽  
Distribution Analysis ◽  
Chamaedaphne Calyculata ◽  
Community Types

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.

scholarly journals FEATURES OF REPRODUCTION OF THE MIDDAY GERBIL (MERIONES MERIDIANUS) IN THE NORTH-WEST PRECASPIAN

2019 ◽  
pp. 6-11
Author(s):  
Rizvan Rizvanovich OMAROV ◽  
Kamil Zubairovich OMAROV
Keyword(s):  
North West ◽  
The North ◽  
Two Factors ◽  
North Western

The article presents data on the nature of reproduction of the midday gerbil in the North-Western Precaspiansea. It is shown that the intensity of reproduction of the midday gerbil reveals a relationship with two factors: the level of fodder resources during the beginning of reproduction and the intensity of their nutrition during this period.

scholarly journals Predicting the Location of Maple Habitat under Warming Scenarios in Two Regions at the Northern Range in Canada

2021 ◽  
Author(s):  
Pratiksha Jain ◽  
Siddhartha Khare ◽  
Jean-Daniel Sylvain ◽  
Raymond Patricia ◽  
Sergio Rossi
Keyword(s):  
Forest Management ◽  
Acer Saccharum ◽  
Acer Rubrum ◽  
Principal Component ◽  
Precipitation Regime ◽  
Local Conditions ◽  
Southern Limit ◽  
The North ◽  
Enhanced Production ◽  
Northern Regions

Abstract Acer saccharum and Acer rubrum, two main maple species in North America, will be affected by ongoing global warming. Several studies predict a southern limit contraction but limited northward expansion of maple distribution for the future. We aimed to understand the main drivers of current maple distribution to quantify potential changes to maple habitat in this context. We identified the local conditions of maple stands and assessed the potential changes under warming scenarios. We selected two regions in Quebec, Canada, at the northern distribution of the species and applied probability distribution function and principal component analysis to identify the factors explaining the occurrence of maple compared with other forest species, croplands, and grasslands. Maple habitat was estimated under warming scenarios up to 2°C. We observed a lower density of maple stands in the north (7.76 %), compared to the south (33.01 %). Warming increased maple stands by 3.54 and 1.45 % in the northernmost and southernmost regions, respectively, with the highest increases being estimated at the initial warming (+1.0°C). We conclude that maple of northern regions can benefit from local warming if precipitation does not become limiting. These changes could increase the potential for the regional maple industry and forest management. Study Implications Future warming may enhance the opportunities to exploit maple and its products at the northern boundary of this species, under a sufficient precipitation regime. Plantations could be considered in habitats favorable for maple, which would allow the value of the resource at the northern edge of the temperate mixedwood forest to be increased. Our spatially explicit outcomes will encourage forest managers and small landowners to plan new maple plantations. The local maple industry and forest management in northern regions could benefit from such an increase in maple habitat and enhanced production of hardwood species.

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

1990 ◽  
Vol 48 (3) ◽  
pp. 58-59
Author(s):  
Daryl A. Cornish ◽  
George L. Smit
Keyword(s):  
Morphological Characteristics ◽  
Oreochromis Mossambicus ◽  
Breeding Cycle ◽  
Limited Information ◽  
North West ◽  
The North ◽  
Sem And Tem ◽  
Sperm Development ◽  
Ultrastructural Characteristics ◽  
The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

Voting in the north west

1971 ◽  
pp. 411-426
Keyword(s):  
North West ◽  
The North
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