Remise en production des bétulaies jaunes résineuses dégradées : étude du succès d'installation de la régénération

2007 ◽  
Vol 83 (5) ◽  
pp. 742-753 ◽  
Author(s):  
Pierre Gastaldello ◽  
Jean-Claude Ruel ◽  
Jean-Martin Lussier
Keyword(s):  
Natural Regeneration ◽  
Poor Quality ◽  
Betula Alleghaniensis ◽  
Light Conditions ◽  
Yellow Birch ◽  
Mixedwood Forests ◽  
The North ◽  
Open Canopy ◽  
Undisturbed Forest ◽  
Better Than

The abundance of poor quality stands in the North American hardwood and mixedwood forests poses important regeneration challenges. These stands have an open canopy with a well-developed shrub layer dominated by noncommercial species. The present study aims at testing the efficiency of a natural regeneration approach using a combination of brushing and spot scarification in the cleared strips. Four high-graded stands from the mixedwood zone in Quebec were selected and strips were cleared with a brush saw. Four microsite types created by the scarification were studied: 1-m and 2-m wide pockets, mounds and undisturbed forest floor. The amount of dispersed yellow birch seeds was adequate for two out of the three years of the study. Yellow birch establishment was in phase with seed years and was better on disturbed microsites. Best establishment was observed in seed spots and light conditions in these microsites after three years were better than on mounds or undisturbed ground. On the latter two, survival will likely be impaired by the poor light conditions. Seed spots remain receptive three years after scarification. Softwood regeneration was poor due to a lack of seed trees. The study has shown that seed tree abundance remains sufficient for natural regeneration even in these open stands. It also showed a very rapid regrowth of competing vegetation when root systems and seed banks were not removed by site preparation. Key words: yellow birch, Betula alleghaniensis, scarification, diameter-limit cutting, competition

scholarly journals Tolerant hardwood natural regeneration 15 years after various silvicultural treatments on an industrial freehold of northwestern New Brunswick

2013 ◽  
Vol 89 (04) ◽  
pp. 512-524 ◽  
Author(s):  
Martin Béland ◽  
Bruno Chicoine
Keyword(s):  
New Brunswick ◽  
Natural Regeneration ◽  
Sugar Maple ◽  
Mineral Soil ◽  
Soil Disturbance ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
American Beech ◽  
Partial Cutting ◽  
Selection Cutting

We examined applicability of various partial cutting systems in order to regenerate tolerant hardwood stands dominated by sugar maple (Acer saccarhum), American beech (Fagus grandifolia) and yellow birch (Betula alleghaniensis) on northern New Brunswick J.D. Irving Ltd. freehold land. Sampling of 1065 one-m2 plots in 31 stands managed by selection cutting, shelterwood method and strip or patch cutting and in six control stands allowed a 15-year retrospective study of natural regeneration in stands of low residual densities and with minimal soil disturbance and no control of competing vegetation. Beech regeneration was most abundant in the patch cuts, yellow birch in shelterwood stands and sugar maple in the selection system areas. Results suggest that initial stand conditions influence the composition of the regeneration more than the prescribed treatment. At the stand scale (a few hectares), sugar maple recruitment was positively influenced by its proportion in the initial stand, and negatively by the cover of herbs and shrubs. Yellow birch regeneration was mainly affected by shrub competition. At the plot (1 m2) scale, mineral soil and decayed wood substrates and ground-level transmitted light were determinant factors for yellow birch regeneration. Beech-dominated stands were likely to regenerate to beech. A dense beech sucker understory was promoted in harvested patches. Areas with dense understory of American beech, shrubs, or herbs require site preparation to reduce interference either before or at the time of partial cutting. Shelterwood seed cutting and selection cutting should leave a residual of 12 m2/ha and 17 m2/ha respectively in seed trees uniformly distributed.

scholarly journals Gap dynamics in Balsam Fir, Abies balsamea - Yellow Birch, Betula alleghaniensis, forests of Québec

2009 ◽  
Vol 123 (2) ◽  
pp. 117 ◽  
Author(s):  
Rémi Hébert ◽  
Jean Huot
Keyword(s):  
Natural Regeneration ◽  
Forest Cover ◽  
Abies Balsamea ◽  
Woody Species ◽  
Balsam Fir ◽  
Regeneration Process ◽  
Betula Alleghaniensis ◽  
Gap Dynamics ◽  
Yellow Birch ◽  
Gap Characteristics

To determine if gap dynamics can play an important role in the natural regeneration process of Balsam Fir (Abies balsamea)-Yellow Birch (Betula alleghaniensis) forests and to determine the effects of gap characteristics on regenerating woody species, we sampled 119 gaps from 64 forest stands in La Mauricie National Park. Gaps averaged 184.5 m² in size. The mean gap age was 7.8 years. Gaps were usually created by broken or uprooted trees and only rarely resulted from Spruce Budworm (Choristoneura fumiferana) outbreaks. We found 25 species that regenerated in the gaps or under the forest cover. When considering all species, significantly more stems/ha were in gaps than under the forest cover. Gap characteristics generally did not influence regenerating woody species. We present a comprehensive model of gap dynamics in Balsam Fir-Yellow Birch forests, starting from a dense canopy, continuing with the creation and colonization of gaps, and ending to the closure of the canopy. Gap dynamics play an important role in the natural regeneration process of Balsam Fir-Yellow Birch forests.Afin de déterminer si la dynamique par trouée peut jouer un rôle important comme processus naturel de régénération de la sapinière à Bouleau Jaune et aussi afin de déterminer les effets des caractéristiques des trouées sur la régénération, nous avons échantillonné 119 trouées dans 64 peuplements forestiers au parc national de la Mauricie. Ces ouvertures avaient une superficie moyenne de 184,5 m². L’âge moyen des ouvertures était de 7,8 ans. Elles étaient généralement créées par un arbre cassé ou déraciné. Peu d’ouvertures étaient créées par des épidémies de la Tordeuse des Bourgeons de l’Épinette. Au total, 25 espèces en régénération ont été rencontrées dans les ouvertures ou sous le couvert forestier. En considérant toutes les espèces, il y avait significativement plus de tiges/ha dans les ouvertures que sous le couvert forestier. Les caractéristiques des trouées n’influençaient généralement pas la régénération. Nous présentons un modèle complet sur la dynamique par trouée dans la sapinière à Bouleau jaune, commençant avec une canopée dense, continuant avec la création et la colonisation des trouées, et se terminant avec la fermeture de la canopée. La dynamique par trouée joue un rôle important dans le régime de perturbations de la sapinière à Bouleau jaune.

Effects of selective cuts on the mycorrhizae of regenerating Betula alleghaniensis and Acer saccharum seedlings in two Quebec mixed deciduous forests

2002 ◽  
Vol 32 (6) ◽  
pp. 1094-1102 ◽  
Author(s):  
Tonia DeBellis ◽  
Paul Widden ◽  
Christian Messier
Keyword(s):  
Ectomycorrhizal Fungi ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Arbuscular Mycorrhizae ◽  
Betula Alleghaniensis ◽  
Yellow Birch ◽  
Negative Effect ◽  
Undisturbed Forest ◽  
Ectomycorrhizal Colonization ◽  
Study Sites

The mycorrhizae of younger (2- to 3-year-old) and older (5- to 12-year-old) yellow birch (Betula alleghaniensis Britton) and sugar maple (Acer saccharum Marsh.) seedlings and saplings were recorded from naturally regenerating plants in gaps created by selective cuts and compared with those of plants of comparable age growing in the undisturbed forest. The levels of ectomycorrhizal colonization and the diversity of ectomycorrhizal fungi (based on morphotyping) were recorded for yellow birch and the levels of colonization and the abundance of arbuscules, vesicles, and coils were reported for the vesicular–arbuscular mycorrhizae of sugar maples. Selective cutting had no negative effect on the mycorrhizal community structure of yellow birch and sugar maple. This may be because of the quick regeneration of the mycorrhizal hosts coupled with the minor levels of soil disruption and relatively small gap size at the study sites. Greater colonization levels in the gaps versus uncut areas were observed in the 2- to 3-year-old maples but not in the 2- to 3-year-old birch seedlings. The types of ectomycorrhizal fungi colonizing the roots of birch seedlings from the gaps did not differ from those in the uncut forest areas.

The Environmental Effects of Flood Control in the Yare Basin

1984 ◽  
Vol 16 (3-4) ◽  
pp. 477-484
Author(s):  
H L Wakeling
Keyword(s):  
Flood Control ◽  
Storm Surges ◽  
Poor Quality ◽  
Grazing Land ◽  
Flood Prevention ◽  
Scenic Beauty ◽  
The North ◽  
Economic Justification ◽  
The North Sea ◽  
Improved Pasture

The paper reviews various methods of flood control in the lower Yare Basin which has been subject to serious flooding caused by storm surges in the North Sea and by fluvial floods. This area is known as the Broads and is an area of scenic beauty, includes many sites of scientific interest and is a popular tourist area. The effects of the different flood control options on the environment are discussed. The primary economic justification for flood prevention was found to arise from the conversion of poor quality marsh grazing land to arable or improved pasture once the risk of saline flooding was removed. The consequences of this change in land use on the flora and fauna have aroused much concern among environmentalists.

Devanagari Text Detection From Natural Scene Images

2020 ◽  
Vol 10 (3) ◽  
pp. 44-59
Author(s):  
Sankirti Sandeep Shiravale ◽  
R. Jayadevan ◽  
Sanjeev S. Sannakki
Keyword(s):  
Edge Detection ◽  
Image Understanding ◽  
Text Detection ◽  
Experimental Results ◽  
Combined Approach ◽  
Natural Scene ◽  
Light Conditions ◽  
The Individual ◽  
Natural Scene Images ◽  
Better Than

Text present in a camera captured scene images is semantically rich and can be used for image understanding. Automatic detection, extraction, and recognition of text are crucial in image understanding applications. Text detection from natural scene images is a tedious task due to complex background, uneven light conditions, multi-coloured and multi-sized font. Two techniques, namely ‘edge detection' and ‘colour-based clustering', are combined in this paper to detect text in scene images. Region properties are used for elimination of falsely generated annotations. A dataset of 1250 images is created and used for experimentation. Experimental results show that the combined approach performs better than the individual approaches.

Aircraft Applications of Insecticides in East Africa. VIII.—An Experiment against the Tsetse Fly, Glossina swynnertoni Aust., in an isolated Area of Thronbush and Thicket

1954 ◽  
Vol 45 (3) ◽  
pp. 613-622 ◽  
Author(s):  
K. S. Hocking ◽  
G. F. Burnett ◽  
R. C. Sell
Keyword(s):  
East Africa ◽  
Apparent Density ◽  
Significant Degree ◽  
Tsetse Fly ◽  
Central Province ◽  
The North ◽  
Insecticidal Treatment ◽  
Bad Weather ◽  
Glossina Swynnertoni ◽  
Better Than

An isolated area of 2,200 acres of thicket and thronbush in the Central Province, Tanganyika, was treated from the air with a DDT-in-oil aerosol in an attempt to eliminate the tsetse fly, Glossina swynnertoni Aust. Eight applications of 0·25 lb. technical DDT per acre were planned to be done at fortnightly intervals.Delays due to unseasonal bad weather reduced this to seven at a slightly higher rate and over a longer-period.G. swynnertoni was reduced from an apparent density of about 7 to zero at the end of the second application. No flies were caught after the fifth application for a period of six months.It is not possible to say whether the few caught since then have been brought in or are the offspring of survivors of the insecticidal treatment.This experiment was more successful than that on the Galapo Block in the same ares, to a highly significant degree, and this is attributed to the vulnerability of the smaller population present. It was doubtfully better than the first treatment of the North Block, also in this area, because the increase in population in the latter block may have been assisted by immigration.

scholarly journals Social Condition of England during the Wars of the Roses

1902 ◽  
Vol 16 ◽  
pp. 159-200
Author(s):  
Vincent B. Redstone
Keyword(s):  
Social Life ◽  
English History ◽  
Class A ◽  
The North ◽  
The Arts ◽  
The Social ◽  
Wars Of The Roses ◽  
Social Habits ◽  
North And South ◽  
Better Than

The social life of the inhabitants of England during the years of strife which brought about the destruction of the feudal nobility, gave to the middle class a new position in the State, and freed the serf from the shackles of bondage, has been for some time past a subject of peculiar interest to the student of English history. If we desire to gain an accurate knowledge of the social habits and customs prevalent during this period of political disturbance, we cannot do better than direct our attention towards that part of the country which was the least affected by the contest between the Houses of York and Lancaster, the eastern district of England, which since the days of King John had enjoyed a remarkable immunity from civil war. Here the powerful lords of the North and South found little support; the vast estates of the old feudal barons were broken up into numerous independent manors. Moreover the arts of peace, in the shape of the mysteries of trade, manufactures, and commerce, widely flourished among the inhabitants of these regions.

The effect of soil temperature and light on sprouting and rooting of root cuttings of hybrid aspen clones

2005 ◽  
Vol 35 (11) ◽  
pp. 2671-2678 ◽  
Author(s):  
N Stenvall ◽  
T Haapala ◽  
S Aarlahti ◽  
P Pulkkinen
Keyword(s):  
Soil Temperature ◽  
Populus Tremuloides ◽  
Hybrid Aspen ◽  
Light Conditions ◽  
Dark Treatment ◽  
Sand Mixture ◽  
Negative Effect ◽  
Soil Temperatures ◽  
Time Required ◽  
Better Than

Root cuttings from five clones of hybrid aspen (Populus tremula L. × Populus tremuloides Michx.) obtained from 2-year-old stock plants were grown in a peat–sand mixture (soil) at four soil temperatures (18, 22, 26, and 30 °C). Half of the cuttings were grown in light and the rest in darkness. The root cuttings that were grown at the highest soil temperature sprouted and rooted significantly better than the cuttings grown at the lower temperatures. Light did not affect the sprouting of root cuttings but did have a negative effect on their rooting. Moreover, the clones varied significantly in sprouting and rooting percentages, as well as in the time required for sprouting. In general, higher soil temperatures hastened sprouting of the cuttings. Sprouting was also faster in the light than in the dark treatment. Differences in soil temperature, light conditions, or clone had no significant effect on rooting time.

Rare forest types in northeastern Ontario: a classification and analysis of representation in protected areas

2010 ◽  
Vol 40 (3) ◽  
pp. 423-435 ◽  
Author(s):  
Charles R. Drever ◽  
James Snider ◽  
Mark C. Drever
Keyword(s):  
Protected Areas ◽  
Local Population ◽  
Red Oak ◽  
Betula Alleghaniensis ◽  
White Pine ◽  
Yellow Birch ◽  
Eastern White Pine ◽  
Habitat Specificity ◽  
White Cedar ◽  
Eastern White Cedar

Our objective was to assess the relative rarity and representation within protected areas of Standard Forest Units (SFUs) in northeastern Ontario by applying the concepts of geographic range, habitat specificity, and local population size. SFUs are stand type classifications, routinely employed by forest managers, based on tree composition, disturbance history, and prescribed silvicultural system. We identified several SFUs as rare because of a narrow distribution, association with only one landform type, or lack of at least one stand larger than an ecoregion-specific threshold. In the Boreal forest, rare SFUs comprised stands dominated by eastern hemlock ( Tsuga canadensis (L.) Carrière), red oak ( Quercus rubra L.), yellow birch ( Betula alleghaniensis Britt.), or eastern white-cedar ( Thuja occidentalis L.). Rare SFUs also included eastern white pine ( Pinus strobus L.) and (or) red pine ( Pinus resinosa Ait.) leading stands managed by shelterwood or seed tree silviculture as well as low-lying deciduous stands and selection-managed stands of shade-tolerant species. In the Great Lakes – St. Lawrence forest, rare SFUs were yellow birch stands, stands dominated by conifer species abundant in the Boreal, and shelterwood-managed hardwood stands. Several rare SFUs had <12% of their total area in protection, i.e., stands dominated by eastern white pine, yellow birch, eastern white pine – red oak, or eastern white-cedar. These rare stand types require increased protection in reserves and tailored silvicultural practices to maintain their probability of persistence.

Auto White Balance Algorithm in Digital Camera

2012 ◽  
Vol 182-183 ◽  
pp. 2080-2084
Author(s):  
Jie Li ◽  
Xue Xiang Wang ◽  
Hao Liu
Keyword(s):  
Hardware Implementation ◽  
Digital Camera ◽  
Low Complexity ◽  
Light Sources ◽  
Light Conditions ◽  
Threshold Method ◽  
White Balance ◽  
White Point ◽  
A New Technique ◽  
Better Than

Auto white balance (AWB) is an important function of digital camera. The purpose of white balance is to adjust the image to make it look like taken under standard light conditions. We present a new technique to detect the reference white point of image in this paper. This technique detects the white point of image by using dynamic threshold method, thus making it more flexible and more applicable compared to other algorithms. We test 50 images which were taken under different light sources, and find that this algorithm is better than or comparable to other algorithms both in subjective and objective aspects. At the same time, this algorithm has low complexity, and it can be easily applied to hardware implementation.

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