Palynostratigraphie et paléoenvironnements du Pléistocène supérieur dans la région du lac Bras d'Or, île du Cap-Breton, Nouvelle-Écosse

1986 ◽  
Vol 23 (4) ◽  
pp. 491-503 ◽  
Author(s):  
A. de Vernal ◽  
R. J. Mott
Keyword(s):  
Boreal Forests ◽  
Mixed Forest ◽  
Abies Balsamea ◽  
Sensu Stricto ◽  
Fagus Grandifolia ◽  
Last Interglacial ◽  
Humid Climate ◽  
Climatic Fluctuations ◽  
Coniferous Species ◽  
Coniferous Boreal Forest

The East Bay and Castle Bay stratigraphic sections along the northeastern shore of Bras d'Or Lake, despite some discontinuities, represent an important part of the Upper Pleistocene. Pollen analysis of these deposits provides a record that can be subdivided into three main units: (1) The first unit reflects the spread of rich forests dominated by thermophilous species such as Quercus, Ostrya, and Pinus strobus. It indicates a warmer and certainly drier climate than the present one. Th/U ages of the order of 120 000 years support a correlation of unit I with the Sangamonian (sensu stricto) interglacial (substage 5 in oceanic climato-stratigraphy). (2) The lower part of unit II, characterized by Abies balsamea, Fagus grandifolia, Tsuga canadensis, and Pinus, reflects the predominance of a mixed forest in the regional landscape. A cool and humid climate, probably not dissimilar to that of present is inferred. Th/U ages of approximately 85 000 years permits correlation of this forest stage with a relatively warm interval of the last interglacial, probably substage 5a. The upper part of unit II reflects a cooler climate and is characterized by pollen assemblages of the coniferous species Abies balsamea and Picea. (3) The lower stratigraphic part of unit III represents the spreading of coniferous boreal forests dominated by Picea, Pinus, and Abies during a cooler interval than at present. An approximate Th/U age of 60 000 years was obtained. Unit III reflects several cycles interpreted as alternating successions of tundra–forest and coniferous boreal forest. It suggests minor climatic fluctuations during a relatively cold interval. The third polynostratigraphic unit covers a significant part of the middle Wisconsinan (stage 3).

scholarly journals Evaluating the Performance of a Forest Succession Model to Predict the Long-Term Dynamics of Tree Species in Mixed Boreal Forests Using Historical Data in Northern Ontario, Canada

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1181
Author(s):  
Guy R. Larocque ◽  
F. Wayne Bell
Keyword(s):  
Populus Tremuloides ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Forest Succession ◽  
Regional Scale ◽  
Abies Balsamea ◽  
Forest Growth ◽  
Northern Ontario ◽  
Phase Dynamics

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur very slowly, simulation models are logical and efficient tools to predict the patterns of forest growth and succession. However, as models are an imperfect representation of reality, it is desirable to evaluate them with historical long-term forest data. Using remeasured tree and stand data from three data sets from two ecoregions in northern Ontario, the succession gap model ZELIG-CFS was evaluated for mixed boreal forests composed of black spruce (Picea mariana [Mill.] B.S.P.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana L.), white spruce (Picea glauca [Moench] Voss), trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), northern white cedar (Thuja occidentalis L.), American larch (Larix laricina [Du Roi] K. Koch), and balsam poplar (Populus balsamefera L.). The comparison of observed and predicted basal areas and stand densities indicated that ZELIG-CFS predicted the dynamics of most species consistently for periods varying between 5 and 57 simulation years. The patterns of forest succession observed in this study support gap phase dynamics at the plot scale and shade-tolerance complementarity hypotheses at the regional scale.

scholarly journals Palaeoecology and Archaeology of the Kärlich–Seeufer Open-Air Site (Middle Pleistocene) in the Central Rhineland, Germany

1996 ◽  
Vol 46 (3) ◽  
pp. 319-334 ◽  
Author(s):  
Sabine Gaudzinski ◽  
Felix Bittmann ◽  
Wolfgang Boenigk ◽  
Manfred Frechen ◽  
Thijs Van Kolfschoten
Keyword(s):  
Boreal Forests ◽  
Archaeological Site ◽  
Sensu Stricto ◽  
Middle Pleistocene ◽  
Recent Analysis ◽  
Small Lake ◽  
Wooden Structure ◽  
Archaeological Sample

The Kärlich–Seeufer archaeological site in Germany's central Rhineland was excavated between 1980 and 1992. The site provides evidence for hominid activity during a Middle Pleistocene interglaciation known up to now only from the Kärlich clay pit and therefore defined as the Kärlich Interglaciation, which is considered to be post-Cromer IV and pre-Holstein (sensu stricto) in age. The site is characterized by Acheulean artifacts, a fauna dominated by Elephas (Palaeoloxodon) antiquus, and a unique and outstanding preservation of wooden and other palaeobotanical remains. Assuming all finds are associated, the site previously was interpreted as an elephant hunting camp with a wooden structure, together with wood and bone implements preserved in situ. Recent analysis of the same features has shown that the site can also be interpreted as a reworked archaeological sample. Hominid occupation occurred in the vicinity of a small lake with prevailing meso-oligotrophic conditions. Expanding boreal forests and fen vegetation characterized the landscape.

Vegetation variation among mesic successional forest stands in northern lower Michigan

1988 ◽  
Vol 66 (6) ◽  
pp. 1080-1090 ◽  
Author(s):  
Mark R. Roberts ◽  
Norman L. Christensen
Keyword(s):  
Quercus Rubra ◽  
Abies Balsamea ◽  
Acer Rubrum ◽  
Pinus Strobus ◽  
Pinus Resinosa ◽  
Fagus Grandifolia ◽  
Prunus Serotina ◽  
Stand Age ◽  
Site Conditions ◽  
Soil Variables

Vegetation composition of the shrub–tree and herb layers was sampled in 70 successional aspen (Populus tremuloides and Populus grandidentata) stands of different ages (1–90 years) on a variety of sites in northern lower Michigan. Physical and chemical characteristics of soil profiles were also measured at each site. Three stand groupings were identified based on site conditions and detrended correspondence analysis (DCA) ordination of the vegetation. Sandy dry-mesic soils support forests of Acer rubrum, Quercus rubra, Pinus resinosa, and Pinus strobus. On lowland sandy soils with a fluctuating water table, Pinus strobus, Abies balsamea, Viburnum lentago, and Viburnum cassinoides are important. Mesic soils with stratified calcareous layers or clay till substrates support Acer saccharum, Fagus grandifolia, Tilia americana, Fraxinus americana, Ostrya virginiana, and Acer pensylvanicum. Canonical correlation analysis (CCA) was used to compare DCA scores with soil variables; first-axis DCA scores were correlated with a suite of soil variables and stand age was correlated with second or third DCA axis scores. Separate DCA ordinations of the dry-mesic and mesic groups revealed successional relations on these sites. On dry-mesic sites, Pinus resinosa and Pinus strobus increase in importance with stand age, while Prunus serotina, Prunus virginiana, Prunus pensylvanica, and the aspens decrease. On mesic sites, early successional species include the aspens, Corylus cornuta, Prunus serotina, and Prunus pensylvanica. Fagus grandifolia, Acer pensylvanicum, Quercus rubra, Viburnum acerifolium, Betula papyrifera, Acer rubrum, and Tilia americana are more abundant in mature mesic-site stands. Ordinations of the herb data were remarkably similar to those for trees and shrubs except on dry-mesic sites. Much of the residual variability in vegetation not accounted for by site conditions and stand age is probably related to historical factors such as the nature of disturbance and variations in seed rain.

Disturbance history affects dead wood abundance in Newfoundland boreal forests

2006 ◽  
Vol 36 (12) ◽  
pp. 3194-3208 ◽  
Author(s):  
Martin T Moroni
Keyword(s):  
Boreal Forests ◽  
Dead Wood ◽  
Black Spruce ◽  
Woody Debris ◽  
Abies Balsamea ◽  
Natural Disturbance ◽  
Diameter Distribution ◽  
Natural Disturbances ◽  
A Minor ◽  
Almost All

Dead wood (dead standing tree (snag), woody debris (WD), buried wood, and stump) abundance was estimated in Newfoundland balsam fir (Abies balsamea (L.) Mill.) and black spruce (Picea mariana (Mill.) BSP) forests regrown following natural and anthropogenic disturbances. Although harvesting left few snags standing, natural disturbances generated many snags. Most were still standing 2 years after natural disturbance, but almost all had fallen after 33–34 years. Snag abundance then increased in stands aged 86–109 years. Natural disturbances generated little WD 0–2 years following disturbance. Harvesting, however, immediately generated large amounts of WD. Thirty-two to forty-one years following disturbance, most harvesting slash had decomposed, but naturally disturbed sites had large amounts of WD from collapsed snags. Harvested sites contained less WD 32–72 years following disturbance than naturally disturbed sites. Amounts of WD in black spruce regrown following harvesting and fire converged 63–72 years following disturbance, despite significant initial differences in WD quantities, diameter distribution, and decay classes. Abundance of WD increased from sites regrown 32–72 years following disturbance to older sites. Precommercial thinning had a minor impact on dead wood stocks. Stumps contained minor biomass. Buried wood and WD biomass were equivalent at some sites.

Vipera berus (Linnaeus, 1758) remains from the Late Pleistocene of Slovakia

2017 ◽  
Vol 38 (2) ◽  
pp. 133-144 ◽  
Author(s):  
Martin Ivanov ◽  
Andrej Čerňanský
Keyword(s):  
Late Pleistocene ◽  
Mixed Forest ◽  
Axial Skeleton ◽  
Species Group ◽  
Climatic Conditions ◽  
Mammalian Fauna ◽  
Humid Climate ◽  
Vipera Berus ◽  
Faunal Assemblages ◽  
The Common

Completely preserved specimens of fossil snakes are extremely rare and ophidian palaeontologists are usually dependent only on disarticulated elements of a postcranial skeleton. Here we present an unusually well-preserved specimen of a small viperid snake from the Late Pleistocene firm travertine at the famous Gánovce-Hrádok Neanderthal mound in Slovakia. The complex study of both cranial and axial skeleton with well-preserved maxilla and basiparasphenoid confirms the presence of a viper from theVipera berusspecies group, and recent distribution ofV. berusspecies complex members supports identification of these preserved remains as belonging to the common adder,V. berus(Linnaeus, 1758). Associated faunal assemblages of the MFG-C and D mammalian fauna groups reported from the firm travertine indicate a humid climate in a predominantly woodland environment with typical forest species in the Gánovce-Hrádok vicinity throughout the Eemian optimum, and mixed forest and steppe environments in the late Eemian to early Weichselian stages. Occurrence ofV. berusdocuments the presence of open or semi-open biotopes with low vegetation. AlthoughV. berusoccurs in the Quaternary glacial/interglacial cycle and throughout the entire warm part, it never dominated herpetofaunal assemblages during the climatic optimum. Therefore, the presence ofV. berusmost likely indicates late Eemian or early Weichselian (interstadial) climatic conditions.

Drivers of arboreal lichen community structure and diversity on Abies balsamea and Betula alleghaniensis in the Avalon Forest Ecoregion, Newfoundland

Botany ◽  
2021 ◽  
Vol 99 (1) ◽  
pp. 43-54
Author(s):  
Rachel D. Wigle ◽  
Yolanda F. Wiersma ◽  
André Arsenault ◽  
R. Troy McMullin
Keyword(s):  
Community Structure ◽  
Boreal Forests ◽  
Abies Balsamea ◽  
Local Environment ◽  
Lichen Species ◽  
Environmental Data ◽  
Betula Alleghaniensis ◽  
Diverse Range ◽  
Clear Cutting ◽  
Lichen Diversity

There is debate about what drives and maintains the structure of arboreal lichen communities and the relative importance of substrate vs. local environment. Here, we examined which lichen species are unique to two tree species [Abies balsamea (L.) Mill. and Betula alleghaniensis Britton] in the boreal forests of the Avalon Peninsula, Newfoundland, and which environmental variables are most important for lichen colonization and community structure. We collected data on lichen diversity from tree boles along with environmental data (tree size, bark pH, canopy cover) for each tree and each site. Multivariate analyses were used to determine the relationship between community structure and environmental data. The results show that a diverse range of tree characteristics are needed to support a diverse range of lichen species. Certain stands, such as old B. alleghaniensis stands, are more suitable to host a unique community of lichens than others. These results can inform land managers on the Avalon, recommending strategies for protected areas and providing forest harvest guidelines that limit clear-cutting of A. balsamea to maintain a diverse community structure and limit harvest of B. alleghaniensis trees in sites less optimal for lichen growth. These baseline data can also be used to monitor changes caused by moose browse and selective harvesting, two locally important threats to lichen diversity.

Influence of Site and Stand Factors on the Distribution of Crustose Lichens Of The Caliciales in a Suboceanic Spruce Forest Area in Central Norway

1996 ◽  
Vol 28 (4) ◽  
pp. 315-330 ◽  
Author(s):  
Håkon Holien
Keyword(s):  
Species Diversity ◽  
Boreal Forests ◽  
Detrended Correspondence Analysis ◽  
Stand Age ◽  
Spruce Forest ◽  
Humid Climate ◽  
Forest Patches ◽  
Young Forests ◽  
Old Trees ◽  
Crustose Lichens

AbstractThe distribution of crustose Caliciales has been surveyed in 100 spruce forest patches in Sør-Trøndelag, central Norway. Relationships between occurrence of the species and a number of site and stand variables were analysed by detrended correspondence analysis (DCA) and direct gradient analysis. Species diversity7 was significantly higher in old forests and in forests at higher altitudes compared to young forests and forests at lower altitudes. Old trees and snags are considered to be the most important structural components in old forests promoting species diversity of the Caliciales. Threatened or vulnerable species, such as Chaenotheca gracilliina, Cybebe gracilenta, Sclerophora coniophaea and S. peronella were confined to forest on rich soils showing no correlation with forest stand age. Chaenotheca brachypoda and C. trichialis were found to be the most typical old forest species among the Caliciales. Humidiphilous species are considered to be less affected by forestry in a humid climate. A change in forestry practice towards methods imitating the natural dynamic processes is considered necessary to maintain species diversity of the Caliciales in boreal forests.

Analysing species-specific light transmission and related crown characteristics of Pinus sylvestris and Betula pendula using a shoot-level 3D model

2013 ◽  
Vol 43 (10) ◽  
pp. 929-938 ◽  
Author(s):  
Anna Lintunen ◽  
Pekka Kaitaniemi ◽  
Jari Perttunen ◽  
Risto Sievänen
Keyword(s):  
Pinus Sylvestris ◽  
Boreal Forests ◽  
Betula Pendula ◽  
Light Transmission ◽  
Light Attenuation ◽  
Mixed Forest ◽  
Ray Casting ◽  
Area Index ◽  
Crown Characteristics ◽  
Species Specific

This is a first attempt to analyse species-specific light attenuation in mixed boreal forests created by shoot-level 3D tree models. The models are configurations of real individual Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) trees grown in mixed-forest stands. We study species-specific differences in radiation transmission by using the ray-casting method. Light transmission was found to be higher in dense birch-dominated stands compared with dense pine-dominated stands because of the higher total foliage area and the higher location of foliage in the pine canopy. Transmission of light per leaf area index (LAI) was nevertheless higher in the pine canopy compared with the birch canopy because of foliage clumping. Especially in clumped canopy, species-specific shoot-level light simulations enable a more realistic estimation of light transmission compared with simpler calculations based on LAI and Beer–Lambert’s law. The observed differences in light-transmission characteristics of the studied species may influence the development of target crowns in the neighbourhood. Light attenuation caused by the dense foliage zone in the upper pine canopy could be avoided in dense stands by mixing species with different vertical foliage distributions.

scholarly journals Coefficients de distribution de la régénération, cinq ans après des coupes avec protection des petites tiges marchandes appliquées dans des sapinières et des pessières noires du Québec

2011 ◽  
Vol 87 (05) ◽  
pp. 669-683 ◽  
Author(s):  
Martin Riopel ◽  
Jean Bégin ◽  
Jean-Claude Ruel
Keyword(s):  
Black Spruce ◽  
Abies Balsamea ◽  
Balsam Fir ◽  
Annual Rainfall ◽  
Deciduous Species ◽  
Partial Cutting ◽  
Coniferous Species ◽  
Breast Height ◽  
Silvicultural Treatments ◽  
Heavy Equipment

For certain mature forests dominated by balsam fir (Abies balsamea [L.] Mill.) or black spruce (Picea mariana [Mill.] BSP), it may be preferable to harvest trees with diameter at breast height greater than 15 cm while conserving smaller ones. This treatment, called harvesting with protection of small merchantable trees, produces strips, where partial cutting is applied, alternating with corridors, which are disturbed by heavy equipment during harvesting. This project studied stocking levels five years after treatment on 4896 sub-plots of 4 m2 in 22 blocks. Stocking coefficients (SC) for coniferous and deciduous species were modeled in order to identify variables affecting stocking. The strips had well-distributed coniferous regeneration, while SC in the corridors were more variable and lower, occasionally less than 60%. Black spruce-dominated sites were not as well stocked as balsam fir-dominated sites. Stocking levels of protected coniferous merchantable trees positively influence coniferous and deciduous SC in the corridors. The presence of coniferous species is also affected by harvest season and total annual rainfall. Alternative silvicultural treatments applicable in certain corridors are presented.

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