scholarly journals Phytocoenotical behaviour of boreal plant species in broadleaved-forest zone communities

Turczaninowia ◽  
2021 ◽  
Vol 24 (3) ◽  
pp. 89-110
Author(s):  
Ilja B. Kucherov ◽  
Andrey A. Zverev
Keyword(s):  
Boreal Forest ◽  
Vaccinium Myrtillus ◽  
Altitudinal Distribution ◽  
Forest Zone ◽  
Oxalis Acetosella ◽  
Spruce Forests ◽  
Coniferous Boreal Forest ◽  
The One ◽  
Associated Species ◽  
Trientalis Europaea

Phytocoenotic behaviour of 11 species of boreal vascular plants and mosses is analyzed within the broadleaved-forest zone in comparison with that in different subzones of the boreal-forest zone, based upon the set of 1417 relevés made in European Russia in 1996–2017. The significance of differences in species cover is estimated by means of the one-way ANOVA. The cover of species like Vaccinium myrtillus, V. vitis-idaea, andHylocomium splendens in broadleaved / spruce forests of zonal types is constantly decreasing southwards. On the contrary, the cover of Luzula pilosain Scots pine forests and Pleurozium schreberi and Dicranum polysetum in paludified Norway spruce forests is subject to southward increase. Finally, Oxalis acetosella and Equisetum sylvaticum demonstrate maximae of their cover in forests of zonal types in the southern-boreal and hemiboreal subzones. The dark-coniferous boreal forest “cortege” of species is breaking down into several different floristic elements in the broadleaved-forest zone. These are: “vaccinietal” species p. p. sensu Yu. D. Kleopov (like Vaccinium myrtillus), “quasi-boreal” species sensu V. B. Sochava (Oxalis acetosella, Maianthemum bifolium, Trientalis europaea), hygromesophytes with aged areas (Equisetum sylvaticum), associated species with European-Ancient-Mediterranean nemoral (Luzula pilosa) or East-Asian boreal-montane (Rubus saxatilis) origins. Phytocoenotical behaviour of species is not always different in the intrazonal and the zonal community types but is rather similar in many cases like those of Vaccinium vitis-idaea and Equisetum sylvaticum. The more distinct differences in species positions are found in the extrazonal communities. The statistically proved differences are lacking in phytocoenotical behaviour of Maianthemum bifolium and Trientalis europaea in different zones and subzones due to either florogenetical, or purely methodical reasons, the latter connected with low abundance but high constancy of these species. Disintegration of vegetation “corteges” and individualization of coenotic patterns of species previously growing together are usually observed at the climatically determined (zonal / subzonal or altitudinal) distribution limits.

scholarly journals Major postglacial summer temperature changes in the central coniferous boreal forest of Quebec (Canada) inferred using chironomid assemblages

2018 ◽  
Vol 33 (4) ◽  
pp. 409-420 ◽  
Author(s):  
Lisa Bajolle ◽  
Isabelle Larocque-Tobler ◽  
Emmanuel Gandouin ◽  
Martin Lavoie ◽  
Yves Bergeron ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Summer Temperature ◽  
Temperature Changes ◽  
Chironomid Assemblages ◽  
Coniferous Boreal Forest

The Role of Bacterial Biofilms in Dental Caries and Periodontal and Peri-implant Diseases: A Historical Perspective

2019 ◽  
Vol 98 (4) ◽  
pp. 373-385 ◽  
Author(s):  
A.P.V. Colombo ◽  
A.C.R. Tanner
Keyword(s):  
Deep Understanding ◽  
Oral Microbiome ◽  
Oral Diseases ◽  
Oral Infections ◽  
Microbial Biofilms ◽  
Holistic Concept ◽  
Dental Diseases ◽  
The One ◽  
Associated Species ◽  
Clinical Conditions

Over the last hundred years, groundbreaking research in oral microbiology has provided a broad and deep understanding about the oral microbiome, its interactions with our body, and how the community can affect our health, be protective, or lead to the development of dental diseases. During this exciting journey, hypotheses were proposed, and concepts were established, discarded, and later revisited from updated perspectives. Dental plaque, previously considered a polymicrobial community of unspecific pathogenicity, is recognized as microbial biofilms with healthy, cariogenic, or periodontopathogenic profiles, resulting from specific ecologic determinants and host factors. The “one pathogen, one disease” paradigm of oral infections has been replaced by a holistic concept of a microbial community as the entity of pathogenicity. Cutting-edge technology can now explore large microbial communities related to different clinical conditions, which has led to finding several novel disease-associated species and potential pathobionts and pathobiomes. This vast amount of data generated over time has widened our view of the etiology of caries and periodontal and peri-implant diseases and has promoted updated strategies to treat and prevent the oral diseases.

scholarly journals Arctic ground squirrel population collapse in the boreal forests of the Southern Yukon

2015 ◽  
Vol 42 (2) ◽  
pp. 176 ◽  
Author(s):  
Jeffery R. Werner ◽  
Charles J. Krebs ◽  
Scott A. Donker ◽  
Rudy Boonstra ◽  
Michael J. Sheriff
Keyword(s):  
Boreal Forest ◽  
Ground Squirrel ◽  
Boreal Forests ◽  
Ground Squirrels ◽  
The Arctic ◽  
Arctic Ground Squirrel ◽  
Forest Zone ◽  
Winter Climate ◽  
Population Collapse ◽  
Predator Pit

Context The arctic ground squirrel (Urocitellus parryii) comprised 17% of the biomass of herbivores in the Yukon boreal forest during the summer months from 1987 to 1996 and was responsible for 23% of the energy flow at the herbivore level. By 2000, ground squirrel populations in this region collapsed to nearly zero and have remained there. Aims We summarise the population monitoring (since 1975) and recent experimental work that has been done on this key herbivore in the Kluane area of the southern Yukon to test one mechanistic hypothesis as the possible explanation for this population collapse and subsequent lack of recovery: predation. Methods Ground squirrels are the preferred summer prey of bird and mammal predators when snowshoe hare (Lepus americanus) populations are declining. We used translocations into formerly occupied habitat and radiotelemetry to determine movements and causes of death from 2009 to 2014. We surveyed 158 sites between 2008 and 2013 to measure the disappearance of colonies in alpine and forest habitats over 25 000 km2. Key results Ground squirrels from 2000 to 2013 comprised a small fraction of the herbivore biomass in the boreal forest zone, down from 17% earlier. Most forest populations (~95%) are currently extinct, whereas just over half (65%) of low-elevation meadow populations are locally extinct. One hypothesis is that ground squirrels in the forest have been driven into a predator pit from which they cannot recover. They remain abundant in alpine tundra (93% occupancy rate) and around airport runways and human habitations (97% occupancy), but there is no apparent dispersal from alpine areas down into the boreal forest. Conclusion The predator pit hypothesis is a likely explanation for the initial collapse and sustained decline in population size from 2000 to 2013. Recent attenuation of the hare cycle and milder winter climate have allowed shrubs to expand throughout the forest, thereby reducing visibility and increasing predation risk. This conclusion will be tested in further research using reintroductions to formerly occupied sites. Implication If the loss of this herbivore from the boreal forest is not reversed, predator pressure on the other major herbivores of the montane forest zone is likely to change significantly.

Comparison of SAR-Based Snow-Covered Area Estimation Methods for the Boreal Forest Zone

2009 ◽  
Vol 6 (3) ◽  
pp. 403-407 ◽  
Author(s):  
K.P. Luojus ◽  
J.T. Pulliainen ◽  
A. Blasco Cutrona ◽  
S.J. Metsamaki ◽  
M.T. Hallikainen
Keyword(s):  
Boreal Forest ◽  
Estimation Methods ◽  
Forest Zone ◽  
Area Estimation ◽  
Snow Covered Area ◽  
Covered Area

scholarly journals Climate variability and long-term expansion of peat lands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

2015 ◽  
Vol 11 (6) ◽  
pp. 5755-5798 ◽  
Author(s):  
S. Panitz ◽  
U. Salzmann ◽  
B. Risebrobakken ◽  
S. De Schepper ◽  
M. J. Pound
Keyword(s):  
Climate Variability ◽  
Boreal Forest ◽  
Climatic Conditions ◽  
Forest Zone ◽  
Norwegian Sea ◽  
Late Pliocene ◽  
Oxygen Isotope Stage ◽  
Cool Temperate ◽  
Vegetation And Climate

Abstract. Little is known about the terrestrial response of high latitude Scandinavian vegetation to the warmer-than-present climate of the Late Pliocene (Piacenzian, 3.60–2.58 Ma). In order to assess Piacenzian terrestrial climate variability we present the first high resolution reconstruction of vegetation and climate change in northern Norway between 3.6–3.14 Ma. The reconstructions are derived from pollen assemblages in the marine sediments of ODP Hole 642B, Norwegian Sea (67° N). The palynological assemblages provide a unique record of latitudinal and altitudinal shifting of the forest boundaries, with vegetation alternating between cool temperate forest during warmer-than-present intervals, and boreal forest similar to today during cooler intervals. The northern boundary of the nemoral to boreonemoral forest zone was displaced at least 4–8° further north and warmest month temperatures were 6–14.5 °C higher than present during warm phases. Warm climatic conditions persisted during the earliest Piacenzian (ca. 3.6–3.47 Ma) with diverse cool temperate nemoral to boreonemoral forests growing in the lowlands of the Scandinavian mountains. A distinct cooling event at ca. 3.47 Ma resulted in a southward shift of vegetation boundaries, leading to the predominance of boreal forest and the development of open, low alpine environments. The cooling culminated around 3.3 Ma, coinciding with Marine Oxygen Isotope Stage (MIS) M2. Warmer climate conditions returned after ca. 3.29 Ma with higher climate variability indicated by the repeated expansion of forests and peat lands during warmer and cooler periods, respectively. Climate progressively cooled after 3.18 Ma, resembling climatic conditions during MIS M2. A high variability of Norwegian vegetation and climate changes during the Piacenzian is superimposed on a long-term cooling trend. This cooling was accompanied by an expansion of Sphagnum peat lands that potentially contributed to the decline in atmospheric CO2-concentrations at the end of the Piacenzian warm period and facilitated ice growth through positive vegetation-snow albedo feedbacks. Correlations with other Northern Hemisphere vegetation records suggest hemisphere-wide effects of climate cooling.

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