The role of climate on the developmental history of Frontenac Peatland, southern Quebec

2000 ◽  
Vol 78 (5) ◽  
pp. 668-684 ◽  
Author(s):  
Martin Lavoie ◽  
Pierre JH Richard
Keyword(s):  
Lake Level ◽  
Elevated Temperatures ◽  
Accumulation Rate ◽  
Critical Factor ◽  
Accumulation Rates ◽  
Developmental History ◽  
Peat Accumulation ◽  
Lake Water Level ◽  
History Of

The developmental stages, hydrological conditions, and net peat accumulation rates at three coring sites of Parc de Frontenac Peatland (Quebec) were reconstructed to examine the role of climate on peat accumulation. During the early to mid-Holocene, elevated temperatures proved to be a more critical factor for sustained peat production than precipitation, because peatland development occurred mostly under a dry climate according to a low lake-level stage lasting from 11 000 to 7000 calibrated (cal.) BP in a nearby lake. Between 7000 and 6000 cal. BP, elevated net peat accumulation rates roughly correspond with a rise in lake water level, suggesting that higher precipitation and (or) less evapotranspiration then favored peat growth. A decrease in peat accumulation occurred from 5000 to 2500-1500 cal. BP, while the lake level was high from 4400 cal. BP. An important increase in net peat accumulation rate is recorded for this entire peatland from 1500 cal. BP. Lack of close timing between lake level changes and changes in peat accumulation rates or surface hydrology suggest that temperature and autogenic processes were often more important than regional water balance in the developmental history of the peatland.Key words: peatlands, paleohydrology, pollen, plant macrofossils, rhizopods, Quebec.

The developmental history of peatlands at Muskiki and Marguerite lakes, Alberta

1989 ◽  
Vol 67 (12) ◽  
pp. 3534-3544 ◽  
Author(s):  
Helen Kubiw ◽  
Michael Hickman ◽  
Dale F. Vitt
Keyword(s):  
Species Composition ◽  
Radiocarbon Dating ◽  
Environmental Changes ◽  
Warm Period ◽  
Vegetation Changes ◽  
Developmental History ◽  
Peat Accumulation ◽  
Fire Activity ◽  
History Of ◽  
Peat Stratigraphy

The peat stratigraphy of fens at Muskiki Lake (52°50′N, 116°51′W) and Marguerite Lake (54°38′N, 110°43′W) in central Alberta was examined to determine the developmental history of the fens on the basis of radiocarbon dating and bryophyte macrofossil analyses. Peat accumulation at Muskiki Lake peatland began about 9000 years BP via lake filling. Expansion of the peatland by paludification and vegetation changes, including string and flark formation, are secondary occurrences, the latter occurring subsequent to environmental changes, including mid-Holocene thermal events. Peat inception at Marguerite Lake began about 2400 years BP via paludification. This delay, relative to Muskiki Lake peatland, may be related to the mid-Holocene warm period. Fire activity and increased wetness, as well as autogenic successional processes, altered species composition and abundance.

Stratigraphy and genesis of the Lake Sixteen peatland, northern Michigan

1986 ◽  
Vol 64 (12) ◽  
pp. 3008-3019 ◽  
Author(s):  
Richard P. Futyma ◽  
Norton G. Miller
Keyword(s):  
Basal Layer ◽  
Developmental History ◽  
Peat Accumulation ◽  
Hydrological Changes ◽  
Alkaline Lake ◽  
Temporal Relationships ◽  
History Of ◽  
Northern Michigan

The Lake Sixteen peatland is a 400-ha mire consisting principally of low-shrub (Chamaedaphne) bog and lesser areas of tree-covered (Picea – Larix) bog and sedge fen adjacent to a 55-ha alkaline lake. The sediments consist of the following superimposed deposits: gyttja, sedge peat, and Sphagnum–ericad–sedge peat. Near the edges of the peatland, highly humified, sometimes woody peat is present as the basal layer instead of gyttja. Radiocarbon-dated pollen stratigraphies from the lake and four sites in the peatland have elucidated the temporal relationships of the various sediment units and the developmental history of the peatland. During the mid-Holocene, probably in response to a change to cooler, moister climate, early Lake Sixteen underwent an expansion resulting in the deposition of gyttja over an increasingly larger area. About 3000 years BP, a sedge fen developed on the edge of the lake. Low-shrub bog replaced the sedge vegetation as the fen mat expanded into the lake. Swamping of bordering forests also allowed expansion of bog vegetation outward from the basin. Hydrological changes accompanying peat accumulation probably promoted vegetational changes within the peatland and the centrifugal spread of bog vegetation through swamping.

The role of climate on the developmental history of Frontenac Peatland, southern Quebec

2000 ◽  
Vol 78 (5) ◽  
pp. 668-684 ◽  
Author(s):  
Martin Lavoie ◽  
Pierre J.H. Richard
Keyword(s):  
Developmental History ◽  
History Of

Holocene peat and carbon accumulation rates in the southern taiga of western Siberia

2004 ◽  
Vol 61 (1) ◽  
pp. 42-51 ◽  
Author(s):  
Wiebe Borren ◽  
Wladimir Bleuten ◽  
Elena D. Lapshina
Keyword(s):  
Bulk Density ◽  
Western Siberia ◽  
Accumulation Rate ◽  
Global Carbon Cycle ◽  
Southern Taiga ◽  
Carbon Accumulation ◽  
Accumulation Rates ◽  
Peat Accumulation ◽  
Global Carbon ◽  
Carbon Accumulation Rates

Although recent studies have recognized peatlands as a sink for atmospheric CO2, little is known about the role of Siberian peatlands in the global carbon cycle. We have estimated the Holocene peat and carbon accumulation rate in the peatlands of the southern taiga and subtaiga zones of western Siberia. We explain the accumulation rates by calculating the average peat accumulation rate and the long-term apparent rate of carbon accumulation (LORCA) and by using the model of Clymo (1984, Philosophical Transactions of the Royal Society of London Series B 303, 605–654). At three key areas in the southern taiga and subtaiga zones we studied eight sites, at which the dry bulk density, ash content, and carbon content were measured every 10 cm. Age was established by radiocarbon dating. The average peat accumulation rate at the eight sites varied from 0.35 ± 0.03 to 1.13 ± 0.02 mm yr−1 and the LORCA values of bogs and fens varied from 19.0 ± 1.1 to 69.0 ± 4.4 g C m−2 yr−1. The accumulation rates had different trends especially during the early Holocene, caused by variations in vegetation succession resulting in differences in peat and carbon accumulation rates. The indirect effects of climate change through local hydrology appeared to be more important than direct influences of changes in precipitation and temperature. River valley fens were more drained during wetter periods as a result of deeper river incision, while bogs became wetter. From our dry bulk density results and our age–depth profiles we conclude that compaction is negligible and decay was not a relevant factor for undrained peatlands. These results contribute to our understanding of the influence of peatlands on the global carbon cycle and their potential impact on global change.

Vegetational gradients in relation to environmental conditions in northwestern European mires

1986 ◽  
Vol 64 (2) ◽  
pp. 375-383 ◽  
Author(s):  
Nils Malmer
Keyword(s):  
Environmental Conditions ◽  
Accumulation Rate ◽  
Nutrient Supply ◽  
Climatic Conditions ◽  
Mineral Nutrient ◽  
Accumulation Rates ◽  
Peat Accumulation ◽  
Surface Microtopography ◽  
Level Ii ◽  
Floristic Variation

Floristically characterized gradients related to (i) mire surface microtopography, (ii) marginal versus central areas, (iii) ombrotrophy and minerotrophy ("poor and rich mires"), and (iv) distance from the sea can be recognized in the mire vegetation of northwestern Europe. Along these gradients variation occurs in (i) oscillations in the water level, (ii) origin and flow of water, and (iii) supply of minerals. These conditions influence the decay processes and the resulting peat accumulation rate, pH, mineral nutrient supply, and productivity. The differences between marginal and open areas result from differences in nutrient supply (N,P,K), while the differences between "poor and rich" mires are due to differences in the reactions of the peat. In Sphagnum-dominated vegetation, most floristic variation results from effects of differences in peat accumulation rates. Climatic conditions, other than atmospheric supply of minerals, are most important in establishing the regional floristic differences in the bog vegetation.

scholarly journals Thermally tolerant symbionts may explain Caribbean octocoral resilience to heat stress

Coral Reefs ◽  
2021 ◽  
Author(s):  
Jessie Pelosi ◽  
Katherine M. Eaton ◽  
Samantha Mychajliw ◽  
Casey P. terHorst ◽  
Mary Alice Coffroth
Keyword(s):  
Heat Stress ◽  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Florida Keys ◽  
Coral Reef Ecosystems ◽  
History Of ◽  
Historical Temperature

AbstractCoral reef ecosystems are under threat from the frequent and severe impacts of anthropogenic climate change, particularly rising sea surface temperatures. The effects of thermal stress may be ameliorated by adaptation and/or acclimation of the host, symbiont, or holobiont (host + symbiont) to increased temperatures. We examined the role of the symbiont in promoting thermal tolerance of the holobiont, using Antillogorgia bipinnata (octocoral host) and Breviolum antillogorgium (symbiont) as a model system. We identified five distinct genotypes of B. antillogorgium from symbiont populations isolated from Antillogorgia colonies in the Florida Keys. Three symbiont genotypes were cultured and maintained at 26 °C (ambient historical temperature), and two were cultured and maintained at 30 °C (elevated historical temperature) for 2 yrs. We analyzed the growth rate and carrying capacity of each symbiont genotype at both ambient and elevated temperatures in culture (in vitro). All genotypes grew well at both temperatures, indicating that thermal tolerance exists among these B. antillogorgium cultures. However, a history of long-term growth at 30 °C did not yield better performance for B. antillogorgium at 30 °C (as compared to 26 °C), suggesting that prior culturing at the elevated temperature did not result in increased thermal tolerance. We then inoculated juvenile A. bipinnata polyps with each of the five symbiont genotypes and reared these polyps at both ambient and elevated temperatures (in hospite experiment). All genotypes established symbioses with polyps in both temperature treatments. Survivorship of polyps at 30 °C was significantly lower than survivorship at 26 °C, but all treatments had surviving polyps at 56 d post-infection. Our results suggest broad thermal tolerance in B. antillogorgium, which may play a part in the increased resilience of Caribbean octocorals during heat stress events.

scholarly journals Rural Governmentality in Alberta: A Case Study of Neoliberalism in Rural Canada

2019 ◽  
Vol 15 (2) ◽  
pp. 27-49
Author(s):  
Lars K. Hallstrom
Keyword(s):  
Rural Communities ◽  
Rural Development ◽  
Developmental History ◽  
Neoliberal Governmentality ◽  
Third Phase ◽  
History Of ◽  
Agricultural Investments ◽  
Rural Policy

Rural communities in Canada have faced a long history of capital and labour flight, resource extraction, and political marginalization. At the same time, despite decades of efforts toward rural development and economic/social diversification, there is little evidence of change or improved resilience in rural Canada. This article seeks to examine this lack of change against the backdrop of that developmental history, and the underlying logics that have informed rural policy-making. Focusing on Alberta, this paper argues that rural communities face a third phase of developmental approaches embedded within a neoliberal governmentality, one that emphasizes equality of opportunity, competition, capacity-building, and collaboration. This approach is simultaneously situated within a broader neoliberal objective of defining both citizens and rural communities as economic actors. In turn, this article examines the scope, scale, and role of energy and agricultural investments as a demonstration of how neoliberal governmentality structures not only how rural development is framed, but constructs economic agency for rural communities as “the only game in town” for the very populations that bear the costs. As a result, the historical failure of rural development is unlikely to change, yet, rather than be understood as problematic, will increasingly be seen as a failure on the part of rural communities themselves.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of a family history of adenocarcinomas in patients with Barrett oesophagus

2001 ◽  
Vol 120 (5) ◽  
pp. A442-A442
Author(s):  
P TSIBOURIS ◽  
M HENDRICKSE ◽  
P ISAACS
Keyword(s):  
Family History ◽  
History Of ◽  
Barrett Oesophagus

Protective Factors and Suicidality in Members of Arab Kindred

Crisis ◽  
2012 ◽  
Vol 33 (2) ◽  
pp. 80-86 ◽  
Author(s):  
Sami Hamdan ◽  
Nadine Melhem ◽  
Israel Orbach ◽  
Ilana Farbstein ◽  
Mohammad El-Haib ◽  
...  
Keyword(s):  
Risk Factors ◽  
Protective Factors ◽  
Suicidal Behavior ◽  
Composite International Diagnostic Interview ◽  
Diagnostic Interview ◽  
Suicidal Risk ◽  
Arab Population ◽  
Psychiatric Interview ◽  
History Of

Background: Relatively little is known about the role of protective factors in an Arab population in the presence of suicidal risk factors. Aims: To examine the role of protective factors in a subsample of in large Arab Kindred participants in the presence of suicidal risk factors. Methods: We assessed protective and risk factors in a sample of 64 participants (16 suicidal and 48 nonsuicidal) between 15 and 55 years of age, using a comprehensive structured psychiatric interview, the Composite International Diagnostic Interview (CIDI), self-reported depression, anxiety, hopelessness, impulsivity, hostility, and suicidal behavior in first-degree and second-relatives. We also used the Religiosity Questionnaire and suicide attitude (SUIATT) and multidimensional perceived support scale. Results: Suicidal as opposed to nonsuicidal participants were more likely to have a lifetime history of major depressive disorder (MDD) (68.8% vs. 22.9% χ2 = 11.17, p = .001), an anxiety disorder (87.5% vs. 22.9, χ2 = 21.02, p < .001), or posttraumatic stress disorder (PTSD) (25% vs. 0.0%, Fisher’s, p = .003). Individuals who are otherwise at high risk for suicidality have a much lower risk when they experience higher perceived social support (3.31 ± 1.36 vs. 4.96 ± 1.40, t = 4.10, df = 62, p < .001), and they have the view that suicide is somehow unacceptable (1.83 ± .10 vs. 1.89 ± .07, t = 2.76, df = 60, p = .008). Conclusions: Taken together with other studies, these data suggest that the augmentation of protective factors could play a very important role in the prevention of incidental and recurrent suicidal behavior in Arab populations, where suicidal behavior in increasing rapidly.

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