Vegetational gradients in relation to environmental conditions in northwestern European mires

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.

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

Canadian Journal of Botany ◽

10.1139/b00-043 ◽

2000 ◽

Vol 78 (5) ◽

pp. 668-684 ◽

Cited By ~ 22

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.

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

Quaternary Research ◽

10.1016/j.yqres.2003.09.002 ◽

2004 ◽

Vol 61 (1) ◽

pp. 42-51 ◽

Cited By ~ 63

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.

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Small-scale spatio-temporal characteristics of accumulation rates in western Dronning Maud Land, Antarctica

Journal of Glaciology ◽

10.3189/002214308784886243 ◽

2008 ◽

Vol 54 (185) ◽

pp. 315-323 ◽

Cited By ~ 10

Author(s):

Helgard Anschütz ◽

Daniel Steinhage ◽

Olaf Eisen ◽

Hans Oerter ◽

Martin Horwath ◽

...

Keyword(s):

Accumulation Rate ◽

Temporal Variations ◽

Spatial Variations ◽

Small Scale ◽

Accumulation Rates ◽

Order Of Magnitude ◽

Dronning Maud Land ◽

Spatio Temporal ◽

Ground Penetrating ◽

Firn Core

AbstractSpatio-temporal variations of the recently determined accumulation rate are investigated using ground-penetrating radar (GPR) measurements and firn-core studies. The study area is located on Ritscherflya in western Dronning Maud Land, Antarctica, at an elevation range 1400–1560 m. Accumulation rates are derived from internal reflection horizons (IRHs), tracked with GPR, which are connected to a dated firn core. GPR-derived internal layer depths show small relief along a 22 km profile on an ice flowline. Average accumulation rates are about 190 kg m−2 a−1 (1980–2005) with spatial variability (1σ) of 5% along the GPR profile. The interannual variability obtained from four dated firn cores is one order of magnitude higher, showing 1σ standard deviations around 30%. Mean temporal variations of GPRderived accumulation rates are of the same magnitude or even higher than spatial variations. Temporal differences between 1980–90 and 1990–2005, obtained from two dated IRHs along the GPR profile, indicate temporally non-stationary processes, linked to spatial variations. Comparison with similarly obtained accumulation data from another coastal area in central Dronning Maud Land confirms this observation. Our results contribute to understanding spatio-temporal variations of the accumulation processes, necessary for the validation of satellite data (e.g. altimetry studies and gravity missions such as Gravity Recovery and Climate Experiment (GRACE)).

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Tree line shifts, changing vegetation assemblages and permafrost dynamics on Galdhøpiggen (Jotunheimen, Norway) over the past ~4400 years

The Holocene ◽

10.1177/09596836211066591 ◽

2021 ◽

pp. 095968362110665

Author(s):

Helen Hallang ◽

Cynthia A Froyd ◽

John F Hiemstra ◽

Sietse O Los

Keyword(s):

Scots Pine ◽

Late Holocene ◽

Accumulation Rate ◽

Climatic Changes ◽

Climatic Conditions ◽

Tree Line ◽

Peat Core ◽

Modern Pollen ◽

Modern Analogue ◽

Downy Birch

An environmental reconstruction based on palynological evidence preserved in peat was carried out to examine late-Holocene alpine tree line dynamics in the context of past climatic changes on Galdhøpiggen (Jotunheimen, southern Norway). We analysed a peat core taken from a mire at the present-day tree line (1000 m a.s.l.), c. 450 m downslope from the lower limit of sporadic permafrost. We adopted a combination of commonly used indicators of species’ local presence to reconstruct past vegetation assemblages, such as the relative pollen abundance (%), pollen accumulation rate (PAR), and presence of indicator species. Additionally, fossil pollen from the peat sequence was compared to modern pollen from a surface moss polster to establish a modern analogue. The results were compared with studies covering the late-Holocene climatic changes in the area. The reconstruction demonstrates that a pine-dominated woodland reached above the present-day tree line at c. 4300 cal. yr BP, suggesting a warmer climate suitable for Scots pine ( Pinus sylvestris) growth at this altitude. Scots pine retreated to lower altitudes between c. 3400 and 1700 cal. yr BP, accompanied by the descent of the low-alpine shrub-dominated belt, in response to cooling climatic conditions. The colder period covered c. 1700–170 cal. yr BP, and an open downy birch ( Betula pubescens) woodland became widespread at 1000 m a.s.l., whilst pine remained sparse at this altitude. From c. 170 cal. yr BP onwards, warming allowed pine to re-establish its local presence alongside downy birch at 1000 m a.s.l.

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Germination Ecology of Catchfly (Silene conoidea) Seeds of Different Colors

Planta Daninha ◽

10.1590/s0100-83582017350100030 ◽

2017 ◽

Vol 35 (0) ◽

Cited By ~ 2

Author(s):

A. TANVEER ◽

M.M. JAVAID ◽

R.N. ABBAS ◽

H.H. ALI ◽

M.Q. NAZIR ◽

...

Keyword(s):

Osmotic Stress ◽

Environmental Conditions ◽

Climatic Conditions ◽

Burial Depth ◽

Weed Species ◽

Successful Management ◽

Nacl Concentration ◽

Seed Polymorphism ◽

Emergence Percentage ◽

Annual Herb

ABSTRACT Catchfly (Silene conoidea), an annual herb, is usually recognized as an emerging weed species in Eurasia and North America. The presence of somatic seed polymorphism might aid in the adaptation of this weed in different climatic conditions. We conducted laboratory and greenhouse experiments to study the seed polymorphism and influence of various environmental factors like temperature, salt stress, osmotic stress and burial depth on the germination and emergence characteristics of catchfly. Optimum germination of seeds of all colors was recorded at a temperature of 15 oC. Germination of catchfly seeds of all colors followed decreasing trend as NaCl concentration increased from 50 mM to 200 mM. Seed germination was maximum (87-96%) at 0 MPa but gradually decreased to 40% as osmotic stress increases up to -0.4 MPa and completely inhibited at 0.6 MPa of all seed colors. A slight increase (from 60 to 95%) in the germination of seeds of black and dark brown colors was observed when seeding depth increased from 0 to 2 cm but decreased when seeding depth increased from 2 to 4 cm in seeds of all colors. There was no emergence of catchfly at seeding depth of 6 cm or greater. Our results concluded that catchfly seeds have the potential to germinate and emerge in various environmental conditions, but germination/emergence percentage of seeds of all colors will be different in different environmental conditions. Soil amendments including deep ploughing may aid for the successful management of this weed in cultivated areas.

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First report on cyanobacterial flora from Masirah Island, Sultanate of Oman

Algologia ◽

10.15407/alg30.04.440 ◽

2020 ◽

Vol 30 (4) ◽

pp. 440-451

Author(s):

M. Shamina ◽

Keyword(s):

Environmental Conditions ◽

Food Industry ◽

Vital Role ◽

Taxonomic Composition ◽

Climatic Conditions ◽

Taxonomic Classification ◽

Biofuel Production ◽

Sultanate Of Oman ◽

First Report ◽

First Time

Cyanobacteria are organisms which play a vital role in various molecular and biotechnological aspects in food industry, agriculture, pharmaceuticals, neutraceuticals, biofuel production, etc., it is necessary to understand its adaptability to various environmental conditions. Furthermore it is equally important to discover new cyanobacterial taxa and with it occasional changes in taxonomic classification, thus the author set out to study cyanobacteria in extreme climatic conditions of desert, where temperatures are mostly above 45 oC. The taxonomic composition of cyanobacteria of Masirah Island, Sultanate of Oman, was studied for the first time. The studied samples were collected during the period of 2017–2019. The ten samples belonged to two orders: Oscillatoriales Schaffner and Synechococcales L.Hoffmann, Komárek & J.Kastovsky. All of them were filamentous non-heterocyst forms. Three species belonged to the genus Leptolyngbya Anagn. & Komárek, the genera Oscillatoria Vaucher ex Gomont and Lyngbya C.Agardh ex Gomont were represented by two species each, while the genera Pseudanabena Lauterborn, Planktolyngbya Anagn. & Komárek and Geitlerinema (Anagn. & Komárek) Anagn. were one species.

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High-resolution magnetostratigraphy of the upper Nacimiento Formation, San Juan Basin, New Mexico, USA: implications for basin evolution and mammalian turnover

10.31233/osf.io/qxw4n ◽

2017 ◽

Author(s):

Caitlin Leslie ◽

Daniel J. Peppe ◽

Thomas E. Williamson ◽

Dario Bilardello ◽

Matthew Heizler ◽

...

Keyword(s):

New Mexico ◽

North America ◽

Accumulation Rate ◽

Global Climate ◽

Sediment Accumulation ◽

San Juan ◽

Accumulation Rates ◽

Fluvial System ◽

San Juan Basin ◽

Geomagnetic Polarity

Lower Paleocene deposits in the San Juan Basin document one of the best records of mammalian change and turnover following the Cretaceous-Paleogene extinctions and are the type section for the Puercan (Pu) and Torrejonian (To) North America Land Mammal age biozones (NALMA). One of the largest mammalian turnover events in the early Paleocene occurs between the Torrejonian 2 (To2) and Torrejonian 3 (To3) NALMA biozones. The Nacimiento Formation are the only deposits in North America where the To2-To3 mammalian turnover can be constrained, however the precise age and duration of the turnover is poorly understood due to the lack of a precise chronostratigraphic framework. We analyzed paleomagnetic samples, produced a 40Ar/39Ar detrital sanidine age, and developed a detailed lithostratigraphy for four sections of the upper Nacimiento Formation in the San Juan Basin, New Mexico (Kutz Canyon, Escavada Wash, Torreon West and East) to constrain the age and duration of the deposits and the To2-To3 turnover. The polarity stratigraphy for the four sections can be correlated to chrons C27r-C26r of the geomagnetic polarity time scale (GPTS). Using the local polarity stratigraphy for each section, we calculated a mean sediment accumulation rate and developed a precise age model, which allows us to determine the age of important late Torrejonian mammalian localities. Using the assigned ages, we estimate the To2-To3 turnover was relatively rapid and occurred over ~120 kyr (-60/+50 kyr) between 62.59 and 62.47 Ma. This rapid duration of the mammalian turnover suggests that it was driven by external forcing factors, such as environmental change driven by the progradation of the distributive fluvial system across the basin and/or changes in regional or global climate. Additionally, comparisons of the mean sediment accumulation rates between the sections that span from the basin margin to the basin center indicate that sediment accumulation rates equalized across the basin from the end of C27r through the start of C26r, suggesting an accommodation minima in the basin associated with the progradation of a distributive fluvial system into the basin. This accommodation minimum also likely led to the long hiatus of deposition between the Paleocene Nacimiento Formation and the overlying Eocene San Jose Formation.

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A 2700-year annual timescale and accumulation history for an ice core from Roosevelt Island, West Antarctica

10.5194/cp-2017-101 ◽

2017 ◽

Cited By ~ 8

Author(s):

Mai Winstrup ◽

Paul Vallelonga ◽

Helle A. Kjær ◽

Tyler J. Fudge ◽

James E. Lee ◽

...

Keyword(s):

Accumulation Rate ◽

Ice Core ◽

Early Period ◽

Volcanic Eruptions ◽

Snow Accumulation ◽

Atmospheric Methane ◽

Accumulation Rates ◽

West Antarctica ◽

Ross Ice Shelf ◽

Accumulation History

Abstract. We present a 2700-year annually resolved timescale for the Roosevelt Island Climate Evolution (RICE) ice core, and reconstruct a past snow accumulation history for the coastal sector of the Ross Ice Shelf in West Antarctica. The timescale was constructed by identifying annual layers in multiple ice-core impurity records, employing both manual and automated counting approaches, and constitutes the top part of the Roosevelt Island Ice Core Chronology 2017 (RICE17). The maritime setting of Roosevelt Island results in high sulfate influx from sea salts and marine biogenic emissions, which prohibits a routine detection of volcanic eruptions in the ice-core records. This led to the use of non-traditional chronological techniques for validating the timescale: RICE was synchronized to the WAIS Divide ice core, on the WD2014 timescale, using volcanic attribution based on direct measurements of ice-core acidity, as well as records of globally-synchronous, centennial-scale variability in atmospheric methane concentrations. The RICE accumulation history suggests stable values of 0.25 m water equivalent (w.e.) per year until around 1260 CE. Uncertainties in the correction for ice flow thinning of annual layers with depth do not allow a firm conclusion about long-term trends in accumulation rates during this early period but from 1260 CE to the present, accumulation rate trends have been consistently negative. The decrease in accumulation rates has been increasingly rapid over the last centuries, with the decrease since 1950 CE being more than 7 times greater than the average over the last 300 years. The current accumulation rate of 0.22 ± 0.06 m w.e. yr−1 (average since 1950 CE, ±1σ) is 1.49 standard deviations (86th percentile) below the mean of 50-year average accumulation rates observed over the last 2700 years.

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Svalbard reindeer (Rangifer tarandus platyrhynchus) antler characteristics reflecting the local environmental conditions

Folia Oecologica ◽

10.2478/foecol-2019-0003 ◽

2019 ◽

Vol 46 (1) ◽

pp. 16-23

Author(s):

Jan Kavan ◽

Veronika Anděrová

Keyword(s):

Environmental Conditions ◽

Rangifer Tarandus ◽

Well Being ◽

Climatic Conditions ◽

High Mountain ◽

Atmospheric Conditions ◽

Individual Subject ◽

Svalbard Reindeer ◽

Invasive Method ◽

Antler Size

AbstractA new non-invasive method based on picture analysis was used to estimate the conditions in Svalbard reindeer populations. The well-being of an individual subject is often expressed through visual indices. Two distinct reindeer populations were compared based on their antler parameters. Relative antler size and number of tines are variables supposed to reflect correspondingly the environmental conditions of sedentary populations within the growing season. The occurrence areas of two studied populations are distinctly isolated – separated with high mountain ridges, glaciers and fjords. The population in Petuniabukta occupies a sparsely vegetated region with harsh climatic conditions, whereas Skansbukta represents an area with continuous tundra vegetation cover, milder climatic conditions and, consequently, also a longer vegetation season. These environmental factors probably caused significant differences in the relative antler size and number of tines in the studied species. The Skansbukta population exhibited a larger relative antler size and higher number of tines than the population in Petuniabukta (both parameters differed significantly, p < 0.01). This difference reflects concisely the different environmental conditions of both locations. A comparison of Skansbukta population antler characteristics between years 2017 and 2018 did not reveal significant changes, most probably due to very similar atmospheric conditions in these two years (in terms of air temperature).

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Accumulation studies at specific sampling areas of the active floodplain in the Upper-Tisza region

Landscape & Environment ◽

10.21120/le/11/1/2 ◽

2017 ◽

Vol 11 (1) ◽

pp. 14-22

Author(s):

Gábor Molnár ◽

Andor Scholtz ◽

Róbert Vass

Keyword(s):

Surface Roughness ◽

Cross Sections ◽

Accumulation Rate ◽

Base Point ◽

Accumulation Rates ◽

Areal Distribution ◽

River Bed ◽

Rate Of Accumulation

In this paper the rate of accumulation was studied along four VO floodplain cross sections of the UpperTisza region between 1974 and 2014. VO floodplain cross sections are based on a mapping base-point grid (established in 1890), and they are located a few kilometers from each other. Furthermore, the roughness changes of different surface types, crossed by the VO floodplain cross-sections, were also determined between 1965 and 2015. The accumulation studies were extended to include the accumulation rates of the cut off meanders located along and/or close to the VO cross-sections. The roughness values increased in all four floodplain VO cross-sections since 1965; in two of them it reached or approximated 100 %. The average accumulation along the VO cross-sections was between 28 and 47 cm (0.73–1.23 cm/year) during the 38-year period. However, its areal distribution showed large differences. The highest values (169–309 cm, i.e. 4.44–8.13 cm/year) were found at the lowest points of the cut off meanders and swales in every case. The accumulation rate of the examined three cut off meanders near the floodplain cross-sections (140 and 1570 meters from the river bed) was lower (0.84–2.5 cm/year), but the study period was significantly longer (154 and 161 years, respectively). Comparing the values of the two periods, it is obvious that the accumulation of the active floodplain accelerates, presumably due to the significant increase of surface roughness.

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