Relationship between testate amoebae (Protozoa: Rhizopoda) and microenvironmental parameters on a forested peatland in northeastern Ontario

1992 ◽  
Vol 70 (12) ◽  
pp. 2474-2482 ◽  
Author(s):  
D. J. Charman ◽  
B. G. Warner
Keyword(s):  
Transfer Functions ◽  
Vegetation Type ◽  
Environmental Parameters ◽  
Testate Amoebae ◽  
Species Assemblages ◽  
Individual Species ◽  
Moss Species ◽  
Wide Range ◽  
Moisture Conditions ◽  
Forested Peatland

The relative abundance of species of testate amoebae (Testacea; Rhizopoda) was established from 107 surface moss samples from a forested peatland in northeastern Ontario. These were related by multivariate analysis to a number of microenvironmental conditions including soil moisture content, water table, bulk density, humification, dominant peat component, pH, peat depth, depth of living moss, dominant surface moss species, vegetation type, microtopographical position, and artificial drainage. Moisture conditions play a key role in determining the species assemblages, pH being a secondary factor. Other environmental parameters related to species assemblages do not necessarily indicate a direct ecological link but are also associated with moisture and nutrient conditions. Individual species are ranked in terms of their preferred moisture conditions and compared with data from Finland. Certain species are restricted to either dry or wet conditions while others tolerate a wide range of moisture. Calculating weighted averages of substrate moisture contents for a greater range of species sampled from a larger number of sites will allow the development of transfer functions for constructing palaeomoisture curves from peatlands.

Testate amoebae as non-pollen palynomorphs in pollen slides: Usefulness and application in palaeoenvironmental reconstruction

2020 ◽  
pp. SP511-2020-34
Author(s):  
L. O. Andrews ◽  
R. J. Payne ◽  
G. T. Swindles
Keyword(s):  
Water Table ◽  
Transfer Functions ◽  
Testate Amoebae ◽  
Water Table Depth ◽  
Qualitative Assessment ◽  
Distribution Data ◽  
Preparation Methods ◽  
Chemical Treatments ◽  
Wide Range ◽  
Qualitative Changes

AbstractTestate amoebae are a frequently used palaeoecological proxy for reconstructing changes in palaeohydrological conditions, particularly in studies of Sphagnum-dominated peatlands. Their use in palaeoecological studies has increased following the development of transfer functions, allowing for the quantitative reconstruction of water-table depth changes through time. Increasingly, they are included in non-pollen palynomorph (NPP) studies alongside a wide range of other proxies, representing a valuable tool, particularly in multi-proxy studies.Testate amoebae have been used for qualitative assessment of palaeohydrology in NPP studies and may aid the verification of environmental interpretations of conditions inferred from curves of NPP with unknown ecology and taxonomy. Their usefulness in such studies is limited by the destruction of tests owing to harsh chemical treatments used in pollen preparation methods. This makes community distribution data of testate amoebae derived by these methods largely unsuitable for quantitative assessment of water-table depth. Furthermore, many palynological studies combine testate amoebae as one single curve, losing further ecological detail. Patterns of change of surviving species, most commonly of Assulina, Archerella, Arcella, Hyalosphenia and Archerella flavum, remain relatively unaffected and therefore can still be useful for interpreting qualitative changes in hydrological conditions through time, particularly when coupled with other proxies.

Extreme Response of Floating Structures in Combined Wind and Waves

2003 ◽  
Vol 125 (2) ◽  
pp. 87-93 ◽  
Author(s):  
P. Teigen ◽  
A. Naess
Keyword(s):  
Numerical Solutions ◽  
Transfer Functions ◽  
Low Frequency ◽  
Water Structure ◽  
Environmental Parameters ◽  
Wave Loads ◽  
Stochastic Loading ◽  
Wide Range ◽  
Extreme Response ◽  
Load Effects

The paper highlights the problem of evaluating the extreme surge response of a floating, deep water structure subjected to stochastic loading from concurrent wind and waves. Additional load effects associated with ocean currents are also briefly discussed. Both long-crested and short-crested waves are considered, whereas the wind field is assumed to be unidirectional. The probability density function (PDF) of the combined wave frequency and low frequency response of the structure, due to waves, is calculated by an eigenvalue analysis and convoluted with the corresponding PDF from the wind loads, to obtain the PDF of the global response. The necessity of employing full, biquadratic transfer functions to evaluate the low frequency part of the wave loads is amply documented. The effect of short-crested versus unidirectional seas on the TLP motion response is discussed at some length, along with various numerical aspects related to the mathematical modelling and to the convergence and accuracy of the obtained solutions. Numerical solutions are presented for a wide range of harsh weather type, environmental parameters.

scholarly journals CREST: Climate REconstruction SofTware

2014 ◽  
Vol 10 (1) ◽  
pp. 625-663 ◽  
Author(s):  
M. Chevalier ◽  
R. Cheddadi ◽  
B. M. Chase
Keyword(s):  
Likelihood Function ◽  
Vegetation Type ◽  
Climate Reconstruction ◽  
Climatic Variables ◽  
Taxonomic Resolution ◽  
Individual Species ◽  
Pollen Data ◽  
Pollen Type ◽  
Wide Range ◽  
Reconstruction Software

Abstract. Several methods currently exist to quantitatively reconstruct palaeoclimatic variables from fossil botanical data. Of these, pdf-based (probability density functions) methods have proven valuable as they can be applied to a wide range of plants assemblages. Most commonly applied to fossil pollen data, their performance, however, can be limited by the taxonomic resolution of the pollen data, as many species may belong to a given pollen-type. Consequently, the climate information associated with different species cannot sometimes not be precisely identified, resulting less accurate reconstructions. This can become particularly problematic in regions of high biodiversity. In this paper, we propose a novel pdf-based method that takes into account the different climatic requirements of each species constituting the broader pollen-type. Pdfs are fitted in two successive steps, with parametric pdfs fitted first for each species, and then a combination of those individual species pdfs into a broader single pdf to represent the pollen-type as a unit. A climate value for the pollen assemblage is estimated from the likelihood function obtained after the multiplication of the pollen-type pdfs, with each being weighted according to its pollen percentage. To test the robustness of the method, we have applied the method to southern Africa as a regional case study, and reconstructed a suite of climatic variables based on extensive botanical data derived from herbarium collections. The reconstructions proved to be accurate for both temperature and precipitation. Predictable exceptions were areas that experience conditions at the extremes of the regional climatic spectra. Importantly, the accuracy of the reconstructed values is independent from the vegetation type where the method is applied or the number of species used. The method used in this study is publicly available in a software package entitled CREST (Climate REconstruction SofTware) and will provide the opportunity to reconstruct reliable quantitative estimates of climatic variables even in areas with high geographical and botanical diversity.

Factors affecting red-osier dogwood seed germination

1992 ◽  
Vol 70 (5) ◽  
pp. 1012-1016 ◽  
Author(s):  
S. N. Acharya ◽  
C. B. Chu ◽  
R. Hermesh ◽  
G. B. Schaalje
Keyword(s):  
Seed Germination ◽  
Germination Percentage ◽  
Collection Site ◽  
Moisture Condition ◽  
Seed Formation ◽  
Factors Affecting ◽  
Year Effect ◽  
Wide Range ◽  
Cornus Stolonifera ◽  
Moisture Conditions

Seeds from 55 populations of native Alberta red-osier dogwood (Cornus stolonifera Michx.) were collected over 2 years (1984 and 1985) to determine the range of variability for seed germination and the effect of ecoregion and moisture conditions in the collection sites on this trait. Each year the unscarified seeds were stored at 3 °C for 30 days, stratified at 3 °C for an additional 30 days and then incubated on an 8 h light: 16 h dark cycle at a temperature of 25:10 °C (light:dark) for germination. A wide range of germination percentages was observed among populations collected in any 1 year. However, the variability was not due to the ecoregion or moisture condition of the collection site. Germination percentage of populations collected in 1984 and 1985 formed five and seven groups, respectively. A study involving eight sites that were common to 1984, 1985, and 1986 revealed a significant effect of population on seed germination. This population effect was not obscured by the combined effects of year, precipitation, temperature, and seed size. The year effect was significant only when population was used as a covariate. Precipitation during seed formation significantly influenced germination performance even after adjustments were made for population and year. Seed germination in red-osier dogwood appears to be influenced by the population from which the seeds are collected and by yearly environmental fluctuations. Therefore, germination studies in this species must include seeds from diverse populations collected over several years. Key words: red-osier dogwood, Cornus stolonifera Michx., germination, population, environment.

scholarly journals Ecology of peatland testate amoebae in Svalbard and the development of transfer functions for reconstructing past water-table depth and pH

2021 ◽  
Vol 131 ◽  
pp. 108122
Author(s):  
Thomas G. Sim ◽  
Graeme T. Swindles ◽  
Paul J. Morris ◽  
Andy J. Baird ◽  
Dan J. Charman ◽  
...  
Keyword(s):  
Water Table ◽  
Transfer Functions ◽  
Testate Amoebae ◽  
Water Table Depth

scholarly journals DISTRIBUTION OF BRYOPHYTES OF AGALYK BASIN (KARATEPA MOUNTAINS OF ZERAVSHAN MOUNTAIN RANGE)

2015 ◽  
Vol 4 (2) ◽  
pp. 80-82
Author(s):  
Holmurod Akimovich Zhalov
Keyword(s):  
Species Composition ◽  
Point Of View ◽  
Mountain Range ◽  
Decayed Wood ◽  
Moss Species ◽  
Comparative Analyses ◽  
Wide Range ◽  
Identification Of Species ◽  
Characteristic Features ◽  
Research Period

From bryological point of view Zeravshan mountain range remains one of the least studied region. Identification of species composition of true mosses and their ecological-biological peculiarities were not earlier aimed for this region. In the territory of Agalyk basin Karatepa mountains can be divided into four types of substrates where moss species occur: soil, bark of living trees, decayed wood, stones. Characteristics of substrate groups become complicated due to wide range of ecological valency of moss species. Most species select not only one, but several substrates for their settling. During the research period in the soils of Agaliksay basin 20 species were recorded belonging to 13 genera and 10 family. On decayed wood 9 species were recorded belonging to 7 genera and 5 family. On the bark of living trees 15 moss species were recorded belonging to 8 genera and 6 family. Epilyte bryophytes occurred on rocky substrates. On rocky substrates of Agaliksay basin 34 moss species were recorded from 16 genera and 13 family. On the basis of results obtained during the study of substrate groups of mosses in Agaliksay basin, we have conducted comparative analyses of studied substrate groups with the purpose of determining their characteristic features.

scholarly journals Mapping Asian anthropogenic emissions of non-methane volatile organic compounds to multiple chemical mechanisms

2013 ◽  
Vol 13 (12) ◽  
pp. 32649-32701 ◽  
Author(s):  
M. Li ◽  
Q. Zhang ◽  
D. G. Streets ◽  
K. B. He ◽  
Y. F. Cheng ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Individual Species ◽  
Chemical Mechanisms ◽  
Mixing Ratios ◽  
Wide Range ◽  
Oxygenated Volatile Organic Compounds ◽  
Volatile Organic ◽  
Species Mapping ◽  
Multiple Chemical

Abstract. An accurate speciation mapping of non-methane volatile organic compounds (NMVOC) emissions has an important impact on the performance of chemical transport models (CTMs) in simulating ozone mixing ratios and secondary organic aerosols. In this work, we developed an improved speciation framework to generate model-ready anthropogenic Asian NMVOC emissions for various gas-phase chemical mechanisms commonly used in CTMs by using an explicit assignment approach and updated NMVOC profiles, based on the total NMVOC emissions in the INTEX-B Asian inventory for the year 2006. NMVOC profiles were selected and aggregated from a wide range of new measurements and the SPECIATE database. To reduce potential uncertainty from individual measurements, composite profiles were developed by grouping and averaging source profiles from the same category. The fractions of oxygenated volatile organic compounds (OVOC) were corrected during the compositing process for those profiles which used improper sampling and analyzing methods. Emissions of individual species were then lumped into species in different chemical mechanisms used in CTMs by applying mechanism-dependent species mapping tables, which overcomes the weakness of inaccurate mapping in previous studies. Gridded emissions for eight chemical mechanisms are developed at 30 min × 30 min resolution using various spatial proxies and are provided through the website: http://mic.greenresource.cn/intex-b2006. Emission estimates for individual NMVOC species differ between one and three orders of magnitude for some species when different sets of profiles are used, indicating that source profile is the most important source of uncertainties of individual species emissions. However, those differences are diminished in lumped species as a result of the lumping in the chemical mechanisms.

scholarly journals Effect of Temperature and Moisture Period on Infection of Rhododendron ‘Cunningham's White’ by Phytophthora ramorum

2009 ◽  
Vol 99 (9) ◽  
pp. 1045-1052 ◽  
Author(s):  
Paul W. Tooley ◽  
Marsha Browning ◽  
Kerrie L. Kyde ◽  
Dana Berner
Keyword(s):  
The United States ◽  
Phytophthora Ramorum ◽  
Effect Of Temperature ◽  
Optimum Temperature ◽  
Detached Leaf ◽  
Wide Range ◽  
Effects Of Temperature ◽  
Gradient Plate ◽  
Whole Plants ◽  
Moisture Conditions

We investigated the temperature and moisture conditions that allow Phytophthora ramorum to infect Rhododendron ‘Cunningham's White’. Most experiments were performed with a single P. ramorum isolate from the NA1 clonal lineage. For whole plants incubated in dew chambers at 10 to 31°C, the greatest proportion of diseased leaves, 77.5%, occurred at the optimum temperature of 20.5°C. Disease occurred over the entire range of temperatures tested, although amounts of disease were minor at the temperature extremes. For whole plants exposed to varying dew periods at 20°C and then incubated at 20°C for 7 days, a dew period as short as 1 h resulted in a small amount of disease; however, at least 4 h of dew were required for >10% of the leaves to become diseased. Moisture periods of 24 and 48 h resulted in the greatest number of diseased leaves. In detached-leaf, temperature-gradient-plate experiments, incubation at 22°C resulted in the greatest disease severity, followed by 18°C and then 14°C. In detached-leaf, moisture-tent experiments, a 1-h moisture period was sufficient to cause disease on 67 to 73% of leaves incubated for 7 days at 20°C. A statistical model for disease development that combined the effects of temperature and moisture period was generated using nonlinear regression. Our results define temperature and moisture conditions which allow infection by P. ramorum on Cunningham's White rhododendron, and show that P. ramorum is able to infect this host over a wide range of temperatures and moisture levels. The results indicate that P. ramorum has the potential to become established in parts of the United States that are outside its current range.

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