Nitrogen Fixation By Associative Cyanobacteria In The Canadian Arctic PDF Download
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Author | : Katherine J. Stewart |
Publisher | : |
Total Pages | : 0 |
Release | : 2010 |
Genre | : Cyanobacteria |
ISBN | : |
Download Nitrogen Fixation by Associative Cyanobacteria in the Canadian Arctic Book in PDF, ePub and Kindle
"Atmospheric N2-fixation by cyanobacteria is a key source of newly fixed N in nutrient-poor arctic ecosystems. To further determine the causes of N limitation and predict long-term responses to climate change the controls of biological N2-fixation must be better understood. Using acetylene reduction assays we evaluated the spatial and temporal variation in N2-fixation by associative cyanobacteria in various ecosystem types in both the low and high Canadian Arctic. The direct and indirect effects of soil moisture, plant community functional composition, and bryophyte and lichen abundance on rates of N2-fixation were examined at sites varying in latitude and vegetation type. The linkages between N and C cycling processes in arctic systems were examined through paired measurements of N2-fixation, inorganic soil N with surface greenhouse gas fluxes, including CO2, N2O and CH4. Total growing season N2-fixation input across a low arctic landscape was estimated at 0.68 kg ha−1yr−1, which is slightly less than twice the estimated average N input 0.39 kg ha−1yr−1 via precipitation. N2-fixation by bryophyte-cyanobacterial associations appear to be very important across the Canadian Arctic. Increasing soil moisture was strongly associated with an increasing presence of bryophytes and increasing bryophyte abundance was a major factor determining higher N2-fixation rates at all sites. Shrubs had a negative effect on bryophyte abundance; competition from vascular plants, potentially through shading, may negatively influence N2-fixation. Soil N status was linked to rates or N2-fixation in both the high and low Arctic indicating that these N2-fixing associations act as important point sources of soil N. Higher rates of nitrification may be associated with warmer and drier vegetation types; however, increasing NO3-N availability does not appear to increase rates of denitrification. Loss of N through denitrification was not a significant factor in the N cycle at the high arctic sites examined. We found many factors control both the spatial and temporal variability of N2-fixation, including topography, microtopography, vegetation characteristics, microclimatic conditions, nifH abundance and availability of other nutrients, such as phosphorus. Moisture, however, appears to be a key factor not only in determining N2-fixation but also by influencing related nutrient cycling processes."--P. ii-iii.
Author | : Katherine Stewart |
Publisher | : |
Total Pages | : |
Release | : 2011 |
Genre | : |
ISBN | : |
Download Nitrogen Fixation by Associative Cyanobacteria in the Canadian Arctic Book in PDF, ePub and Kindle
Atmospheric N₂-fixation by cyanobacteria is a key source of newly fixed N in nutrient-poor arctic ecosystems. To further determine the causes of N limitation and predict long-term responses to climate change the controls of biological N₂-fixation must be better understood. Using acetylene reduction assays we evaluated the spatial and temporal variation in N₂-fixation by associative cyanobacteria in various ecosystem types in both the low and high Canadian Arctic. The direct and indirect effects of soil moisture, plant community functional composition, and bryophyte and lichen abundance on rates of N₂-fixation were examined at sites varying in latitude and vegetation type. The linkages between N and C cycling processes in arctic systems were examined through paired measurements of N₂-fixation, inorganic soil N with surface greenhouse gas fluxes, including CO₂, N₂O and CH₄. Total growing season N₂-fixation input across a low arctic landscape was estimated at 0.68 kg ha⁻~yr⁻~, which is slightly less than twice the estimated average N input 0.39 kg ha⁻~yr⁻~ via precipitation. N₂-fixation by bryophyte-cyanobacterial associations appear to be very important across the Canadian Arctic. Increasing soil moisture was strongly associated with an increasing presence of bryophytes and increasing bryophyte abundance was a major factor determining higher N₂-fixation rates at all sites. Shrubs had a negative effect on bryophyte abundance; competition from vascular plants, potentially through shading, may negatively influence N₂-fixation. Soil N status was linked to rates or N₂-fixation in both the high and low Arctic indicating that these N₂-fixing associations act as important point sources of soil N. Higher rates of nitrification may be associated with warmer and drier vegetation types; however, increasing NO₃-N availability does not appear to increase rates of denitrification. Loss of N through denitrification was not a significant factor in the N cycle at the high arctic sites examined. We found many factors control both the spatial and temporal variability of N₂-fixation, including topography, microtopography, vegetation characteristics, microclimatic conditions, nifH abundance and availability of other nutrients, such as phosphorus. Moisture, however, appears to be a key factor not only in determining N₂-fixation but also by influencing related nutrient cycling processes.
Author | : Turid Liengen |
Publisher | : |
Total Pages | : 131 |
Release | : 1997 |
Genre | : |
ISBN | : 9788257503024 |
Download Free-living Cyanobacteria and Their Nitrogen Fixation Activity in a High Arctic Environment Book in PDF, ePub and Kindle
Author | : T. BIRKEMOE |
Publisher | : |
Total Pages | : |
Release | : 2000 |
Genre | : |
ISBN | : |
Download Does collembolan grazing influence nitrogen fixation by cyanobacteria in the high Arctic? Book in PDF, ePub and Kindle
Author | : TILAK M |
Publisher | : |
Total Pages | : 203 |
Release | : 1996 |
Genre | : |
ISBN | : |
Download Role of Associative Cyanobacteria in Nitrogen Fixation by Azolla Book in PDF, ePub and Kindle
Author | : A.N. Rai |
Publisher | : Springer Science & Business Media |
Total Pages | : 357 |
Release | : 2007-05-08 |
Genre | : Science |
ISBN | : 0306480050 |
Download Cyanobacteria in Symbiosis Book in PDF, ePub and Kindle
Cyanobacterial symbioses are no longer regarded as mere oddities but as important components of the biosphere, occurring both in terrestrial and aquatic habitats worldwide. It is becoming apparent that they can enter into symbiosis with a wider variety of organisms than hitherto known, and there are many more still to be discovered, particularly in marine environments. The chapters cover cyanobacterial symbioses with plants (algae, bryophytes, Azolla, cycads, Gunnera), cyanobacterial symbioses in marine environments, lichens, Nostoc-Geosiphon (a fungus closely related to arbuscular mycorrhiza fungi) symbiosis, and artificial associations of cyanobacteria with economically important plants. In addition, cyanobiont diversity, sensing-signalling, and evolutionary aspects of the symbiosis are dealt with. Renowned experts actively involved in research on cyanobacterial symbioses deal with ecological, physiological, biochemical, molecular, and applied aspects of all known cyanobacterial symbioses. This volume on cyanobacteria in symbiosis complements the two earlier volumes on cyanobacteria published by Kluwer (Molecular Biology of Cyanobacteria, edited by D.A. Bryant and Ecology of Cyanobacteria, edited by B.A. Whitton and M. Potts). Together, the three volumes provide the most comprehensive treatment of cyanobacterial literature as a whole. The book will serve as a valuable reference work and text for teaching and research in the field of plant-microbe interactions and nitrogen fixation.
Author | : Danielle Alyce Griffith |
Publisher | : |
Total Pages | : 176 |
Release | : 2014 |
Genre | : |
ISBN | : |
Download Nitrogen Fixation by the Cyanobacterium Nostoc Punctiforme in Response to Variation in Nitrogen Availability, Temperature and Atmospheric CO2 Concentrations Book in PDF, ePub and Kindle
The predominant input of available nitrogen (N) in boreal forest ecosystems originates from moss-associated cyanobacteria, which fix unavailable atmospheric N2, contribute to the soil N pool, and thereby support forest productivity. Although increases in N availability, temperature, and atmospheric CO2 concentrations are expected in Canada's boreal region over the next century, little is known about the combined effects of these factors on N2 fixation by axenic cyanobacteria or the associated mechanisms. I assessed changes in N2 fixation by Nostoc punctiforme under different global environmental change scenarios and examined correlations between the response and changes in growth, heterocyst percentage, and heterocyst activity. With available N present, N. punctiforme did not perform N2 fixation or form heterocysts. Elevated CO2 stimulated growth and N2 fixation, but this result was influenced by a temperature-mediated growth cycle. Overall, my findings suggest a decrease in boreal N2 fixation rates in response to global environmental change.
Author | : Susanne Liebner |
Publisher | : Walter de Gruyter GmbH & Co KG |
Total Pages | : 285 |
Release | : 2021-01-18 |
Genre | : Science |
ISBN | : 3110497085 |
Download Microbial Life in the Cryosphere and Its Feedback on Global Change Book in PDF, ePub and Kindle
The cryosphere stands for environments where water appears in a frozen form. It includes permafrost, glaciers, ice sheets, and sea ice and is currently more affected by Global Change than most other regions of the Earth. In the cryosphere, limited water availability and subzero temperatures cause extreme conditions for all kind of life which microorganisms can cope with extremely well. The cryosphere’s microbiota displays an unexpectedly large genetic potential, and taxonomic as well as functional diversity which, however, we still only begin to map. Also, microbial communities influence reaction patterns of the cryosphere towards Global Change. Altered patterns of seasonal temperature fluctuations and precipitation are expected in the Arctic and will affect the microbial turnover of soil organic matter (SOM). Activation of nutrients by thawing and increased active layer thickness as well as erosion renders nutrient stocks accessible to microbial activities. Also, glacier melt and retreat stimulate microbial life in turn influencing albedo and surface temperatures. In this context, the functional resilience of microbial communities in the cryosphere is of major interest. Particularly important is the ability of microorganisms and microbial communities to respond to changes in their surroundings by intracellular regulation and population shifts within functional niches, respectively. Research on microbial life exposed to permanent freeze or seasonal freeze-thaw cycles has led to astonishing findings about microbial versatility, adaptation, and diversity. Microorganisms thrive in cold habitats and new sequencing techniques have produced large amounts of genomic, metagenomic, and metatranscriptomic data that allow insights into the fascinating microbial ecology and physiology at low and subzero temperatures. Moreover, some of the frozen ecosystems such as permafrost constitute major global carbon and nitrogen storages, but can also act as sources of the greenhouse gases methane and nitrous oxide. In this book we summarize state of the art knowledge on whether environmental changes are met by a flexible microbial community retaining its function, or if the altered conditions also render the community in a state of altered properties that affect the Earth’s element cycles and climate. This book brings together research on the cryosphere’s microbiota including permafrost, glaciers, and sea ice in Arctic and Antarctic regions. Different spatial scales and levels of complexity are considered, spanning from ecosystem level to pure culture studies of model microbes in the laboratory. It aims to attract a wide range of parties with interest in the effect of climate change and/or low temperatures on microbial nutrient cycling and physiology.
Author | : Brian A. Whitton |
Publisher | : Springer Science & Business Media |
Total Pages | : 753 |
Release | : 2012-07-05 |
Genre | : Science |
ISBN | : 9400738552 |
Download Ecology of Cyanobacteria II Book in PDF, ePub and Kindle
Cyanobacteria have existed for 3.5 billion years, yet they are still the most important photosynthetic organisms on the planet for cycling carbon and nitrogen. The ecosystems where they have key roles range from the warmer oceans to many Antarctic sites. They also include dense nuisance growths in nutrient-rich lakes and nitrogen-fixers which aid the fertility of rice-fields and many soils, especially the biological soil crusts of arid regions. Molecular biology has in recent years provided major advances in our understanding of cyanobacterial ecology. Perhaps for more than any other group of organisms, it is possible to see how the ecology, physiology, biochemistry, ultrastructure and molecular biology interact. This all helps to deal with practical problems such as the control of nuisance blooms and the use of cyanobacterial inocula to manage semi-desert soils. Large-scale culture of several organisms, especially "Spirulina" (Arthrospira), for health food and specialist products is increasingly being expanded for a much wider range of uses. In view of their probable contribution to past oil deposits, much attention is currently focused on their potential as a source of biofuel. Please visit http://extras.springer.com/ to view Extra Materials belonging to this volume. This book complements the highly successful Ecology of Cyanobacteria and integrates the discoveries of the past twelve years with the older literature.
Author | : Canada. Environment Canada |
Publisher | : |
Total Pages | : |
Release | : 1976 |
Genre | : |
ISBN | : |
Download Nitrogen Fixation in Arctic Marine Sediments Book in PDF, ePub and Kindle