Nitrogen fixation by associative cyanobacteria in the Canadian Arctic.
Atmospheric N\u2082-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 N\u2082-fixation must be better understood. Using acetylene...
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University of Northern British Columbia
2011
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ftunbcolumbiadc:oai:unbc.arcabc.ca:unbc_16350 2024-05-19T07:34:35+00:00 Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. Stewart, Katherine (Author) Coxson, Darwyn (Thesis advisor) University of Northern British Columbia (Degree granting institution) 2011 electronic Number of pages in document: 165 https://unbc.arcabc.ca/islandora/object/unbc:16350/datastream/PDF/download https://unbc.arcabc.ca/islandora/object/unbc%3A16350 https://doi.org/10.24124/2011/bpgub778 English eng University of Northern British Columbia Copyright retained by the author. http://rightsstatements.org/vocab/InC/1.0/ Nitrogen -- Fixation -- Canada Northern Cyanobacteria -- Canada QR89.7 .S74 2010 Text thesis 2011 ftunbcolumbiadc https://doi.org/10.24124/2011/bpgub778 2024-04-19T00:30:46Z Atmospheric N\u2082-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 N\u2082-fixation must be better understood. Using acetylene reduction assays we evaluated the spatial and temporal variation in N\u2082-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 N\u2082-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 N\u2082-fixation, inorganic soil N with surface greenhouse gas fluxes, including CO\u2082, N\u2082O and CH\u2084. Total growing season N\u2082-fixation input across a low arctic landscape was estimated at 0.68 kg ha\u207b~yr\u207b~, which is slightly less than twice the estimated average N input 0.39 kg ha\u207b~yr\u207b~ via precipitation. N\u2082-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 N\u2082-fixation rates at all sites. Shrubs had a negative effect on bryophyte abundance; competition from vascular plants, potentially through shading, may negatively influence N\u2082-fixation. Soil N status was linked to rates or N\u2082-fixation in both the high and low Arctic indicating that these N\u2082-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 NO\u2083-N availability does not appear to increase rates of denitrification. Loss of N through denitrification was not a significant ... Thesis Arctic Climate change UNBC's Digital Institutional Repository (University of Northern British Columbia) |
institution |
Open Polar |
collection |
UNBC's Digital Institutional Repository (University of Northern British Columbia) |
op_collection_id |
ftunbcolumbiadc |
language |
English |
topic |
Nitrogen -- Fixation -- Canada Northern Cyanobacteria -- Canada QR89.7 .S74 2010 |
spellingShingle |
Nitrogen -- Fixation -- Canada Northern Cyanobacteria -- Canada QR89.7 .S74 2010 Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. |
topic_facet |
Nitrogen -- Fixation -- Canada Northern Cyanobacteria -- Canada QR89.7 .S74 2010 |
description |
Atmospheric N\u2082-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 N\u2082-fixation must be better understood. Using acetylene reduction assays we evaluated the spatial and temporal variation in N\u2082-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 N\u2082-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 N\u2082-fixation, inorganic soil N with surface greenhouse gas fluxes, including CO\u2082, N\u2082O and CH\u2084. Total growing season N\u2082-fixation input across a low arctic landscape was estimated at 0.68 kg ha\u207b~yr\u207b~, which is slightly less than twice the estimated average N input 0.39 kg ha\u207b~yr\u207b~ via precipitation. N\u2082-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 N\u2082-fixation rates at all sites. Shrubs had a negative effect on bryophyte abundance; competition from vascular plants, potentially through shading, may negatively influence N\u2082-fixation. Soil N status was linked to rates or N\u2082-fixation in both the high and low Arctic indicating that these N\u2082-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 NO\u2083-N availability does not appear to increase rates of denitrification. Loss of N through denitrification was not a significant ... |
author2 |
Stewart, Katherine (Author) Coxson, Darwyn (Thesis advisor) University of Northern British Columbia (Degree granting institution) |
format |
Thesis |
title |
Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. |
title_short |
Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. |
title_full |
Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. |
title_fullStr |
Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. |
title_full_unstemmed |
Nitrogen fixation by associative cyanobacteria in the Canadian Arctic. |
title_sort |
nitrogen fixation by associative cyanobacteria in the canadian arctic. |
publisher |
University of Northern British Columbia |
publishDate |
2011 |
url |
https://unbc.arcabc.ca/islandora/object/unbc:16350/datastream/PDF/download https://unbc.arcabc.ca/islandora/object/unbc%3A16350 https://doi.org/10.24124/2011/bpgub778 |
genre |
Arctic Climate change |
genre_facet |
Arctic Climate change |
op_rights |
Copyright retained by the author. http://rightsstatements.org/vocab/InC/1.0/ |
op_doi |
https://doi.org/10.24124/2011/bpgub778 |
_version_ |
1799472696081252352 |