Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra
The effects of a 10-year climate warming experiment on nitrogen (N) cycling in high arctic tundra ecosystems were examined along a soil moisture gradient at Alexandra Fiord, Ellesmere Island, Canada (78°53'N, 75°55'W). Open top chambers were established in 1992 to passively warm five tundr...
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ftunivbritcolcir:oai:circle.library.ubc.ca:2429/14038 2023-05-15T13:15:26+02:00 Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra Rolph, Sandra Gale 2003 3891086 bytes application/pdf http://hdl.handle.net/2429/14038 eng eng For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. Text Thesis/Dissertation 2003 ftunivbritcolcir 2019-10-15T17:50:53Z The effects of a 10-year climate warming experiment on nitrogen (N) cycling in high arctic tundra ecosystems were examined along a soil moisture gradient at Alexandra Fiord, Ellesmere Island, Canada (78°53'N, 75°55'W). Open top chambers were established in 1992 to passively warm five tundra plant communities within the range predicted for a doubling of atmospheric CO₂. Inorganic N availability, measured using ion exchange membranes, was consistently higher in the warmed plots throughout the growing season in three plant communities. Soluble organic N availability increased significantly with warming in a wet sedge meadow. Net N mineralization in buried bag incubations was not significantly affected by the warming treatments; however, net N immobilization was four-times higher in the warmed plots compared to the controls in the sedge meadow. Reciprocal transplantation of buried bags between temperature treatments indicated that the increase in net N immobilization was a result of changes in soil properties during the nine-year experiment, in conjunction with continued temperature enhancement. Significant reductions in litter quality, measured as C:N ratios, were observed for woody and herbaceous growth forms in the warmed treatments at the end of the growing season. Reproductive parts had higher C:N than vegetative parts, and C:N increased with warming. Therefore, previously observed increases in reproductive effort with warming have likely reduced litter quality. Despite this potential for negative litter quality feedbacks to N availability with warming, soil organic matter was not significantly affected by the ninth year of the experiment. We hypothesize that the short-term changes in soil N transformations and increased N availability have contributed to the increases in plant growth observed in the warmed plots, and that shifts in the relative availabilities of NO₃, NH₄, and SON may have contributed to changes in the species composition of the tundra plant communities. However, this negative feedback to greenhouse warming may be strongly constrained by longer-term litter quality feedbacks to soil organic matter quality, and N availability in high arctic tundra ecosystems. Arts, Faculty of Geography, Department of Graduate Thesis Alexandra Fiord Arctic Ellesmere Island Tundra University of British Columbia: cIRcle - UBC's Information Repository Alexandra Fiord ENVELOPE(-75.797,-75.797,78.885,78.885) Arctic Canada Ellesmere Island |
institution |
Open Polar |
collection |
University of British Columbia: cIRcle - UBC's Information Repository |
op_collection_id |
ftunivbritcolcir |
language |
English |
description |
The effects of a 10-year climate warming experiment on nitrogen (N) cycling in high arctic tundra ecosystems were examined along a soil moisture gradient at Alexandra Fiord, Ellesmere Island, Canada (78°53'N, 75°55'W). Open top chambers were established in 1992 to passively warm five tundra plant communities within the range predicted for a doubling of atmospheric CO₂. Inorganic N availability, measured using ion exchange membranes, was consistently higher in the warmed plots throughout the growing season in three plant communities. Soluble organic N availability increased significantly with warming in a wet sedge meadow. Net N mineralization in buried bag incubations was not significantly affected by the warming treatments; however, net N immobilization was four-times higher in the warmed plots compared to the controls in the sedge meadow. Reciprocal transplantation of buried bags between temperature treatments indicated that the increase in net N immobilization was a result of changes in soil properties during the nine-year experiment, in conjunction with continued temperature enhancement. Significant reductions in litter quality, measured as C:N ratios, were observed for woody and herbaceous growth forms in the warmed treatments at the end of the growing season. Reproductive parts had higher C:N than vegetative parts, and C:N increased with warming. Therefore, previously observed increases in reproductive effort with warming have likely reduced litter quality. Despite this potential for negative litter quality feedbacks to N availability with warming, soil organic matter was not significantly affected by the ninth year of the experiment. We hypothesize that the short-term changes in soil N transformations and increased N availability have contributed to the increases in plant growth observed in the warmed plots, and that shifts in the relative availabilities of NO₃, NH₄, and SON may have contributed to changes in the species composition of the tundra plant communities. However, this negative feedback to greenhouse warming may be strongly constrained by longer-term litter quality feedbacks to soil organic matter quality, and N availability in high arctic tundra ecosystems. Arts, Faculty of Geography, Department of Graduate |
format |
Thesis |
author |
Rolph, Sandra Gale |
spellingShingle |
Rolph, Sandra Gale Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
author_facet |
Rolph, Sandra Gale |
author_sort |
Rolph, Sandra Gale |
title |
Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
title_short |
Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
title_full |
Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
title_fullStr |
Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
title_full_unstemmed |
Effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
title_sort |
effects of a ten-year climate warming experiment on nitrogen cycling in high arctic tundra |
publishDate |
2003 |
url |
http://hdl.handle.net/2429/14038 |
long_lat |
ENVELOPE(-75.797,-75.797,78.885,78.885) |
geographic |
Alexandra Fiord Arctic Canada Ellesmere Island |
geographic_facet |
Alexandra Fiord Arctic Canada Ellesmere Island |
genre |
Alexandra Fiord Arctic Ellesmere Island Tundra |
genre_facet |
Alexandra Fiord Arctic Ellesmere Island Tundra |
op_rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
_version_ |
1766268631949246464 |