Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic
The literature of disturbance ecology reveals that, under present climatic conditions, non-native plants have little or no role in high arctic tundra revegetation. Rather, it has been suggested that indigenous flora, especially long-lived perennial graminoids, are crucial to recovery. However, few l...
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Format: | Thesis |
Language: | English |
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McGill University
1993
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Online Access: | http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196 |
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ftcanadathes:oai:collectionscanada.gc.ca:QMM.41196 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
Theses Canada/Thèses Canada (Library and Archives Canada) |
op_collection_id |
ftcanadathes |
language |
English |
topic |
Tundra plants -- Ecology -- Canada Northern Plant succession -- Canada Vegetation dynamics -- Canada Revegetation -- Canada |
spellingShingle |
Tundra plants -- Ecology -- Canada Northern Plant succession -- Canada Vegetation dynamics -- Canada Revegetation -- Canada Forbes, Bruce Cameron Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic |
topic_facet |
Tundra plants -- Ecology -- Canada Northern Plant succession -- Canada Vegetation dynamics -- Canada Revegetation -- Canada |
description |
The literature of disturbance ecology reveals that, under present climatic conditions, non-native plants have little or no role in high arctic tundra revegetation. Rather, it has been suggested that indigenous flora, especially long-lived perennial graminoids, are crucial to recovery. However, few long-term data are available on past impacts within productive sedge-meadows in the High Arctic, and none which consider the non-vascular flora. This thesis combines biogeographical and patch dynamics perspectives to focus on $ geq$21 yr of natural and assisted recovery of vegetation and soils from a wide range of dated anthropogenic surface disturbances at three Canadian Arctic sites. Empirical, experimental and archival investigations were made among climatically similar, but widely disjunct, coastal lowlands of contrasting geologies on Baffin, Devon, and Cornwallis Islands. These data encompass minerotrophic and oligotrophic wetlands in which the vascular floras show minimal differentiation yet the sampled bryofloras share only 31.8% of their total taxa. The occurrences chosen for study are representative of the most widespread, small-scale human impacts in the North, including vehicular, pedestrian, construction, and pollution disturbances. It was determined that rutting from even a single passage of a tracked vehicle in summer resulted in significant reductions in species richness and biomass. On slopes $ geq$2$ sp circ$, these same small ruts have drained large areas of peatlands, a serious cumulative impact. Long-term effects of drainage include the local extinction of populations of Sphagnum spp. and rhizomatous vascular aquatics, and changes in the chemistry and thermal regime of drained mineral soils. Other effects include significant changes in biomass and the concentrations of macronutrients in the leaves of dominant species. These effects were magnified in peatlands drained where multi-pass vehicle movements occurred. Species richness displayed an inverse relationship with trampling intensity and the soils of heavily trampled ground remained severely compacted after 21 years. These patches were dominated by dense swards of ruderal grasses. Nutrient concentrations in the leaves of the latter and other colonizing and surviving species tended to increase with trampling intensity. Trampled patches and archaeological sites appeared selectively grazed by several herbivores. Although humans initiated the disturbances within these patches, it is the animals which are responsible for many of the dynamics of patch change over the long-term. Classification and ordination procedures revealed linkages between the floristic associations of trampled meadows on Baffin Island and archaeological sites on Devon and Cornwallis Islands. One critical implication is that even low levels of human impact may give rise to ruderal plant communities which are extremely persistent. These patches are poor in terms of species richness, but contribute to habitat heterogeneity at the landscape level and comprise preferred forage for local vertebrate herbivores. Archaeological excavation and restoration revealed that at least some stores of viable seed exist in both mesic and wet tundra soils and point to the importance of initial floristic composition (sensu Egler 1954). From a long-term perspective, the data establish that mesic tundra vegetation and soils are easily disturbed and recover much more slowly than their low arctic counterparts under similar disturbance regimes. |
author2 |
Wenzel, George W. (advisor) |
format |
Thesis |
author |
Forbes, Bruce Cameron |
author_facet |
Forbes, Bruce Cameron |
author_sort |
Forbes, Bruce Cameron |
title |
Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic |
title_short |
Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic |
title_full |
Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic |
title_fullStr |
Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic |
title_full_unstemmed |
Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic |
title_sort |
anthropogenic tundra disturbance and patterns of response in the eastern canadian arctic |
publisher |
McGill University |
publishDate |
1993 |
url |
http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196 |
op_coverage |
Doctor of Philosophy (Department of Geography.) |
long_lat |
ENVELOPE(-54.464,-54.464,-61.072,-61.072) |
geographic |
Arctic Baffin Island Canada Cornwallis |
geographic_facet |
Arctic Baffin Island Canada Cornwallis |
genre |
Arctic Baffin Island Baffin Tundra |
genre_facet |
Arctic Baffin Island Baffin Tundra |
op_relation |
alephsysno: 001341730 proquestno: NN87977 Theses scanned by UMI/ProQuest. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196 |
op_rights |
All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
_version_ |
1766328657575411712 |
spelling |
ftcanadathes:oai:collectionscanada.gc.ca:QMM.41196 2023-05-15T14:56:34+02:00 Anthropogenic tundra disturbance and patterns of response in the eastern Canadian Arctic Forbes, Bruce Cameron Wenzel, George W. (advisor) Doctor of Philosophy (Department of Geography.) 1993 application/pdf http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196 en eng McGill University alephsysno: 001341730 proquestno: NN87977 Theses scanned by UMI/ProQuest. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41196 All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. Tundra plants -- Ecology -- Canada Northern Plant succession -- Canada Vegetation dynamics -- Canada Revegetation -- Canada Electronic Thesis or Dissertation 1993 ftcanadathes 2014-02-16T01:06:57Z The literature of disturbance ecology reveals that, under present climatic conditions, non-native plants have little or no role in high arctic tundra revegetation. Rather, it has been suggested that indigenous flora, especially long-lived perennial graminoids, are crucial to recovery. However, few long-term data are available on past impacts within productive sedge-meadows in the High Arctic, and none which consider the non-vascular flora. This thesis combines biogeographical and patch dynamics perspectives to focus on $ geq$21 yr of natural and assisted recovery of vegetation and soils from a wide range of dated anthropogenic surface disturbances at three Canadian Arctic sites. Empirical, experimental and archival investigations were made among climatically similar, but widely disjunct, coastal lowlands of contrasting geologies on Baffin, Devon, and Cornwallis Islands. These data encompass minerotrophic and oligotrophic wetlands in which the vascular floras show minimal differentiation yet the sampled bryofloras share only 31.8% of their total taxa. The occurrences chosen for study are representative of the most widespread, small-scale human impacts in the North, including vehicular, pedestrian, construction, and pollution disturbances. It was determined that rutting from even a single passage of a tracked vehicle in summer resulted in significant reductions in species richness and biomass. On slopes $ geq$2$ sp circ$, these same small ruts have drained large areas of peatlands, a serious cumulative impact. Long-term effects of drainage include the local extinction of populations of Sphagnum spp. and rhizomatous vascular aquatics, and changes in the chemistry and thermal regime of drained mineral soils. Other effects include significant changes in biomass and the concentrations of macronutrients in the leaves of dominant species. These effects were magnified in peatlands drained where multi-pass vehicle movements occurred. Species richness displayed an inverse relationship with trampling intensity and the soils of heavily trampled ground remained severely compacted after 21 years. These patches were dominated by dense swards of ruderal grasses. Nutrient concentrations in the leaves of the latter and other colonizing and surviving species tended to increase with trampling intensity. Trampled patches and archaeological sites appeared selectively grazed by several herbivores. Although humans initiated the disturbances within these patches, it is the animals which are responsible for many of the dynamics of patch change over the long-term. Classification and ordination procedures revealed linkages between the floristic associations of trampled meadows on Baffin Island and archaeological sites on Devon and Cornwallis Islands. One critical implication is that even low levels of human impact may give rise to ruderal plant communities which are extremely persistent. These patches are poor in terms of species richness, but contribute to habitat heterogeneity at the landscape level and comprise preferred forage for local vertebrate herbivores. Archaeological excavation and restoration revealed that at least some stores of viable seed exist in both mesic and wet tundra soils and point to the importance of initial floristic composition (sensu Egler 1954). From a long-term perspective, the data establish that mesic tundra vegetation and soils are easily disturbed and recover much more slowly than their low arctic counterparts under similar disturbance regimes. Thesis Arctic Baffin Island Baffin Tundra Theses Canada/Thèses Canada (Library and Archives Canada) Arctic Baffin Island Canada Cornwallis ENVELOPE(-54.464,-54.464,-61.072,-61.072) |