Landscape variability of vegetation change across the forest to tundra transition of central Canada
Widespread vegetation productivity increases in tundra ecosystems and stagnation, or even productivity decreases, in boreal forest ecosystems have been detected from coarse-scale remote sensing observations over the last few decades. However, finer-scale Landsat studies have shown that these changes...
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ftqueensuniv:oai:https://qspace.library.queensu.ca:1974/22675 2024-06-02T08:01:29+00:00 Landscape variability of vegetation change across the forest to tundra transition of central Canada Bonney, Mitchell Geography and Planning Treitz, Paul Danby, Ryan 2017-09-09T21:48:27Z application/pdf http://hdl.handle.net/1974/22675 eng eng Canadian theses http://hdl.handle.net/1974/22675 Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada ProQuest PhD and Master's Theses International Dissemination Agreement Intellectual Property Guidelines at Queen's University Copying and Preserving Your Thesis This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. NDVI Landsat Treeline Canada Vegetation productivity Random Forest Boreal forest Tundra Bulk vegetation volume Greening Arctic Northwest Territories Landscape variability Forest-tundra ecotone Time-series Remote sensing thesis 2017 ftqueensuniv 2024-05-06T10:47:32Z Widespread vegetation productivity increases in tundra ecosystems and stagnation, or even productivity decreases, in boreal forest ecosystems have been detected from coarse-scale remote sensing observations over the last few decades. However, finer-scale Landsat studies have shown that these changes are heterogeneous and may be related to landscape and regional variability in climate, land cover, topography and moisture. In this study, a Landsat Normalized Difference Vegetation Index (NDVI) time-series (1984-2016) was examined for a study area spanning the entirety of the sub-Arctic boreal forest to Low Arctic tundra transition of central Canada (i.e., Yellowknife to the Arctic Ocean). NDVI trend analysis indicated that 27 % of un-masked pixels in the study area exhibited a significant (p < 0.05) trend and virtually all (99.3 %) of those pixels were greening. Greening pixels were most common in the northern tundra zone and the southern forest-tundra ecotone zone. NDVI trends were positive throughout the study area, but were smallest in the forest zone and largest in the northern tundra zone. These results were supported by ground validation, which found a strong relationship (R2 = 0.81) between bulk vegetation volume (BVV) and NDVI for non-tree functional groups in the North Slave region of Northwest Territories. Field observations indicate that alder (Alnus spp.) shrublands and open woodland sites with shrubby understories were most likely to exhibit greening in that area. Random Forest (RF) modelling of the relationship between NDVI trends and environmental variables found that the magnitude and direction of trends differed across the forest to tundra transition. Increased summer temperatures, shrubland and forest land cover, closer proximity to major drainage systems, longer distances from major lakes and lower elevations were generally more important and associated with larger positive NDVI trends. These findings indicate that the largest positive NDVI trends were primarily associated with the increased ... Thesis Arctic Arctic Ocean Northwest Territories Tundra Yellowknife Queen's University, Ontario: QSpace Arctic Arctic Ocean Northwest Territories Yellowknife Canada North Slave Region ENVELOPE(-116.043,-116.043,62.802,62.802) |
institution |
Open Polar |
collection |
Queen's University, Ontario: QSpace |
op_collection_id |
ftqueensuniv |
language |
English |
topic |
NDVI Landsat Treeline Canada Vegetation productivity Random Forest Boreal forest Tundra Bulk vegetation volume Greening Arctic Northwest Territories Landscape variability Forest-tundra ecotone Time-series Remote sensing |
spellingShingle |
NDVI Landsat Treeline Canada Vegetation productivity Random Forest Boreal forest Tundra Bulk vegetation volume Greening Arctic Northwest Territories Landscape variability Forest-tundra ecotone Time-series Remote sensing Bonney, Mitchell Landscape variability of vegetation change across the forest to tundra transition of central Canada |
topic_facet |
NDVI Landsat Treeline Canada Vegetation productivity Random Forest Boreal forest Tundra Bulk vegetation volume Greening Arctic Northwest Territories Landscape variability Forest-tundra ecotone Time-series Remote sensing |
description |
Widespread vegetation productivity increases in tundra ecosystems and stagnation, or even productivity decreases, in boreal forest ecosystems have been detected from coarse-scale remote sensing observations over the last few decades. However, finer-scale Landsat studies have shown that these changes are heterogeneous and may be related to landscape and regional variability in climate, land cover, topography and moisture. In this study, a Landsat Normalized Difference Vegetation Index (NDVI) time-series (1984-2016) was examined for a study area spanning the entirety of the sub-Arctic boreal forest to Low Arctic tundra transition of central Canada (i.e., Yellowknife to the Arctic Ocean). NDVI trend analysis indicated that 27 % of un-masked pixels in the study area exhibited a significant (p < 0.05) trend and virtually all (99.3 %) of those pixels were greening. Greening pixels were most common in the northern tundra zone and the southern forest-tundra ecotone zone. NDVI trends were positive throughout the study area, but were smallest in the forest zone and largest in the northern tundra zone. These results were supported by ground validation, which found a strong relationship (R2 = 0.81) between bulk vegetation volume (BVV) and NDVI for non-tree functional groups in the North Slave region of Northwest Territories. Field observations indicate that alder (Alnus spp.) shrublands and open woodland sites with shrubby understories were most likely to exhibit greening in that area. Random Forest (RF) modelling of the relationship between NDVI trends and environmental variables found that the magnitude and direction of trends differed across the forest to tundra transition. Increased summer temperatures, shrubland and forest land cover, closer proximity to major drainage systems, longer distances from major lakes and lower elevations were generally more important and associated with larger positive NDVI trends. These findings indicate that the largest positive NDVI trends were primarily associated with the increased ... |
author2 |
Geography and Planning Treitz, Paul Danby, Ryan |
format |
Thesis |
author |
Bonney, Mitchell |
author_facet |
Bonney, Mitchell |
author_sort |
Bonney, Mitchell |
title |
Landscape variability of vegetation change across the forest to tundra transition of central Canada |
title_short |
Landscape variability of vegetation change across the forest to tundra transition of central Canada |
title_full |
Landscape variability of vegetation change across the forest to tundra transition of central Canada |
title_fullStr |
Landscape variability of vegetation change across the forest to tundra transition of central Canada |
title_full_unstemmed |
Landscape variability of vegetation change across the forest to tundra transition of central Canada |
title_sort |
landscape variability of vegetation change across the forest to tundra transition of central canada |
publishDate |
2017 |
url |
http://hdl.handle.net/1974/22675 |
long_lat |
ENVELOPE(-116.043,-116.043,62.802,62.802) |
geographic |
Arctic Arctic Ocean Northwest Territories Yellowknife Canada North Slave Region |
geographic_facet |
Arctic Arctic Ocean Northwest Territories Yellowknife Canada North Slave Region |
genre |
Arctic Arctic Ocean Northwest Territories Tundra Yellowknife |
genre_facet |
Arctic Arctic Ocean Northwest Territories Tundra Yellowknife |
op_relation |
Canadian theses http://hdl.handle.net/1974/22675 |
op_rights |
Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada ProQuest PhD and Master's Theses International Dissemination Agreement Intellectual Property Guidelines at Queen's University Copying and Preserving Your Thesis This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
_version_ |
1800745857068302336 |