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This study is the second attempt to use the Basal Temperature of Snow (BTS) method to map permafrost in mountainous regions of northwestern Canada. It differs from the first study which took place in Wolf Creek in terms of (1) the methodology used to evaluate BTS, (2) the strategy used to avoid spatial autocorrelation in residuals, and (3) the climatic regions investigated. Two study areas, part of the Ruby Range (61° 12' N, 138° 19' W) and Haines Summit (59° 37' N, 136° 27' W) were selected for BTS sampling based on differing climatic conditions and previous knowledge of permafrost elevations from active rock glaciers. A total of 30 BTS measurements were made in the Ruby Range in the winter of 2006 and a total...
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Lake sediment cores collected from four lakes (Upper Fly Lake 61.04°N, 138.09°W, 1326 m a.s.l.; Jenny Lake 61.04°N, 138.36°W, 817 m. a.s.l.; Donjek Kettle 61.69°N, 139.76°W, 732 m a.s.l.; Lake WP02 61.48°N, 139.97°W, 1463 m a.s.l.) in the southwest Yukon provide records of postglacial climatic variability in the region. A 13,000 year pollen record from Upper Fly Lake indicated that herbaceous tundra existed on the landscape from 13.6 to 11 ka, followed by birch shrub tundra until 10 ka, when Picea forests were established in the region. Pollen-, chironomid-, and ostracode-inferred paleoclimate reconstructions showed a long-term cooling with increasing moisture from the late glacial through the Holocene. The early...
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Permanent electrode arrays were set up at ten monitoring sites from Whitehorse, Yukon, to Fort St. John, British Columbia, in order to gain a clearer perspective of the effectiveness of electrical resistivity tomography (ERT) monitoring over an annual cycle of freezing and thawing. This research forms part of a longer-term project that is attempting to use ERT to examine changes in permafrost resulting from climate change. Inter-site and intra-site variability were examined by installing and maintaining data-loggers to monitor active layer and shallow permafrost temperatures, air temperatures, and snow depths at each site from August 2010-August 2011. Additional site information was collected on each ERT survey...
Dendrochronological techniques were used to study white spruce ( Picea glauca [Moech] Voss) dynamics in the altitudinal forest-tundra ecotone in the southwest Yukon Territory. At two sampling sites, all Picea glauca individuals within 9 delineated quadrats in the forest-tundra and forest were sampled to estimate dates of establishment and growth variations using tree-ring chronologies. Regeneration in the forest-tundra ecotone was low from the late 1800s to the mid-1900s, however has increased since the 1920s. Recent peak periods of establishment parallel increased radial growth trends, which may have resulted from the long-term warming trend of the 20 th century. Seedling proximity to pre-established individuals...
This biogeographical study documents the modern distribution of ostracodes in the southwest Yukon Territory and northern British Columbia, Canada. The study tested the hypothesis that dissolved ion composition and concentrations of the lake water are the primary determinants of the distribution of modern ostracodes in this region. A total of 28 freshwater species representing 8 genera were identified in the 33 study lakes. Species common in the southwest Yukon are widely distributed throughout North America, and include Cyclocypris ampla , Candona candida , Cypria turneri , Cypria ophtalmica , and Candona protzi . Concentrations of ostracode valves were highest in four lakes with moderate conductivity values ranging...
Categories: Publication; Types: Citation; Tags: M1-Invertebrates
Solifluction lobe process and morphology were studied on an alpine slope (1800 m a.s.l) above Kluane Lake, south-western Yukon Territory. Contemporary rates of surface movements, measured by theodolite survey, were found to be greatest in the first two weeks of spring thaw, and movements were consistently faster on lobe treads than on lobe risers. Precise monitoring of thaw-consolidation parameters on a lobe indicated that most thaw-settlement occurred when the soil was saturated to the surface. At the slope scale, surface rates increased downslope in response to gradients in soil moisture, while long-term rates of lobe advance, inferred from 14 C dating of buried organic horizons, were found to be similar among...
Solifluction lobe process and morphology were studied on an alpine slope (1800 m a.s.l) above Kluane Lake, south-western Yukon Territory. Contemporary rates of surface movements, measured by theodolite survey, were found to be greatest in the first two weeks of spring thaw, and movements were consistently faster on lobe treads than on lobe risers. Precise monitoring of thaw-consolidation parameters on a lobe indicated that most thaw-settlement occurred when the soil was saturated to the surface. At the slope scale, surface rates increased downslope in response to gradients in soil moisture, while long-term rates of lobe advance, inferred from 14 C dating of buried organic horizons, were found to be similar among...
This study is the first known attempt in North America to use the basal temperature of snow (BTS) method to predict the distribution of mountain permafrost. The study site, Wolf Creek Research Basin, Yukon Territory (60°30'N, 135°13'W), is a 195 km 2 basin ranging in elevation from 650-2100 m with a mean annual air temperature of about -4°C at 1235 m a.s.l. A modeled BTS surface, based on 394 measured BTS values and with elevation and potential incoming solar radiation as independent variables, was created within a GIS environment with an r2 value similar to European results. The distribution of permafrost within the basin was identified from pits and boreholes. A subsequent logistic regression was used to compare...
The data from nine permafrost thermal monitoring sites at widely separated locations across northern Canada were examined individually, spatially, and temporally. Three sites are in Nunavut (Alert, Iqaluit, and Baker Lake), two in the Northwest Territories (Table Mountain and Wrigley), and four in the Yukon Territory (Wolf Creek, Sixty Mile, Alpine Burwash, and Red Creek). The sites have between one and five boreholes that are instrumented to between 3 and 60 m with records of varying durations. Most of the boreholes are co-located with weather stations recording air temperatures and snow depths. A comprehensive analysis of each site is presented assessing the relations between climate and permafrost temperatures,...
Permanent electrode arrays were set up at ten monitoring sites from Whitehorse, Yukon, to Fort St. John, British Columbia, in order to gain a clearer perspective of the effectiveness of electrical resistivity tomography (ERT) monitoring over an annual cycle of freezing and thawing. This research forms part of a longer-term project that is attempting to use ERT to examine changes in permafrost resulting from climate change. Inter-site and intra-site variability were examined by installing and maintaining data-loggers to monitor active layer and shallow permafrost temperatures, air temperatures, and snow depths at each site from August 2010-August 2011. Additional site information was collected on each ERT survey...
This study investigates the succession following fire in a relatively dry area of the boreal forest, the Shakwak Trench, southwest Yukon. The postfire successional regime is determined by an analysis of age structure and composition of tree populations in stands of different ages. The dendroecological approach used in this study is based on the sampling of one plot in each of 11 fires ranging from A.D. 1844-1998. Picea glauca established 0-4 years after fire and reached a period of maximum establishment after 20-40 years. Populus tremuloides was generally recruited immediately after fire and was no longer present after approximately 20 years, at which point, the Picea glauca began to dominate. Salix spp. were found...
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Near-surface air temperature inversions are a common element of northern environments. Seasonal and inter-annual variations of low-level inversion characteristics were examined using 47 years of twice-daily radiosonde data from Whitehorse airport (1956-2003). Nocturnal low-level inversion events occurred throughout the year in 68% of the 0400h PST radiosonde ascents. Afternoon (1600h PST) inversion events, in contrast, were primarily a winter phenomena, limited to 24% of the readings between October and March, and were deepest and strongest during the winter months. Shorter, weaker, lower magnitude inversions appeared progressively more frequently during the 1974-2003 warming at Whitehorse. The impact (1956-2003)...
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Dendrochronological techniques were used to study white spruce ( Picea glauca [Moech] Voss) dynamics in the altitudinal forest-tundra ecotone in the southwest Yukon Territory. At two sampling sites, all Picea glauca individuals within 9 delineated quadrats in the forest-tundra and forest were sampled to estimate dates of establishment and growth variations using tree-ring chronologies. Regeneration in the forest-tundra ecotone was low from the late 1800s to the mid-1900s, however has increased since the 1920s. Recent peak periods of establishment parallel increased radial growth trends, which may have resulted from the long-term warming trend of the 20 th century. Seedling proximity to pre-established individuals...
Basal Temperature of Snow (BTS) measurements were used as the primary inputs to a high resolution (30 x 30 m grid cells) empirical-statistical regional permafrost probability model for the southern and central Yukon, and northernmost British Columbia (59° - 65°N). Data from seven individual study areas distributed across the region were combined using a blended distance decay technique, with an eighth area used for validation. The model predictions are reasonably consistent with previous permafrost maps for the area with some notable differences and a much higher level of detail. The modelling gives an overall permafrost probability of 52%. North of 62°N, permafrost becomes more extensive in the lowland areas whereas...
The links between climate and permafrost are well known, but the precise nature of the relationship between air and ground temperatures remains poorly understood, particularly in complex mountain environments. Although previous studies indicate that elevation and potential incoming solar radiation (PISR) are the two leading factors contributing to the existence of permafrost at a given location, additional factors may also contribute significantly to the existence of mountain permafrost, including vegetation cover, snow accumulation and the degree to which individual mountain landscapes are prone to air temperature inversions. Current mountain permafrost models consider only elevation and aspect, and have not been...
Permanent electrode arrays were set up at ten monitoring sites from Whitehorse, Yukon, to Fort St. John, British Columbia, in order to gain a clearer perspective of the effectiveness of electrical resistivity tomography (ERT) monitoring over an annual cycle of freezing and thawing. This research forms part of a longer-term project that is attempting to use ERT to examine changes in permafrost resulting from climate change. Inter-site and intra-site variability were examined by installing and maintaining data-loggers to monitor active layer and shallow permafrost temperatures, air temperatures, and snow depths at each site from August 2010-August 2011. Additional site information was collected on each ERT survey...
This study investigates the succession following fire in a relatively dry area of the boreal forest, the Shakwak Trench, southwest Yukon. The postfire successional regime is determined by an analysis of age structure and composition of tree populations in stands of different ages. The dendroecological approach used in this study is based on the sampling of one plot in each of 11 fires ranging from A.D. 1844-1998. Picea glauca established 0-4 years after fire and reached a period of maximum establishment after 20-40 years. Populus tremuloides was generally recruited immediately after fire and was no longer present after approximately 20 years, at which point, the Picea glauca began to dominate. Salix spp. were found...
Lake sediment cores collected from four lakes (Upper Fly Lake 61.04°N, 138.09°W, 1326 m a.s.l.; Jenny Lake 61.04°N, 138.36°W, 817 m. a.s.l.; Donjek Kettle 61.69°N, 139.76°W, 732 m a.s.l.; Lake WP02 61.48°N, 139.97°W, 1463 m a.s.l.) in the southwest Yukon provide records of postglacial climatic variability in the region. A 13,000 year pollen record from Upper Fly Lake indicated that herbaceous tundra existed on the landscape from 13.6 to 11 ka, followed by birch shrub tundra until 10 ka, when Picea forests were established in the region. Pollen-, chironomid-, and ostracode-inferred paleoclimate reconstructions showed a long-term cooling with increasing moisture from the late glacial through the Holocene. The early...
Categories: Publication; Types: Citation; Tags: Paleo and Holocene
This study is the first known attempt in North America to use the basal temperature of snow (BTS) method to predict the distribution of mountain permafrost. The study site, Wolf Creek Research Basin, Yukon Territory (60°30'N, 135°13'W), is a 195 km 2 basin ranging in elevation from 650-2100 m with a mean annual air temperature of about -4°C at 1235 m a.s.l. A modeled BTS surface, based on 394 measured BTS values and with elevation and potential incoming solar radiation as independent variables, was created within a GIS environment with an r2 value similar to European results. The distribution of permafrost within the basin was identified from pits and boreholes. A subsequent logistic regression was used to compare...
This study investigates the succession following fire in a relatively dry area of the boreal forest, the Shakwak Trench, southwest Yukon. The postfire successional regime is determined by an analysis of age structure and composition of tree populations in stands of different ages. The dendroecological approach used in this study is based on the sampling of one plot in each of 11 fires ranging from A.D. 1844-1998. Picea glauca established 0-4 years after fire and reached a period of maximum establishment after 20-40 years. Populus tremuloides was generally recruited immediately after fire and was no longer present after approximately 20 years, at which point, the Picea glauca began to dominate. Salix spp. were found...
map background search result map search result map Seasonal cycling in electrical resistivities at ten thin permafrost sites, southern Yukon and northern British Columbia Validation of the Basal Temperature of Snow (BTS) method to map permafrost in complex mountainous terrain, Ruby Range, Yukon Territory and Haines Summit, British Columbia Holocene environmental variability inferred from lake sediments, southwest Yukon Territory, Canada Characteristics of low-level temperature inversions, Whitehorse Yukon Territory: 1956--2003 White spruce dynamics in the forest-tundra ecotone, the southwest Yukon Territory Characteristics of low-level temperature inversions, Whitehorse Yukon Territory: 1956--2003 Validation of the Basal Temperature of Snow (BTS) method to map permafrost in complex mountainous terrain, Ruby Range, Yukon Territory and Haines Summit, British Columbia Holocene environmental variability inferred from lake sediments, southwest Yukon Territory, Canada White spruce dynamics in the forest-tundra ecotone, the southwest Yukon Territory Seasonal cycling in electrical resistivities at ten thin permafrost sites, southern Yukon and northern British Columbia