ALBERT

Description: The Hudson Bay Lowlands (HBL) is the largest peatland complex in North America. More than 75% of the HBL occurs in Ontario, where the provincial government mandates that ecosystem carbon storage and sequestration be considered in land-use planning. Accomplishing this task requires identifying carbon indicators and assessing their responses to changing ecosystem processes, such as succession, permafrost thaw, and evapotranspiration (ET). Therefore, we synthesized information on peat carbon indicators and ecosystem process from the literature. Findings indicate that the long-term carbon accumulation, carbon dioxide (CO 2 ) sequestration, peat depth, and peatland age were similar ( p 〉 0.10) between dry and wet peatland features. Furthermore, CO 2 sequestration displayed the highest variability and ponds were net CO 2 emitters. Recent carbon accumulation, CH 4 emission, and ET were highest ( p 〈 0.01) in wet features, with CH 4 emission displaying wide variation. Increased active layer thickness (105 ± 92 cm per 100 years) in permafrost was the most variable ecosystem process analyzed in this study, while variation in permafrost loss (53 ± 23% per 100 years) was similar to that of carbon accumulation and ET rates. Processes creating wet and pond conditions may increase landscape-scale CO 2 and CH 4 emissions to the atmosphere, weakening peatland carbon sinks. Dry conditions may reduce CH 4 emissions but potentially increase peatland susceptibility to fire. Knowledge of these changes should be useful for climate change vulnerability and adaptation assessments for large landscapes. However, better understanding of variability in CO 2 sequestration, CH 4 emission, and permafrost dynamics is required to design such assessments for small landscapes. Content Type Journal Article Pages 84-102 DOI 10.1657/1938-4246-46.1.84 Authors Jim McLaughlin, Ontario Forest Research Institute, Ontario Ministry of Natural Resources, 1235 Queen Street East, Sault Ste. Marie, Ontario, P6A 2E5, Canada Kara Webster, Canadian Forest Service, Great Lakes Forestry Centre, 1219 Queen Street East, Sault Ste. Marie, Ontario, P6A 2E5, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: The Hudson Bay Lowlands (HBL) constitute a globally significant carbon pool; the paleoecological record provides an opportunity to investigate long-term drivers of change in carbon accumulation and related changes in vegetation. We present a Holocene record from the Victor Fen site (VM-3-3) in Ontario's HBL to reconstruct vegetation history, quantify rates of carbon accumulation, and determine the role of paleoclimatic drivers. Pollen analysis indicates initiation of peat accumulation over a mineral substrate, accompanied by relatively rapid rates of carbon accumulation, following emergence from the Tyrrell Sea ~6900 yrs BP. The earliest vegetation assemblage consisted of a tidal marsh, quickly succeeding to a Typha marsh, then a poor fen dominated by Sphagnum and Cyperaceae by 6400 yrs BP. Rapid rates of isostatic uplift at the time likely contributed to these changes. Once established, this fen community persisted without major vegetation change until the most recent century, when the abundance of shrub and Cyperaceae pollen increased, suggesting increasingly minerotrophic conditions. Average rate of long-term carbon accumulation (LORCA) for the whole record (mean = 22.8 g C m -2 yr -1 ) is similar to other northern peatlands, and higher than the Holocene average for an adjacent bog. Increased precipitation after ~2400 yrs BP may have contributed to the higher LORCA reconstructed for the late Holocene, but the increased precipitation did not coincide with any apparent changes in vegetation as inferred from pollen assemblages. Content Type Journal Article Pages 6-18 DOI 10.1657/1938-4246-46.1.6 Authors Benjamin C. O'Reilly, Department of Geography, University of Toronto, 100 St. George Street, Room 5047, Toronto, Ontario, M5S 3G3, Canada Sarah A. Finkelstein, Department of Earth Sciences, University of Toronto, 22 Russell Street, Toronto, Ontario, M5S 3B1, Canada Joan Bunbury, Department of Geography and Earth Science, University of Wisconsin-La Crosse, 2025 Cowley Hall, La Crosse, Wisconsin 54601, U.S.A. Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: The objective of this paper is to examine the thermodynamic and dynamic forcing of sea ice within the Hudson Bay System, including Hudson Bay, Hudson Strait, and Foxe Basin. Changes in fall and spring sea ice extents (SIEs) are examined in relation to seasonal surface air temperatures (SATs) and winds, as are changes in freeze-up dates and breakup dates. The proportional leverage of the fall (lag1) and spring SATs and winds on ice is statistically examined per basin. Results show SATs have increased significantly since the mid-1990s and that increases in the fall are higher than the spring period. Fall SATs are highly related to fall SIEs ( R 2 = 0.79-0.82). For every 1 °C increase in SAT, SIE decreases by 14% (% of basin area) within the Hudson Bay System; a 1 °C increase delays freeze-up by 0.7 to 0.9 weeks on average. Spring SIEs and breakup dates are shown to be highly correlated with fall (lag1) and spring SATs, and with U and V component winds. Proportionately, spring and fall SATs combined play a dominant role (70-80%) in SIE, and the remaining leverage is attributed to dynamic forcing (winds). The relative leverage of fall (lag1) SATs and surface winds are shown to be significant and vary by basin. The open water season has on average increased by 3.1 (±0.6) weeks in Hudson Bay, 4.9 (±0.8) weeks in Hudson Strait, and 3.5 (±0.9) weeks in Foxe Basin. Content Type Journal Article Pages 66-83 DOI 10.1657/1938-4246-46.1.66 Authors Klaus P. Hochheim, Centre for Earth Observation Science (CEOS), Clayton H. Riddell Faculty of Environment, Earth, and Resources, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada David G. Barber, Centre for Earth Observation Science (CEOS), Clayton H. Riddell Faculty of Environment, Earth, and Resources, University of Manitoba, Wallace Building, 125 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: This study presents a paleoenvironmental and paleoclimatic reconstruction of western subarctic Québec based on the watershed geomorphology of Lake Kaapumticumac (including terraces, stratigraphy, and peatlands) as well as lake sediments, with reference to stratigraphy, grain size, and organic matter content. The integration of data from diverse sources provides valuable information about the regression of the Tyrrell Sea, lake isolation, and lake level fluctuations. Marine processes dominated prior to ca. 6960 cal yr BP, while the marine-lacustrine transition lasted about 500 years (ca. 6960-6400 cal yr BP). In comparison to other study sites in the Whapmagoostui-Kuujjuarapik area, the earlier isolation of Lake Kaapumticumac is consistent with its higher elevation and its greater distance from Hudson Bay. After 6400 cal yr BP, lake evolution was primarily influenced by the climate. Two major climatic periods were recorded: first, the Hypsithermal (ca. 6400-3500 cal yr BP), during which warm conditions caused partial terrestrialization of Lake Kaapumticumac; and second, the post-Hypsithermal or Neoglacial (ca. 3500 cal yr BP to ca. 200 cal yr BP), which triggered the rise in lake levels and caused levees to form in several places around the lake. Content Type Journal Article Pages 55-65 DOI 10.1657/1938-4246.46.1.55 Authors Donald Cayer, Centre d'études nordiques and Département de géographie, Université Laval, Québec (Québec), G1V 0A6, Canada Najat Bhiry, Centre d'études nordiques and Département de géographie, Université Laval, Québec (Québec), G1V 0A6, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: Science in the Snow; Fifty Years of International Collaboration through the Scientific Committee on Antarctic Research. By David W. H. Walton and Peter Clarkson, with additional material by Colin Summerhayes Content Type Journal Article Category Book Review Pages 287-288 DOI 10.1657/1938-4246-46.1.287 Authors John C. Behrendt, Institute of Arctic and Alpine Research (INSTAAR), University of Colorado at Boulder, UCB 450 Boulder, Colorado 80309-0450, U.S.A. Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: Macrofossil analysis of the peat and topographic surveys of two palsa fields (Fields 3 and 4) within a permafrost peatland located in subarctic Québec was conducted to trace the factors that contributed to their differential development. The two palsa fields are visibly different in terms of their geomorphology, ecology, and hydrology. According to our results, the evolution of the two fields was largely synchronous in terms of the respective trophic conditions. Moreover, the climate certainly played a significant role in the evolution of this ecosystem. For example, the cooling of the Neoglacial period would have favored the ombrotrophication of both sites, whereas the Little Ice Age conditions would have contributed to palsa formation. Despite the synchronous changes within the two fields, significant differences were also noted. These include the rate of peat accumulation, the number of species found in the peat monoliths, and the presence or absence of forest cover during the ombrotrophic phase. The topography of the underlying substrate would also have influenced the hydrological conditions. For example, a light slope toward the northwest engendered a faster trophic impoverishment in Field 4. In addition, streaming water in Field 3 favored the preservation of wet and rich conditions that triggered the following changes: more diverse vegetation, the significant accumulation of peat, and the formation of higher palsas. Content Type Journal Article Pages 40-54 DOI 10.1657/1938-4246-46.1.40 Authors Marie-Ève Fillion, Département de géographie, Centre d'études nordiques (CEN), Université Laval, Québec, QC, G1V 0A6, Canada Najat Bhiry, Département de géographie, Centre d'études nordiques (CEN), Université Laval, Québec, QC, G1V 0A6, Canada Mustapha Touazi, Département de géographie, Centre d'études nordiques (CEN), Université Laval, Québec, QC, G1V 0A6, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: Although widely distributed throughout Arctic and subarctic regions, thermokarst ponds and lakes remain relatively unexplored regarding geomorphological changes in their catchments and their internal properties in relation to climate change over the past decades. This study synthesizes recent landscape evolution and modern sedimentology of limnologically diverse thermokarst ponds near southeastern Hudson Bay, Canada. Spatio-temporal analysis of permafrost mounds, thermokarst ponds, and vegetation surface areas over the past five decades revealed that the recent climate-induced decrease of permafrost-affected areas was not primarily compensated by thermokarst pond development, but rather by a remarkable increase in vegetation cover. These changes appeared to be modulated by topographical and hydrological gradients at the study site, which are associated with eastward increasing thickness of postglacial marine deposits. At a more contemporary timescale, physico-chemical measurements made on sedimenting materials (sediment traps) and freshly deposited lacustrine sediments of selected thermokarst ponds revealed striking differences both among ponds and between the oxic epilimnion and the oxygen-depleted hypolimnion. These findings underscore the major influence of local landscape properties and oxycline development on pond sedimentology and geochemistry, such as the transport of detritic particles and the concentration of redox-sensitive elements. Content Type Journal Article Pages 251-271 DOI 10.1657/1938-4246-46.1.251 Authors Frédéric Bouchard, Institut national de la recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Québec (QC), G1K 9A9, Canada Pierre Francus, Institut national de la recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Québec (QC), G1K 9A9, Canada Reinhard Pienitz, Centre d'études nordiques (CEN), Pavillon Abitibi-Price, Université Laval, 2405 de la Terrasse, Québec (QC), G1V 0A6, Canada Isabelle Laurion, Institut national de la recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Québec (QC), G1K 9A9, Canada Stéphane Feyte, Institut national de la recherche scientifique, Centre Eau Terre Environnement (INRS-ETE), 490 de la Couronne, Québec (QC), G1K 9A9, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: There is concern over the fate of surface water bodies at high latitudes as a consequence of rising global temperatures. The goal of this study is to characterize climatic change that has occurred in the northern Hudson Bay Lowlands (HBL), Canada, from 1943 to 2009, to determine if this has resulted in a change to pond surface areas and to predict if changes may continue in the future. Climate change and changes to pond volume and size over the past ~60 years were examined using a combination of field methods/instrumental records (1943-2009), modeling (1953-2009; 1961-2100), and remote sensing/imagery analyses (1947-2008). Results demonstrate that temperatures are warming and breakup dates are earlier, but this has not significantly increased the duration of the open-water period or pond evaporation rates, which can be highly variable from year to year. Annual precipitation, primarily summer rainfall, has increased, lessening the summer moisture deficit and leading to wetter conditions. The observed changes of a smaller summer moisture deficit are predicted to continue in future, although there is less certainty with predictions of future precipitation than there is with predictions of air temperature. Thus, ponds are likely not at risk for drying and instead may be at risk for expansion. Despite the increases in summer rainfall, imagery analysis of 100 ponds shows that pond surface areas have fluctuated over the study period but have not increased in size. Content Type Journal Article Pages 272-285 DOI 10.1657/1938-4246-46.1.272 Authors Merrin L. Macrae, Interdisciplinary Centre for Climate Change (IC 3 ) and Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada Laura C. Brown, Interdisciplinary Centre for Climate Change (IC 3 ) and Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada Claude R. Duguay, Interdisciplinary Centre for Climate Change (IC 3 ) and Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada Jennifer A. Parrott, Interdisciplinary Centre for Climate Change (IC 3 ) and Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada Richard M. Petrone, Interdisciplinary Centre for Climate Change (IC 3 ) and Department of Geography and Environmental Management, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: Climate and land-use changes are going to leave an indelible mark on the hydrology and globally significant peatlands of the Hudson Bay Lowlands (HBL), Canada. With forecasts for warmer and drier conditions over the next century, the relative contribution of water from surface and subsurface sources affecting both water quantity and quality will undoubtedly shift. Unfortunately, no empirical data exist for any streams or rivers of the HBL on the relative contributions of surface water and groundwater to streamflow, making assessment of future change difficult. Here we report the first data on sources of water to streams and rivers across a range of catchment sizes in the James Bay Lowland (JBL) ecoregion of the HBL. Solute chemistry was determined for a range of potential end members, end members were identified, and a chemical mixing model approach was used to determine the relative end-member contributions to streamflow across a range of catchment sizes (~30-2000 km 2 ). The relative contributions of bedrock-derived groundwater to streamflow increased with catchment area from 40% under dry conditions, and were ~50% lower under wet conditions across all catchments. Runoff contributions from peatlands were relatively constant over space and time (53-67%), but the fraction of streamflow composed of rain and snowmelt varied dramatically between wet and dry periods, and among catchments. Given the importance of peatland-derived surface waters, future changes in precipitation and temperature could have significant implications for streamflow in the JBL, particularly during summer base-flow conditions. Moreover, the definition of reference catchments for baseline/impact monitoring must be carefully considered, given the potential for variation in hydrochemistry across physiographically similar catchments. Content Type Journal Article Pages 236-250 DOI 10.1657/1938-4246-46.1.236 Authors Julia Orlova, Department of Geography, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3K7, Canada Brian A. Branfireun, Department of Geography, University of Toronto Mississauga, 3359 Mississauga Road North, Mississauga, Ontario, L5L 1C6, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014

Description: Due to shallow depth and high surface area-to-volume ratio, ponds of the Hudson Bay Lowlands are vulnerable to climatic and hydrological changes, but relations between hydrological processes and limnological conditions remain unknown. Here, we measured water balance and limnological variables (water chemistry, suspended sediments, chlorophyll- a ) at 20 ponds near Churchill (Manitoba) three times during the ice-free season of 2010 to explore relations among hydrological connectivity, basin morphometry, and water-chemistry variations. Using principal components analysis, we identified that the ponds followed one of four distinctive "seasonal water chemistry trajectories" (SWCT1-4). Most of the ponds that lacked apparent hydrologic connectivity displayed SWCT1, characterized by rising alkalinity and ionic content between early June and late July due to evaporative concentration. In contrast, most ponds with apparent hydrological connectivity displayed SWCT2 or SWCT3, characterized by marked changes in suspended sediment and total nitrogen concentrations due to inflow that transferred allochthonous materials from the catchment. Ponds in SWCT2 likely possessed temporary hydrological connections during periods of relatively high water supply and exhibited marked decline of suspended sediment and total nitrogen content when hydrological connection was lost. Most ponds in SWCT3 maintained active hydrological connections during all or most of the ice-free season and possessed relatively high suspended sediment and total nitrogen concentrations throughout the season. Ponds in SWCT4 possessed relatively stable water chemistry due to greater water depth and local features that reduced wind-induced sediment resuspension. We conclude that hydrological connectivity and basin morphometry exert important influence on seasonal pond water-chemistry dynamics. Content Type Journal Article Pages 218-235 DOI 10.1657/1938-4246-46.1.218 Authors Jerry White, Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada Roland I. Hall, Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada Brent B. Wolfe, Department of Geography and Environmental Studies, Wilfrid Laurier University, 75 University Avenue West, Waterloo, Ontario, N2L 3C5, Canada Erin M. Light, Department of Geography and Environmental Studies, Wilfrid Laurier University, 75 University Avenue West, Waterloo, Ontario, N2L 3C5, Canada Merrin L. Macrae, Department of Geography and Environmental Management, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada LeeAnn Fishback, Churchill Northern Studies Centre, P.O. Box 610, Churchill, Manitoba, R0B 0E0, Canada Journal Arctic, Antarctic, and Alpine Research Online ISSN 1938-4246 Print ISSN 1523-0430 Journal Volume Volume 46 Journal Issue Volume 46, Number 1 / February 2014