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Impacts of Tall Shrub Expansion on Tundra Ecosystem Function

Impacts of Tall Shrub Expansion on Tundra Ecosystem Function

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The expansion of the number and size of tall shrubs on the tundra ecosystem affects where animals live, the availability of food for prey animals and the amount of water available to move across the landscape. The ability to predict change during this expansion is imperative to understanding how the land is changing.

Drivers and Consequences of Alder Expansion at the Treeline-Tundra Ecotone

  • Researcher: Cory Wallace, PhD Student (2014–present)
  • Supervisor: Jennifer Baltzer (Laurier)

Cory WallaceWarming temperatures have resulted in a large increase in the size and abundance of shrubby vegetation in the Arctic tundra over the past few decades. At Trail Valley Creek Research Station, we found that alder patches did have different soil conditions, particularly differences in nutrient availability, greater snow depth, and drier soils as well as greater cover of evergreen shrubs and fewer species specialized to tundra conditions. This data also allowed us to test whether any of these conditions were influenced by the physical characteristics (e.g. density and average height) of individual patches. We are investigating where across the landscape green alder seedlings will establish by mapping the locations of individual seedlings and comparing this to local environmental conditions and seed density. This work will give us both a better understanding of the environmental impacts of green alder shrub expansion in the tundra of the Northwest Territories and a sense of where to expect future expansion to occur. These two pieces of information will help refine the picture of what a future, more shrubby tundra will look like and the impact this may have on wildlife habitat, local water resource availability, and regional climate change.

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Water Use by Tall Shrubs in Tundra Environments

  • Researchers: Katie Black, MSc (2015–17)
  • Supervisor: Jennifer Baltzer (Laurier)

Katie BlackClimate warming is driving the expansion of shrubs across the tundra, especially in areas that have a higher potential of accumulating moisture, such as hill slopes and drainage channels. We offer estimates of seasonal variation in green alder daily cumulative sap volume and green alder patch transpiration on the low Arctic tundra, supporting incorporation of shrub water use estimates into models predicting the magnitude and impacts of tundra shrubbing on evapotranspiration. Green alder is expanding rapidly across the low Arctic tundra of the Northwest Territories and understanding the implications of its expansion is essential for predicting future tundra conditions.

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Instrumentation Support Across Multiple Sites

Gabriel Hould GosselinThe primary focus of my work is to design, install and maintain eddy covariance and micrometeorological instrumentation, as well as to support other CANet activities at six sites on a latitudinal gradient across the Northwest Territories and northern British Columbia. I specialize in establishing water vapour, carbon dioxide and methane fluxes at a landscape scale using the eddy covariance technique. These datasets are imperative to provide better process-based understanding of how boreal forest, peatland and tundra ecosystems under the influence of rapidly changing permafrost conditions function as an integral part of the climate system.

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Spatial and Temporal Variability of the Snow Environment in the Western Canadian Arctic

  • Researcher: Philip Mann, MSc (2014–17)
  • Supervisor: Phil Marsh (Laurier)

Philip MannMy research quantifies spatial variations in end-of-winter snow cover by using a variety of new techniques in Trail Valley Creek. Snow cover in the Western Canadian Arctic is a significant input to the hydrological mass balance, it produces shelter and habitat for animals and humans, and supports interactions with vegetation and climate. It is also greatly impacted by wind erosion, redistribution and deposition of snow during high wind events over the winter months. As a result, the end-of-winter snow cover is characterized by significant small-scale spatial variations in snow depth, density, snow water equivalent and runoff. Therefore, as the climate and vegetation continue to change in the coming decades, it is expected that there will be great changes in snow cover and, consequently, impacts on water resources, animal habitats and vegetation.

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High-Resolution Spatial Variability in Spring Snowmelt for an Arctic Shrub-Tundra Watershed

  • Researcher: Branden Walker, MSc (2015–18)
  • Supervisor: Phil Marsh (Laurier); research associate (2018-present)

Branden WalkerMy research is aimed at understanding how Arctic hydrological systems are responding to a rapidly warming climate. As a previous master’s student, my research applied novel techniques such as unmanned aerial systems (UAS) to map snowpack conditions across shrub-tundra headwater catchments. This research addresses uncertainties relating to future changes in snow distribution with increasing shrub expansion into tundra regions and changing precipitation regimes. My work also aims to increase our knowledge of the complex and rapid changes to basin snow cover conditions over the spring melt to improve our understanding of the spring freshet response which is integral to improving our ability to forecast these systems under further climate warming scenarios. Alongside my ongoing research interests, I am also responsible for the management and operations of the Trail Valley Creek Research Station.

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