Latitudinal Gradients in Boreal Tree Form and Function


PROJECT LEAD: Jennifer Baltzer (Laurier)
PROJECT TEAM MEMBERS: Ana Sniderhan (PhD student, Laurier)

Rebecca Warren (Research Technician, Université de Montréal)

Rajit Patankar (Post doctoral fellow (PDF), Laurier)

Gord McNickle (Purdue University, USA; former PDF Laurier)

Chris Pappas (PDF, Université de Montréal)

Oliver Sonnentag (collaborator, Université de Montréal)

William Quinton (collaborator, Laurier)

Philip Marsh (collaborator, Laurier)

PROJECT LOCATION: Field sites include Scotty Creek, Havikpak Creek, and Trail Valley Creek, NWT, Wild Boy Creek, Northeastern BC, and Prince Albert, SK. Experimental work is conducted in the Centre for Cold Regions and Water Science at Laurier.

Objective 1: Gain a thorough understanding of how the changing environment across the latitudinal and permafrost gradient in the NWT is impacting growth of the dominant tree species, Picea mariana (black spruce).

Approach: Lloyd and Bunn (2007) have used dendrochronology to address circumpolar variability in growth response to climate warming in many boreal tree species to different extents, however, their study was limited to only three sites where P. mariana was sampled. Additionally, they were not able to define the mechanisms driving variability in growth response. Though P. mariana growth has been studied across a broad latitudinal gradient in boreal Quebec, this scale of study has not been performed across the species’ extent on permafrost – one of the most rapidly changing landscapes as the climate warms. P. mariana is a widespread, dominant tree species in the boreal region, and understanding how it has performed within the variable landscapes in the Northwest Territories and what is driving its response as the climate has changed is integral to predicting the future face of the boreal forest. Tree ring sampling will be conducted to span black spruce sites on discontinuous and continuous permafrost and up into the taiga-tundra interface. To supplement our extensive sampling effort, we will also make use of pre-existing tree-ring data from permanent sample plots across the Northwest Territories.

Objective 2: Assess the degree to which differences in growth responses are a function of local adaptation (i.e., ecotypic variation) vs. individual plasticity.

Approach: Seeds from populations across the entire N-S range of black spruce have been collected (joint effort between Laurier researchers and ENR forestry staff). This includes populations as far south as the southern limit of boreal forest in Saskatchewan and as far north as the taiga-tundra interface in Inuvik. Seeds from five populations in total traversing the latitudinal and permafrost gradient will be grown together in a common garden study at the Centre for Cold Regions and Water Science in Waterloo, ON. We experimentally modified nutrient availability and carbon dioxide concentrations to assess the plasticity of response of individuals from each population to variability in resource conditions. Responses of growth and physiology to experimental conditions were assessed for each population in each treatment.

Objective 3: Characterize differences in tree function across the range of the species in NW Canada.

Approach: At each of the sites mentioned above, sap flow instrumentation has or will be deployed to measure water use in black spruce, larch and whit spruce (where possible), how this varies locally and regionally and its ecohydrological contribution across this region. Other key functional traits relating to carbon uptake and storage will be made on trees at each site as well as dominant understory vegetation.