Base de données de recherche des TNO

étiquettes: permafrost, vegetation, climate change, carbon dioxide, peatlands, methane, boreal forests

Objectif(s): To determine the net effect of permafrost thawing-induced biophysical and biogeochemical feedbacks to the climate system.

Description du projet: Through this project the principal investigator will address the following objectives: What is the net effect of permafrost thawing-induced biophysical and biogeochemical feedbacks to the climate system? How do these two types of feedback differ between the sporadic and discontinuous permafrost zones? Is the reported decrease (increase) in net carbon dioxide (methane) exchange based on flux measurements made over mostly tundra sites in the continuous permafrost zone generalizable to boreal forest and peatland ecosystems with sporadic and discontinuous permafrost? Do the net ecosystem carbon dioxide and methane exchanges of boreal forest and peatland ecosystems in different permafrost zones respond differently to higher/lower precipitation inputs than, for example, thawing/growing season lengths? Identical to Scotty Creek, Havkipak Creek and Trail Valley Creek, the core component of this project at Smith Creek is a 15-m micrometeorological tower on which the eddy covariance system and supporting instrumentation will be installed. The eddy covariance system comprises a three-dimensional sonic anemometer to measure wind velocities, an open-path gas analyzer for carbon dioxide and water vapor concentrations and an open-path gas analyzer for methane concentrations. The covariance of the vertical wind velocities and the different concentrations will allow for the calculation of the respective fluxes between the landscape and the atmosphere. These quasi-continuous measurements are complemented by repeated surveys of surface and frost table topography, vegetation, micrometeorological and environmental conditions to understand the influence of spatial and temporal permafrost dynamics on vegetation composition and structure, by remote sensing-based footprint analysis to characterize landscape heterogeneity/homogeneity, and by continuous near-surface remote sensing to interpret eddy covariance measurements in a phenological framework. The vulnerability of permafrost landscapes to climate change has been widely acknowledged but the understanding of its consequences for boreal forest ecosystem structure, functioning and services is still insufficient. This research in the Wrigley area will rely heavily on local assistance and expertise (e.g., snowmobiling, trail maintenance, lodging) on a campaign basis as offered, for example, through Brave Adventures in Wrigley. Based on the researchers extensive network of contacts across the Northwest Territories, research results of this project will be presented informally in public meetings to local communities but also to local federal and territorial government agencies. The fieldwork for this study will be conducted from April 20, 2015 to September 5, 2015.