Base de données de recherche des TNO

étiquettes: physical sciences, climatology, permafrost, climate change, carbon budget, carbon fluxes, forest ecosystem, tundra ecosystems

Objectif(s): To determine the net effect of permafrost thawing-induced biophysical and biogeochemical feedbacks to the climate system and how these two types of feedback differ between the discontinuous and continuous permafrost zones .

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 discontinuous and continuous permafrost zones? Is the reported decrease (increase) in net Carbon Dioxide (CO2)-Methane (CH4) exchange based on plot- (<1m2) and ecosystem-scale (~1km2) flux measurements made over mostly tundra sites in the continuous permafrost zone generalizable to boreal forest and peatland ecosystems with discontinuous and continuous permafrost? Do the net ecosystem CO2 and CH4 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? The core components of this project are two existing micrometeorological towers operated by Environment Canada, one at Havikpak Creek and one at Trail Valley Creek. At each tower principal investigator will be installing eddy covariance systems comprising a three-dimensional sonic anemometer to measure wind velocities, an open-path gas analyzer for CO2 and water vapour 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 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 acknowledged but the understanding of its consequences for boreal forest and tundra ecosystem structure, functioning and services is still insufficient. 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 June 11, 2014 to September 12, 2014.