Abstracts

Water Conditions of Boreal Forest Ecosystems under Various Climate Change Scenarios - A Modelling Assessment

Shusen Wang¹, Y. Zhang, and R. Fernandes
¹Natural Resources Canada
shusen.wang@CCRS.NRCan.gc.ca

Ecosystem water conditions control several key processes in the physical climate system, in the land surface hydrological and biogeochemical cycles, and in the ecosystem productivity and services. Water stress of a forest ecosystem can significantly affect its energy partitioning between latent and sensible heat which influence the local weather and climate, tree growth, soil microbial activity, ecosystem carbon sequestration, and greenhouse gas exchange. Large variations in precipitation over the Canadian boreal forest region, particularly the deciduous forests, play a key role in the annual variations of tree growth, ecosystem productivity, and even species distribution. How the water conditions will change with the projected climate change and how it will affect the ecosystem productivity still remain largely uncertain. In this study, we used the Ecological Assimilation of Land and Climate Observations (EALCO) model to investigate the water conditions of a boreal deciduous forest under various climate change scenarios projected by the climate models included in IPCC 3rd assessment report. Results suggest that while temperature increase will tend to accelerate the ecosystem evapotranspiration and increase ecosystem water use, CO² concentration increase in the atmosphere can significantly reduce the canopy stomatal conductance which could offset the increase of evapotranspiration and reduce water stress impact under dry conditions. The changes in snow cover and melting, growing season length, and leaf area index induced by plant growth also affect the ecosystem water conditions. The overall ecosystem water conditions are assessed based on the different climate changes scenarios referenced by IPCC.

2005-04-05