Influence of Populus tremuloides density on air and soil temperature

Abstract

Density manipulation of overstory aspen provides increased light levels to promote growth of understory spruce, while it may also impact the air and soil temperature. We monitored temperature for three growing seasons in young mixedwood stands of variable density at two boreal locations in Alberta, Canada. Results indicate that partial aspen cover provides frost protection that may be location specific. Mean air temperature was similar or increased slightly across aspen densities during the growing season, while mean soil temperature significantly increased with decreasing overstory cover. The amount of accumulated air and soil heat over the growing season was inversely related to aspen density. The differential impact of density on temperature contributes to variation in growth relationships and may explain regional differences in competition effects.

Keywords:

• Aspen
• boreal mixedwoods
• frost
• temperature
• white spruce

Acknowledgements

We are grateful to the Western Boreal Growth and Yield Association (WESBOGY) (in particular Weyerhaeuser and DMI) for permission to use their long-term study sites. Funding was provided by Natural Sciences and Engineering Research Council and University of Alberta. We thank Sandra Babiuk and Susan Humphries for assistance with fieldwork.