Response of soil CO2 and O2 concentrations to forest soil compaction at the Long-term Soil Productivity sites in central British Columbia

Abstract

The concentrations of soil CO2 and O2 at three Long-term Soil Productivity sites located in the Sub-Boreal Spruce biogeoclimatic zone of British Columbia, Canada, were monitored over several growing seasons. These sites were treated with three levels of soil compaction and three levels of organic material removal following forest harvest. Both compaction and depth had a significant effect upon soil CO2 concentrations and average values increased in response to deeper sampling and compaction. Removal of the forest floor and other organic materials had no significant effect upon soil CO2 and O2 concentrations. Mean soil CO2 concentrations varied from site to site and data collected over three growing seasons also showed that mean CO2 values in response to compaction fluctuated significantly from year to year. The high levels of soil CO2 observed in this study (up to 40 000 µ L L−1), especially in response to the compaction treatments, may have had a substantial effect upon whole plant carbon allocation as well as soil nutrition available to trees growing on the treated plots. Although mean soil O2 also decreased in response to compaction and sampling depth, these lower concentrations did not approach the levels required to influence plant growth. Key words: Soil, compaction, carbon dioxide, oxygen, long-term soil productivity