Belowground biomass dynamic in eastern Canadian forest ecosystems

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I am studying long-time fluctuations in biomass of roots of eastern Canadian forests dominated by balsam fir or sugar maple. Their coarse roots represent a large, long-lasting portion of their biomass. The fine, absorbing roots, on the other hand, constitute a continually turning over biomass. The fine roots do not last long and must be replenished. Growth of coarse roots and, particularly, the replacement of dying fine roots cost trees much of their fixed carbon (C). These investments reflect on the amount of free CO2 in the atmosphere, as does the release of C from respiration and decay of dead roots. By estimating variation in production and mortality of the roots, my studies provide an important input to modeling C cycling of Earth's ecosystems. Such models predict changes in atmospheric CO2 concentrations and the resultant change of climate. I excavate coarse roots to determine their biomass but I look for other tree characteristics whose measurement can predict coarse root biomass with acceptable accuracy. I study fine roots by observing them with a camera through transparent tubes (minirhizotrons) placed in the soil. Based on the time of appearance, disappearance, and size of the roots, I estimate changes in fine root biomass over time. I use this approach to study differences in fine root dynamics between the studied species and to determine effects of tree aging on belowground productivity and biomass. I will also use it to study effects of thinning and logging on belowground biomass. These treatments radically change conditions at forest sites and leave large amounts of dead biomass in roots and stumps. However, they also increase productivity of residual trees and, from renewal of vegetation at harvested sites, create conditions for renewed productivity. My studies will provide data useful for planning forest operations to maximize the removal of CO2 from the atmosphere and to reduce its release from forest ecosystems. Hence, my studies may add to options for reducing concentrations of atmospheric CO2 by choosing effective methods of forest management.