Dynamics of coarse and fine root biomass in eastern species of contrasting silvical characteristics

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Knowledge about root biomass growth and turnover is required to accurately estimate carbon storage and dynamics in forest ecosystems. Species and locale-specific data on belowground biomass is very limited. This research will evaluate biomass dynamics and net primary production (reflecting the net carbon balance resulting from growth and death) of root systems of balsam fir and sugar maple. It will focus on effects of the climate and forest management on biomass dynamics and allocation of carbon to root systems of the trees. It will provide species-specific data enabling verification of current approaches to estimating belowground biomass and carbon stocks of Maritime forests. It will improve the ability to model potential effects of climate change and of forest management practices that alter biomass balance by removing some and leaving some to decay, and that changes tree density and, consequently, growth conditions for residual trees. Studies of root biomass dynamics are difficult because roots are not easily accessible for measurements. Dynamics of fine roots will be determined from measurements made on images from transparent tubes (minirhizitrons) inserted into the soil and by evaluating and weighing roots recovered from soil cores. These methods evaluate the abundance and longevity of fine roots enabling the estimate of their biomass dynamics. Coarse roots will be excavated with compressed air and their dry biomass will be determined at the laboratory. Equations for estimating the biomass of coarse roots from easier to measure aboveground characteristics will be developed and compared among the study sites. A new method of estimating net primary productivity of coarse roots will be developed for determining year-to year variation in belowground biomass and carbon dynamics.