Nutrient and Biomass Contributions of Downed Woody Debris in Boreal Mixedwood Forests of Northeastern Ontario

Harvest-related decreases of downed woody debris (DWD) in forests may have important ecological implications; however, patterns of nutrient release from decaying DWD are poorly understood. The importance of DWD was investigated relative to biomass and nutrient pools in six, second-growth boreal mixedwood forest stands, differing by harvest regime near Kapuskasing, Ontario. Nutrient concentrations and mineralization trends using ion exchange resins at three proximities during the decay of Abies balsamea and Populus tremuloides were also examined. Concentrations of N, P, Ca, and Mg increased with decay, whereas K decreased. DWD was a minor contributor to biomass and nutrient pools. Inorganic N, P, Ca, and Mn were significant between harvest types with decay class interaction for N, Ca, and Mn. Species and proximity effects were found for Al, Fe, and K. These results suggest DWD may be a minor contributor to biomass and nutrient pools, but highlights its dynamic nature.MAS