Effects of open-top chambers and substrate type on biogeochemical processes at disturbed boreal forest sites in northwestern Quebec
Dabros, A. and J.W. Fyles . 2009. Plant and Soil 327:465-479
Abstract
Open-top chamber (OTC) climate change
simulation was used to predict the potential effects of
climate change on biogeochemistry, including: 1) soil
decomposition of three litter types (trembling aspen
(Populus tremuloides Michx.), black spruce (Picea
mariana (Miller) BSP), and Sphagnum); 2) soil
nutrient supply rates, and; 3) soil acidity. We assessed
the effects of OTCs on these biogeochemical factors
in the presence or absence of Sphagnum moss
substrate at post-fire and logging sites, in the
transitional mixedwood-boreal zone of northwestern
Quebec. Higher air temperatures and cooler, drier
soils created by the OTC treatment resulted in lower
decomposition rates and a higher C:N ratio of aspen
litter, and lower Ca concentrations of the Sphagnum
litter after 14 months of incubation, as well as lower
K concentrations of spruce litter after 24 month
incubation. There were no effects of the OTC
treatment on decomposition rates for Sphagnum and
spruce litter. The nutrient supply rates of Ca and Mg
were consistently lower in the OTCs. The supply rates
of N were significantly higher in the control plots at
the logging site than at any other combination of the
OTC treatment and disturbance site. Soil pH was
lower in the OTCs by the end of the growing seasons
in 2006 and 2007. The results suggest that the impact
of climatic changes, as simulated by the OTC
treatment, on the soil system of mixedwood-boreal
post-disturbance sites is likely to affect biogeochemical
processes such as nutrient supply rates and the
soil pH, but the effects on decomposition may be
minimal.
Key Words
Open-top chambers, Climate change, Soil pH, Soil nutrient supply rates, Decomposition rates, Post-disturbance boreal forest sites
