We examine the atmospheric budget of CO2 at temperate continental sites in the Northern Hemisphere. On a monthly time scale both surface exchange and atmospheric transport are important in determining the rate of change of CO2 mixing ratio at these sites. Vertical differences between the atmospheric boundary layer and free troposphere over the continent are… More

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Substantial research seeks to improve estimates of ecosystem processes and fluxes at a range of scales, notably from the stand scale (<1 km2) using ecosystem physiology and eddy covariance techniques, to the landscape (∼102 km2) and global (108 km2) scales using a variety of modeling and data acquisition approaches. One approach uses remotely sensed ecosystem… More

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Effects of shoot water potential (Ψ) and leaf-to-atmosphere vapor pressure difference (VPD) on gas exchange of jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) B.S.P.), and aspen (Populus tremuloides Michx.) were investigated at the northern edge of the boreal forest in Manitoba, Canada. Laboratory measurements on cut branches showed that net photosynthesis (An)… More

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Fire is the dominant stand-replacing agent in the Canadian boreal forest, but few quantitative measurements are available on the micrometeorological effects of fire. Airborne flux measurements during the BOREAS experiment were referenced to age of burn along a 500-km transect through Saskatchewan and Manitoba, Canada. These data for 1-, 5-, and 7-year-old burns were supplemented… More

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Root biomass, net primary production and turnover were studied in aspen, jack pine and black spruce forests in two contrasting climates. The climate of the Southern Study Area (SSA) near Prince Albert, Saskatchewan is warmer and drier in the summer and milder in the winter than the Northern Study Area (NSA) near Thompson, Manitoba, Canada…. More

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A process-based, general ecosystem model (BIOME–BGC) was used to simulate daily gross primary production, maintenance and heterotrophic respiration, net primary production and net ecosystem carbon exchange of boreal aspen, jack pine and black spruce stands. Model simulations of daily net carbon exchange of the ecosystem (NEE) explained 51.7% (SE = 1.32 g C m−2 day−1)… More

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Soil surface CO2 flux (RS) is overwhelmingly the product of respiration by roots (autotrophic respiration, RA) and soil organisms (heterotrophic respiration, RH). Many studies have attempted to partition RS into these two components, with highly variable results. This study analyzes published data encompassing 54 forest sites and shows that RA and RH are each strongly… More

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The objective of this study was to quantify carbon (C) distribution for boreal black spruce (Picea mariana (Mill.) BSP) stands comprising a fire chronosequence in northern Manitoba, Canada. The experimental design included seven well-drained (dry) and seven poorly-drained (wet) stands that burned between 1998 and 1850. Vegetation C pools (above-ground + below-ground) steadily increased from 1.3 to… More

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