We compared vertical gradients in leaf gas exchange, CO2 concentrations, and refixation of respired CO2 in stands of Populus tremuloides Michx., Pinus banksiana Lamb. and Picea mariana (Mill.) B.S.P. at the northern and southern boundaries of the central Canadian boreal forest. Midsummer gas exchange rates in Populus tremuloides were over twice those of the two… More

in    0

Continuous automatic chamber and eddy covariance (EC) measurements were made at an old aspen forest (SOA) located at southern boreal treeline in Saskatchewan, Canada to examine the temporal variability in soil (Rs), tree bole (Rb), and ecosystem respiration (RE) during 2001. Climatic conditions were significantly warmer and drier than the 30-year climate normal, resulting in… More

in    0

Interdisciplinary field experiments for global change research are large, intensive efforts that study the controls on fluxes of carbon, water, trace gases, and energy between terrestrial ecosystems and the atmosphere at a range of spatial scales. Forest ecophysiology can make significant contributions to such efforts by measuring, interpreting, and modeling these fluxes for the individual… More

in    0

There is much uncertainty about the net carbon (C) exchange of boreal forest ecosystems, although this exchange may be an important part of global C dynamics. To resolve this uncertainty, net C exchange has been measured at several sites in the boreal forest of Canada as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). One of… More

in    0

We measured stem respiration rates during and after the 1994 growing season of three common boreal tree species at sites near the northern and southern boundaries of the closed-canopy boreal forest in central Canada. The growth respiration coefficient (rg; carbon efflux per μmole of carbon incorporated in structural matter) varied between 0.25 and 0.76, and… More

in    0

The energy balance components were measured throughout most of 1994 in and above a southern boreal aspen (Populus tremuloides Michx.) forest (53.629°N 106.200°W) with a hazelnut (Corylus cornuta Marsh.) understory as part of the Boreal Ecosystem-Atmosphere Study. The turbulent fluxes were measured at both levels using the eddy-covariance technique. After rejection of suspect data due… More

in    0

Area-averaged fluxes are constructed from a combination of aircraft and tower data collected during BOREAS. The averaging area includes both conifer and deciduous forests, wetlands, burned areas and bodies of water. The area-averaged water vapour flux is closely related to the area-averaged solar radiation while the area-averaged carbon dioxide flux and water use efficiency (WUE)… More

in    0

The seasonal water and energy exchange of a boreal aspen forest underlain by a hazelnut understory is described. Measurements of above-aspen latent and sensible heat, short-wave and net radiation, and photosynthetically active radiation are compared to those measured above the hazelnut understory. Understory radiation measurements were made using a tram system. Energy storage at each… More

in    0