Thomas Andrew Black

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[1] Clouds and aerosols alter the proportion of diffuse radiation in global solar radiation reaching the Earth’s surface. It is known that diffuse and direct beam radiation differ in the way they transfer through plant canopies and affect the summation of nonlinear processes like photosynthesis differently than what would occur at the leaf scale. We(More)
[1] Disturbances are important for renewal of North American forests. Here we summarize more than 180 site years of eddy covariance measurements of carbon dioxide flux made at forest chronosequences in North America. The disturbances included stand‐ replacing fire (Alaska, Arizona, Manitoba, and Saskatchewan) and harvest (British Columbia, Florida, New(More)
The seasonal phenology of the leaf area index (LAI) is a major determinant of net ecosystem production in deciduous forest ecosystems. This study describes seasonal and inter-annual differences in LAI in a boreal aspen-hazelnut forest in central Saskatchewan, Canada, between 1994 and 2003, and relates the differences in LAI to annual net ecosystem(More)
A novel A-Ci curve (net CO2 assimilation rate of a leaf -An- as a function of its intercellular CO2 concentration -Ci) analysis method (Plant, Cell & Environment 27, 137-153, 2004) was used to estimate the CO2 transfer conductance (gi) and the maximal carboxylation (Vcmax) and electron transport (Jmax) potentials of ageing, non-senescing Pseudotsuga(More)
In 2001–03, continuous eddy covariance measurements of carbon dioxide (CO2) flux were made above mature boreal aspen, black spruce, and jack pine forests in Saskatchewan, Canada, prior to and during a 3−year drought. During the 1st drought year, ecosystem respiration (R) was reduced at the aspen site due to the drying of surface soil layers. Gross ecosystem(More)
Kevin Schaefer, Christopher R. Schwalm, Chris Williams, M. Altaf Arain, Alan Barr, Jing M. Chen, Kenneth J. Davis, Dimitre Dimitrov, Timothy W. Hilton, David Y. Hollinger, Elyn Humphreys, Benjamin Poulter, Brett M. Raczka, Andrew D. Richardson, Alok Sahoo, Peter Thornton, Rodrigo Vargas, Hans Verbeeck, Ryan Anderson, Ian Baker, T. Andrew Black, Paul(More)
Global estimation and monitoring of plant photosynthesis (known as Gross Primary Production--GPP) is a critical component of climate change research. Modeling of carbon cycling requires parameterization of the land surface, which, in a spatially continuous mode, is only possible using remote sensing. The increasing availability of high spectral resolution(More)
Using a helicopter-mounted portable spectroradiometer and continuous eddy covariance data we were able to evaluate the photochemical reflectance index (PRI) as an indicator of canopy photosynthetic light-use efficiency (LUE) in four boreal forest species during the Boreal Ecosystem Atmosphere experiment (BOREAS). PRI was calculated from narrow waveband(More)
We conducted a root-exclusion experiment in a 125-year-old boreal black spruce (Picea mariana (Mill.) BSP) stand in 2004 to quantify the physical and biological controls on temporal dynamics of the rhizospheric (R(r)) and heterotrophic (R(h)) components of soil respiration (R(s)). Annual R(r), R(h) and estimated moss respiration were 285, 269 and 57 g C(More)