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FLUXNET is a global network of micrometeorological flux measurement sites that measure the exchanges of car­ bon dioxide, water vapor, and energy between the biosphere and atmosphere. At present over 140 sites are operating on a long-term and continuous basis. Vegetation under study includes temperate conifer and broadleaved (deciduous and evergreen)(More)
Volcanic aerosols from the 1991 Mount Pinatubo eruption greatly increased diffuse radiation worldwide for the following 2 years. We estimated that this increase in diffuse radiation alone enhanced noontime photosynthesis of a deciduous forest by 23% in 1992 and 8% in 1993 under cloudless conditions. This finding indicates that the aerosol-induced increase(More)
The Farquhar-von Caemmerer-Berry (FvCB) model of photosynthesis is a change-point model and structurally overparameterized for interpreting the response of leaf net assimilation (A) to intercellular CO₂ concentration (Ci). The use of conventional fitting methods may lead not only to incorrect parameters but also several previously unrecognized consequences.(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)
Studies with the variable J method have reported that mesophyll conductance (gm ) rapidly decreases with increasing intercellular CO2 partial pressures (Ci ) or decreasing irradiance. Similar responses have been suggested with the online isotope discrimination method, although with less consistency. Here we show that even when the true gm is constant, the(More)
Jingfeng Xiao ⁎, Qianlai Zhuang , Beverly E. Law , Jiquan Chen , Dennis D. Baldocchi , David R. Cook , Ram Oren , Andrew D. Richardson , Sonia Wharton , Siyan Ma , Timothy A. Martin , Shashi B. Verma , Andrew E. Suyker , Russell L. Scott , Russell K. Monson , Marcy Litvak , David Y. Hollinger , Ge Sun , Kenneth J. Davis , Paul V. Bolstad , Sean P. Burns ,(More)
Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate–carbon cycle feedbacks. However, directly observed relationships between climate and terrestrial CO2 exchange with the atmosphere(More)
Christopher R. Schwalm, Christopher A. Williams, Kevin Schaefer, Ryan Anderson, M. Altaf Arain, Ian Baker, Alan Barr, T. Andrew Black, Guangsheng Chen, Jing Ming Chen, Philippe Ciais, Kenneth J. Davis, Ankur Desai, Michael Dietze, Danilo Dragoni, Marc L. Fischer, Lawrence B. Flanagan, Robert Grant, Lianhong Gu, David Hollinger, R. César Izaurralde, Chris(More)
Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or(More)
Micrometeorological measurements of nighttime ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used(More)