scholarly journals Evaluation of cropland maximum light use efficiency using eddy flux measurements in North America and Europe

2011 ◽  
Vol 38 (14) ◽  
pp. n/a-n/a ◽  
Author(s):  
Tiexi Chen ◽  
Guido R. van der Werf ◽  
A. J. Dolman ◽  
M. Groenendijk
2012 ◽  
Vol 118 ◽  
pp. 60-72 ◽  
Author(s):  
Chaoyang Wu ◽  
Jing M. Chen ◽  
Ankur R. Desai ◽  
David Y. Hollinger ◽  
M. Altaf Arain ◽  
...  

2020 ◽  
Author(s):  
Xiaolan Li ◽  
Xiao-Ming Hu ◽  
Changjie Cai ◽  
Qingyu Jia ◽  
Yao Zhang ◽  
...  

<p>CO<sub>2</sub> fluxes and concentrations are not well understood in Northeast China, where dominant land surface types are mixed forest and cropland.  Here, we analyzed the CO<sub>2</sub> fluxes and concentrations using Eddy Covariance (EC) measurements, satellite observations, and the Weather Research and Forecasting model coupled with the Vegetation Photosynthesis and Respiration Model (WRF-VPRM).  We also used WRF-VPRM outputs to examine CO<sub>2</sub> transport/dispersion, and to quantify the biogenic and anthropogenic contributions to atmospheric CO<sub>2</sub> concentrations.  Finally, we investigated the uncertainties of simulating CO<sub>2</sub> fluxes related to four VPRM parameters (including maximum light use efficiency, photosynthetically active radiation half-saturation value, and two respiration parameters) using offline ensemble simulations with randomly selected parameter values.  The results indicated that mixed forests acted as a larger CO<sub>2</sub> source and sink than rice paddies on average in 2016 due to a longer growth period and stronger ecosystem respiration, although the minimum EC-measured daily mean net ecosystem exchange (NEE) was smaller at rice paddy (-10 μmol m<sup>-2</sup> s<sup>-1</sup>) than at mixed forest (-6.5 μmol m<sup>-2</sup> s<sup>-1</sup>) during the growing season (May through September).  The monthly fluctuation of column-averaged CO<sub>2</sub> concentrations (XCO<sub>2</sub>) exceeded 10 ppm in Northeast China during 2016.  Biogenic contribution (large negative in summer and insignificant in other months) offset about 70% of anthropogenic contribution of XCO<sub>2</sub> in this region.  WRF-VPRM modeling successfully captured seasonal and episodic variations of NEE and CO<sub>2</sub> concentrations, however, the NEE in mixed forest was overestimated during daytime, mainly due to the uncertainties of VPRM parameters, especially maximum light use efficiency.</p>


2014 ◽  
Author(s):  
Kanako Muramatsu ◽  
Shinobu Furumi ◽  
Noriko Soyama ◽  
Motomasa Daigo

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