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Chinese Journal of Applied Ecology ›› 2017, Vol. 28 ›› Issue (11): 3663-3674.doi: 10.13287/j.1001-9332.201711.029

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Flux footprint of winter wheat farmland ecosystem in the North China Plain

WU Dong-xing1, LI Guo-dong1,2*, ZHANG Xi1   

  1. 1 College of Environment and Planning, Henan University, Kaifeng 475004, Henan, China
    2 Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, Ministry of Education, Kaifeng 475004, Henan, China
  • Online:2017-11-18 Published:2017-11-18
  • Contact: *mail:liguodonghd@163.com
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (U1404401), Henan Province University Scientific and Technological Innovation Team Support Project (161RTSTHN012), Henan University Resource and Environment Research Institute Project (HD-ZHS-201403) and Henan University Emerging Intersect and Characteristic Subject Breeding Project (XXJC20140003)

Abstract: The flux data of winter wheat farmland ecosystem observed by eddy covariance system in the North China Plain from 2013 to 2014 were used to combine with the footprint model FSAM. The temporal and spatial distributions of footprint of winter wheat farmland ecosystem in the North China Plain were analyzed. The differences of footprint distribution in different atmospheric stratification and growing seasons were contrastively studied. The results indicated that in the predominant wind direction, the source areas of stable atmospheric stratification were larger than unstable atmospheric stratification during the growing season of winter wheat. When the wind direction was between 0°-90°, the source area of stable atmospheric stratification was about 17.8 m longer than unstable atmospheric stratification in initial growing season. The source area of stable atmospheric stratification was about 11 m longer than unstable atmospheric stratification in late growing season. The location of the maximum flux footprint in initial growing season was 15 m (stable atmospheric stratification) and 12.4 m (unstable atmospheric stratification) further away from the observing tower than late growing season, respectively. Meanwhile, the location of the maximum flux footprint in stable atmospheric stratification was 5 m (initial growing season) and 2.4 m (late growing season) further away from the observing tower than unstable atmospheric stratification, respectively. When the wind direction was non-dominant between 90°-180°, the location of the maximum flux footprint in diffe-rent growing seasons and atmospheric stratification were 67.8 and 53.4, 47.0 and 30.8 m away from the observing tower, respectively. When the wind direction was between 270°-360°, the location of the maximum flux footprint in different growing seasons and atmospheric stratification were 58.8 and 42.0, 41.1 and 33.1 m away from the observing tower, respectively. The flux information was mainly from the northeast, southwest and southeast, which accounted for 35.4%, 32.5% and 19.4% of the whole gro-wing season scale, respectively. The major changes of flux footprint in the whole gro-wing season of winter wheat were observed from 16.0 to 173.8 m in the northeast and from 14.7 to 209 m in the southwest. The flux information was all from the farmland ecosystem. The characteristics of diurnal variations of flux footprint in two typical dates were obvious. The source area changed with atmospheric stratification and wind direction. The flux information was all from farmland ecosystem at night, while little flux information was from residential area and orchard at daytime. The quantitative results of this study could provide basis for the research of flux footprint in farmland ecosystem.