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Diel and Seasonal Dynamics of Ecosystem‐Scale Methane Flux and Their Determinants in an Alpine Meadow
Author(s) -
Chen Weinan,
Zhang Fangyue,
Wang Bingxue,
Wang Jinsong,
Tian Dashuan,
Han Guangxuan,
Wen Xuefa,
Yu Guirui,
Niu Shuli
Publication year - 2019
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2019jg005011
Subject(s) - eddy covariance , atmospheric sciences , diel vertical migration , environmental science , growing season , seasonality , vapour pressure deficit , canopy conductance , plateau (mathematics) , diurnal temperature variation , sink (geography) , photosynthetically active radiation , canopy , primary production , dry season , ecosystem , climatology , transpiration , ecology , photosynthesis , botany , biology , geography , geology , cartography , mathematical analysis , mathematics
Temporal variations of methane flux (FCH 4 ) and its underlying mechanisms still remain poorly understood. To quantify diurnal and seasonal patterns of FCH 4 and investigate its determinants, we monitored FCH 4 using eddy covariance in an alpine meadow on the Qinghai‐Tibetan Plateau, China, from June 2015 to December 2016. As a strong CH 4 sink, the alpine meadow on the Qinghai‐Tibetan Plateau consumed 0.41 ± 0.04 Tg CH 4 /year. There was an obvious diurnal pattern with more CH 4 uptakes during the nighttime than the daytime for both growing and nongrowing season. The diurnal FCH 4 during the growing and nongrowing season were positively correlated with air temperature (Ta), volumetric water content, friction velocity (u * ), and vapor pressure deficit. The growing season FCH 4 showed a significant quadratic polynomial relationship with the canopy conductance (G w ) and gross primary production). FCH 4 was significantly higher in the growing season than in the nongrowing season. The seasonal FCH 4 was negatively correlated with soil temperature and net radiation (Rn) but not with volumetric water content and gross primary production. Ridge regression models indicated that Ta and u * explained 83% of the variation in the diel dynamics of FCH 4 during the growing season and explained 72% of the variation during the nongrowing season. Rn accounted for 49% of variations of FCH 4 at the seasonal scale. The temporal patterns and the environmental controlling factors revealed in this study may improve model parameterization for biosphere‐atmosphere CH 4 exchange simulation as well as the methane budget estimation.