Microclimate and CO2 fluxes on continuous fine days in the Xihu desert wetland, China
QianQian GOU1,2,3*, JianJun QU1,2, ZhiWen HAN1
1 Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; 2 Dunhuang Gobi and Desert Ecology and Environment Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Dunhuang 736200, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China
Microclimate and CO2 fluxes on continuous fine days in the Xihu desert wetland, China
QianQian GOU1,2,3*, JianJun QU1,2, ZhiWen HAN1
1 Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China; 2 Dunhuang Gobi and Desert Ecology and Environment Research Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Dunhuang 736200, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China
摘要 The Xihu desert wetland is located in an extremely arid area in Dunhuang, Gansu province of Northwest China. The area is home to an unusual geographic and ecological environment that is considered unique, both in China and the world. Microclimate is not only related to topography, but is also affected by the physical properties of underlying ground surfaces. Microclimate and CO2 flux have different characteristics under different underlying surface conditions. However, until now, few studies have investigated the microclimate characteristics and CO2 flux in this area. The eddy covariance technique (ECT) is a widely used and effective method for studying such factors in different ecosystems. Basing on data from continuous fine days obtained in the Dunhuang Xihu desert wetland between September 2012 and September 2013, this paper discussed and compared the characteristics of daily microclimate variations and CO2 fluxes between the two periods. Results from both years showed that there was a level of turbulent mixing and updraft in the area, and that the turbulent momentum flux was controlled by wind shear under good weather conditions. The horizontal wind velocity, friction wind velocity and vertical wind velocity were commendably consistent with each other. Air temperature in the surface layer followed an initial decreasing trend, followed by an increasing then decreasing trend under similar net radiation conditions. With changes in air tem-perature, the soil temperature in the surface layer follows a more obvious sinusoidal fluctuation than that in the subsoil. Components of ground surface radiation during the two study periods showed typical diurnal variations. The maximum diurnal absorption of CO2 occurred at around 11:00 (Beijing time) in the Xihu desert wetland, and the concentrations of CO2 in both periods gradually decreased with time. This area was therefore considered to act as a carbon sink during the two observation periods.
Abstract: The Xihu desert wetland is located in an extremely arid area in Dunhuang, Gansu province of Northwest China. The area is home to an unusual geographic and ecological environment that is considered unique, both in China and the world. Microclimate is not only related to topography, but is also affected by the physical properties of underlying ground surfaces. Microclimate and CO2 flux have different characteristics under different underlying surface conditions. However, until now, few studies have investigated the microclimate characteristics and CO2 flux in this area. The eddy covariance technique (ECT) is a widely used and effective method for studying such factors in different ecosystems. Basing on data from continuous fine days obtained in the Dunhuang Xihu desert wetland between September 2012 and September 2013, this paper discussed and compared the characteristics of daily microclimate variations and CO2 fluxes between the two periods. Results from both years showed that there was a level of turbulent mixing and updraft in the area, and that the turbulent momentum flux was controlled by wind shear under good weather conditions. The horizontal wind velocity, friction wind velocity and vertical wind velocity were commendably consistent with each other. Air temperature in the surface layer followed an initial decreasing trend, followed by an increasing then decreasing trend under similar net radiation conditions. With changes in air tem-perature, the soil temperature in the surface layer follows a more obvious sinusoidal fluctuation than that in the subsoil. Components of ground surface radiation during the two study periods showed typical diurnal variations. The maximum diurnal absorption of CO2 occurred at around 11:00 (Beijing time) in the Xihu desert wetland, and the concentrations of CO2 in both periods gradually decreased with time. This area was therefore considered to act as a carbon sink during the two observation periods.
This work was supported by the National Science-technology Support Plan Projects “Key Techniques Research and Demon¬stration of Ecological Remediation of Dunhuang” (2012B-AC08B07). We sincerely thank Prof. JieMin WANG for his contribution during the data processing.
引用本文:
QianQian GOU, JianJun QU, ZhiWen HAN. Microclimate and CO2 fluxes on continuous fine days in the Xihu desert wetland, China[J]. 干旱区科学, 2015, 7(3): 318-327.
QianQian GOU, JianJun QU, ZhiWen HAN. Microclimate and CO2 fluxes on continuous fine days in the Xihu desert wetland, China. Journal of Arid Land, 2015, 7(3): 318-327.
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