Characteristics of Carbon Flux in Sandy Grassland Ecosystem under Natural Restoration in Horqin Sandy Land
CHEN Yinping
,
NIU Yayi
,
LI Wei
,
LI Yuqiang
,
GONG Xiangwen
,
WANG Xuyang
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School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730000, Gansu, China;Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China;University of Chinese Academy of Science, Beijing 100049, China;Northwest Agriculture and Forestry University, Yangling 712100, Shaanxi, China
The characteristics of net ecosystem CO2 exchange (NEE) at different time scales were investigated in sandy grassland ecosystem under natural restoration in Horqin Sandy Land, based on the year-round (1 January 2017~31 December 2017) eddy covariance system. The results showed that:1) The monthly mean diurnal variation of NEE changed apparently with a single peak curve; there were obvious absorption peaks during the growing season (from May to September) while obvious release peaks during the non-growing season (from October to April). At the seasonal scale, the absorption peak and the release peak appeared alternately; the growing season was a carbon sink (with a net CO2 absorption of 202.11 g·m-2), whereas a carbon source for non-growing season (with a net CO2 release of 298.13 g·m-2). The annual carbon budget of the sandy grassland ecosystem showed a carbon source, with a net CO2 release of 96.02 g·m-2·a-1. 2) The NEE was significantly (P < 0.01) negatively linearly related to the temperature (both air and soil temperatures) during the growing season, but on the contrary during the non-growing season. However, the NEE was significantly (P < 0.01) positively linearly related to the soil water content during both the growing and non-growing seasons. The temperature and soil water content had significant synergistic effect on NEE.