干旱区生态环境知识资源中心

A better understanding of the responses of various ecosystem CO2 fluxes to human activity is vital for restore degraded grasslands and mitigating global warming. However, still undefined how CO2 exchanges (e.g. net ecosystem carbon exchange, NEE; gross ecosystem productivity, GEP and ecosystem respiration, ER) will respond to the fenced and grazed at a meadow steppe northwest of China. Base on an infrared gas analyzer linked to a clear plexiglass incubation chamber, we conducted an experimental study to examine effects of fenced meadow (from 2005 to now) on NEE, GEP and ER over the growing seasons from 2012 to 2015. Results showed that net carbon up take was found in all treatments in four years, with the NEE ranging from 3.96 to -0.01 mu mol/(m(2).s), the cumulative values were -105.73 +/- 20.80 and -99.28 +/- 18.43 g C/ (m(2).yr) for fenced and grazed meadows, respectively. Compare with grazed meadow, fenced meadow significantly increased (P<0.05) NEE (5%, 10%, 7% and 9% from 2012 to 2015, respectively) could primarily be attributed to greater stimulation of GEP than ER. These results suggested that fenced meadow prevails over grazed meadow in maintaining carbon balance in arid and semi-arid grasslands.