Chin J Plant Ecol ›› 2008, Vol. 32 ›› Issue (6): 1301-1311.DOI: 10.3773/j.issn.1005-264x.2008.06.011

• Original article • Previous Articles     Next Articles

EFFECTS ON CARBON FLUX OF CONVERSION OF GRASSLAND STEPPE TO CROPLAND IN CHINA

ZHANG Wen-Li1,2, CHEN Shi-Ping2, MIAO Hai-Xia2, LIN Guang-Hui2,*()   

  1. 1College of Chemistry and Life Science, China Three Gorge University, Yichang, HuBei 443002, China
    2State Key Laboratory Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2008-02-20 Accepted:2008-06-25 Online:2008-02-20 Published:2008-11-30
  • Contact: LIN Guang-Hui

Abstract:

Aims In light of increasing interest in understanding carbon fluxes of terrestrial ecosystems under changing climate and escalating human influences, our study examined the dependence of carbon fluxes on abiotic and biotic factors and explored the effects of conversion of grassland to cropland on ecosystem C fluxes.

Methods Our study was carried out in Duolun (42o02′ N, 116o17′ E; 1 350 m asl), a semiarid agriculture-pasture transition region in southeastern Inner Mongolia, China. We used the chamber method during the growing season.

Important findings There was no difference in net ecosystem exchange of carbon dioxide (NEE) between wheat field and steppe at the beginning of the growing season. NEE of wheat field became higher than that of steppe in late June. No differences were found between the two ecosystems from mid-July to August 1st. NEE of wheat field became significantly lower than that of steppe starting in mid-August. During the growing season, the maximum of NEE in steppe was -11.26 µmol CO 2·m-2·s-1, while that in wheat field was -12.29 µmol CO 2·m-2·s-1. Mean NEE in steppe (-5.33 µmol CO 2·m-2·s-1) was a little lower than that in wheat field (-7.66 µmol CO 2·m-2·s-1). Leaf area index (LAI) was the main factor controlling NEE of the two ecosystems. Poor soil nutrient levels also might limit NEE in these ecosystems. Because of characteristics of wheat, the sensitivity of NEE response to LAIwas lower in wheat field than steppe in the middle and late growing season. Lower soil volume water content (10 cm depth) in wheat field limited total ecosystem respiration (TER) and decreased the sensitivity of TER to temperature.

Key words: chamber method, net ecosystem gas exchange, total ecosystem respiration, leaf area index