Journal of Geographical Sciences ›› 2012, Vol. 22 ›› Issue (5): 859-873.doi: 10.1007/s11442-012-0968-4

• Ecology and Environment • Previous Articles     Next Articles

Land-use impact on soil carbon and nitrogen sequestration in typical steppe ecosystems, Inner Mongolia

HE Nianpeng1, ZHANG Yunhai2, DAI Jingzhong3, HAN Xingguo2, BAOYIN Taogetao4, YU Guirui1   

  1. 1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, CAS, Beijing 100093, China;
    3. Inner Mongolia Agricultural University, Hohhot 010018, China;
    4. Institute of Natural Resources, Inner Mongolia University, Huhhot 010021, China
  • Received:2011-06-17 Revised:2012-03-22 Online:2012-10-15 Published:2012-10-15

Abstract:

To explore the optimal land-use for soil carbon (C) sequestration in Inner Mongolian grasslands, we investigated C and nitrogen (N) storage in soil and soil fractions in 8 floristically and topographically similar sites which subjected to different land-use types (free-grazing, grazing exclusion, mowing, winter grazing, and reclamation). Compared with free-grazing grasslands, C and N storage in the 0-50 cm layer increased by 18.3% (15.5 Mg C ha-1) and 9.3% (0.8 Mg N ha-1) after 10-yr of grazing exclusion, respectively, and 21.9% (18.5 Mg C ha-1) and 11.5% (0.9 Mg N ha-1) after 30-yr grazing exclusion, respectively. Similarly, soil C and N storage increased by 15.3% (12.9 Mg C ha-1) and 10.2% (0.8 Mg N ha-1) after 10-yr mowing, respectively, and 19.2% (16.2 Mg C ha-1) and 7.1% (0.6 Mg N ha-1) after 26-yr mowing, respectively. In contrast, soil C and N storage declined by 10.6% (9.0 Mg C ha-1) and 11.4% (0.9 Mg N ha-1) after 49-yr reclamation, respectively. Moreover, increases in C and N storage mainly occurred in sand and silt fractions in the 0-10 cm soil layer with grazing exclusion and mowing. Our findings provided evidence that Inner Mongolian grasslands have the capacity to sequester C and N in soil with improved management practices, which were in the order: grazing exclusion > mowing > winter grazing > reclamation.

Key words: carbon, grazing, land-use, nitrogen, reclamation, soil fractions