Abstract:

Characteristics of soil carbon and nitrogen of Stipa bungeana community, Artemisia ordosica community, Cynanchum komarovii community and weeds community Erdos, Inner Mongolia were studied. There were no significant seasonal differences of organic carbon content in 0～10, 10～30 and 30～60cm soil depths of all plant communities. The seasonal differences of total nitrogen in 0～10 and 10～30cm soil depths of all communities were significant, the content in May was higher than that in Jul. and Sept. and the difference between Jul. and Sept. was not obvious. Seasonal differences of nitrate nitrogen content in 0～10cm soil depths of communities were significant, and the content in May was higher than that in Jul. and Sept. Seasonal differences of ammonium nitrogen content of all soil layers were significant in all communities, and the content in May was higher than that in Jul., then higher than that in Sept. The vertical distribution of organic carbon and total nitrogen contents in different soil depths of all communities were similar in different seasons. That was decreased with the soil depths. However, there were no vertical distribution trends of the nitrate and ammonium nitrogen contents in all four community soils in different seasons, only the nitrate nitrogen content in 0～10cm soil was higher than that in other soil layers in May. Although some of the differences of organic carbon contents in all soil layers in different seasons among plant communities were significant, most of the differences of total nitrogen contents in 0～10cm soil among communities were significant, and the differences of nitrate and ammonium nitrogen contents in all soil layers in May and Jul. among the communities were more significant, there were no obvious trends about these differences among them.

Key words: Plant community types, Soil, Characteristics of carbon, nitrogen, Erdos