THE SUCCESSIONS AND INTERACTIONS OF THE RODENT ANDPLANT COMMUNITIES OF ABANDONED FIELDS IN DESERTSTEPPE AT CHAGAN-AOBAO, INNER MONGOLIA
HSIA WU-PING AND CHONG WEN-CHIN(Institute of Zoology, Academia Sinica)
The present paper deals with the successions and interactions of the rodent and plant communities, under a desert steppe condition. Five abandoned fields were selected as samples for study. The first field was abandoned soon after it had been plowed. The others were abandoned for 1-, 2-, 3-, and 4-years. Plants were recorded and rodents were trapped on the fields. The results of observations were as follows.1. The first year after the fields were abandoned was an inhabiting period of the annual plants of which the absolutely dominant species was Salsola collina. The second and third years after abandonment were a period of invading of perennial grasses such as Clistogenes squanosa. In the forth year, the original dominated plants such as some species of Stipa appeared, and the vegetation cover developed gradually toward the climax community.2. The succession of the rodent communities was in the following sequence. The ground squirrel, Citellus dauricus mongolicus was the dominant species in the unplowed grassland, and the gerbil, Meriones unguiculatus increased in number and replaced the position of the ground squirrel as the dominant species after the fields were abandoned. But up to the forth year, the number of ground squirrels began to recover and it was slightly over the number of the gerbils.3. Bioccnologically, we believe that after destroying the community, Stipa spp.-Citellus dauricus which existed before the exploitation of the fields, a new community, Salsola collina-Meriones unguiculatus occured, when the fields were abandoned, then it developed to Salsola collina + Clistogenes squanosa-Meriones unguiculatus + Citellus dauricus community, and lastly recovered to the climax community, Stipa spp.-Citellus dauricus.4. By the activities of the gerbils, many "mosaics" of the vegetation cover had been formed around their borrow colonies. They were characterized by the well-growing Salsola collina and therefore would last the succession process.