Species Composition and Spatial Distribution of Ants in the Grassland Region in the West of Jilin Province
吉林西部草原地区蚂蚁种类及分布

The species composition and distribution of ants were investigated on Changling Studhorse Farm in Jilin,located in the south of Songnen Plain where ants were the dominant species among fauna in the soil large-size. The sampling areas were classified into seven categories: grazing-land, old-field, farmland, Populus spp. plantation, country pathway, yard and mowing-grassland. Fourteen of ant species found in these habitats, belonging to 9 genera and 3 subfamilies, were Tetramorium caespitum (L.), Messor aciculatus (Smith), Leptothorax galeatus Wheeler, Pristomyrmex pungins Mayr, Tapinoma gleatus Wheeler, Formica gagatoides (Ruzsky), F. sinae Emery, F. glauca Ruzsky, F. transkaucasica Nasonov, Cataglyphis aenescens (Nylander), Lasius alienus (Foerster), L. fuliginosus (Latreille), L. flavus (Fabricius) and Camponotus japonicus Mayr,among which F. sinae and T. caespitum were the dominant species in all the habitats except mowing grassland. The species of ants was the most in the old-field and the plantation, so was the density of nest outlets, but those in grazing-land and farmland both were the lest. L.alienus, L. flavus and T.caespitum distributed in the mowing grassland and built obvious anthills. The anthill of L.alienus was almost circular with the diameters of 0.85 m and 0.73 m, but that of L.flavus was ovoid with the diameters of 1.04 m and 0.82 m. The anthill density, which was 0.37 anthills per m 2 at the edge of the mowing grassland, significantly decreased from the edge to the center of the mowing grassland, and nearly no anthill was found at the center. The method of the Mean Crowding was used to test the spatial pattern, and it was concluded that the distribution of anthills was aggregative. The main factors limiting the distribution of ants were also discussed.