Abstract
The earth hummock in the Utsukushigahara highlands in central Nagano Prefecture in Central Japan has been a valuable example of this type of rare micro-topography of the mid-latitude. The loss of species from the plant community of the earth hummock as a result of the influence of alien plant species and human activities is of much concern.Because of their ecological value, these plant communities must be conserved. Therefore, the plant communities and the environmental conditions on the hummock and its immediate surroundings were investigated to determine the relationship between community structures and environmental conditions so that conservation strategies could be developed. The results of TWINSPAN analysis showed that the study area contained mainly two community types and that the species identified could be classified into nine species groups. The height of the representative community type on the earth hummock was higher than that of the community type of the surrounding area. Soil moisture percentage and the amount of snow cover in the hummock were lower than in the surrounding area. The results suggest that alien plant species were able to invade and become established in the representative community type on the earth hummock as a result of these characteristic environmental conditions.
