关键词: 黄土丘陵区, 油松, 群落特征, 空间格局

Abstract: The community characteristics of natural Pinus tabulaeformis forest distributed in Hilly Loess Regions were investigated. the results showed that were 67 seed plants belonging to 23 families,54 generas.belonged to temperate biome,As regards to the physiognomy of the community Hemicryptophyta made up 75.9% of the total, dominating the community.In the community,96 species with middle-sized leaves made up 57.8%,and there were 139 single leaf species accounted for 83.7% of the total, There was a complicated vertical structure in the community,which could be divided into three layers:Arbor layer,shrub layer and herb layer.In addition,there were also a lot of inter-stratum plants in the community.It is also found that the lack of seedlings,saplings and small trees was due to both the selfthinning caused by intraspecific competition and the alien-thinning by inter-specific competition for the light resource in the stand.The dynamics of the community showed that the community was stable and in a process of development.

Key words: Dioscorea opposita Hilly Loess Regions, Pinus tabulaeformis, community characteristics, spatial distribution pattern