[Community characteristics of Pinus armandi forest on Qinling Mountains]

The community characteristics of Pinus armandi forest distributed on the mid-west zone of Qinling Mountains' south slope were investigated. The results showed that there were 166 seed plants belonging to 51 families, 111 generas. Among them, 65 genera, 66.7% of the total, belonged to temperate biome. There was a closely relationship between Pinus armandi forest and the temperate biome. As regards to the physiognomy of the community, phanerophyte 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 population of P. armandi was characterized with the patch size about 100 m2. The dynamics of the community showed that the community was stable and in a process of development.