Abstract: Liugujian Nature Reserve (LNR hereafter) is a vital part of middle subtropical vegetational zone in the mountainous region in South Anhui. It is an inartificial species gene store, with 994 species of seed plants in 529 genera of 134 families and 35 rare conserved plants. The floristic elements, whose origin is ancient, are complex, with many ancient families and genera as well as many relic species. Many southern and northern floristic components are found in LNR, which shows that it is a transitional region, and the vertical and horizontal vicarism is obvious. According to the geographic distribution of 529 genera, they can be categorized into 14 distribution types, which shows the flora is correlated widely with that of the world. The ratio of R/T is 0.70, with 56.9% temperate elements and 40.0% tropical elements, so it is slightly higher than that in Huangshan Mountain (0.57), Qingliangfeng (0.53) as well as Tiantangzhai (0.51), and is similar to that in Qiyun Mountains (0.77), which shows there exists higher tropical character than that in Huangshan Mountain, Qingliangfeng, Tiantangzhai, and has similar character to Qiyun Mountains. The vertical zonation of vegetations is conspicuous, and the vegetations from base belt to top belt are arranged in turn as follows: agriculture-cultivated belt (below the elevation of 700 m), mixed evergreen-deciduous broadleaved forest belt (700~1 100 m), deciduous broadleaved forest belt (1 100～ 1 300 m), mountain shrubbery belt (1 300～1 500 m) and alpine meadow belt (above 1 500 m), among which the typical vegetation is mixed evergreen-deciduous broadleaved forest belt, whose diversity indices are as follows: Simpson index is 8.82±2.70，Shannon-Wiener index is 2.62±0.27，PIE index is 0.88±0.05 and evenness index is 0.78±0.07, which shows that the species diversity of the community is rich, with uniform species distribution and stable structure. Based on the ordination of PCA, 21 floras are grouped into South China, East China and North China flora, respectively. In order to protect and restore the evergreen broadleaved forest, middle subtropical evergreen-deciduous broadleaved forest and some rare, endangered plants such as Pseudotsuga gaussenii, et al. more efficiently here, some protection measures are proposed in present paper.

Key words: Liugujian, seed plants diversity, flora, PCA, protection strategy