| Pinus tabulaeformis is the dominant species in the most widely distributed in northern China. The species is resistant to low temperatures, dry conditions and poor soil nutrient status. A 400m2 (20m x20m) plot of natural Pinus tabulaeformis was established in the Ma Chibei area of the Taiyue Mountain in July 2007. According to the data, the spatial distribution pattern of the trees and shrubs in the plot was evaluated using four indexes. And on the base of the important value of the shrubs, useχ2, AC and PC value to study the interspecific association of the shrub species. Finnally, on the base of four season herb data, the dynamic of diversity of the herb wre anylized use diversity indexes. The result showed that:A total of 3561 trees with a DBH≥lcm were recorded in the plot, which includes 35 species, The DBH distribution of Pinus tabulaeformis shows a maximum frquency in the diameter range 28-36cm. Pinus tabulaeformis shows a clumped spatial distribution at three different sampling scales (5mx5m,10m×10m,20 mx20m). The biggest diameter class (d≥44cm) were randomly distributed while others showed clumped. A total of 27 species of shrub in the plot,15 species with the inportant value more then 0.50, the tallest individual were 4.4m, clumped distribution appears on most of the species, multiple pairs and pairs of the species showed a positive correlation of the community.77 herb species were found four seanons together, species with single family and single genus occupied a main part, The distribution of frequency of the species in each season differs little, the species with the frequency of D and E in each season were both Carex duriuscula and Carex lanceolata.The biodiversity of late summer is the highest, with other seasons no obvious difference. The vertical structure of every season were obvious, while compared with each other, the change were not obvious also the difference of horizontal structure is not obvious.
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