| It's a strong correlation between forest structure and forest function. The stand structure is appropriate or not relates directly to if it could fully play function in forest ecological benefit, economical benefit and social benefit. This paper was carried out surveys on orientalis forest plantations of limestone mountain in Xuzhou. The stand structure and species diversity were analyzed, and thinning and gap disturbance effects on forest structure were studied. At last, the best density of Platycladus orientalis in Xuzhou was discussed. The main research results are as follows:(1) There are 89 species of vascular plants of Plantations orientalis in Xuzhou, belonging to 82 genera,46 families. The species diversity was lower in tree layer and shrub layer, and higher in herb layer. Diameter structure is the single-peak gaussian distributions, typical of pure forest distribution of the diameter of the structure. Different small places the diameter rank distribution were different, species diversity of shrub layer and herb layer also varies greatly.(2) Thinning can significantly improve the understory plant species diversity. The species, Margalef index, Simpson index and Shannon-Weiner index both in the twice thinned plots and once thinned plots were significantly higher than not thinned plots.(3) The height of boundary trees of forest gaps is slightly lower than trees in forests, but the DBH is significantly greater. The forest gaps in Platycladus orientalis had an important role in the update of the understory plant. Diversity of species in gaps was significantly higher than the forest.(4) The existing density of Platycladus orientalis stand is between 725 plants/ha to 3,475 plants/ha.The reasonable Xuzhou density of Platycladus orientalis stand should be between 2325 plants/ha to 3,225 plants/ha.In order to increase stability of Platycladus orientalis in Xuzhou, it's proposed to thin and open gaps in larger density forests, the initial intensity should be controlled in 10-30%. |
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