The Effects Silvicultural Measures Have On Plant Species Diversity Of Eucalyptus Industrial Forest Plantation In Southern Guangxi

What effects large area of eucalyptus plantation for industrial raw material have on biodiversity has drawn worldwide’s attention. In this study, based on different measures, we selected8forest stands,16sample plots and64quads targetedly and in the method of community survey statistical analysis、α diversity measure and Excel to explore the biodiversity of eucalyptus plantation for industrial raw material in south of Guangxi (the most important eucalyptus industrial forest area in Guangxi), which focus on the change characteristic of biodiversity with different measures. This study provides scientific evidences for maintaining and cultivating the biodiversity of eucalyptus industrial forest. The main results are as follows:(1)There are71families,158genera and207species of wild vascular bundle plants,(including varieties, subspecies, cultivar and variant, similarly hereinafter). Among them, there are8families,9genera and12species of pteridophyte;1family,1genera and1species of gymnosperms;62families,148genera and191species of angiosperm plants(including55families,125 genera and164species Dicotyledonous plants;7families,23genera and27species of monocotyledon plants.)(2)There’re42-62types of plants in every forest stand, according to100m2survey statistics, the species richness is33-48, which is less than the zonal vegetation, but shows little differences.Herbs has the highest degree of importance, which includes Ageratum conyzoides, Bidens pilosa, Dicranopteris linearis and Eupatorium odoratum ect. Among them, Ageratum conyzoides, Bidens pilosa and Eupatorium odoratum are exotic breeds. Only one of the forest stand shows shrubbery as the higher degree of importance, and Litsea glutinosa and Clerodendrum mandarinorum are its main kind.(3)At the beginning of forestations, clearing forestation species diversity of plants in the forest stand is slightly higher than that of the opposite one, which is due to the thoroughly clean-up after the burning. Most seeds gets better conditions in the earth. There are also artificial fertilizations. Therefore, most of the positive herb species take the opportunity to "come swarming", which resulted in a short-term high in species and diversity index. On the other hand, some shrub species suffer from heavy loss in the burning. It disappears gradually after squeezed by the advantage herbs.(4) Between replanting reforestation and sprout regeneration, the latter species diversity was higher than the former, which is due to the comprehensive clean-up in the sprout regeneration plot, where more bush species are preserved. It not only benefits the conservation of water and soil, but also benefits the stability of biodiversity.(5) The use of herbicides does great harm to biodiversity and the soil conditions. Relatively speaking, manual weeding preserves more species resources, which plays a positive role in maintaining species diversity.(6) Compared to large area of concentrated eucalyptus industrial forest plantation, the one with appropriate natural plants as isolation belt has a richer plant species diversity, which is due to the benefits of seeds spreading around the field by birds, insects and wind. It does help maintain the biodiversity greatly.(7) This study explores measures of maintaining the plant species diversity of eucalyptus industrial forest in a forest management way, and puts forward the following suggestions:try not to choose the less artificial methods such as clearing forestation, spout regeneration; preserve natural plant appropriately to avoid large area of concentrated forestation; combine two weeding methods and try to reserve valuable plants for birds.