Study On The Controlling Factors To Alien Species In Invade And Settle Stage

Alien species would directly endanger terrestrial, freshwater and marine ecosystems, and make the irreversible loss of the biodiversity. At present, a large number of successful invasion of alien species in China, and cause huge economic losses. However, the mechanisms that underlie invasiveness are still not well explained. Therefore, to in-depth study the mechanism for invasion of alien species is very necessary. This will help us improve our ability to predict and control potentially invasive species.In this paper, we studied the germination, plant growth dynamics, biomass allocation between alien-native species, as well as the seasonal dynamics of invaded community by control trial in initial stage of sub-tropical secondary forests. We analyzed the differences between topography, light, community biodiversity on the impact of invasive herb. We also studied alien species'adaptability under different dominance of dominant species as well as nitrogen and disturbance levels in community. The objective of this research was to explore which factor play a major influence, in the initial stage of alien species invade The results are as follows:1. There are 281 species in total in Xingangshan, belonging to 87 families, usually the 5 species:Woodwardia japonica, Rubus hirsutus,Dicranopteris pedata, Pteridium aquilinum var. latiusculum, Miscanthus jloridulus are dominant species in the herb layer, and have the biggest coverage。It represent the initial stage of sub-tropical secondary forests after cultivated. The detrended corres pondence analysis (DCA) shows species tend to distribute in the low-altitude, low-intensity light area.2. Over time, species diversity within subplot to be rising, seeds adding will reduce the original species diversity in communities. The exotic sustained by seed germination, the important value of the rise. Correlation between adding species and coverage, number of species in communities mostly negative; to the community diversity are usually positively, which shows an new species into the community can increase the diversity, although but there is a inhibition of species within the community. In response to environmental differences, different alien species differences in the adaptation to the environment; in the Biomass allocation, the alien plants will be more resources to support the growth of trophic structures in the community with high coverage with local species differences.3. The native dominant species in community would play growth inhibition to the alien plant. The dominant species within the community are inclined to give priority to resources for the trophic structure of the growth, reduce nutrient for breeding expenditure, which is conducive to compete for more light resources. Compared with native species, the exotic species are a significant reducing reproduction costs when resource use in the pressure.