The Invasion Mechenisms Of Phytolacca Americana Linn. And Its Control Techniques In Sandy Coastal Shelter Forests

Invasion has done a lot harm to the biodiversity, it is a global environment problem. Our objective was to reveal the influence and mechanism of reproduction and dispersal of Phytolacca americana Linn., in order to provide guidance for controlling its ecological invasion effectively.we conducted field surveys under the Robinia pseudoacacia forest, Pinus thunbergii forest, mixed forest,Amorpha fruticosa shrubs in Lingshan Bay National Forest Park. There were 5 transects be established at 15m interval from forest edge to interior. One-way ANOVA was used to test the diversity. P. americana Linn. was the most serious in R. pseudoacacia L. forest. it was more serious on forest edge than interior in all sites. Dominant herbages were changed by invasion. The herbage diversity showed a decreasing trend according to the invasive degree.The quantities of seed ranged from 596 to 1987 seeds per square meter in four type forests, and decreased from forest edge to interior. Its seeds has long dormant period, and low natural germination rate, which would increase obviously under artificial treatment.The seed rain began in the middle of September, and ended in late December, and it occurred on forest edge was prior to that of forest interior besides Amorpha fruticosa shrubs. There were 2 seed rain peaks at the end of October and the middle of December.The seed rain was 984 seeds per square meter in the R. pseudoacacia L. forest, and they were account for 43.34%, 42.41%, 45.87% in other sites respectively, which decreased from forest edge to interior. There was a decreasing trend of dispersal distance of seed rain from edge to interior, together with the seed rain deceased with the distance increasing from its mother plant. The maximal dispersal and average weighted mean distances ranged from 150 to 210 and 59.3 to 81.0 centimeters.The seeds were widely dispersed in the forest soil, which ranged from 699.3 (P. thunbergii forest) to 2082.7 (R. pseudoacacia L. forest) seeds per square meter. Its seed densities in soil bank showed a decreasing trend from forest edge to interior. In vertical space, all seeds were distributed within top 5 cm in depth, in which, that of 0～2 cm level was most abundant, that of litter layer was in the next place. Many seeds were vigorous in different soil depth.P. americana Linn. has obvious allelopathic effect on other plants, the effect on germination rate and speed was more and more intensified with its concentration increasing. In the same consistency, the effect of P. americana Linn. leaf was higher than that of root, its stem was the weakest.Mowing and spraying quizalofop-p-ethyl, paraquat can reduce the seeds output to some extent, however P. americana Linn. was died out by removing top root of and spraying glyphosate, the two methods can control its invasion fleetly and effectively.The study revealed the invasion mechanisms of P. americana Linn., which were referential for predicting the invasive potential. It provided a guidance for controlling its ecological invasion effectively. The findings were important for restraining its dispersal, reducing or eliminating the harm.