The Investigation And Construction Of Risk Assessment System For Alien Plants In Southern Of Hunan

With the high speed of increasing integration of global economy,international trade and tourism industry,the alien plant invasion in China is becoming more and more common,and the harm caused by it is more and more serious.Southern Area in Hunan is also facing the same situation and with the huge challenge of alien species invasion.To carry out the investigation of alien plants in southern Hunan and to establish in exotic plants in the region of invasive risk assessment system is necessary to find out the species and the distribution of alien plant,strengthen prevention and scientific management of invasive alien plant so that the promotion of the ecological and sustainable development of economic construction in southern area,Hunan can be guaranteed,which has important significance.This study obtained the following conclusions:1.The Species CompositionRecording 91 species of alien plants in southern Hunan province,belonging to 71 genera and 30 families,which Compositae(17 species),Leguminosae(13 species),Amaranthaceae(8 species)and Gramineae(8 species),etc families have more species,which were formed the main part of alien plants in southern Hunan.The distribution area types of genus,life style,and country of origin of 91 alien plants were analyzed.The results showed that alien plants in southern Hunan,the number of herbaceous species was the most,79 species,accounting for 86.81%of the total number of alien plants in the region.Most species are native to the Americas(66 species)and Europe(12 species)which are accounted for 85.71%of the total number of species;tropic distribution genera(40 genus)occupy obvious advantages,accounting for 70.16%of the total number of genus of alien plants in the region.2.Construction of Risk Assessment System for Alien PlantsThis study adopts multi index comprehensive evaluation method and constructs on the alien plants in southern Hunan in multi levels and multi index system of risk assessment,The assessment system consists of four primary index,13 secondary indicators,39 three-level index(operation index)and each index weights are given assignments and definitions,with strong operability.3.The Division of Risk Hierarchy of Alien Plants Invasion Based on the risk assessment system,the risk assessment of 91 species of alien plants in southern Hunan can be evaluated.According to the assessment results,91 species of alien plants(in southern Hunan)risk is divided into three grades:grade Ⅰ(high risk)60-100 points,grade II(have a certain risk)40-59 points,grade Ⅲ(low risk)0-39 points,and the appropriate risk level is given the corresponding management strategies.In these alien plants,there are 12 kinds of grade Ⅰ,there are 48 kinds of grade Ⅱ,and 31 kinds of grade Ⅲ.4.New Records of Alien PlantsThis study found that there are seven species of new record alien plants in Hunan,which are according to the alien plants in southern Hunan,field survey and literature review.They are namely Nasturtium officinale(Cruciferae),Gaura parviflora(Onagraceae),Myriophyllum aquaticum(Haloragaceae),Thalia dealbata(Marantaceae),Passiflora foetida(Passifloraceae),Silphium perfoliatum(Compositae)and Lantana camara(Verbenaceae).