Investigation On Alien Plants And The Risk Of Invasion In The Three Urban Wetland Parks

In recent years,the construction of urban landscape architecture pursues “new” and “rare”.Wide range of plant introduction,garden plants exchanges are very frequent.Moreover,introduced a large number of alien plants has brought a great risk of invasion.Changsha also faces the same situation and huge challenges.Researching on alien plant surveys and invasion risks in the three urban wetlands parks(Xihu Park,Yanghu Wetland Park,Songyahu Wetland Park)of Changsha,not only can accurately understand the background information of alien plants in urban wetland park of Changsha,but also provide scientific methods and basic data for in-depth study of the invasion risk of alien plants in wetland parks.It can strengthen the prevention and control and scientific management of alien invasive plants and promote the sustainable development of ecological civilization construction and economic construction of Changsha.This study showed the following main results:1.Species composition of alien plants and alien invasive plants:There are 117 species of alien plants in the three urban wetland parks of Changsha,involving 49 families and 96 genera.Most of these plants are Compositae(22 species),Leguminosae(10 species)and Gramineae(8species)plants,There are 40 species of invasive alien plants in the three urban wetland parks(17 families,32 genera and 37 species of them are in Xihu Park;16 families,29 genera and 35 species are in Yanghu WetlandPark;15 families,30 genera and 37 species are in Songyahu Wetland Park.)of Changsha,involving 17 families and 33 genera.Analysis of the origin,distribution type,life style and introduction route of 40 alien invasive plants.Among these alien invasive plants,most of them are originated from the Americas,accounting for 70.00% of the total number,mostly herbaceous,reaching 38 species,accounting for 95.00% of the total species,ubiquitous in the world and the pantropical region(14 families),most of which are introduced as green ornamental plants.2.Invasive trait analysis of alien plants:Analyzes 25 traits related to invasion ability basing on the results of the field investigation,and selected 8 characteristic indicators,which can be used to predict the invasiveness of alien plants.Provide scientific basic data for construction invasive risk assessment systems of alien plants in Changsha.3.Construction of alien plant risk assessment system:Used the Analytic Hierarchy Process(AHP)to construct a multi-level and multi-index risk assessment system for alien plants in the three urban wetland parks of Changsha,which has strong operability.The result shows that 40 of them are of high risks of invasion,12 of them are of medium risks of invasion,65 of them are of low risks of invasion.It can be seen that the invasive risk of alien plants in wetland parks of Changsha is very high,which requires high attention of relevant departments.Besides,some alienplants are currently not included in the list of alien invasive plants,such as Pontederia cordata,Cortideria selloana,Glandularia tenera and Oenothera speciosa are also have the potential of invasion,which cannot be ignored.It needs to be strengthened management to prevent problems before they occur.