Invasive Risk Assessment Of Herbaceous Ornamental Plants In Parks In Chongqing

Ornamental plants are a huge pool of potential invasive alien species,and herbaceous plants are one of the main components of ornamental plants.Therefore,it is of great significance to assess the invasive risks of herbaceous ornamental plants.In this study,we selected the parks in Chongqing that are mainly composed of ornamental plants,and the investigated their herbaceous ornamental plants composition.Then we extracted plant invasion related indicators from existing studies for risk assessment.According to plants’ responses,including invasive and non-invasive plants,to the selected indicators,we screened those invasion risk assessment indicators for herbaceous ornamental plants in parks in Chongqing.And then we established Chongqing herbaceous ornamental plants invasion risk assessment models.By assessing the invasive risks of exotic herbaceous ornamental plants in Chongqing with our established model,we screened out species with high invasive potential.Finally,combined with the global distribution data of highly invasive potential species and climatic and geographical factors,we simulated the species suitable areas then predict the invasion risk of herbaceous ornamental plants in different areas of Chongqing park.The results showed that:(1)There were 245 species of herbaceous ornamental plants in Chongqing parks belonging to 56 families and 161 genera,of which 48.6% were alien species.There was a high planting frequency of exotic species in parks in Chongqing,and Americas is the main origin of exotic herbaceous ornamental plants in our investigated parks.(2)The invasive risk assessment models of herbaceous ornamental plants included11 indicators from three aspects: the history of invasive/naturalization,climate and distribution,and colonization and spread.The overall accuracy of the model is 96.7%,with the assessment accuracy of invasive plants and non-invasive plants being 100%and 94.1%,respectively.The area under the ROC curve is 0.892,indicating that the models had a good evaluation efficiency and a high evaluation accuracy for both invasive and non-invasive plants.(3)Forty-four of the herbaceous ornamental plants in parks in Chongqing had high invasive potentials,and the main species with high invasive potential were Compositae and Gramineae.Tagetes erecta,Thalia dealbata,Canna glauca,Cortaderia selloana,Iris pseudacorus and Begonia cucullate had high planting frequency in parks in Chongqing.(4)Of the 44 species with high invasion potential,16 species had more than 10%habitats in Chongqing,among which Tagetes erecta,Thalia dealbata and Iris pseudacorus had high invasion risk in most areas of Chongqing.(5)35.9% of Chongqing municipality was threatened by more than 10 species with high invasion potential,among which the most species of suitable species were found in Wuling mountain town cluster of south eastern Chongqing.However,considering the planting frequencies of species with high invasion potential,the invasion risk of park herbaceous ornamental plants is greater in the main metropolitan area than in the rest of areas.So we suggested to reduce the application of high invasive potential species in urban greening.