Ecological Distribution and Risk Evaluation of an Alien Plant, Conyza canadensis in Xuchang Suburbs

DONG Dong-ping,WANG Chun-xiao(Department of Urban and Environmental Science,Xuchang University,Xuchang 461000,China)

Xuchang suburbs;alien plant;Conyza canadensis;ecological distribution;damage evaluation

In order to identify the ecological distribution and damage conditions of the alien plant Conyza canadensis in Xuchang suburbs,the field investigation,laboratory analysis and creation of a risk evaluation system are used to study the plant.The results show that Conyza canadensis is widely distributed in the place of no agricultural plants and other bare ground such as the roadside,wasteland,garbage dumps,agricultural side,construction sites,etc,where the density range is 18-110 plants/m2,sequenced as:orchard>wasteland>garbage dumps>nursery>roadside>residential area of town;the coverage range is 10%-90%,and the sequence is:orchard>wasteland>nursery>garbage dumps>roadside>residential area of town;the average plant height is 134 cm,and the highest one is 275 cm;autumn is the most serious season when Conyza canadensis harmed,and in some places such as orchard,wasteland and garbage dumps,etc,it is easy to form a single large area of priority community.According to the analysis of the established damage evaluation index of alien plants,the harm rank of Conyza canadensis is first-level(the hazard risk index R=9.55),showing that it brings serious harm to Xuchang's agricultural production and ecological environment,and it also has some adverse effects on the biodiversity and the social economy.Therefore,prevention and control of Conyza canadensis need to be strengthened.