Primary Study On Biological Characteristics And Distribution Of Alien Invasive Plants In Yunnan

The harmful effects caused by alien invasive plants are becoming wider because of the global warming and human interference in Yunnan.It is an effective measure to reduce the invasion risk of plants in Yunnan by studying their biological characteristics and then propose the control ways of management.We found 247 alien invasive plants under 149 genera which belonging to 51 families in the study based on literatures.database and specimen records,etc.We analyzed the main biological characteristics of these alien invasive plants including their life form,reproduction type,mode of clonal reproduction,flowering and fruit time,length of flowering,color of flower,propagule type,color.shape,sizes,surface structures and other appendages of propagule.The results show that the dominant families are Composite,Gramineae and Leguminosae.More than half of the alien invasive plants originated from America.The annual or short-lived perennial herb,using seed to reproduct,tiller,flowering and fruit time is concentrated in summer and autumn,short flowering and special diaspores characteristics are the dominant representation of biological characteristics of alien invasive plants in Yunnan.Kunming,Xishuangbanna,Yuxi.Honghe and Pu'er have the largest distribution species of alien invasive plants among the 16 prefectures in Yunnan Province.Among the 129 counties in Yunnan Province,Panlong,Jinghong,Mengla,Xishan and Wuhua have more species number of invasive plants than others.Annual mean Average T emperature(AAT),Annual mean Precipitation(AP),Longitude(LGD)and Latitude(LTD)are the major environmental factors affecting the distribution of the alien invasive plants,and negative correlation between alien invasive plants and latitude and longitude.The major social and economic factors related to the species distribution of the alien invasive plants are Gross Domestic Products by Region(GDP)and Total Population(TP),and significant positive correlation between alien invasive plants and GDP.When analyzed on the basis of eight flora distribution regions,most alien invasive plants are at region ?(representive of southwestern Yunnan)and region V(central Yunnan).Ageratina adenophorum and Bidens pilosa were present in 129 counties ofYunnan Province.Pharbitis purpurea,Conyza canadensis,Galinsoga parviflora,and Solanum khasianum are also relatively wider spread species in the county level.We made the fields surveys at the campuses of Yunnan University,Yunnan Normal University and Changshui International Airport in Kunming in order to verify the composition and distribution of Yunnan's alien invasive plants.The results in these sites show the high similar characters with that of the provincial level.The problems caused by alien invasive plants in Yunnan is very serious with the increase of disturbance.It is important to reduce the impact of plant invasion by understanding the biological characteristics and distribution of alien invasive plants in Yunnan,and the ways for the management of the invasive plants is also proposed through this study.