Study On The Ecological Characteristics Of Invasion Species Eupatorium Adenophrum And Eupatorium Odoratum In Guangxi

The paper study on the ecological characteristics of invasion species:Eupatorium adenophorum Spreng. and Eupatorium odoratum L..We analyze the ecological fators which affect two species'growth and grade their distribution.We also predict their future invasion dynamic and their risk assessment in the other areas of Guangxi. The results are as follows. (1)There are Eupatorium adenophorum distribution in 20 counties,among the 47 counties in Guangxi where were investigated. At present, Longlin, Tianlin, Xilin are gradeâ… distribution area; Leye, Lingyun, Youjiang distrit, Napo are gradeâ…¡distributon area; Tian'e, Pingguo, Jingxi, Debao are grade â…¢distribution area; Nanning, Mashan, Hengxian, Yongxin distrit and Chengbei distrit of Nanning are grade â…£distribution area. The area where was invaded by Eupatorium adenophorum is exceed 141,000 hm2, it is preliminary estimated that Guangxi economic losses cause by Eupatorium adenophorum is exceed 63,450,000 yuan.There are Eupatorium odoratum distribution in 33 counties. Chongzuo, Ningming, Fusui, Qinzhou, Shangsi, Fangcheng, Beihai, Hepu are gradeâ… distribution area; Youjiang distrit, Longzhou, Pingxiang, Napo, Jingxi, Debao, Tiandeng, Daxin, Tianyang, Tiandong are grade â…¡distribution area; Donglan, Bama, Fengshan, Du'an, Dahua, Lingshan, Pubei, Bobai are grade â…¢distribution area; Tian'e, Nandan, Hechi, Nanning, Mashan, Luchuan are grade â…£distribution area. The area where was invaded by Eupatorium adenophorum is exceed 83,300 hm², it is preliminary estimated that Guangxi economic losses cause by Eupatorium adenophorum is exceed 37,500,000 yuan. (2) Analyzing density and plant-branch pattern, the results show that the average density of Eupatorium adenophorum is 145m^-2 with the maximum density 350 m^-2 and the minimum 75m^-2. The average density of Eupatorium odoratum is 133m^-2 with the maximum density 320m^-2 and the minimum 32m^-2. The numbers of secondary branch(S) are higher than that of tertiary branches(T), and tertiary branches(T) are higher than that of primary branch (P). The orders of the branching angles were S > T > P. (3) Species diversity of plant communities where Eupatorium odoratum and Eupatorium odoratum inhabit was measured and analyzed by using the indices of species richness, Simpson, Shannon-Wiener, Pielou.The results show that the indices where Eupatorium adenophorum grows are lower than that in where the species not appear by 43.65%,55.13%,55.68%. The indices where Eupatorium odoratum grows are lower than that in where the species not appear by 33.55%,37.78%,17.98%. (4) The invasive pattern was studied by sampling randomly. Such 18 variables as"elevation", "slope-orientation", "slope-deflection", "landscape", etc. were be quantified to decide the different invasion of this dangerous alien species. The results show that the principal component analysis demonstrated all the ecological message of Eupatorium adenophorum included in those variables could be decided by four most principal factors,ie. "Factor of Damp and Light"(The first Principal Component), "Factor of General Ecological Characteristics"(The second),"Factor of landform"(The third), and "Factor of vegetation"(The fourth). The ecological message of Eupatorium odoratum included in those variables also could be decided by four most principal factors. ie. "Factor of General Ecological Characteristics"(The first Principal Component), "Factor of Damp and Light"(The second), "Factor of vegetation"(The third), and "Factor of climate"(The fourth). In principal, the occurring frequency of Eupatorium adenophorum will be related to 16 ecological factors as "elevation", "temperature", "slope-orientation", etc..The occurring frequency of Eupatorium odoratum will be related to 16 ecological factors as "slope-deflection", "Landscape", etc. (5) Eupatorium adenophorum and Eupatorium odoratum adapt to Guangxi climate, landform. According to the risk assessment, Eupatorium adenophorum will invade the east, middle, southeast of Guangxi, even the whole province. Eupatorium odoratum will invade the east, west, northwest of Gungxi. They will invade the other area of Guangxi and threat neighbour provinces, Hunan, Guizhou, Guangdong,etc.. So we must take measures to prevent and control this two invasive species.