Study On Species And Distribution Pattern Of Alien Invasive Plants In Southeast Tibet

In recent years,with the rise of heteropet fever and release fever,invasive alien species have become the main factor threatening the survival of native plants and animals,which has damaged the national security.Recently,China’s first case of illegal release of animals was pronounced,marking the improvement of the species safety law,but also from the side shows the great harm of species invasion.In order to study the status quo of invasive alien species in southeast Tibet,this paper carried out a survey of invasive alien species in the county,understood the status quo of invasive alien plants in southeast Tibet,identified the distribution pattern of invasive plants,and conducted risk assessment of the invasive alien plants in the field investigation by AHP.The Max Ent prediction model was then used for four representative alien invasive plants(Erigeron annuus 、 Galinsoga parviflora 、 Ageratum conyzoides、Bidens pilosa)The prediction of suitable areas is made,and the potential suitable areas in the next 20 years are obtained,and the trend of their diffusion is defined.Then the counties and districts in Tibet are found to be vulnerable to invasion,providing some basis for relevant government departments to provide targeted policies for prevention.The conclusions of this paper are as follows:1.A total of 114 species of invasive plants belonging to 84 genera and 33 families were investigated and counted in southeast Tibet.Most invasive plants were mainly composed of Compositae,gramineae,Solanaceae and amaranthus.Most invasive plants were mainly annual herbs.The most invasive plants were found in Zayu County with 58 species,followed by 44 species in Metoi County,27 species in Bayi District of Nyingchi City,25 species in Milin County,24 species in Jiacha County,20 species in Lang County,17 species in Bomi County,14 species in Zuogong County,13 species in Badu County,and 8 species in Mankang County.Among the invasive alien plants in southeast Tibet,Compositae were the most common species in the first to third class.In this survey,the most frequent invasive alien plants were Compositae In this survey,the most frequent exotic invasive plants are Dysphania schraderiana、Erigeron sumatrensis、Galinsoga parviflora Cav.2.Through analytic hierarchy process(AHP),23 invasive exotic plants with high risk value,60 invasive plants with medium risk value and 23 invasive exotic plants with low risk value were obtained in combination with the objective practice in southeast Tibet.Among the invasive exotic plants with high risk value,Tagetes minuta 、 Alternanthera philoxeroides 、 Dysphania ambrosioides、Bidens pilosa、Phytolacca americana,These plants have been found malignant invasion in field investigation.And in the exotic plants with a risk value of Avena fatua、Eleusine indica.,These weeds are relatively common and difficult to clean up,so relevant units need to strengthen the research efforts,improve the technical level,and provide convenience for farmers.3.The MaxEnt prediction model is used to predict(Erigeron annuus、Galinsoga parviflora、Ageratum conyzoides、Bidens pilosa)Four species were common in the field survey,and occupied the main part of the quadrat,there were large-scale clusters of alien invasive plants.It is found that precipitation and temperature are the main factors affecting the distribution of these invasive plants.The prediction results show that,Erigeron annuus、Galinsoga parviflora、Amaranthus retroflexus,In Tibet Autonomous Region,the areas of adequate living are mainly concentrated in Nyingchi City,Qamdo City,Shannan City,Lhasa City,and may expand to the eastern part of Xigaze and parts of Ngari and Nagqu.The Ageratum conyzoides、Bidens pilosa,They are mainly distributed in the southeast of Tibet and expand to the surrounding areas.Although their current distribution range is relatively limited,it is highly possible to expand to the west and north.