Risk Assessment And Control Strategies Of The Invasive Plants In The National Nature Reserve Of Chongqing Jinyun Mountain

The biological invasion has become one of the most troublesome global environmental problems,which not only destroyed the ecological environment,but made a large number of economic losses in 21 st century.In recent years, many natural reserves were invaded by exotic plant on different level.Some scholars had got a series of achievements,which were about the study of invasive plants in natural reserves of different provinces.Jinyun Mountain, located in Beibei district of Chongqing, is a national nature reserve. The flora of Jinyun mountain is very ancient, there are so many rare plants among the plant resources, it has high value about protection, scientific research, teaching, tourism and so on.Because of many roads built, economic development, frequent human activities,the more and more invasive plants got in the protected areas,which brought some bad influence on the native plants and ecological environment,so we must inspect the invasive plants and make the risk assessment as soon as possible. This paper used pest risk analysis(pest risk analysis, PRA) assessment system, accoding to the plants, biological characteristics, life habits, route of transmission and so on,we have putted forward some reasonable and effective prevention and control countermeasures in order to provide the basic materials of protection and development about Jinyun Mountain Natural Reserve.The research achievements are as follows:(1) The list of invasive plants in Jinyun Mountain has been compiled. The list included 57 species in 23 families and 46 genera of invasive plants.The Compositae including 13 species,the Gramineae including 4 species, the Amaranthaceae including 6 species, the Leguminosae including 7 species,above the 5 families contain 34 species,which occupied 59.65% of jinyun mountain invasive plant species. The main kinds of afferent pathway are intentional and unintentional.The largest number of invasive plants is come from America and Europe. Herbs are the main species(2) Through to reserve the distribution of the invasive plant species regional analysis found that human activity is intrusion protection zone of influence of main factors on the distribution of plant, such as residential area, road adjacent to the densely populated areas, traffic is high, intrusion invasion of plant species richness was higher. The trees on both sides of road is covered with Anredera cordifolia, Oxalis rubra in the flower bed inside become dominant species, in Baiyun Village the Anredera cordifolia and Alternanthera philoxeroides cause harm to the plants on farmland, flower beds, in Rays yard, the Setaria palmifolia in the wasteland, slope mass distribution, pose a threat to native plants.Based on the analysis of the distribution area of the protected area, it is found that the population density is the main factor that affects the distribution of the protection area. In the area where the population density is concentrated, the species richness of the invading plants in the area and the road is very high, which indicates that the degree of human disturbance has a great influence on the distribution of the invasive plants.(3)In protected areas,the different vegetation types of intrusion resistance ability of plants was different, in the amount and type of invasive plants warm coniferous forest, needle and broad-leaved mixed forest rarely, for the protection of the basic no harm, in the Fuxing Temple, Sheshen Cliff, only sporadic distribution of Setaria palmifolia. In less deserted spots, and high vegetation coverage areas, such as Qinglong village, Gao guanyin, there is no invasive plants.(4)By using the method of risk assessment index system, a integrated risk assessment system with multiple-level and multiple-indicator was established aims to the invasive plants in Jinyun Mountain.By using the principle of analytic hierarchy process, the weight of the index system has been determined. The total score of the index system is 100 points, each indicator given different points according to its weight ratio.The environmental adaptation is 11%, the invasive history is 10%,the condition of growth and escape is 13%,the biological characteristics is 18%,the dispersal mode and ability is 16%,the potential hazards and influence is 17%,the control difficulty is 15%.(5)According to risk assessment score, the 57 kinds of plants of Jinyun Mountain were divided into low, medium and high three levels, the low risk level including 25 kinds of plants, which accounted for 43.86% of the total number of the invasive plants,these plants are ornamental, edible species; the medium risk level including 23 kinds of plants, which accounted for 40.35% of the total number of the invasive plants,most of these plants are the escape species;the high risk level including 9 species,which accounted for 15.79% of the total number of the invasive plants,the Setaria palmifolia, Conyza canadensi and Alternanthera philoxeroides are widely distributed,strongly adapted,strongly producted,big threat to habitat surrounding plants.(6)Through for the protection of the invasive plant distribution characteristic is analyzed, and the regional intrusion plant risk assessment, proposed protected areas in the future before the introduction of introduced species were evaluated strictly; to invasive plants invasion on habitat restoration; to strengthen the inspection and Quarantine of plant invasion; to have been affected by the invasive plant harm serious regional control was carried out; in areas of invasive plants invasion easily set up monitoring points, in order to observe the invasive plants damage dynamics.