1. Break in
It refers to the possibility of alien species being introduced into the local area through various channels, which consists of three indicators: the occurrence degree, the introduction mode and the preventive measures. (1) Occurrence degree of introduction place: refers to the distribution of the species in the introduction place. If the harm of alien species is very serious, but it has occurred widely in the local area and its risk has already occurred, it cannot be included in the assessment scope. (2) Introduction channel: refers to the channel through which alien species enter the local area from the place of origin through intentional or unintentional introduction. For intentionally introduced species, the demand for introduction mainly depends on the utilization value of the species. For unintentional species, the possibility of introduction mainly depends on the intensity of human activities, such as the more frequent traffic, trade and tourism activities, the easier it is to bring exotic species to the local area. (3) Preventive measures: administrative measures and technical means to prevent the introduction of alien species and the effectiveness of relevant international conventions.
2. Adaptability
It refers to the possibility of establishing a population of alien species in the introduction place, which consists of four indicators: adaptability, stress resistance, climate suitability and suitability of other limiting factors.
(1) Adaptability: refers to the adaptive range of the species to one or more ecological factors, including the adaptive range to climate, food, host and soil.
(2) Stress resistance: refers to the tolerance of species to stress, including low temperature, high temperature, water stress, pesticides, fires, etc.
(3) Climatic suitability: refers to the similarity of climate between the existing distribution area and the introduction area of this species. Climatic factors are one of the most important factors that determine the survival of species, including temperature, light, rainfall and other climatic factors. (4) Suitability of other limiting factors: Other ecological factors that limit the survival and reproduction of alien species besides climate factors. These ecological factors vary from species to species. Animals must have suitable food, plants and soil are closely related, and microorganisms must have suitable hosts. In addition, the life history of many species has its special laws, and other ecological factors should be considered.
3. Diffusibility
Refers to the possibility of the spread, migration and diffusion of alien species in the introduction area. It consists of six indicators: growth rate, reproductive capacity, diffusion capacity, suitable climate range, other limiting factors range and alien species control mechanism. (1) growth rate: refers to the increase of alien species biomass per unit time. This index reflects the growth characteristics of alien species, and it is generally believed that alien invasive species grow relatively fast. (2) Reproductive capacity: refers to the number of offspring produced by alien species in a unit time. The reproductive ability of species is closely related to the reproductive mode, and the reproductive ability of asexual plants or parthenogenetic animals is strong. Alien invasive species generally have strong reproductive ability. (3) Diffusibility: refers to the ability of individuals or propagules of alien species to move from one habitat to another. The diffusion distance of plants is determined by three factors: mobility, reproductive factors and topography. Generally, only plant propagules have fluidity, which depends on the weight, size, volume and special structure (wings, barbed hooks, airbags, etc.) of the propagules. ). The active diffusion ability of microorganisms mainly depends on the fluidity of the medium. (4) Suitable climate range: refers to the area of climate zone suitable for the growth and reproduction of alien species. (5) Scope of other limiting factors: In addition to climate factors, the distribution of other ecological factors that limit the survival and reproduction of alien species. (6) Control mechanism: natural factors and artificial measures to control the spread of alien species. Natural factors refer to natural enemies of alien species, organisms that compete with alien species and organisms that inhibit the growth and reproduction of alien species in nature; Man-made measures include physical, chemical, biological and ecological substitution measures taken by human beings to remove and control alien species.
Step 4 hurt
Refers to the adverse effects that exotic species have or may have on the economy, environment and human health in the introduced place. It consists of four indicators: economic importance, ecological environment importance, human health importance and other adverse effects. (1) Economic importance: refers to the economic losses caused by exotic species to agricultural and forestry production, trade, tourism and transportation. (2) Importance of ecological environment: refers to the adverse effects and harms of exotic species on the composition, structure and function of the ecosystem, species diversity and genetic diversity. (3) Other adverse effects: In addition to economy, environment and human health, the adverse effects of alien species on social stability and cultural traditions.