Biological invasion refers to the phenomenon that a certain organism becomes a wild state after natural introduction or artificial introduction from the field, and causes certain harm to the local ecosystem. These creatures are called alien species.
Alien species are the taxa of species, subspecies, or below that appear outside of their past or present natural distribution and diffusion potential, including all parts, gametes, or propagules that may survive, and then multiply.
Invasive alien species have the characteristics of strong ecological adaptability, strong reproductive ability and strong dissemination ability: the invaded ecosystem has sufficient resources, lack of natural control mechanisms, and high frequency of human entry.
(1) Invasive microorganisms: mainly pathogenic microorganisms that cause harm to crops, forest trees and economic fish and shrimp, excluding human and livestock diseases.
(2) Invasive plants: mainly refers to harmful plants that cause harm and threats in different ecosystems such as agriculture, forestry, wetlands, grasslands, fresh water, and oceans, such as herbs, vines, shrubs, algae, etc.
(3) Invasive animals: mainly refers to harmful insects, moths, fish, amphibians and reptiles that cause harm to agriculture, forestry, animal husbandry and fishery production.
Due to the lack of natural enemies, these alien invaders not only destroy the food chain, threaten the survival of other creatures, but also bring huge economic losses to the world. According to the World Conservation Union (IUCN), the economic losses caused by alien species invasions to the world exceed $400 billion annually.
With the increasing frequency and closeness of economic and cultural exchanges between countries and regions, with the increasing global environmental instability, all ecological wars without smoke--"biological invasion" are quietly being launched around the world, resulting in ecological disasters. It is seriously threatening the economic development of the countries of the world and the global ecological security.
The introduction of alien species is a concept closely linked to biological invasion. Any biological species is always formed at a specific location and then gradually adapted to the natural habitat of the displaced or introduced land through migration or introduction.
Gradually expand the scope of its existence, which is called the introduction of alien species (referred to as introduction).Proper introduction will increase the diversity of the organisms in the introduced area and will greatly enrich people's material life. On the contrary, inappropriate introduction can cause alien species lacking natural enemies to rapidly multiply and rob other living organisms, leading to ecological imbalances and the reduction and extinction of other native species, seriously endangering a country's ecological security.
With the changes of climatic environment and other factors, some species that are not harmful after a period of introduction may gradually become "invasive species". Therefore, in a sense, the results of introduction of exotic species have A certain degree of unpredictability. This also makes the prevention and control of alien species invasion more complicated and difficult.
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