What is biological invasion?

"Biological invasion" refers to the phenomenon that a certain organism is introduced naturally or artificially from other places and becomes wild, causing certain harm to the local ecosystem. There are many restrictive factors to prevent the malignant expansion of alien species in their origin, among which predation and parasitic natural enemies play a key role, and they can control the population density under a certain number. Therefore, those alien species usually do not cause great harm to their countries of origin. But once they invade new areas and lose the control of their original natural enemies, the population density will increase rapidly and spread to disaster. In nature, there is a food chain in the ecological environment, and natural enemies restrict each other. Once a creature is artificially extinct and introduced, it will have a series of unimaginable consequences. Therefore, some foreign scholars list the secondary effects such as blind introduction, habitat atrophy and fragmentation, over-hunting and species extinction as the four major reasons for species extinction, and call them "devil quartet" figuratively.

Biological invasion can be divided into intentional and unintentional. With the introduction of species, on the one hand, these immigrants may benefit mankind, on the other hand, they may have a certain impact on the local ecological environment and even economic development.

How to solve the problem of "illegal immigration" or "biological invasion" in biology, so that it will not cause harm in foreign countries? The expert's answer is: first, we should be careful in introducing and strengthen the management of introducing; Secondly, it is necessary to find out the species and harm status of existing alien harmful species in China; The third is to strengthen the prevention and comprehensive management of known major alien harmful species.

The book "Preventing biodiversity loss caused by biological invasion" adopted by IUCN in Switzerland in February 2000 pointed out: "For thousands of years, oceans, mountains, rivers and deserts have provided isolated natural barriers for the evolution of rare species and ecosystems. In recent centuries, due to global changes, these barriers have become ineffective, and alien invasive species have crossed the ocean to reach new habitats and habitats and become alien invasive species. "