Are biological intruders, that is, aliens, harmful? Please answer from the point of view that "alien creatures are not necessarily harmful", please! ! !

Biological invasion does more harm than good, but it still has some advantages. The introduction of new species has provided many conditions and opportunities for human development and created huge economic benefits for countries and regions around the world. According to some examples (when the reproduction of alien species has not yet formed a certain scale and can be controlled manually):

1。 As pasture or feed

Because there are many examples introduced as pasture or feed, for example, Alternanthera philoxeroides, alfalfa, Melilotus flavescens, sunflower, millet, white grass, Pennisetum, Sudan grass, ryegrass, water hyacinth, barley, Eichhornia crassipes and so on. Long-term overgrazing and grassland degradation in China's animal husbandry have increased the demand for new high-quality fast-growing grasses, which provides an excellent opportunity for foreign grass seed companies to dump grass seeds in China. At present, a large number of new forage experiments are being carried out, mostly to test whether the varieties provided by foreign grass seed companies can grow rapidly on our land. Worryingly, some of them have become dangerous alien invasive species.

2。 As an ornamental plant

Such as Pogostemon cablin, Coreopsis lanceolata, cosmos, Heliqiu, Tagetes erecta, Solidago canadensis, Petunia, etc. A series of aquatic plants were introduced into the ocean like aquariums.

3。 As a medicinal plant

12000 Many kinds of organisms used in Chinese medicine are mostly native to China, some are exotic species, and some have become invasive species. Such as soap grass, cassia obtusifolia, cassia obtusifolia, evergreen, wangjiangnan, Phytolacca acinosa, Datura stramonium, ice eggplant and so on.

4。 As a plant for improve that environment

In order to quickly solve the problems of ecological environment degradation, vegetation destruction, soil erosion, water pollution and so on, people often look at some characteristics of alien species unilaterally, which provides an excellent opportunity for the invasion of alien species. At present, many areas are actively carrying out vegetation restoration, but some of the species used are dangerous alien species. At present, some species have invaded, such as Spartina alterniflora, Mikania micrantha and Eichhornia crassipes. Spartina alterniflora was introduced from the salt marsh vegetation on the east coast of the United States in 1979. First, 1980 and 10 were planted in Fujian coastal areas, and then widely publicized. 1982 expanded to Jiangsu, Guangdong, Zhejiang and Shandong. The purpose of introduction is to protect beaches and revetments, improve soil, green beaches and improve the ecological environment of beaches. Now this species has fled from Zhejiang, Fujian, Guangdong and Hong Kong. 1990, the annual loss of aquaculture in Dongwuyang, Ningde, Fujian alone reached more than 10 million yuan. This species has become a serious problem in coastal areas, affecting the local fishery output and threatening mangroves.

Exotic species are also widely used in urban landscape construction and beautification, which often causes complete changes in local ecosystems and landscapes. Like the lawn.

5。 As food

Food is a part of China's traditional culture, and its emphasis on food diversity is unmatched by any other ethnic group in the world. In order to pursue the color, fragrance, taste, novelty and novelty of food, people introduce a large number of edible animals and plants, but they don't know that this will also cause biological invasion, such as sweet apricots, amaranth and sunflower introduced as vegetables; Guava, Passiflora edulis, and Physalis alkekengi, which are introduced as fruits, are used as raw materials for the production of bean jelly, as well as edible animals such as Pomacea canaliculata and Pomacea canaliculata. The skin of some mammals has high economic value, such as muskrat and nutria. People widely promote farming to obtain animal skins, and as a result, biological invasion has also formed.

6。 As a pet

Some animals are widely farmed as pets in cities, and some parrots with strong viability, such as Cacacatua sulpurea and Trichoglossus haematotus, have greatly increased their numbers in the local wild, overusing fruiting shrubs or eating young leaves, endangering local vegetation. Trachemys scripta is a global invasive species, which can be found in almost all pet markets in China from north to south. Although the harm of the Brazilian tortoise has not been reported in China, it has been listed as one of the most dangerous 100 invasive species in the world by the World Conservation Union (IUCN, 200 1), and the Brazilian tortoise is also the vector of disease transmission. The introduction of "pet rats" from South America in Taiwan Province Province has also aroused the fear of disease spread.

7。 As an aquaculture species

Aquaculture is one of the important industries with a long history in China. Almost all the waters that can be used for aquaculture, such as rivers, lakes, ponds, reservoirs, rice fields, parks, etc., are engaged in aquaculture to some extent. The exotic species involved include imported from abroad, such as Procambarus clarkii, Macrobrachium rosenbergii, red crayfish, rainbow trout and tilapia. European eel (Anguilla japonica), etc.

8。 Introduction of Botanical Gardens, Zoos and Wildlife Parks

Many cities in our country have zoos, botanical gardens and bird gardens. Many exotic plants escaped from the botanical garden, naturalized and invaded. Although there are no reports of invasions in zoos, some species naturally reproduce in the wild. For example, starlings have formed a natural population in Beijing. In particular, it has become fashionable to establish wildlife parks in various places, and a large number of species are scattered in natural areas. If management measures are not strengthened to prevent exotic species from escaping from zoos, botanical gardens, bird gardens and wildlife parks (which may carry exotic wildlife diseases), these potential alien invasive species sources may bring disastrous ecological invasion.