Species introduction of alien species, what is the difference between alien species and invasive ali

The difference between alien species and invasive alien species is that "invasive alien species" focuses on the adverse consequences caused to the local ecosystem; "Alien species" focuses on species that are not native and may have no impact on local ecosystems, may be detrimental or beneficial.

"Invasive species" is different from "alien species", it specifically refers to harmful alien species, such as the aforementioned "water hyacinth", "pine wood nematode", "rice grass", etc., and its scope is smaller than that of "alien species";

"Alien species invasion" is also different from "alien species introduction", which specifically refers to the process of invasive species spreading from their native places to invasion sites through natural or man-made routes, and damaging the biodiversity and ecosystems of the invasion sites and even endangering human health, resulting in economic losses and survival disasters.

An alien species is a species, subspecies or following taxa that occurs outside its past or present natural range and dispersal potential (i.e., cannot exist outside its natural range or without direct or indirect introduction or human care), including all its parts that may survive and reproduce subsequently, gametes or propagules.

The introduction of alien species is a concept closely related to the invasion of alien species. Any biological species always first forms in a specific place, and then gradually adapts to the natural living environment of the migration or introduction site through migration or introduction, and gradually expands its living range, this process is called the introduction of alien species (referred to as introduction).

1. Eupatorium purpurea.

Native to Central America, it was discovered in southern Yunnan in 1935 and may have been introduced via Burma. It is distributed in Yunnan, Guangxi, Guizhou, Sichuan (southwest), Taiwan, and the upper limit of vertical distribution is 2500 meters. Globally invasive species.

2. Mikania.

Mikania, perennial grassy or woody vine, slender stem, creeping or climbing, multi-branched, the leaves in the middle of the stem are triangular ovate to ovate, the base is heart-shaped, the apex is acute, the edge is serrate, the head inflorescence is numerous, often arranged in a compound inflorescence at the end of the branch, containing 4 small flowers, all are sturdy amphoteric flowers, 4 total bracts, the base of the narrow oval total bract has a line-like oval small bract, and the flowers are fragrant.

It is a globally invasive species found in Hong Kong, Macao and the Pearl River Delta region of Guangdong.

3. Hollow lotus seed grass.

Hollow lotus seed grass, perennial herb. Rhizome propagation. 3 April, rhizome budding is unearthed; The stolons are well developed, rooting at the nodes, and the segments of the stem can also germinate into plants.

The leaves are opposite, with short stalks, and the leaves are oblong-elliptic to obovate-lanceolate. The capitate inflorescence is solitary in the leaf axils, composed of 10 20 sessile white florets, with a peduncle in total; The bracts and bracts are dry membranous, persistent.

4. Ragweed. ragweed, an annual grass, 20 250 cm high. Stems erect, ridged, multi-branched, lower leaves opposite, upper leaves alternate, leaves triangular, 1 3 pinnate deeply lobed. The inflorescence is unisexual, monoecious; About 50 60 are arranged in racemes at the ends of the branches, the corolla pale yellow, the bracts obovate, inverted conical, capsular, without corolla and crown hairs, the columella 2, filamentous, protruding from the bracts.

Invasion pathways of alien species:

1. Natural invasion.

This kind of invasion is not caused by human causes, but is caused by biological hazards caused by natural migration of plant seeds or animal larvae, eggs or microorganisms through wind vectors, water flows or by insects and birds. For example, ragweed gradually spread from North Korea to China due to the destruction of the surrounding vegetation caused by the construction of railways and highways.

2. Intentional introduction.

Intentional human introductions that purposefully transfer a species beyond its natural range and dispersal potential (such introductions may be authorized or unauthorized). These invasive species are thriving in the absence of natural predators due to the alteration of the species' living environment and food chain.

3. Unintentional introduction.

Unintentional introduction is when a species spreads beyond its natural range through humans or human teleportation systems, resulting in unintentional introductions.

Although this method of introduction is artificial, it has no subjective intention to introduce it. For example, the red fire ants invaded the southern United States in the early 20th century due to negligence in epidemic prevention and control, and eventually caused very important problems and economic losses in the United States in agriculture and environmental health.

Alien species invasion is a global problem, through natural invasion, artificial introduction, etc., after the settlement of the invasion site, these alien species will cause serious damage to the local biodiversity, ecological environment, so that the economy suffers a heavy blow.

Invasive alien species are:

1. African giant snail.

It is a medium-to-large terrestrial snail. Adult shells are generally 7-8 cm long, and can grow to more than 20 cm at most. Nocturnal, omnivorous, mostly active in humid environments, preferring to be seen in rain and at night.

2. Bullfrogs. The bullfrog is a large edible frog with delicate flesh, delicious flavor, and rich nutrition. Bullfrogs, commonly known as American water frogs, are large, fast-growing, and productive. Native to North America, it has spread to all continents of the world and is the main farmed species of edible frogs everywhere.

3. Crayfish.

Crayfish is a freshwater economic shrimp that is popular because of its delicious meat. Because of its omnivorous nature, fast growth rate and strong adaptability, it has formed an absolute competitive advantage in the local ecological environment. It feeds on aquatic weeds, algae, aquatic insects, animal carcasses, etc., and kills each other when food is scarce.

4. Mikania.

Mikania is also known as small-flowered cranium or small-flowered pseudozea. It is a perennial herbaceous plant of the Asteraceae family, smooth to pubescent.

5. Fushou snail.

Fushou snail is a mollusk of the family Bottle Snail and the family Bottle Snail. The appearance of the shell is similar to that of a snail. It has a spiral-shaped snail shell, the color varies with the environment and the age of the snail, and it is shiny and has several fine longitudinal lines.

At present, 544 species of invasive alien species have been confirmed in China, of which more than 100 species have occurred in a large area and caused serious harm. Examples can be found in animals (mammals, birds, amphibians, reptiles, fish, insects, crustaceans, molluscs, etc.), plants (trees, shrubs, herbs) and microorganisms (bacteria, viruses). Among the 100 most threatened alien species in the world published by the IUCN, more than 50 species have invaded China.

In the past 10 years, China has discovered the invasion of dangerous and explosive species such as western flower thrips, Q-type whitefly, and clover spotted diver fly, with an average increase of 1 to 2 species per year. In addition, the frequency of interceptions of potentially invasive species in China has increased dramatically.

Fushou snail Fushou snail, also known as large bottle snail, is native to the Amazon River basin in South America. In the 70s and 80s of the 20th century, it was introduced into Taiwan, Guangdong and other places, and the initial value was very high and quite popular, but its flesh was soft and lacked the crispiness of the local snails, which led to a great decline in sales, and people were forced to abandon them, so the Fushou snails became wild animals in rivers, ditches and ponds. Due to the miscellaneous, strong fecundity and fast development rate of the snail, it soon became a harmful animal in Fujian, Guangdong, Guangxi, Zhejiang, Shanghai and other places, and the snail often gnawed on the leaves and stems of aquatic plants, seriously affecting the growth of plants.

In Luzhai County, Guangxi, the occurrence density of Fushou snail in paddy fields was as high as m2, and the damage rate of rice was generally 7% 15%, and the highest was 64%. Fushou snail harms lotus root, young snail gnaws on the lotus leaf floating on the water surface from the bottom of the leaf, causing the leaf to become perforated or missing, and the leaf is eaten in severe cases, and it is difficult to pull out of the water surface; Fushou snails also harm other aquatic plants such as daffodils. In addition, the snail is also an intermediate host of a zoonotic parasitic disease, which is very likely to cause health problems to the surrounding residents. At present, the control of Fushou snail is mainly chemical control, supplemented by artificial control, and biological control has not been carried out.

Brazilian tortoises are also called red-eared turtles and red-eared painted turtles. The Brazilian tortoise is not native to Brazil, but to the Mississippi River and the Rio Grande River basin in North America. It is used by many families as pets for breeding or ornamental pets, but there are still restaurants that use it as a food animal.

Today, however, it has been listed by the International Union for Conservation of Nature as one of the world's 100 most dangerous invasive species, making it a global "wanted man". Brazilian tortoises are highly fertile and have a high survival rate. Its "marriage" with native turtles has led to genetic contamination of native freshwater turtles, which has seriously affected the living environment of native turtles.

Not only that, but it is also the main culprit in the spread of Salmonella, which has been shown to be transmitted to and among homeothermic animals, including humans. In recent years, due to factors such as pet abandonment, religious release, and breeding escape, Brazilian tortoises are widespread in the wild in China and are spreading rapidly. There are populations living in the wild in the Xiangjiang River in Hunan, the Pearl River in Guangdong, the Suzhou Creek in Shanghai, the West Lake in Zhejiang, the Qiantang River and the Jiangsu section of the Yangtze River.

At present, Chinese law has banned the import of Brazilian tortoises, but the embarrassing thing is that there are no laws and regulations in China to restrict the sale of Brazilian tortoises, so it is difficult to really make Brazilian tortoises disappear from the market.

Alien species invasion is a global problem, through natural invasion, artificial introduction, etc., after the settlement of the invasion site, these alien species will cause serious damage to the local biodiversity, ecological environment, so that the economy suffers a heavy blow.

Alien species include crayfish, water hyacinth, snails, Brazilian turtles, purple jasmine, cinchona, fetal squid, tilapia, etc. Crayfish: Crayfish are crustacean, decapod, crayfish aquatic animals.

Water hyacinth: Water hyacinth generally refers to phoenix eye blue. Phoenix-eyed blue floating water herb.

The fibrous roots are well developed and brownish-black. Fushou snail: Fushou snail is a mollusk of the family Bottle Snail and the family Bottle Snail.

The appearance of the shell is similar to that of a snail. It has a spiral shell, the color varies with the environment and the age of the snail, it is shiny and has several fine longitudinal lines, and the head and gastropods are protruding when crawling. <

Alien species include crayfish, water hyacinth, snails, Brazilian turtles, purple jasmine, cinchona, fetal squid, tilapia, etc.

1. Crayfish: Crayfish is an aquatic animal of the crustacea, decapoda and crayfish family. Also known as crayfish, crayfish, and freshwater crayfish.

It resembles a shrimp and has a hard carapace. The adult body is about centimeter long, dark red, the carapace part is nearly black, and there is a wedge-shaped stripe on the back of the abdomen. Juvenile shrimp are uniformly grey, sometimes with black ripples.

2. Water hyacinth: Water hyacinth generally refers to phoenix eye blue. Phoenix-eyed blue floating water herb. The fibrous roots are well developed and brownish-black.

3. Fushou snail: Fushou snail is a mollusk of the family Bottle Snail and bottle snail. The appearance of the shell is similar to that of a snail. It has a spiral shell, the color varies with the environment and the age of the snail, it is shiny and has several fine longitudinal lines, and the head and gastropods are protruding when crawling.

4. Brazilian tortoise: The Brazilian red-eared tortoise is a subspecies of the Brazilian tortoise of the family Ze Turtle and the genus Painted Turtle. The adult body is oblong, the dorsal carapace is gently raised, the ridge is distinct, and the posterior margin is serrate.

The head is broad, the snout is blunt, and the neck has yellow-green longitudinal stripes, and there are 1 long red patches on each side of the back of the eyes. The head and neck flanks and ventral surfaces are sandwiched with yellow-green linear strips.

5. Tilapia: Tilapia is native to Africa and is a tropical fish, with more than 100 species of tilapia, including subspecies. Tilapia has the characteristics of fast generation, high yield, miscellaneous diet, few diseases, and strong fecundity. Tilapia (African crucian carp) is the main aquaculture product in China.