Examples of biological invasion

Criteria for defining invasive species:

1) is introduced into non-native areas through intentional or unintentional human activities;

2) Self-regeneration ability has been formed in the local natural or artificial ecosystem;

3) Causing obvious damage or influence to the local ecosystem or geographical structure;

4) Species imported from China and non-native species from other countries.

From natural distribution areas (it can be other countries and other parts of China).

Introduced through intentional or unintentional human activities.

Self-regeneration ability has been formed in local natural or artificial ecosystems.

Cause obvious damage or influence to the local ecosystem or landscape.

★ Why do alien species cause invasion?

The ecosystem is formed through long-term evolution, and the species in the system have been competing, repelling, adapting and helping each other for hundreds and thousands of years before they form a close relationship of interdependence and mutual restriction. After the introduction of alien species, they may be excluded from the system because they cannot adapt to the new environment, and they must be helped to survive; It is also possible that this introduced species may become real invaders, upset the balance, change or destroy the local ecological environment, because there are no competing or restricted creatures in the new environment.

★ What problems will the invasion of alien species bring?

Directly reduce the number of species

Indirectly reduce the number of species that depend on local species for survival.

Change the local ecosystem and landscape

The ability to control and resist fires and pests is reduced.

The ability of soil conservation and nutrition improvement is reduced.

The ability to conserve water and improve water quality is reduced.

The ability to protect biodiversity is reduced.

★ What losses have the invasive species caused us?

Biodiversity and loss of its functions, including:

Ecosystem benefits

Biological resources

Social welfare

40% of the world economy and about 80% of the needs of the poor come from biodiversity.

Losing the uniqueness of local species and ecological landscape,

Ecotourism income

Native biological products

Social welfare

The more globalization prevails, the higher the local unique value.

Income from surrounding agriculture and forestry decreased.

Pest control expenditure

Weed control cost

Decline of soil fertility

Decline of water resources regulation and control ability

Sustainable agriculture and forestry depend on the surrounding or good ecosystem as a barrier to pests and fires, and protect soil, nutrition and water resources.

The most dangerous large-scale project of introducing alien species intentionally or unintentionally is being carried out in China.

Large-scale planting of exotic species in the process of returning farmland to forests.

Including eucalyptus, exotic pine, exotic larch and planting economic trees at inappropriate altitudes and areas.

Large-scale soil erosion control and pasture cultivation mainly rely on the introduction of grass seeds from abroad (especially the United States), while the cultivation, research and utilization of local grass seeds in China are few.

Greening of protected areas

Using alien species to restore vegetation

afforestation of city

Ornamental plants have introduced a large number of invasive alien species.

Using alien species to restore vegetation

A great deal of evidence shows that freshwater and mariculture have seriously damaged the biodiversity and ecosystem of water areas.

Golden dragon with five claws

Blue passion fruit

What can we do?

The intentional introduction and diffusion of alien species should be controlled in the following aspects:

What species?

Where is the introduction?

How much is introduced

application area

It is forbidden to introduce exotic species near the reserve.

Intentional introduction is prohibited unless it is proved that it will not cause harm to the ecosystem and the environment, and local species do not have the same function.

All vegetation restoration projects prohibit the use of exotic species.

Alternanthera philoxeroides

(Alternanthera philoxeroides)

water hyacinth

(water hyacinth)

Promote the use of local species

Strengthen the sustainable utilization of local species

Strengthen the research on provenance cultivation of local tree species

Mobilize people to collect and cultivate seeds of local species.

Establish an early warning system for invasive species

The establishment of China alien species information system.

Establish a global information system based on * * * sharing information and experience.

Establish and update the list of the most dangerous invasive species, and establish a convention to limit the spread of these species.

Some alien invasive species:

Mammals:

nutria

muskrat

sewer rat

Birds:

Sulfur crested cockatoo

Rainbow parrot

Canada Goose (Canada Goose)

Reptiles among reptiles:

Caenorhabditis elegans

Amphibians among amphibians:

Bullfrog (bullfrog)

Fish fish:

bighead

Goby (goby)

Top trunnion (pseudo Bora Parva)

Mosquito-eating fish (mosquito-eating fish)

Live vector (pomfret family)

perch

silver carp

Crustaceans:

Procambarus clarkii

A mollusk, a mollusk:

Amazon snail (Ampullaria gigas)

Giant African snail

Insect insert:

Termites (termites)

Hemiberlesia matsuzaka

American white moth

Banana moth

Pine scale of Pinus elliottii

Liriomyza sativae (Liriomyza sativae)

Rice and water are like the Lissorhoptrus oryzophilus in America.

Periplaneta americana (Periplaneta americana)

blattella germanica

Apple aphid

Grape root lice

Nematodes:

Bursaphelenchus xylophilus

Fungi Fungi:

sweet potato black rot

Wild animal diseases:

Infectious pancreatic necrosis of salmon (IPNV)

Plants:

Mexican tea (Chenopodium ambrosioides)

Alternanthera philoxeroides

Alternanthera philoxeroides

amaranthus tricolor

Cactus (Cactus)

False forsythia and golden dew

Solanum rostratum

Plantago americana (Plantagineae)

The mirror of Venus (Triodanis)

Pogostemon fragrans (win thistle)

ragweed

Lantern grass

Erigeron daisy

Eupatorium adenophorum on weeds

Mikania micrantha

Tall yellow goldenrod of North America.

Spartina (Spartina)

Damn ryegrass

water hyacinth

Petunia palmatum

Heart cone

Lantana camara

Parthenocissus quinquefolia

Ranunculus ternatus

Wedelia trilobata (Wedelia trilobata)

Castor (castor)

Common parthenocissus (parthenocissus)

Anredera cordifolia, a sweet potato with heart-shaped leaves.

Sweet clover

White sweet clover

Tubular longevity flower

Crying lantana (lantana Montenegro)

False leek oleander leaves

Tall fescue (Festuca arundinacea)

Thunbergia Grani Flora

Eupatorium odoratum

Cactus fruit

Saikui coromandel coast fake mallow (malvastrum coromandelium)

Phleum pratense

Carpet grass (carpet grass)

Equisetum multiflorum

Cordyceps sinensis (paspalum expansum)

Pennisetum (Pennisetum)

green bristlegrass

Sudan grass (Sudan grass)

Lolium multiflorum

Bulb barley

alfalfa

Mexican thistle

Coreopsis pilosula

Coreopsis lanceolata (Coreopsis lanceolata)

cornflower

Marigold Aztec Marigold (Marigold)

White morning glory

Common morning glory

Jasmine (mirabilis jalapa)

Mimosa pudica

Oxalis corymbosa

Hemp (Indian hemp)

Cassia seed, a sensitive plant-like senna leaf.

Cassia senna

Talinum Panic Flower of Fame (Talinum Panicle)

Wangjiangnan coffee senna

Phytolacca americana

Hawksbard velvet plants (Crassocephalum crepidioides)

Chicory (chicory)

Alien invasive species refer to those species, subspecies or sub-taxonomic units that have appeared in the past or now outside their natural distribution range and diffusion potential (that is, they cannot exist without direct or indirect introduction or human care), including all parts, gametes or propagules that may survive and reproduce. Alien invasive species is an ecosystem. In this ecosystem, this species originally existed side by side. It came in with the help of human activities and crossed insurmountable spatial barriers. Under the natural conditions of human beings, the barriers of mountains and rivers and the differences of natural geographical factors such as climate, soil, temperature and humidity constitute obstacles to species migration. It is quite accurate to rely on the natural diffusion ability of species to enter a new ecosystem. Although there are also cases where animals, plants or pathogens enter the new system due to changes in climate and geological structure, more and more species migrate intentionally or unintentionally due to human activities.

The invasion of alien species is closely related to the establishment, stability and evolution mechanism of ecosystem. After the alien species are introduced into the new balanced ecosystem, they may be excluded from the system because they cannot adapt to the new environment, and they must rely on the help of human beings to survive; It is also possible that it just adapts to the local climate and soil conditions, and there is no creature to compete or limit it in the new harsh environment. At this time, this alien species will become real invaders, break the ecological balance, change or destroy the local ecological environment, and become an alien invasive species.

When alien species establish populations in natural or semi-natural ecosystems or habitats and change or threaten local biodiversity, it becomes an alien invasion.

Invasion and diffusion mechanism in foreign invasion

When an alien species enters a new ecosystem, whether it finally invades depends on two factors: the characteristics of the alien species entering the new environment and whether the environment is easy to be invaded by this species.

Characteristics of alien invasive species.

If the environmental conditions such as temperature, humidity, altitude, soil and nutrition are suitable, alien species will breed in the new ecosystem. Although many alien species can form natural populations, most of them remain at a low level and will not cause harm. Alien invasive species that cause biological disasters often have the following characteristics: (1) Strong ecological adaptability; (2) Strong reproductive ability; (3) Strong communication skills.

2. Characteristics of invasive ecosystems

Almost all ecosystems are more or less invaded by alien species, but some of them are more vulnerable to invasion. Like alien invasive species, these fragile ecosystems have some common characteristics. (1) has enough available resources; (2) Lack of natural control mechanism; (3) The frequency of artificial entry is high.

3. Areas vulnerable to invasion by alien species

According to the introduction route of alien invasive species and the characteristics of invasive species and ecosystem, we can predict the areas where alien species are easy to invade in China. (1) Near important ports and docks, on both sides of railways and highways. Exotic species introduced by international freight often land near ports and ports first, and then start to spread and establish small populations after encountering suitable environmental conditions; Ballast water discharged by ships and marine species attached to camps often settle in ports; Exotic species carried by trains and cars can easily settle and spread on both sides of railways and highways. (two) forests and grasslands that are considered to be seriously disturbed. Human activities can directly bring exotic species. Forests, grasslands and other ecosystems were originally stable, but it is seriously believed that deforestation and overgrazing will degrade the ecosystem, reduce its diversity and create favorable conditions for the invasion of alien species. (3) Islands, waters and pastures with low species diversity and simple habitats. Species diversity is low, natural inhibition is low, natural enemies are few, exotic species are easy to survive, and the population is easy to expand. (four) due to fire, flood, drought and other sudden natural disasters and damage to the ecological environment. In these ecological environments, the ecosystem is severely damaged in a short time, the species composition and community structure become simple, and invasive species can easily occupy a large number of niches and become dominant species. (5) Warm and humid areas with good climatic conditions. For example, due to its geographical and climatic conditions, southern China often provides good conditions for the outbreak of alien invasive species.

Human activities and alien invasive species

The most fundamental reason of biological invasion is that human activities have brought these species to places where they should not appear. So we call these species "harmful", which is actually unfair to these species. They just stay in the wrong place, and the cause of this mistake is often some irresponsible activities of human beings. The key to the problem of alien invasive species is man-made.

1, intentionally introduced

It refers to the intentional introduction of a species by human beings, which purposefully focuses a species outside its natural distribution range and diffusion potential (this introduction can be authorized or unauthorized).

2. Unintentional introduction

Refers to the use of people or people's communication system as a medium to introduce a species unintentionally and spread it to places outside its natural distribution.

Harm of alien biological invasion

(A) the impact on the ecology

Why do exotic creatures not cause harm in the country of origin, but may have adverse effects after entering new areas? Due to the limitation of habitat, natural enemies, competition among species and human interference, a certain organism has actually formed a harmonious ecosystem with the external environment, so the species is very "moderate" in the ecosystem; When people consciously introduce (or unintentionally bring) this species into the new environment of ecosystem B, only this species is introduced or brought in, but it is not (nor possible) introduced at the same time in the habitats of origin, natural enemies, competition and interference. Therefore, this species may "do whatever it wants" in the more suitable environment of ecosystem B, develop explosively, and be anti-customer-oriented, which will have a negative impact on ecosystem B, that is, in the more suitable environment of ecosystem B. When a species is introduced into a new habitat, if it becomes wild out of human control, it is easy to spread wildly under suitable climate, soil, water and transmission conditions, forming a large-scale single-superior community, destroying local animals and plants, endangering the survival of local endangered animals and plants, and causing the loss of biodiversity.

The mechanism and ecological impact of alien invasive species on the ecosystem are as follows:

1. The competition and occupation of local species niches make local species lose their living space.

2. Competing for food with local species or directly killing local species will affect the survival of local species.

3. Secrete and release chemicals to inhibit the growth of other species. Some exotic organisms such as ragweed can release allelochemicals such as phenolic acids, polyacetylenes, sesquiterpene lipids and sterols, which have obvious inhibitory and repulsive effects on millet such as Gramineae and Compositae. Mikania micrantha can also secrete allelochemicals to affect the growth of other plants.

4. By forming a large-scale single-superior community, species diversity is reduced, and other species that rely on local species diversity have no suitable habitat. The coverage rate of water hyacinth in rivers, lakes and ponds can often reach 100%, which leads to the death of aquatic animals due to the decrease of dissolved oxygen in water. The dominance of ragweed was 0.85 ~ 1.0 and the community diversity was 0 ~ 0.62. Due to Mikania micrantha crowding out local plants, macaques on Neilingding Island in Guangdong lack suitable food and can only be artificially fed at present. The spread of Eupatorium odoratum in Xishuangbanna Nature Reserve has endangered local plants such as Polygonum perfoliatum and herbivorous insects that depend on Polygonum perfoliatum for survival. Ranunculus ternatus in Gulangyu, Xiamen, climbs green trees, forming a large single-superior community on the crown, affecting the photosynthesis of trees and causing death.

5. Excessive utilization of local soil moisture is not conducive to soil and water conservation. Eucalyptus grandis was introduced from Australia and planted in many forest farms in Hainan Island and Leizhou Peninsula. Some places absorb a lot of water, which is very unfavorable to soil and water conservation and causes soil dryness. Continuous planting on a piece of land will make the soil fertility lower and lower, and even form a barren land. Therefore, the introduction of Eucalyptus grandis should be tailored to local conditions and controlled purposefully according to needs.

6. Destroy the naturalness and integrity of the landscape. Four species of American cactus introduced in the late Ming Dynasty formed dominant communities in the coastal areas of South China and southwest dry-hot valleys. The original natural vegetation landscape there is hard to see. Some invasive species, especially lianas, such as Ranunculus ternatus in Xiamen, can completely destroy the well-developed and rich forest landscape.

7. Affect genetic diversity. With the fragmentation of habitat, the remaining secondary vegetation is often divided, surrounded and infiltrated by invasive species, which further fragmentates the protozoan population and causes inbreeding and genetic drift of some vegetation. It is worth noting that, unlike the destruction of the environment by human beings, the destruction of the environment and the threat to the ecosystem by alien invasive species are long-term and lasting. When human beings stop polluting an environment, the environment will start soon and gradually recover; However, when an alien species stops being introduced into an ecosystem, the individuals of the introduced species will not disappear automatically, but most of them will use them to reproduce and spread in the new environment without the control of their original natural enemies, and it is often very difficult to control or remove them. However, local endemic species that have been extinct due to the exclusion and competition of alien species cannot be recovered. Therefore, the threat of alien species to biodiversity should be paid enough attention.

Impact on society and culture

Alien invasive species reduce species diversity by changing the natural ecosystem, and also do serious harm to local society, culture and even people's health. China is a multi-ethnic country, and all ethnic groups, especially the Dai, Miao and Buyi, have their unique animal and plant resources and distinctive ecosystems around them, which play an important role in the formation of local unique national culture and lifestyle. However, due to the constant competition of exotic invasive plants such as Eupatorium adenophorum and Eupatorium adenophorum, biological invasion is silently weakening the foundation of national culture.

Exotic species will pose a direct threat to human health. Ragweed pollen is one of the main pathogens of human allergy, and the "hay fever" caused by it has brought great harm to human health in many countries around the world. Some exotic animals, such as Ampullaria gigas, are intermediate hosts of human and animal parasitic diseases, and muskrats can spread hare fever, which is easy to bring health problems to surrounding residents. Mad cow disease, foot-and-mouth disease and AIDS are great challenges to human survival.

Impact on the economy

Alien invasive species will bring direct and indirect economic harm. It is conservatively estimated that exotic species bring hundreds of billions of dollars in economic losses to China economy every year.

1. Alien invasive plants and animals have become the main pests that directly endanger the economic development of agriculture and forestry.

Alien invasive animals and plants will bring direct economic harm to farmland, horticulture, lawn, forest, animal husbandry and aquaculture. The yield loss caused by Alternanthera philoxeroides in the whole growth period of rice, wheat, corn, sweet potato and lettuce reached 45%, 36%, 65, 438+09%, 63% and 47% respectively. Guangdong, Yunnan, Jiangsu, Zhejiang, Fujian, Shanghai and other provinces and cities have to salvage water hyacinth manually every year. Only Wenzhou City, Zhejiang Province and Putian City, Fujian Province spent 6.5438+0.00 million yuan and 5 million yuan respectively on artificial fishing of water hyacinth. There is no accurate statistics on the total cost in China, which exceeds at least 654.38+0 billion yuan. The agricultural irrigation and irrigation brought by water hyacinth was first discovered by Liriomyza sativae in Hainan in 1993. By 1998, it has occurred in 2 1 provinces and cities across the country, with an area exceeding1300,000 hectares. It parasitized 22 families 1 10 plants, especially vegetables and melons, and suffered seriously. Bursaphelenchus xylophilus, known as "Bursaphelenchus xylophilus", has spread to six provinces in Jiangsu and Zhejiang in just ten years, covering an area of about 66,000 hectares, posing a great threat to scenic spots such as Huangshan and Zhangjiajie.

In international trade activities, exotic species often cause trade frictions between countries and become an important excuse or means of trade sanctions. In recent years, the problem of Anoplophora glabripennis has caused tens of millions of economic losses to the foreign trade of wooden packaging products exported to the United States.

2. Exotic pests bring losses to tourism by affecting the ecosystem.

For example, in Kunming, Yunnan Province, an ideal tourist route on Daguan River was built in 1970s and 1980s, and tourists can visit Dianchi Lake and Xishan Mountain by boat from downtown Kunming. However, since the early 1990s, the water hyacinths in Daguan River and Dianchi Lake have grown wildly, covering the whole Daguan River and part of Dianchi Lake, forcing this tourist route to be cancelled, and the original supporting tourist facilities on both sides of Daguan River have to be scrapped or used for other purposes.

3. Exotic organisms cause indirect economic losses by changing a series of adverse effects such as water, soil and climate. Compared with direct economic losses, indirect losses are often difficult to calculate. But it doesn't mean that the indirect loss is small. For example, a large number of water hyacinth plants died and mixed with sediment deposited on the bottom of the water, which raised the riverbed and gradually turned many rivers, ponds and lakes into swamps, some of which were abandoned, which adversely affected the surrounding climate and natural landscape and aggravated the harm of drought and flood disasters; Moreover, water hyacinth plants absorb a lot of toxic substances such as heavy metals and sink into the water after death, which causes secondary pollution to the water quality and aggravates the pollution degree. Although these losses are difficult to calculate accurately, they cannot be ignored.