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What is ecological invasion? What does it tell us about species introduction?

basic concept

Biological invasion refers to the phenomenon that a certain organism is introduced naturally or artificially from other places and becomes wild, which causes certain harm to the local ecosystem. These creatures are called alien species. Exotic species refer to those species, subspecies or taxonomic units that have appeared in the past or now beyond their natural distribution 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 have the characteristics of strong ecological adaptability, strong reproductive ability and strong communication ability. Invasive ecosystem has the characteristics of abundant available resources, lack of natural control mechanism and high frequency of human entry. The "exotic" of alien species is defined by the ecosystem.

Invasion case

blattella germanica

Blattella germanica, native to Germany, is called Blattella germanica. Due to international trade, it is imported into China in the process of commodity circulation and transportation. Because its posture is very similar to that of cockroaches, its individual size is a quarter of that of ordinary cockroaches, and it belongs to a kind of cockroaches.

The reproductive speed of Blattella is thousands of times faster than that of common cockroaches. After about half a month, its young eggs can grow into adults, and the population is several times or even thousands of times that of ordinary cockroaches. The living habits of cockroaches are similar to those of ordinary cockroaches, and they like to move in hotels, Chinese and western kitchens, bars, restaurants, private rooms and other places. Its harm to people is similar to that of cockroaches, mainly because they spread many harmful substances and germs into people's food and utensils during their activities, endangering people's life and health.

Blattella germanica is the smallest indoor cockroach, and its body length is below15 mm. The adults are brownish yellow. There are two parallel brown longitudinal stripes on the back plate of the chest.

Blattella germanica can experience 4-5 generations a year.

Blattella germanica egg sheath has been dragged at the end of the female insect until the nymph is hatched. Nymphs therefore spread everywhere with their mothers.

After molting for 5-7 times, the nymph becomes an adult, and the nymph period is 30-56 days.

It has been nearly twenty years since Blattella germanica officially settled in China on a large scale, and it has spread from a few big cities to almost all small and medium-sized cities, even small market towns and rural areas. According to the data of the National Center for Disease Control and Prevention, a female Blattella germanica can breed up to one million offspring a year. With the extensive use of pesticides for control, Blattella germanica has developed strong drug resistance, and most pesticides are ineffective. Because of the existence and uncontrollable of Blattella germanica, cockroaches have replaced mice as the first of the four pests!

Excerpt from cockroach control network

With the increasingly frequent and close economic and cultural exchanges between countries and regions, and with the increasing global environmental instability, all ecological wars without smoke-"biological invasion" are quietly starting all over the world, and the ecological disasters caused by them are seriously threatening the economic development and global ecological security of all countries in the world.

Known as the "Purple Devil", the water hyacinth (commonly known as "Water hyacinth" in China) is rampant in waters around the world, which is the most typical example of alien species invasion. From 65438 to 0884, Eichhornia crassipes, originally from Venezuela in South America, was sent to the World Expo in New Orleans, USA. People from all over the world saw its gorgeous flowers and brought them back to their respective countries as ornamental plants. As everyone knows, Eichhornia crassipes with strong reproductive ability has since become the number one harmful plant in all countries. In Africa, Eichhornia crassipes is all over the Nile; In Thailand, Eichhornia crassipes covers the Chao Phraya River; In the southern United States, the inland rivers along the Gulf of Mexico are also blocked by dense Eichhornia crassipes, which not only leads to the impassability of ships, but also leads to the extinction of fish and shrimp and the stink of river water. Dianchi Lake in Yunnan, China was also accused by experts of suffering from "ecological cancer" because of the crazy spread of water hyacinth.

In addition, the rabbit disaster in Australia, poisonous algae in the Mediterranean, zebra mussels in the Great Lakes of the United States, frogs in Hawaii, and the invasion of exotic species such as Eupatorium adenophorum, Spartina, Bursaphelenchus xylophilus, Solidago canadensis, crayfish and Hyphantria cunea are all examples. Due to the lack of natural enemies, these foreign 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 report of the International Union for Conservation of Natural Resources (IUCN), the global economic losses caused by the invasion of alien species exceed 400 billion dollars every year.

Cause of invasion

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

Undoubtedly, the correct planting will increase the biodiversity of the introduction area and greatly enrich people's material life. For example, the United States introduced soybeans from China in the early 20th century, and the planting area increased from more than 60 million mu to more than 400 million mu now. At present, the United States has become the largest soybean producer and exporter. As far as China is concerned, as early as 126 BC, after Zhang Qian returned from his mission to the western regions, the history of China turned a page in introducing exotic species. Alfalfa, grapes, broad beans, carrots, peas, pomegranates, walnuts and other species began to be introduced into the Central Plains along the Silk Road, and corn, peanuts, sweet potatoes, mangoes, betel nuts, figs, papaya and walnuts were introduced into the Central Plains.

On the contrary, improper introduction will make alien species lacking natural enemies multiply rapidly, rob other creatures of their living space, lead to ecological imbalance and the reduction and extinction of other native species, and seriously endanger the ecological security of a country. Species introduction in this sense is called "alien species invasion". Therefore, alien species that have caused serious harm to the ecological environment of equal places are called "invasive species".

It is not difficult to see that "invasive species" is different from "alien species", which refers to harmful alien species, such as Eichhornia crassipes, pine nematode, Spartina, etc., and its category is smaller than "alien species". The "alien species invasion" is also different from the "alien species introduction", which refers to the process that alien invasive species spread from their native places to the invasive places through natural or artificial channels, destroying the biodiversity and ecosystem of the invasive places, and even endangering human health, thus causing economic losses and survival disasters.

It is worth mentioning that with the change of climate and environment, some species that are harmless for a relatively long time after introduction may gradually become "invasive species". Therefore, in a sense, the results of the introduction of alien species are unpredictable to some extent. This also makes the prevention and control of alien species invasion more complicated and difficult.

Invasion channel

Generally speaking, biological invasion channels include the following three types:

▲ (1) Natural invasion

This invasion is not man-made, but the invasion of alien species caused by biological hazards caused by natural migration of plant seeds or animal larvae, eggs or microorganisms through wind, water or insects and birds.

Such as Eupatorium adenophorum, Mikania micrantha and Liriomyza sativae are all invaded by natural factors.

▲ (2) Unintentional introduction

Although this way of introduction is artificial, there is no subjective intention to introduce it, but with the import and export trade, ships or inbound tourism are inadvertently introduced.

For example, "Bursaphelenchus xylophilus" was brought in by China traders with wooden packing boxes when importing equipment. Millions of tons of ballast water discharged by ships sailing in world waters has also become the main channel for unintentional introduction of aquatic organisms. In addition, fruits, vegetables, meat and even the soles of passengers carried by inbound tourists may become channels for unintentional invasion by foreign creatures.

▲ (3) Intentional introduction

It should be said that this is the most important channel for alien invasion. In order to develop agriculture, forestry and fishery, countries all over the world often introduce excellent animal and plant varieties consciously. For example, in the early 20th century, New Zealand introduced kiwifruit from China, and the United States introduced soybeans from China. However, due to the lack of a comprehensive risk assessment system, countries around the world have introduced a large number of pests, such as Spartina, Alternanthera philoxeroides, Ampullaria gigas and so on, while introducing excellent varieties. Because these invasive species have changed the living environment and food chain of species, they are flooded without the restriction of natural enemies. Most of the pests in the world are introduced into countries around the world through this channel.

(four) international cooperation in the prevention and control of alien species invasion and the legislative practice of other countries.

As a global ecological phenomenon, alien species invasion has gradually become an important reason for sacrificing diversity and species extinction. According to the data provided by IUCN, there are 10954 species of wild animals, 1/3 species of fish and 1/4 species of mammals, birds and reptiles in the world, all of which are highly endangered. If it develops at this rate to 265,438+000 years, on the earth, [6]

Faced with such a grim situation, more and more countries gradually realize that one country alone cannot stop the wanton invasion of alien species, and active international cooperation can more effectively alleviate the threat of alien species to biodiversity.

serious consequences

After alien pests invade new suitable growth areas, their populations will multiply rapidly and gradually develop into new local "dominant species", which will seriously damage the local ecological security. Specifically, the consequences mainly include the following:

■ First, the invasion of alien species will seriously destroy biodiversity and accelerate species extinction.

Biodiversity is a complex system with different levels, including all plants, animals, microbial species and their genetic information, as well as organisms and living environment. [2] Although the biodiversity of a country or region is endowed by nature, any country must invest a lot of manpower and material resources to try its best to maintain its biodiversity. However, the invasion of alien species is the number one enemy threatening biodiversity. After the introduction of invasive species into different places, due to the lack of natural enemies and other restrictive factors that can limit their reproduction, the consequences are rapid diffusion, massive expansion, formation of dominant species, and competition with local species for limited food and space resources, which directly leads to the degradation or even extinction of local species.

■ Second, the invasion of alien species will seriously destroy the ecological balance.

The invasion of alien species will affect the water and other nutrients in plant soil, as well as the structural stability and genetic diversity of biological communities, thus destroying the local ecological balance. For example, Mikania micrantha, an exotic species introduced from Australia and invaded many forest farms in Hainan Island and Leizhou Peninsula, is extremely dry because it can absorb a lot of soil moisture, which is very unfavorable to soil and water conservation. In addition, Mikania micrantha can secrete chemicals to inhibit the growth of other plants, which once seriously affected the production and development of the whole forest farm.

■ Third, the invasion of alien species will directly threaten the survival of other organisms and even human health because of the pathogenic microorganisms it may carry.

For example, dutch elm disease, which originated in East Asia, invaded Europe twice at 19 10 and 1970, causing elm death in most European countries. Another example is ragweed introduced to China 40 years ago. Pollen fever caused by its pollen will do great harm to human health. When pollen drifts from July to September every year, allergic people will have asthma, sneezing, runny nose and other symptoms, and even die of other complications.

Fourthly, the introduction of alien species will also cause huge economic losses to the affected countries.

It is very difficult for any country to completely eradicate alien invasive species. In fact, the management cost of controlling its spread is quite expensive. In Britain, in order to control 12, the most dangerous alien invasive species, in 1989- 1992, the photoherbicide cost 344 million dollars, while in the United States, it costs 3 million dollars to control the propagation and spread of Eichhornia crassipes every year. Similarly, the annual cost of salvaging water hyacinth in China is as high as $565,438.

According to the research report submitted by the United States, India and South Africa to the United Nations, the economic losses caused by alien species invasion in these three countries are 654.38+05 billion US dollars, 654.38+03 billion US dollars and more than 80 billion US dollars respectively. [4] According to the report of the International Union for Conservation of Natural Resources, exotic species spread rapidly in Africa, seriously damaging biodiversity and economic development, and causing billions of dollars in economic losses every year. Howard, the drafter of the report, believes that the damage caused by alien species to Africa may be just the tip of the iceberg, and its impact on Africa's ecological and economic development may be much greater than estimated.

International regulations

At present, the invasion of alien species, as a global problem, has attracted wide attention from countries and international organizations. International organizations such as the International Union for Conservation of Natural Resources and the International Maritime Organization (IMO) have formulated technical documents on how to introduce exotic species and how to prevent, eliminate and control the invasion of exotic species. The United States, Australia, New Zealand and other countries have successively established various technical guidelines and guidelines for the prevention and control of alien species invasion, and made corresponding legislation to strengthen the defense ability and comprehensive management ability of alien invasive species.

From 1982 to 1988, under the organization of the Scientific Committee on Environmental Issues (SCOPE), many scientists began to discuss the nature of alien species invasion.

At the World Conference on Environment and Development held in Rio de Janeiro, Brazil from 65438 to 0992, the participating countries signed the International Convention on Biological Diversity (including China), which is the most important global convention on biosafety. Regarding the invasion of alien species, Article 8 of the Convention clearly stipulates: "The impact of alien invasive species on biodiversity must be prevented and controlled." At the same time, the Convention also requires each State Party to directly or require any natural or legal person under its jurisdiction who provides the organisms specified in the Convention to provide any existing information about the use and safety of these organisms in the State Party and any existing information about the possible adverse effects of these organisms to the State Party that will introduce these organisms.

In addition, two international rules closely related to the control of alien species: SPS Agreement (namely Agreement on Sanitary and Phytosanitary Measures) and TBT Agreement (namely Agreement on Technical Barriers to Trade) also clearly stipulate that in order to protect production safety and national security, some technical barriers can be set up to prevent the invasion of pests.

In fact, as early as 1982, the United Nations Convention on the Law of the Sea clearly stipulated that all countries must take all necessary measures to prevent, reduce and control the major and harmful changes in the marine environment that may be caused by the intentional or accidental introduction of new alien species into specific parts of the marine environment.

In general, more than 40 international conventions, agreements and guidelines have been adopted to prevent the invasion of alien species, and many agreements are being formulated. Although many conventions are not binding to a certain extent, and although there are still some gaps and contradictions in formulating quarantine standards among countries, these documents still play an increasingly important role in a certain scope, and the International Maritime Organization, the World Health Organization and the Food and Agriculture Organization of the United Nations are also more actively committed to strengthening international cooperation in preventing and controlling the invasion of alien species.

Looking around the world, the legislative measures to prevent and control the invasion of alien species in the United States and Australia are worth learning.

As one of the countries suffering from the most serious invasion of alien species in the world, the American government started the corresponding legislative work as early as the early 1990s. 1990, the United States Congress passed the Non-Native Species Act, which aims to study the shipping practice in the United States and help master how to introduce alien species and how to prevent the introduction of harmful species. 5438+0999+ 10 When the first international conference on marine biological invasion was held in MIT as scheduled, President Clinton issued a presidential decree to set up an invasive species committee composed of representatives from various departments. The committee must cooperate with the federal government, states, relevant scientists, universities, shipping industry, environmental protection agencies and farm organizations, and assist each other to carry out the work of resisting alien invasive species.

Due to its special geographical location, the prevention and control of alien species invasion in Australia mainly focuses on two aspects: first, how to prevent and control more than 220 kinds of harmful weeds that have a serious impact on agriculture and forestry; The second is how to remove the threat of the invasion of marine alien species carried by ship ballast water. Based on this, from 65438 to 0996, Australia first formulated the National Strategy for Biodiversity Conservation in Australia, aiming at preventing and controlling harmful alien species by formulating various environmental impact assessment plans and establishing biological methods to minimize the risk of introduction of alien species.

1997 national weed strategy (latest revision of 1999) was jointly issued by Australia and New Zealand Environment and Protection Committee, Australia and New Zealand Agriculture and Resource Management Committee and Australian Forestry Department. The National Weed Strategy mainly stipulates three objectives of exotic weed management, and defines the respective obligations and responsibilities of the government, communities, land owners and land users, and finally puts forward corresponding action strategies. In addition, in view of the introduction of weeds, Australia has also established a set of weed risk assessment system (WRA), which evaluates the risk of intentionally introduced exotic plants by formulating questions and scoring standards.

In order to prevent the invasion of marine harmful species, the Australian Quarantine and Inspection Bureau issued the world's first mandatory normative document on ballast water-ballast water guide (latest revision of 1999) on1,requiring all ships entering Australian waters to be subject to mandatory ballast water management. In addition, this document also specifies the discharge, reporting and quarantine of ballast water in detail.

China game

Current situation of biological invasion in China

China has a vast territory, diverse habitats and diverse ecosystems. Most exotic species can easily find suitable growth and breeding sites in China, which makes China more vulnerable to the invasion of exotic species.

For a long time, due to the lack of sufficient understanding and systematic investigation and research on the invasion of alien species, China has still been unable to provide authoritative catalogue materials reflecting the invasion of alien species into China. Although the State Environmental Protection Administration announced the first batch of 16 "alien invasive species" [7], the actual number of invasive animals and plants is far more than these. According to preliminary statistics, at present, the known alien invasive species in China include at least 300 invasive plants, 40 invasive animals and 1 1 invasive microorganisms. Among them, eight invasive plants such as water hyacinth, Alternanthera philoxeroides, Spartina alterniflora and Mikania micrantha have brought serious harm to agriculture and forestry, and the most serious pests are American white moth, pine wood nematode and potato beetle 14 species. The harmful alien species announced by the State Environmental Protection Administration 16 are Eupatorium adenophorum, Mikania micrantha, Alternanthera philoxeroides, ragweed, poisonous wheat, Spartina alterniflora, Eupatorium odoratum, Eichhornia crassipes, false sorghum, sugarcane borer, Pinus elliottii, bark beetles, Hyphantria cunea and African snails.

These alien invasive organisms have become the number one enemy of agriculture, forestry and animal husbandry production and biodiversity protection in China.

On the one hand, it has caused huge economic losses to agriculture, forestry and animal husbandry in China. It is estimated that only a few major alien invasive species cause direct economic losses to China as high as 50 billion yuan every year.

On the other hand, it also makes the task of maintaining biodiversity in China more arduous. According to the survey, about half of the alien invasive species in 100 published by IUCN have invaded China. In line with this, among the 640 world endangered species listed in the International Convention on Endangered Wild Fauna and Flora, 156 are all in China. Therefore, it is urgent to maintain biodiversity and fully resist the invasion of alien species.

Analysis on the current situation and existing problems of biological invasion prevention and control legislation in China

At present, China has not formulated special regulations on the management of exotic species, and has not established a risk assessment mechanism, a comprehensive management mechanism and a tracking and monitoring mechanism for the introduction of exotic species. Compared with the developed countries in the world, the legislation to prevent the invasion of alien species is still in its infancy, and its main problems are:

1, the legislation is scattered and the operability is not strong.

At present, laws and regulations related to the prevention and control of alien species are mainly scattered in the Environmental Protection Law, Marine Protection Law, Agriculture Law, Fisheries Law, Entry-Exit Animal and Plant Quarantine Law and other laws and regulations, which are not only too scattered and unsystematic, but also too principled and lack pertinence and operability.

For example, although the Environmental Protection Law involves the protection of environmental organisms, it does not explicitly raise the issue of foreign invasion and its prevention and control. For another example, the Agricultural Law, which was revised and implemented on March 1 2003, added in the first paragraph of Article 64 that "the introduction of biological species resources from abroad should be registered or approved according to law, and corresponding safety control measures should be taken", but up to now, China has not established a corresponding alien species file classification management system and a regular investigation and tracking monitoring system. How to carry out "safety control"?

2. Lack of unified and coordinated management institutions.

So far, there is no special organization to prevent the invasion of alien species in China, and the departments involved are AQSIQ, State Environmental Protection Administration, Ministry of Agriculture, Ministry of Forestry and so on. Due to their respective responsibilities, there are different degrees of disconnection between the prevention of alien species before invasion and the response after invasion. Sadly, some invasive species that could have been shut out at the beginning of the invasion or could have been completely eradicated eventually flooded because of the management system problems, and the management department also missed the opportunity to stop and curb their growth and reproduction again and again.

3. The relevant regulations are still relatively thin, and many legal systems need to be established or further improved.

For a long time, the content of alien species control in China only focuses on pest quarantine, and rarely involves risk assessment system, tracking monitoring system and comprehensive management system; Nor does it involve the objectives, procedures and means to prevent the invasion of alien species.

Perfection of Legislation on Prevention and Control of Alien Species Invasion in China

1. Establish a unified and coordinated management organization.

At this point, the practice of the United States is worth learning. Before 1999, the United States did not set up a special organization to lead the prevention and control of alien species invasion. However, the increasingly serious invasion crisis and the firm determination to oppose the invasion led to the birth of the American Invasive Species Committee, whose main responsibility is to actively cooperate with various departments, institutions and units at different levels, regions and types, and to supervise the implementation of cooperation plans among various departments.

Specific to China, we should set up a unified coordination and management organization including quarantine, environmental protection, marine, agriculture, forestry, trade, scientific research institutions and other departments. This institution should proceed from the national interests, not from the departmental interests, and comprehensively carry out the prevention and control of alien species. Before the introduction of alien species, the agricultural or forestry or marine management department shall, jointly with scientific research institutions, conduct introduction risk assessment, the environmental protection department shall conduct environmental assessment, and the quarantine department shall conduct strict port control, and coordinate actions in various ways to effectively carry out the prevention and control of alien species.

2. Improve the risk assessment system.

In order to prevent the invasion of alien species, the first task is defense, and the risk assessment system of alien species is to strive to keep pests firmly in the first place at the first time.

The weed risk assessment system established in Australia is worth learning. The evaluation system designs 49 questions according to the information, biological characteristics, propagation and transmission mode and climate parameters of the species to be introduced, answers each question by questionnaire, scores the answers of each question, adds up the scores of all questions, and decides whether to introduce the species according to the comparison between the final score and the standard value. Generally includes three kinds of results:

One is to allow species to be imported; Second, the species is not allowed to be imported; Third, more evaluation is needed for this factory.

Through such a weed risk assessment system, it can indicate the possibility that the ecosystem is affected by introduced species, thus avoiding the introduction of some weeds that harm the ecosystem to a great extent.

For a long time in China, the quarantine department only carried out general pest quarantine according to the quarantine catalogue. If the foreign object has no pests or diseases, or is not a pest or weed, it can generally pass the customs safely. Therefore, for the pests that were introduced for the first time or whose harmfulness could not be found in a short time, no scientific risk assessment was conducted, which led to a large number of pests being openly introduced into China. Fortunately, this issue has aroused widespread concern in China. The Provisions on Risk Analysis and Management of Imported Plants and Plant Products promulgated by the General Administration of Quality Supervision, Inspection and Quarantine on June 5438+February 9, 2000 (implemented on February 1 2003) set a special chapter to stipulate the "risk assessment" system, and stipulated that the General Administration of Quality Supervision, Inspection and Quarantine should adopt qualitative, quantitative or both legislative methods to carry out the risk assessment system. The establishment of this system is undoubtedly a major institutional progress to resist the invasion of alien species in China, but in my opinion, there are still two shortcomings:

First, the main body of risk assessment is limited to the quarantine department, lacking coordination and cooperation with other production departments and scientific research institutions. There is no doubt that scientific risk assessment should be based on a comprehensive understanding of the biological characteristics, reproductive and communication capabilities of the species and the information of all related species, and the cooperation of various departments and scientific research institutions is an important way to obtain sufficient information:

Therefore, the provisions on the subject of risk assessment are not reasonable, and the scope of cooperation should be expanded.

Second, there is a lack of specific evaluation indicators, and only some factors that should be considered in the evaluation are stipulated, which is not practical.

The author thinks that the risk index evaluation system of alien species invasion should be established, that is, different questions should be set according to their genetic characteristics, reproductive and diffusion ability, biological characteristics and their impact on the ecological environment, and the risk degree should be quantified according to the answer scores, so as to make the risk evaluation more targeted and operable.

3. Establish a tracking and monitoring system

If an alien species is not tracked and monitored after it is introduced, once it is proved to be a pest or gradually transformed into a pest with the change of climatic conditions, it is likely to be a serious ecological disaster if it gives up the opportunity of complete eradication at the initial stage of transmission.

From this, we can easily draw a conclusion: firstly, a file classification system of introduced species should be established, and the time and place of their entry into China should be registered in detail; Secondly, it is necessary to regularly monitor its growth and reproduction, grasp its survival and development trends, and establish a tracking and monitoring system for alien species. Once a problem is found, it can be solved in time. It will neither pose a threat to China's ecological security, nor need to invest huge sums of money in governance.

4. Establish a comprehensive management system.

For invasive harmful species, it is necessary to ensure the establishment of a sustainable control and management technology system through a comprehensive management system. Once alien harmful species invade, it is very difficult to eradicate them completely. Therefore, it is necessary to give full play to the advantages of various control methods through the comprehensive application of biological methods, physical methods and chemical methods in order to achieve the best control effect on alien invasive species.

5, strengthen quarantine work, the establishment of alien species epidemic reporting system and information sharing system.

On the one hand, quarantine departments should strengthen quarantine, crack down on smuggling animals and plants and evade quarantine incidents; In areas where alien invasive species are most likely to enter, strengthen personnel cooperation and strengthen quarantine forces.

On the other hand, strengthen scientific research and information exchange, establish a multi-level reporting and analysis system of exotic species epidemic situation at provincial, municipal and county levels, establish an inquiry system of exotic species epidemic situation, realize information sharing, help farmers or breeders master the disease and minimize risks.

Overview of situation

The introduction of different species from different ecosystems has brought great negative impact on social economy and ecological environment. With the continuous improvement of the existing legal response mechanisms in various countries and the deepening of international cooperation, the work of preventing and controlling the invasion of alien species will surely achieve greater results, although this work still has a long way to go.

Some experts also believe that biological invasion may not be as terrible as we thought, and there is not enough credible evidence to show that there is an "invasive species crisis". They believe that the natural ecosystem itself is constantly changing, and there are always some new species entering an ecosystem, and the result is not necessarily harmful-for example, the biodiversity in some places will increase with the intervention of invasive species.

Annotate

①: "Exotic species bring billions of dollars in income to Africa every year" [J]. World Scientific Research and Development, 2003, (4): 10 1

2. Ginger. "Research progress of biodiversity and countermeasures after China's entry into WTO" [J]. World Science and Technology Research and Development, 2003, (10): 1.

③: Zhang Runzhi, Sang Weiguo, Sun Jianghua, Xue Dayong and Le Kang. "Biological Invasion and Control of Alien Invasive Species" [J]. Frontier, 56 (6): 12.

(4) Chen Sai. "Alien species invasion and its environmental legal regulation standards" [J]. Xinjiang Environmental Protection, 2002,24 (4): 32.

⑤: "Exotic species bring billions of dollars in income to Africa every year" [J]. World Scientific Research and Development, 2003, (4): 10 1

6. Cai Shouqiu. On Biosafety Law [J], Journal of Henan University of Political Science and Law, 2002, (2): 4

⑦: The 16 harmful alien species announced by the State Environmental Protection Administration include Eupatorium adenophorum, Mikania micrantha, Alternanthera philoxeroides, ragweed, poisonous wheat, Spartina alterniflora, Eupatorium odoratum, Eichhornia crassipes, false sorghum, sugarcane borer, Pinus elliottii, bark beetles, Hyphantria cunea and so on.

⑧: David Theodore Lopez, "Invasive Biology: Criticism of Pseudoscience"