1. Economic loss: China is one of the countries that suffered the most from alien species invasion. From south to north, from east to west, the troubles brought by these alien invaders can be seen almost everywhere.
2、
Extinction of species: 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.
3. Destruction of ecology: 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.
4. Threatening health: For example, ragweed introduced to China 40 years ago, its pollen-induced "hay fever" will do great harm to human health.
Case of biological invasion of ragweed
1, destroying the ecology. Invasion of bare land can become the dominant species after one year. Because of its strong vitality, it can cover and suppress native plants, causing the destruction of the original ecosystem, reducing agricultural production, consuming water and nutrition in the land, and causing great losses in agriculture; The spread of ragweed has eroded a large area of land, leading to crop failure and posing a great threat to the ecological environment.
2, pollen allergy.
The direct harm of ragweed to human body is the pollen emitted after flowering. The pollen of this grass contains water-soluble protein, which can be released quickly after contact with people, causing allergic reactions. It is the main pathogen of pollen allergy in autumn, which easily leads to "hay fever" that is harmful to health.
Mild symptoms cause cough and asthma; In severe cases, it can cause emphysema, and the infection recurs year after year, getting worse year by year.