The so-called invasive plants refer to plants that enter another environment from the original place of growth due to man-made or natural reasons, causing losses to the organisms, agriculture, forestry, animal husbandry and fishery production in this environment, damaging human health and destroying ecological balance.
For example, fake sorghum looks like sorghum, but its stems and seeds contain a small amount of cyanide. This plant has great vitality. If there is fake sorghum in the crop field, the crop yield will be reduced by about 20%. Not only that, the root penetration of fake sorghum is very strong. The root system of a false sorghum can add up to more than 1 km long. If it grows on the dam, it will also pose a great threat to the safety of the dam. Therefore, once the fake sorghum grows on the ground, it is difficult to eliminate it.
According to relevant literature, there are many invasive plants like fake sorghum. At present, there are more than 380 invasive plants in China, among which water hyacinth, Alternanthera philoxeroides, ragweed, Eupatorium adenophorum, Eupatorium odoratum, Spartina, Mikania micrantha and Chrysanthemum have brought serious harm to China's agriculture. These exotic plants threaten the agro-ecosystem of China, the habitat of livestock and fish, and affect our health.
One of the biggest characteristics of invasive plants is that after entering a new environment, their viability is very strong, robbing the living space and nutrients of other creatures around them. Li Jingming, director of the Energy and Ecological Construction Division of the Science and Technology Development Center of the Ministry of Agriculture, said that water peanuts can reduce rice production by 45%.
In Guangdong, Mikania micrantha often covers bananas, lychees, longan, wild oranges and some shrubs and trees, which makes it difficult for these plants to carry out normal photosynthesis and die. In Caohai Lake, Kunming City, Yunnan Province, there used to be 16 kinds of local higher plants, but with the rampant growth of water hyacinth, most local aquatic plants such as seaweed lost their living space and died. At present, there are only three local higher plants left in Caohai Lake.
In addition, invasive plants themselves may carry toxins, which will bring unexpected diseases to local animals and plants. For example, Eupatorium adenophorum contains toxins that can cause asthma in horses and sheep. Liangshan Yi Autonomous Prefecture in Sichuan Province once lost more than 60,000 sheep a year due to the invasion of Eupatorium adenophorum, and the loss of animal husbandry reached 2 1 more than 10,000 yuan. Eupatorium adenophorum has a strong ability to absorb soil fertility, which can greatly exhaust soil nutrients and destroy soil fertility.
Invasive plants are not easy to eradicate, and the cost of eradication is also high. For example, Guangdong, Yunnan, Jiangsu, Zhejiang, Fujian, Shanghai and other provinces and cities have to salvage water hyacinth manually every year, and the cost of salvaging water hyacinth in Shanghai exceeds 60 million yuan a year. However, water hyacinth has brought more economic losses to agricultural irrigation, grain transportation, aquaculture and tourism.
The harm of invasive plants does not stop there. There are special animal and plant resources and unique ecosystems around the Dai, Miao and Buyi communities in China. These natural resources play an important role in the formation of local national culture and lifestyle. However, due to the continuous expansion of invasive plants such as Eupatorium odoratum, which gradually replaced the local plant resources, many traditional crops gradually disappeared and the ancient lifestyle was being forced to change.
In addition, alien invasive organisms will also pose a direct threat to human health. Every time ragweed blooms, allergic people will have asthma, sneezing, runny nose and other symptoms, and weak people will have other complications, leading to death. The "hay fever" caused by ragweed has brought trouble to people in many countries in the world.
There are three main ways for alien harmful plants to invade. First of all, it is spread by plants themselves or natural forces. The second is to bring some harmful plants into China through trade and transportation. The above-mentioned fake sorghum seeds seen in Chiwan Port, Shekou, Shenzhen, entered in this way. In addition, some domestic institutions and individuals have consciously introduced some plants to develop agricultural production and beautify the landscape without knowing the harm. There are similar harmful plants among these plants. In this regard, our country has had a painful lesson.
From 1960s to 1980s, China introduced Spartina to protect beaches from British and American aggression. In recent years, this plant has spread wildly in coastal areas, covering an increasing area. The wanton spread of Spartina not only destroyed the habitat of coastal organisms, but also suffocated many coastal cultured species. In addition, this plant will also block the navigation channel, affect the ship's departure from the port, hinder the flow of seawater, lead to the decline of water quality and cause red tides, compete with coastal beach plants for growth space, and lead to the death of local plants. Therefore, it is necessary to block the invasion channels of harmful plants from the source.
The dangers of invasive plants are constantly emerging, which makes people realize that "ecological security" is as worthy of attention as environmental protection. In order to maintain ecological security, on the one hand, we should keep harmful plants out of the country, on the other hand, we should control harmful plants in China.
First of all, put an end to the invasion of harmful plants from the source and intensify the inspection of harmful plants by inspection and quarantine departments. At present, the staff of relevant inspection and quarantine departments have received strict professional training and higher education in related fields. Coupled with the inspection and quarantine experience accumulated in their work, under normal circumstances, known harmful plants can hardly escape their eyes.
In addition, in order to better prevent the invasion of harmful plants from inspection and quarantine, China often sends relevant quarantine personnel to inspect the origin of imported plants, so as to know what pollution there is in the local soil, what diseases and pests are in the process of plant growth, and what harmful weeds are easily mixed with products in the field. According to their understanding, there are fake sorghum in the fields of South American countries. It is estimated that the fake sorghum seeds mixed in soybeans were brought in together when the machine was harvested.
For the harmful plants that have invaded our country, the most common method is to pull them out manually and use chemicals. This plant is "burly" and can reach more than 4 meters in height. The three-leaf ragweed grows very densely here. This kind of grass has strong vitality and can survive for 5 years in harsh environment. Its seeds go with the wind, and once it takes root, it is difficult to eradicate it, and it is difficult to grow other plants around it.
It is said that the stems of some finless porpoises are as thick as wrists, and it is difficult to pull them out by manpower. To deal with them, you have to cut them with a knife and wear protective gloves, which is a lot of work. In addition, the use of chemical agents is very limited, because some ragweed is scattered in other crops, and large-scale drug use is not only costly, but also may cause harm to other plants.