Where in our country is the ecological imbalance caused by the introduction of exotic plants

American white moth. The American white moth [Hlyphantria cunea (drury)], also known as the American lamp moth and autumn curtain caterpillar, belongs to the order Lepidoptera, the family of lamp moths. It is a worldwide quarantine pest that attracts worldwide attention.

It mainly harms fruit trees, street trees and ornamental trees, especially broad-leaved trees. It causes serious harm to garden trees, economic forests, farmland shelterbelts, etc. At present, it has been included in the first batch of invasive alien species in China.

Origin: North America.

Distribution status in China: It is now distributed in Liaoning, Hebei, Shandong, Tianjin, Shaanxi and other places.

Causes and Hazards of Introduction: Introduced to Europe in 1940, it has now been introduced to more than 10 countries in Europe, as well as Japan, the Korean Peninsula, and Turkey. In 1979, it was introduced into Dandong, Liaoning, China, and in 1981, it was introduced into Rongcheng County, Shandong Province by fishermen from Liaoning Province, and spread in Shandong one after another, found in Tianjin in 1995, and found in Wugong County, Shaanxi Province in 1985 and formed a hazard.

It is mainly spread through wood, wood packaging, etc., and can also be further spread by flying. It has strong fecundity and rapid diffusion, and can spread outward by 35-50 km per yearIt can harm more than 200 kinds of plants such as fruit trees, trees, crops and wild plants, in the places where the orchards are dense and tourist areas, boulevards, when the occurrence is serious, the whole leaves can be eaten up, causing some branches or even the whole plant to die, seriously threatening the sericulture industry, forest fruit industry and urban greening, causing amazing losses.

In addition, the damaged trees are weakened, susceptible to other pests and diseases, and reduce their ability to withstand cold and stress. The larvae like to eat mulberry leaves, which poses a threat to sericulture.

There is a plant.

Purple-stemmed Zeland, Mikania, poison weed, false sorghum, ragweed, etc.

On the first floor, there are plants, not animals.

Biological invasions do not happen alone, but at the same time as global environmental change. It can be said that almost all major processes of global environmental change (such as climate change, biodiversity loss, land use change, nitrogen deposition, environmental pollution, etc.) interact with biological invasion processes (Mooney & Hobbs, 2000; perrings et al., 2010), not only is a revolution in evolutionary history (Cox, 2004), but it is also likely to have difficult ecological, economic, and social consequences. In the case of climate change alone, its interaction with biological invasions could have five major consequences (Hellmann et al.)., 2008):

changing the transport and introduction mechanisms of invasive species; (2) changing the constraints of climate on invasive species, leading to the emergence of new invasive species; (3) the distribution of existing invasive species was changed and expanded to new areas; (4) altering the impacts of existing invasive species; (5) The existing countermeasures for the management of invasive species need to be adaptively adjusted, or their management efficiency will be changed. Therefore, as one of the important processes of global change, biological invasion should be studied in conjunction with other processes to understand the pattern, mechanism and consequences of such interactions.

From Li Bo and Ma Ping, "Biological Invasions: Opportunities and Challenges in Translational Ecology Faced by Chinese Scholars", Biodiversity Science, 2010, 18(6): 529-532

China's judgment is able to introduce a large number of excellent foreign animals and plants, and can find suitable growth areas for potatoes, the main reason is that the climate is complex and more samples

Therefore, d

Vegetation status in China.

According to the Flora of Beijing, there are 2,056 species of vascular plants (including cultivated plants) in Beijing, belonging to 869 genera and 169 families. Among them, there are 20 families, 30 genera and 75 species of ferns; gymnosperms 9 families, 18 genera, 37 species; There are 104 families, 821 genera, and 1944 species of angiosperms. According to the analysis of floristic composition, the most common species of aunangiosperms were inulin, Poaceae, Fabaceae and Rosaceae, followed by Liliaceae, Cyperaceae, Umbellifera, Ranunculaceae, Cruciferaceae and Caryophyllaceae, reflecting that the floristic components were mainly composed of North China.

In addition, there are Eurasian steppe components in the plain area, such as Tribulus terrestris, Porphyllum pigtail, Tamarix, Suaeda salsa, etc., and the deep mountainous areas retain European Siberian components, such as North China larch, spruce, round-leaved deer hoof grass, Dancing crane grass, etc.; At the same time, tropical related species are also common in the low mountain plains, such as T. stinkensis, (left wood, right Luan) tree, jujube, vitex, yellow grass, white sheep grass, etc. These reflect the complex diversity of the flora that makes up Beijing.

The zonal vegetation in the Beijing area is the distribution of temperate deciduous broad-leaved forest with temperate coniferous forest. Before the Sui and Tang dynasties, the mountainous areas of Beijing were densely forested and species flourished. Since the Liaojin Dynasty, especially in the Yuan, Ming and Qing dynasties, before the liberation, there has been a long period of man-made destruction, and it has become a Shaolin area.

In recent years, the mountain has been closed for afforestation, and it has gradually recovered. According to the survey of vegetation in the mountainous areas in the early 80s, the total forest area is 159,410,000 acres (excluding fresh orchards), and the forest coverage rate is 10,7. The largest area of tree species was in Liaodong forest, followed by Pinus tabuliformis forest.

Among several mountainous counties, Huairou, Yanqing and Miyun counties have the largest forest area, with 38.65 million mu, 31.23 million mu and 30.84 million mu respectively, followed by Pinggu, Mentougou, Fangshan and Changping.

The total volume of standing timber in the city is 405,820,000 cubic meters, less than 0,5 cubic meters per capita (9,3 cubic meters per capita in the country and 83 cubic meters in the world). The grasslands in Beijing are concentrated in the mountainous areas, which are secondary and are the products of deforestation.

The grassland in the mountainous area is 5.1 million mu, accounting for 33 of the total area of the mountainous area. However, due to the lack of management and long-term use, the quality of grassland declined, with only 20 2 for the first and second grasslands, and 79 8 for the third, fourth and fifth grasslands. Poisonous weeds are multiplying day by day.

In the 10 years of the 80s, due to the vigorous promotion of afforestation, the forest coverage rate showed an increasing trend. Resources.

Let's talk about Lianling briefly. I'll show you the way. From the disorderly logging of the Great Northern Wilderness at the beginning, to the planned logging now. Describe a process and phases. If we talk about the problem of shacks, it is the degradation of grasslands, the increasing desertification, and the spread of feasts to cities

man-made destruction, indiscriminate deforestation, serious desertification, and serious soil erosion; the extinction of native species and the invasion of alien species; Natural disaster; Difficulties in protecting;

Lack of protection and caretakers, indiscriminate reclamation and deforestation.