Early Thistle Yan Chunqiu
In the late spring, Beijing is a good scenery of the red willow and green, but the flying poplars and catkins flying all over the world are annoying. Those citizens and tourists with more sensitive constitutions are even more miserable.People can't help asking, why can't this small flying embarrassment every year?
Beijing's flying flip mainly comes from a large number of poplars and willows grown in this city.The poplars and willow trees are divided into male and female plants.Every spring, the female willow tree will grow a lot of small balls. When the small ball grows up, it will swell and expose a cotton -shaped floc.These fluffs are seeds, and they are spread through wind and insects to complete reproduction.
According to the census of the garden department, there are 2 million willow trees in Beijing, which accounts for 5.4%of the total amount of garden greening trees; female poplars and willow trees in the fifth rings also exceed 280,000.The three districts of Haidian are concentrated in parks, rivers, highways, and old communities.
In mid -to -late April each year, as long as the maximum temperature of three consecutive days exceeds 25 degrees Celsius, and the air is dry and the weather is clear, the fruity of a poplar plant that has just matured will be cracked, revealing the white fluff that is closely clustered insideEssenceEach female plant can grow 300,000 to 15 million Yangxu every spring.When the wind blows, these Yang Su, which is only a little heavier than the air, will float in the air and fly up and down on the streets and alleys, forming a spectacular but uncomfortable flying snow scene, with a length of 20Yu Tian.
Flying flip contacts people's skin may cause skin allergies, itching, and red eyes; if they enter the respiratory tract, they may cause cough and respiratory edema, aggravate asthma, chronic bronchitis and other respiratory diseases.In the spring, the number of receptions of the outpatient clinic of Beijing Hospital will surge, and a doctor in the relevant departments will take an average of 20 to 30 patients with allergies because of flying.
At the same time, Yang and catkins are also fluffy and flames. The 10 square meters willow willow can burn in two seconds.On May 1, 2017, the Beijing Crab Island Resort suddenly caught fire. 89 electric buses and 16 private cars turned into ashes.Afterwards, the fire department discovered that there were a large number of poplars and willow trees around the parking lot, and a thick layer of willow wool accumulated on the ground. The fire was likely to be caused by the cigarette butter cigarette butter cigarette butter.
The harm of Feixu is so great. Why are there so many female poplars and willow trees in Beijing?
This starts from the 1960s and 1970s.At that time, Beijing was troubled by sandstorms.According to statistics from Beijing's Guanxiang Tower Sand dust data, in the 1950s, the sand and dust in Beijing were the most serious. The average number of daily sand and dust in spring was as high as 26 days, and there were 10 to 20 days in the 1980s.In 1977, the United Nations Environmental Planning Agency determined that Beijing was a marginal city in the world's desertization.
In the 1970s, under the call of the founding leader of the Communist Party of China Mao Zedong's greening, China set off a tree planting campaign, and Beijing also launched a vigorous war of people's greening.
However, the most prominent problem of tree planting activities is that the survival rate of saplings is not high.Beijing has tried to grow poplars, willow trees, fir trees, eucalyptus, puffy, pork pine, etc., but the selection is still suitable for the poplar and willow trees that are suitable for growing in the north.The first choice for Beijing green tree species.As for the flying troubles that the willow tree may bring, at that time, it was basically not considered.
After many years of strong planting trees, the number of sand and dust in Beijing in spring has decreased significantly, and it has fallen to about three days after 2010.But with the growth of the willow tree, the problem of flying flip began to highlight.Forestry experts explained that most of the Yangliu family plants will take more than 10 years to bloom and bear fruit. Nowadays, most of Beijing's Feixu comes from large -scale willow trees began in the 1970s.
In recent years, Beijing has begun to take various methods such as species control, selection of new trees, sparse branches, high -level grafting, and suppression of inflorescence formation.The Beijing Garden Greening Bureau stipulates that since 2015, in various garden greening projects, the use of Yang and willow -lumin female strains.
Some people question, is it so difficult to treat Feixu?Isn't it good to cut those willow trees?
But it is definitely not a good idea to cut it.Because the willow tree has always been part of the Beijing vegetation, its ecological effect is far greater than the influence of flying flip.Forestry experts estimate that a poplar with a diameter of 20 cm can absorb 172 kg of carbon dioxide in one year and release 125 kg of oxygen; a willow tree with a diameter of 20 cm can absorb 281 kg of carbon dioxide in one year and release 204 kg of oxygen.If these trees are removed in large quantities, it will inevitably destroy the environmental quality and landscape of the city and cause more serious ecological losses.
In 2017, Beijing launched the Yangliu Feixu Governance Test and Demonstration Project, and completed the census positioning of the willow females in the five rings of Beijing.Officials from the Beijing Gardening Department told the media that they will use methods such as changing tree species, dredging, pruning, nourishing needle, and transsexual surgery to comprehensively treat 400,000 willow females.By2020
However, from the perspective of the severity of Beijing this spring, it is probably a difficult task to achieve the goal of governance of the disaster in Beijing next year.
