The secret behind Beijing's "snowfall" in April is...

Auditing expert: Yang Yanhui, Senior Garden Engineer, Beijing Haidian Water Ecological Construction Development Co., Ltd.

As spring deepens, it is the season of willow flowers and mist. Along with the warmth of spring comes the fluttering willow catkins, which are like the willow catkins flying in the wind. This romance is actually a bit of a "double-edged sword". For example, for allergy patients, this is a season that requires extra protection.

Source: CCTV News

According to the poplar and willow catkin warning issued by Beijing Meteorological Bureau, the first peak period of catkins in Beijing occurred between April 12 and 18 , mainly affecting the inner city of the Fifth Ring Road, and the catkins tree species was Populus tomentosa. The second peak period was from late April to early May , and the main catkins tree species were Populus occidentalis, Populus alba, Weeping Willow and Salix matsudana. The third peak period was in mid-May , mainly in mountainous areas, with no obvious impact on urban areas. Poplar and willow catkins have obvious periodicity and seasonality , and the catkins period will last about 50 days. During the catkins period, the peak period is from 10 a.m. to 4 p.m. every day.

The peak period of flying catkins has arrived. At present, each district in Beijing has established a professional emergency prevention and control service team. The Beijing Municipal Bureau of Landscape and Greening has organized professional personnel to inspect and supervise throughout the city. Once flying catkins are discovered, relevant departments will arrive at the scene to deal with them within 30 minutes to ensure that the impact of flying catkins is minimized.

Why are catkins flying everywhere in spring?

I believe that people living in Beijing, when they see such a scene every spring, can't help but wonder and sigh: Where do these flying catkins come from?

The flying catkins in Beijing mainly come from poplar and willow trees , which are dioecious, and the flying catkins come from the female plants of poplar and willow. Generally speaking, the flying catkins season starts with white poplar and ends with willow .

Source: Phoenix.com

Every spring, after pollination, the female flowers of poplars and willows will produce capsules, which are wrapped with white fluff and seeds. After the mature capsules crack open, the fluff will fly with the seeds in the wind, reproducing offspring. This is the flying catkins that everyone sees.

Flying catkins are a normal physiological phenomenon of plants , but they will fly all over the sky when the temperature rises, the sunlight is sufficient and the air humidity is low.

Why plant willow trees?

Since willow trees are a nuisance, why are there so many of them planted in Beijing? This story dates back to the early days of the founding of New China.

At that time, my country's forest coverage rate was only 8.9%. There were only 87 kilometers of roadside trees and 476 hectares of public green space in Beijing. Beijing was hit by sandstorms. Every spring, the most frightening thing was the yellow sand that covered the sky. Therefore, in the 1960s and 1970s, urban greening took off, and a tree planting campaign was launched across the country. Beijing also launched a vigorous "People's Greening War".

The "Miyun County Iron Girl Afforestation Team" of that year persisted in afforestation all year round.

Source: Beijing Daily

What trees to plant has become an urgent problem to be solved. In the selection of tree species, willow trees stand out among a number of "competing trees" because of their strong adaptability, alkali and drought resistance, fast growth, strong resistance to pollution and low cost !

In this way, poplars and willows became the first choice of tree species for Beijing's greening, and the national greening project gradually formed a pattern of "poplars in the north and fir trees in the south". It can be said that poplars and willows made great contributions to saving Beijing from the sandstorms that year.

Use technology to make flying catkins disappear

In fact, not all willow trees produce flying catkins. Only female trees produce flying catkins . Male trees do not produce flying catkins.

In recent years, Beijing has carried out scientific breeding, demonstration and promotion of male white poplars . Beijing Municipal Bureau of Landscape and Greening, in cooperation with Beijing Forestry University, has introduced new varieties suitable for Beijing without flying catkins, and selected five excellent varieties such as "Beijing Xiong No. 1". At present, Beijing has bred and stored more than 200,000 excellent non-flying catkin poplar seedlings (including non-flying catkin ancient white poplars) , and more than 50,000 have been used in the renewal and transformation of old, weak, sick and disabled female flying catkin poplars.

"Beijing-Xiong No. 1" Source: Beijing Forestry University

Recently, this variety has been recognized as a Beijing-produced fine variety . The successful selection and breeding of the "Beijing Xiong No. 1" fine variety not only protects and utilizes Beijing's ancient white poplar tree resources, but also provides an effective way to alleviate the flying catkins problem that has plagued Beijing citizens from the root.

In addition, you can also suppress the flying catkins of poplar and willow trees by giving them medicine. Before the catkins of poplar and willow trees form flying catkins, you can predict their flying time in advance and spray them with medicine to make them fall off in advance.

The catkin inhibitors applied to the poplar trees in the park can inhibit the formation of flower buds on the poplar trees.

Source: Science Popularization China

A-choo! What should we do when catkins come flying?

1. Take good personal protection . Disposable dust masks, sunglasses, protective glasses, gauze scarves, etc. can effectively block flying catkins. Wash your face with clean water in time after going out, and clean your nose and mouth with saline.

2. For outdoor activities such as outdoor exercise, try to choose periods such as morning, evening or after rain when the flying catkins are lighter.

3. Remember to close the screen windows to prevent flying catkins from flying into the room. Indoor flying catkins can be cleaned up in time with a vacuum cleaner, or sprayed with water to moisten them and then swept.

4. Increase inspections of vehicles, precision instruments and other equipment , and clean up any accumulated flying catkins in a timely manner.

5. No research has shown that flying catkins themselves can cause allergies. If sensitive people experience allergic symptoms, they should go to the hospital in time to check for allergens .

6. The climate is dry in spring and flying catkins can cause irritability. Pay attention to adjusting your mood and maintain a healthy and peaceful state of mind .

"Snow flying all over the sky" may also be "fire shooting up into the sky"

Flying catkins contain 90% fiber and grease, which will make the fire spread very quickly. When the flying catkins catch fire, they will first drift away with the wind, forming flying fire. When it attaches to other flammable and combustible materials, it will ignite the flammable and combustible materials, increasing the difficulty of firefighting.

Firefighters simulated a wild scene by covering many dead branches and fallen leaves with poplar fluff, and then ignited them with lighters.

Source: Beijing Fire Department

So, how to prevent willow catkin fires?

1. For willow catkins attached to flammable materials, you can first clean them by pouring sand, sweeping and burying them to avoid leaving fire hazards.

2. Do not place combustibles such as cardboard boxes, branches, and firewood piles around buildings. In places where electric bicycle centralized charging devices are set up outdoors, more attention should be paid to promptly clean up combustibles and eliminate hidden dangers.

3. Parking lots and residential property management departments should promptly clean up poplar and willow catkins in the area to prevent fires from igniting vehicles and causing further losses. Private car owners should strengthen vehicle maintenance to prevent catkins from accumulating in large quantities in the engine compartment of the car and causing fires.

4. Gas stations, chemical companies, and flammable and explosive places should increase the intensity of road sprinkling and wetting , and promptly remove willow catkins accumulated in corners to reduce fire risks.

5. Whether indoors or outdoors, be sure to keep a close eye on fire and do not throw cigarette butts around to avoid causing a fire.

If you discover a fire, be sure to call the "119" emergency number in time to avoid major fire accidents!

Please be prepared to spend the snow season smoothly