又到一年飞絮季 北京绘“杨柳地图”
为了应对这一状况，北京市已经绘制了在春天造成大范围飞絮的杨柳树雌株分布地图，力争到2020年使杨柳飞絮明显改善。
[Photo/Xinhua]
Beijing has mapped its female poplar and willow trees to try to contain catkins that descend on the city each spring.
北京已经绘制了杨柳树雌株的分布地图，试图控制在每年春天都出现的柳树和杨树飞絮。
catkin['kætkɪn]：n. [植]柔荑花序(如柳絮等)
The Chinese capital has been blanketed by catkins each spring for decades.
几十年来，北京每年春天都深受杨柳飞絮的困扰。
The trees were planted in the 1960s and 1970s as a cheap, easy-to-maintain and quick-growing way to make Beijing greener.
这些树木是在上世纪六七十年代种植的，因为这种绿化树木对北京来说价格便宜、易于维护而又生长快速。
Female trees look very similar to the males. The capital’s parks authority began a survey in 2017 to find out where female willows and poplars were planted so it could neutralize the catkins and go some way to sparing citizens weeks of sneezing and watery eyes as pollen spread, Beijing Youth Daily reported on Monday.
雌株从外观看起来与雄株非常相似。据《北京青年报》本周一报道，北京市公园管理部门2017年开始进行调查，以确定杨柳树雌株都分布在哪里，这样就可以控制飞絮，从而在一定程度上让市民免受数周花粉传播导致的打喷嚏和流眼泪等症状困扰。
neutralize['nju:trəlaiz]：vt.中和;使无效
Aerial photography was used, with urban areas inside the Fifth Ring Road – where most of the city’s population lives – divided into 2,866 grids, each of 250,000 square meters, Qin Yongsheng, an official with the Beijing Gardening and Greening Bureau, said.
北京市林业工作总站副站长秦永胜说，调查人员采用航拍技术，把五环内城区划分成2866张航片网格图。每个网格的范围是25万平方米。北京市绝大多数市民都生活在五环内。
Three hundred students from Beijing Forestry University trained to identify the female varieties plotted the trees’ locations by species and growth, and marked them for follow-up action if required.
北京林业大学的300名经过培训的学生担任了此次的调查人员，他们按照种类和生长速度确定杨柳树雌株的分布，并标记位置，为后续行动做准备。
The survey found there were 284,000 female willows and poplars inside the Fifth Ring Road, with nearly 38 percent in the Chaoyang district. In some areas, there were about 10,000 such trees within one grid, with the highest densities found in the southwest of the city, between the Fourth and Fifth ring roads.
调查发现，北京五环内共有杨柳树雌株28.4万株，其中近38%在朝阳区。在一些地区，一个网格内大约有1万株雌株，密度最高的是在北京西南四环和五环之间。
Up to 60 percent of the poplar trees are growing well, and that means they produce catkins.
其中多达60%的杨树生长态势良好，也就意味着它们能产生很多杨絮。
“The higher the density, the more serious the catkin phenomenon,” Qin was quoted as saying.
“密度越高，飞絮现象就越严重，”秦永胜说。
The parks authority tried using inhibitors to curb budding last year but it did not work well, it said. Other measures have been introduced this year.
公园管理部门曾在去年尝试使用抑制剂阻止雌株发芽，但没有奏效。工作人员在今年还采取了其他措施。
inhibitor [ɪn'hɪbɪtə]：n. [助剂]抑制剂，抗化剂
“We have trimmed some branches. We will also use high-pressure water guns to take down the seeds and sweep them away,” Wang Xiaoping, another bureau official, was quoted as saying. “We aim to significantly improve the catkin situation by 2020.”
据报道，北京市园林绿化局副巡视员王小平说：“园林工人已经对杨树和柳树的枝条进行修剪，还用高压喷雾车对着树冠冲洗，冲走杨柳絮，力争到2020年使杨柳飞絮明显改善。”
除此以外，还可以对柳树采用高位嫁接(top grafting)，将雌株变成雄株，以变性来达到绝育目的，相当于给柳树做了绝育手术(sterilization surgery)。
既然杨柳絮这么恼人，能不能把杨树柳树都砍了呢?
Beijing has banned the planting of female poplars and has decided to increase the diversity of trees used in landscaping, but it has ruled out felling poplars and willows as they are a big part of the capital’s streetscapes and have adapted well to the environment.
北京已禁止种植雌株杨树，并决定增加园林绿化树木的多样性。但由于杨树和柳树是北京街景很重要的一部分，且对环境适应良好，北京已排除了砍伐杨树和柳树的可能性。
中国工程院院士、著名林学家沈国舫表示，杨柳树的生态作用远远大于飞絮的影响，治理杨柳飞絮千万不能一砍了之。目前北京杨柳树品种数量很多，且大都已经形成大树，如果大量伐除这些树木，不仅会引起城市环境质量和景观的下降(damage environmental quality and urban landscape)，还会造成更为严重的生态损失(ecological loss)。
除了具有良好的景观效果，杨柳树还具有释氧固碳(oxygen releasing and carbon fixation)，降温增湿(cooling and humidification)、减菌杀菌(reducing and killing bacteria)，吸收有毒有害物质等显著的生态功能。据介绍，杨树和柳树具有显著的抗大气污染的能力，对有害气体(hazardous gas)、颗粒物(particles)及重金属(heavy metal)的抗性和吸收吸附能力极强，是城市园林绿化的优良抗污树种(pollution-resistant tree species)，在抗大气污染的某些能力方面优于国槐和侧柏。
The government will also start a citywide inspection of the fire risks that come with catkins.
政府还将开展全市范围的杨柳絮火灾风险大检查。
High-pressure water jets will be used to reduce floating catkins, and officials have asked the urban cleaning department to clear away the debris in a timely manner.
工作人员将使用高压水枪减少飞絮，政府已要求环卫部门及时清理地面毛絮。
Cao Xiaojia, a doctor specializing in skin diseases at Chinese People's Liberation Army 306 Hospital in Beijing, said willow seeds are a common allergen in spring, with patients displaying symptoms such as red and itchy skin.
北京市解放军第306医院的皮肤病医生曹晓佳说，在春天，柳絮是常见的过敏原，很多病人表现出皮肤发红瘙痒等症状。
allergen ['ælədʒ(ə)n]：n. [医]过敏原
"Those who are sensitive should take precautions such as wearing a mask when going out and avoiding eating spicy food," she said.
她说：“对其敏感的人们要采取防范措施，比如外出戴口罩，避免吃辛辣食物。”
