A decision made 70 years ago to reforest vast swathes of Japan with just two kinds of trees has coming back to haunt the country.
70年前作出的一项决定，是只用两种树在日本大片土地上重新造林，如今却反过来困扰着这个国家。
In February, videos showing what looked like waves of smoke blowing off an evergreen forest went viral in Japan.
今年2月，一些视频在日本走红，画面中看起来像是一阵阵烟雾从常绿森林上方飘散出来。
It wasn't smoke – it was pollen, and the videos were a warning to tens of millions of residents of the archipelago nation: prepare your masks and allergy medicine.
那不是烟，而是花粉；这些视频是在提醒这个群岛国家数千万居民：准备好口罩和抗过敏药。
Every spring (which is already arriving earlier in Japan due to climate change) you'll seeing people of all ages wearing masks on the streets of cities across the country.
每年春天（由于气候变化，日本的春天已经来得更早），你都会在日本各地城市的街道上看到各个年龄段的人戴着口罩。
The reason: hay fever, driven by all the pollen.
原因是：由大量花粉引发的花粉症。
Hay fever – also known as allergic rhinitis – has now become a national crisis in Japan, with an estimated 43% of the population experiencing medium to severe symptoms.
花粉症，也称过敏性鼻炎，如今已成为日本的一场全国性危机，估计有43%的人口出现中度至重度症状。
This compares to 26% in the UK and 12-18% in the US.
相比之下，英国的比例为26%，美国为12%至18%。
As well as the discomfort, these allergies could leading to sleep loss and poor concentration, and sufferers are more likely to experience other conditions such as asthma and food allergies.
除了带来不适，这些过敏还可能导致睡眠不足和注意力下降，患者也更容易出现哮喘、食物过敏等其他病症。
At the peak of Japan's hay fever season, the economic impact from both sick days and lower consumer spending is estimated at $1.6bn (£1.2bn) per day.
在日本花粉症季节的高峰期，因病假和消费者支出下降造成的经济影响估计每天达16亿美元（12亿英镑）。
So why does Japan have such worse allergies?
那么，为什么日本的过敏问题如此严重？
The reason has little to didn't with poor health or pollution, or even the natural environment, but decisions made by leaders more than 70 years ago in the decades after World War Two.
其原因与健康状况不佳、污染，甚至自然环境都关系不大，而是源于二战后数十年间领导者在70多年前作出的决定。
During the war, oil and gas shortages led Japan to turning to the nation's most abundant natural resource – forests – as a source of fuel for home and industry.
战争期间，石油和天然气短缺使日本转向本国最丰富的自然资源——森林——将其作为家庭和工业燃料来源。
The result was widespread deforestation of natural forests, with the mountains around major cities like Tokyo, Osaka and Kobe completely stripped bare of trees.
其结果是天然林遭到大范围砍伐，东京、大阪和神户等大城市周边的山地树木被完全剥光。
"After World War Two, many of Japan's mountains became barren, causing disasters in various regions," says Noriko Sato, a professor and forestry researcher at Kyushu University in Fukuoka, Japan.
日本福冈九州大学教授兼林业研究员佐藤纪子说：“第二次世界大战后，日本许多山地变得荒芜，在各地引发了灾害。”
(Bare mountains can increase the incidence of landslides and flooding).
（光秃的山地会增加山体滑坡和洪水发生的概率。）
"large-scale afforestation was carried out by public works, funded by tax revenues, to prevent soil erosion."
“为了防止水土流失，政府通过由税收资助的公共工程开展了大规模造林。”
Aiming for rapid reforestation, the government chose to plant reams of only two different native, fast-growing evergreen species that could quickly reforest landscapes and provide wood for future use in construction: the Japanese cedar, sugi, and the Japanese cypress, hinoki.
为了迅速恢复森林，政府选择大量种植仅两种本土、快速生长的常绿树种，它们既能快速让地貌重新覆盖森林，又能为未来建筑提供木材：日本柳杉，即杉；以及日本扁柏，即桧。
Today, these hinoki and sugi plantation forests still cover around 10 million hectares (25 million acres) – a fifth of Japan's entire land areas.
如今，这些桧和杉人工林仍覆盖约1000万公顷（2500万英亩），相当于日本全部陆地面积的五分之一。
The problem is, sugi and hinoki trees also produce large amounts of lightweight pollen which can easily drift into cities.
问题在于，杉树和扁柏也会产生大量轻质花粉，而这些花粉很容易飘进城市。
It's this pollen, often released all at once from the monoculture plantations, that is responsible for most seasonal allergies in Japan.
正是这种花粉，常常从单一种植林中一次性大量释放出来，导致了日本大多数季节性过敏。
The issue has become all the worse since these trees release ever more pollen after maturing at 30 years of ageing – now the case for nearly all of them.
问题变得更加严重，因为这些树在30年树龄成熟后会释放越来越多的花粉，而如今几乎所有这些树都已达到这一阶段。
"Pollen allergies have become a national health issue in Japan," says Sato.
佐藤说：“花粉过敏已成为日本的全国性健康问题。”
"Addressing this problem is urgent."
“解决这个问题刻不容缓。”
In 2023, Japan declared allergies a national social problem and the central government set out an ambitious plans – reduce pollen by 50% in 30 years.
2023年，日本宣布过敏问题为全国性社会问题，中央政府提出了一项雄心勃勃的计划：在30年内将花粉量减少50%。
As a first step, it aims to reduce the forest areas planted with sugi trees by 20%.
作为第一步，该计划旨在将种植柳杉的森林面积减少20%。
But swapping out forests covering over 2% of Japan in 10 years is a massive endeavour.
但要在10年内替换覆盖日本国土面积逾2%的森林，是一项艰巨的工程。
Plus, simply cutting these trees down won't being enough – they also needs to be replaced with new forests to avoid soil erosion or accidentally undercutting Japan's own climate targets.
此外，仅仅砍掉这些树还不够，它们还需要被新的森林取代，以避免土壤侵蚀，或无意中削弱日本自身的气候目标。
Walking through sugi or hinoki plantation forests is eerie – all the trees are the same height and there are few birds or insects.
走在柳杉或扁柏人工林中会让人感到诡异：所有树木都一样高，而且几乎看不到鸟类或昆虫。
The ground is spongy with dry needles, and there's little light or sound.
地面铺满干枯针叶，踩上去松软有弹性，几乎没有光线，也几乎听不到声音。
It's a stark contrast to Japan's natural forests, which teem with biodiversity and sound.
这与日本天然森林形成鲜明对比，后者生物多样性丰富，也充满各种声响。
With their diverse tree species like red pine, larch and maple, these forests support more of all kinds of wildlife.
这些森林拥有赤松、落叶松和枫树等多样树种，能够养活更多各类野生生物。
Japan's unique geography has made it one of the world's biodiversity hotspots, but habitat loss and invasive species have led much of its unique wildlife to become increasingly at risk.
日本独特的地理条件使其成为世界生物多样性热点之一，但栖息地丧失和入侵物种已使其许多独有野生生物面临越来越高的风险。
With the monoculture plantation forests causing so many problems, it makes sense that Japan is now trying to replace them with something better.
鉴于这些单一树种的人工林造成了如此多问题，日本如今试图用更好的东西来取代它们，也就合情合理了。
But it's a daunting challenge.
但这是一项艰巨的挑战。
The reason?
原因是什么？
Japan has a lot of forests.
日本有很多森林。
In fact it's one of the most forested industrialised nations in the world, with forests covering 68% of its land, a third of which are sugi and hinoki plantations.
事实上，日本是世界上森林覆盖率最高的工业化国家之一，森林覆盖其68%的土地，其中三分之一是杉树和扁柏人工林。
The US, by contrast, is 34% forested; the UK just 13%.
相比之下，美国的森林覆盖率为 34%；英国仅为 13%。
Across Japan, forests can be found right by cities.
在日本各地，城市旁边就能看到森林。
Japanese even has a word for the transition area between city and forest: satoyama.
日语甚至有一个词专门指城市与森林之间的过渡地带：里山。
Still, even before the 2023 government declaration, some local actors and non-profits had begun efforts to turn these forests into biodiverse ecosystems, and some are already seeing the benefits.
不过，即使在2023年政府发布声明之前，一些地方行动者和非营利组织已经开始努力把这些森林转变为生物多样性更高的生态系统，其中一些已经看到了成效。
The small town of Nishiawakura, Okayama, for example, has created an entire economy around reducing the 84% of its forests made up only of hinoki and sugi, turning wood into heating for eel farms as well as chopsticks and timber.
例如，冈山县西粟仓这个小镇围绕减少其森林中84%仅由扁柏和柳杉构成的部分，建立起一整套经济体系，把木材转化为鳗鱼养殖场所需的热能，同时也制成筷子和木料。
In 2020, Kobe, a larger port city in central Japan with a dense urban core and vast forests within its city limits, began an effort to turn more than 180 hectares (445 acres) of plantation back into natural broadleaf forests in a 15-year cycle.
2020年，位于日本中部的较大港口城市神户开始了一项为期15年的行动，要把180多公顷（445英亩）人工林恢复为天然阔叶林；这座城市拥有密集的城市核心区，市域内还有大片森林。
Every year, an area is selectively clear-cut, removing sugi, hinoki but also other invasive species like bamboo.
每年，都会有一片区域被选择性皆伐，清除柳杉、扁柏，同时也清除竹子等其他入侵物种。
Broadleaf trees are left, and with more sun coming through to the ground, they grow back, along with other new seedlings either planted by staff or brought by birds or animals.
阔叶树被保留下来，随着更多阳光照到地面，它们会重新生长，同时还有工作人员栽下或由鸟类和动物带来的其他新树苗一起长起来。
With its scheme now about halfway done, local government workers say they have been pleasantly surprised by how quickly biodiversity has returned.
随着这一计划目前已完成约一半，当地政府工作人员表示，生物多样性恢复之快令他们惊喜。
"Our wildlife monitoring is showing more animals and insects returning, including badgers, pond turtles, many species of frogs, and rare insects too, which is encouraging," says Atsushi Okada, head of the Kobe City Environmental Bureau.
神户市环境局局长冈田敦说：“我们的野生动物监测显示，越来越多动物和昆虫正在回归，包括獾、池龟、多种青蛙，还有稀有昆虫，这令人鼓舞。”
As well as addressing the pollen issue, the scheme aims to fulfil the Kobe's pledge to increase its protected areas to 30% of all land by 2030.
除了应对花粉问题外，该计划还旨在兑现神户的承诺，即到2030年将保护区面积增加到全部土地的30%。
More diverse forests should also protect the city against the landslides and natural disasters poised to become more frequent due to climate change, says Daisuke Tochimoto, a forester with the City of Kobe.
神户市林务员枥本大辅说，更多样化的森林还应能保护这座城市免受山体滑坡和因气候变化而可能变得更频繁的自然灾害影响。
As for the cut trees, they are used for heating, furniture production and Japanese white charcoal, a smoke-free barbeque fuel which could also be used in industrial processes.
至于被砍伐的树木，它们会被用于取暖、家具生产以及制作日本白炭；这种无烟烧烤燃料也可用于工业流程。
The hope is that, over time, the project can become financially sustainable and not reliant on public funds, says Okada.
冈田说，人们希望随着时间推移，这个项目能够在财务上实现可持续，不再依赖公共资金。
Similar projects are beginning in other parts of Japan.
类似项目也开始在日本其他地区展开。
One project in Hotani, Osaka, is now restoring wetlands and grasslands.
大阪穗谷的一个项目目前正在恢复湿地和草地。
And the largest effort aims to turn 10,000 hectares (25,000 acres) of plantation forests in Gumna prefecture to meadows and mixed deciduous woodland.
其中规模最大的行动旨在将Gumna县1万公顷（2.5万英亩）的人工林改造成草地和混交落叶林。
Smaller-scale projects are also common, says Akira Mori, a professor of biodiversity and ecosystem services at the University of Tokyo, pointing to dozens of initiatives around Japan.
东京大学生物多样性与生态系统服务教授森章说，规模较小的项目也很常见，并指出日本各地已有数十项相关举措。
Since the goals of removing 20% of the plantations was announced, the country has designated approximately 980,000 hectares (2.4 million acres) of sugi plantation forests as areas for focused logging and replanting.
自日本宣布移除20%人工林的目标以来，该国已将约98万公顷（240万英亩）的柳杉人工林划定为重点采伐和重新造林区域。
Still, not all of this is being turned into broadleaf forests: some of it is fresh plantations, often planted with low-pollen or pollen free sugi.
不过，并非所有这些土地都在被改造成阔叶林：其中一部分是新的人工林，常常种植低花粉或无花粉的柳杉。
Japan's ministry of agriculture, forestry and fisheries did not respond to a request for comment on how much of this allocated area has been removed and replanted so far.
日本农林水产省没有回应置评请求，未说明迄今这些指定区域中已有多少被清除并重新种植。
Still, these efforts may not yet be large enough to make much of a difference to the pollen.
不过，这些努力的规模可能还不够大，尚不足以对花粉问题产生显著影响。
And even if it achieves the goal, 80% of the plantation forests will remain.
而且，即使实现了这一目标，仍会有80%的人工林保留下来。
So Japan is also trying other ways to tackle hay fever.
因此，日本也在尝试其他方法来应对花粉症。
Pollen data and forecasts, for example, are being used to better understand of where dispersion is likely, allowing authorities to selectively cut down the worst offending forests, and researchers are even looking at spraying trees with solutions to suppress pollen.
例如，花粉数据和预测正被用于更好地了解花粉可能扩散到哪里，从而让有关部门能够有选择地砍伐问题最严重的森林，研究人员甚至还在考虑向树木喷洒溶液以抑制花粉。
In 2023, one forecasting company distributed thousands of pollen-detecting robots – whose eyes going different colours depending on pollen levels – across Japan.
2023年，一家预测公司在日本各地投放了数千个花粉检测机器人，这些机器人的眼睛会根据花粉浓度呈现不同颜色。
Medicine is another prong to the attack, with the development of new treatments to better ease the symptoms of pollen exposure.
医学是应对这一问题的另一条战线，研究人员正在开发新疗法，以更好地缓解接触花粉引发的症状。
One Japanese trial, for example, showed a long-acting under-the-tongue immunotherapy tablet was were still helping alleviate symptoms two years after treatment.
例如，日本的一项试验显示，一种长效舌下免疫治疗片在治疗结束两年后仍有助于缓解症状。
Other scientists have even been experimenting with genetically modified rice designed to alleviate allergy symptoms.
其他科学家甚至一直在试验旨在缓解过敏症状的转基因水稻。
(Read more about the new wave of effective cures for seasonal allergies ).
（阅读更多关于新一波有效治疗季节性过敏方法的内容。）
When the sugi and hinoki forests were first planted in the 1950s and 60s, they weren't meant to stand forever.
20世纪50年代和60年代最初种下杉木和扁柏林时，人们并不打算让它们永远留在那里。
At the time, it was assumed they would be gradually cut down and replanted over time, as had been the case before the war.
当时，人们以为这些树会像战前那样，随着时间推移逐渐被砍伐并重新栽种。
But as Japan's economy boomed in the late 60s and 70s, major cities like Kobe and Tokyo grew rapidly, and it ended up being cheaper to import wood from other countries such as Malaysia and Indonesia.
但随着日本经济在20世纪60年代末和70年代繁荣发展，神户、东京等大城市迅速扩张，最终从马来西亚和印度尼西亚等其他国家进口木材变得更加便宜。
In 2011, though, Japan set a goal of relying less on forestry imports, and has seen its domestic wood use grow from 26% in 2010 to nearly 42% in 2020.
不过，2011年，日本设定了减少对林产品进口依赖的目标，并见证其国产木材使用比例从2010年的26%增长到2020年的近42%。
Of course, if Japan is going to exploit its forests, it has to avoid the same mistakes made in Southeast Asia, where cheap wood means the clear-cutting of tropical forests.
当然，如果日本要开发利用本国森林，就必须避免东南亚曾犯下的同样错误；在那里，廉价木材意味着热带森林被皆伐。
Junichi Mishiba, forest project coordinator at the non-profit Friends of the Earth Japan, worries that more incentives to cut down trees is leading to bad environmental practices.
日本非营利组织“地球之友日本”的森林项目协调员三柴淳一担心，更多鼓励砍伐树木的激励措施正在导致不良的环境做法。
"There is an increase in clear-cut areas resulting from policies promoting harvesting," he says.
他说：“由于鼓励采伐的政策，皆伐面积正在增加。”
To support its efforts to replace the plantations, in 2024 the national government began collecting a new tax of 1000 yen ($6/£5) per year on all residents.
为支持替换人工林的努力，2024年日本中央政府开始向所有居民每年征收一项1000日元（约6美元/5英镑）的新税。
The money is being used to support sustainable forestry, including reducing plantation forests and replacing older sugi with new, low-pollen seedlings, especially in urban areas.
这笔资金正被用于支持可持续林业，包括减少人工林，并用新的低花粉树苗替换老龄柳杉，尤其是在城市地区。
Data on its impact is not yet available, but Mori argues the support is not enough, with municipalities often lacking the capacity and expertise to design and monitor such changes to forests.
关于其影响的数据目前尚不可得，但森认为这种支持还不够，因为各市町村往往缺乏设计和监测此类森林改造所需的能力和专业知识。
A 2023 report by the Forest Declaration Assessment noted that in recent years, only 30-40% of Japan's newly harvested land has been replanted
森林宣言评估组织2023年的一份报告指出，近年来，日本新采伐土地中只有30%至40%得到了重新造林。
Good forest management will be essential, agrees Mika Akesaka, an associate professor of economics at Kobe University.
神户大学经济学副教授明坂美香也认为，良好的森林管理将至关重要。
Leaving felled trees unmanaged, for example, can increase landslide risk and reduce water retention capacity, she says.
她说，例如，任由被砍倒的树木无人管理，可能会增加山体滑坡风险，并降低蓄水能力。
Mishiba, though, fears that by focusing only on seasonal allergies rather than wider ecological indicators, Japan is once again prioritising short-term solutions.
不过，三柴担心，日本只关注季节性过敏，而不是更广泛的生态指标，这意味着日本再次把短期解决方案置于优先位置。
The country needs to think 50 or even 100 years ahead, he says, considering biodiversity, climate and the role of the people who will live alongside these forests.
他说，日本需要向前思考50年甚至100年，考虑生物多样性、气候，以及未来将与这些森林共同生活的人们所扮演的角色。
Japan's ministry of agriculture, forestry and fisheries did not respond to a request for comment on these concerns.
日本农林水产省没有回应就这些担忧置评的请求。
Urgency to act is also growing because of another unplanned factor – climate change.
由于另一个意外因素——气候变化——采取行动的紧迫性也在上升。
Around the world, temperature and weather shifts are impacting pollen spread and Japan saw its earliest pollen dispersal ever in 2025.
在全球范围内，气温和天气变化正在影响花粉传播，而日本在2025年出现了有记录以来最早的花粉扩散。
"Pollen dispersal is greatly influenced by weather conditions such as temperature and wind," says Mai Sato, a spokesperson with the Japan Weather Association (JWA), a forecasting company which releases regular pollen forecasts to the public.
“花粉扩散很大程度上受温度、风等天气条件影响，”日本气象协会发言人佐藤舞说；该协会是一家预报公司，会定期向公众发布花粉预报。
Japan's vast forests also themselves hold huge amounts of carbon, and sugi plantations are responsible for almost half the carbon sequestered by its forests each year.
日本广袤的森林本身也储存着大量碳，而杉树人工林几乎贡献了日本森林每年所封存碳量的一半。
Japan is leaning heavily on this carbon sequestration to achieve its net zero goal, and encourages it with a carbon credits scheme.
日本正高度依赖这种碳封存来实现其净零目标，并通过碳信用计划加以鼓励。
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Still, since 2004 Japan has seen a declining trend in the yearly amount being absorbed which it attributes to the maturity of its forests.
不过，自2004年以来，日本每年吸收的碳量呈下降趋势，日本将其归因于森林趋于成熟。
Research has shown that since ageing trees absorb less carbon, thinning forests of old trees and planting new, younger and more diverse species will be essential to keeping Japan's forests an effective carbon sink.
研究表明，由于老龄树木吸收的碳更少，疏伐老树森林并种植新的、更年轻且更多样化的树种，对于保持日本森林作为有效碳汇至关重要。
Japan's ministry of agriculture, forestry and fisheries did not respond to a request for comment on how the plans to replant sugi and hinoki forests may impact its climate goals.
日本农林水产省未回应有关重新种植杉木和扁柏林的计划可能如何影响其气候目标的置评请求。
Before the 1960s, Japan didn't even have a word for hay fever.
20 世纪 60 年代以前，日本甚至还没有表示花粉症的词。
Japanese cedar pollinosis was first identified in 1963 and, according to researchers at the time, was new to the country.
日本柳杉花粉症最早于1963年被确认，而据当时的研究人员称，这种病在日本此前并不存在。
The hope is that with the return of more natural, diverse forests, Japan can one day go back to enjoying its springs – without the sneezes.
人们希望，随着更自然、更多样化的森林回归，日本有朝一日能够重新享受春天，而不再喷嚏连连。
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