Japan is gripped by mass allergies. A 1950s project is to blame
Japan is gripped by mass allergies. A 1950s project is to blame
日本正饱受大规模过敏症困扰，罪魁祸首竟是 20 世纪 50 年代的造林计划
A decision made 70 years ago to reforest vast swathes of Japan with just two kinds of tree has come back to haunt the country. 70 年前，日本决定大面积种植仅有的两种树木以进行再造林，如今这一决策正让该国深受其害。
In February, videos showing what looked like waves of smoke blowing off an evergreen forest went viral in Japan. 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. 今年 2 月，一段视频在日本社交媒体上疯传，画面中常绿森林上方飘散着如同烟雾般的物质。那并非烟雾，而是花粉。这些视频向这个岛国数千万居民发出了警告：准备好口罩和抗过敏药物。
Every spring (which is already arriving earlier in Japan due to climate change) you’ll see people of all ages wearing masks on the streets of cities across the country. The reason: hay fever, driven by all the pollen. 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. This compares to 26% in the UK and 12-18% in the US. 每年春天（受气候变化影响，日本的春天来得越来越早），你都能看到全国各地的城市街头，各个年龄段的人们都戴着口罩。原因就是花粉引发的花粉症。花粉症（又称过敏性鼻炎）现已成为日本的国家级危机，据估计，43% 的人口会出现中度至重度症状。相比之下，英国的这一比例为 26%，美国为 12% 至 18%。
As well as the discomfort, these allergies can lead to sleep loss and poor concentration, and sufferers are more likely to experience other conditions such as asthma and food allergies. 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. So why does Japan have such bad allergies? The reason has little to do 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. 除了身体不适，这些过敏症状还会导致失眠和注意力不集中，患者也更容易患上哮喘和食物过敏等其他疾病。在日本花粉症的高峰期，因病假和消费减少带来的经济损失估计每天高达 16 亿美元（约 12 亿英镑）。那么，为什么日本的过敏情况如此严重？原因与健康状况、污染甚至自然环境关系不大，而是源于 70 多年前二战后几十年里领导层所做出的决策。
An overlooked crisis / 被忽视的危机
During the war, oil and gas shortages led Japan to turn to the nation’s most abundant natural resource – forests – as a source of fuel for home and industry. The result was widespread deforestation of natural forests, with the mountains around major cities like Tokyo, Osaka and Kobe completely stripped bare of trees. 战争期间，石油和天然气的短缺促使日本转向其最丰富的自然资源——森林，将其作为家庭和工业的燃料来源。结果导致天然林遭到大面积砍伐，东京、大阪和神户等大城市周边的山脉树木被彻底砍光。
“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. (Bare mountains can increase the incidence of landslides and flooding). “Large-scale afforestation was carried out by public works, funded by tax revenues, to prevent soil erosion.” 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. “二战后，日本许多山脉变得荒芜，导致各地灾害频发，”日本福冈九州大学教授兼林业研究员佐藤纪子（Noriko Sato）说。（光秃秃的山脉会增加山体滑坡和洪水的发生率）。“为了防止水土流失，政府利用税收开展了大规模的公共造林工程。”为了实现快速再造林，政府选择了大量种植仅有的两种本土速生常绿树种，它们能迅速覆盖地表并为未来的建筑提供木材：日本柳杉（sugi）和日本扁柏（hinoki）。
Today, these hinoki and sugi plantation forests still cover around 10 million hectares (25 million acres) – a fifth of Japan’s entire land area. The problem is, sugi and hinoki trees also produce large amounts of lightweight pollen which can easily drift into cities. It’s this pollen, often released all at once from the monoculture plantations, that is responsible for most seasonal allergies in Japan. The issue has become all the worse since these trees release ever more pollen after maturing at 30 years of age – now the case for nearly all of them. 如今，这些扁柏和柳杉人工林仍覆盖着约 1000 万公顷（2500 万英亩）的土地，占日本国土总面积的五分之一。问题在于，柳杉和扁柏树会产生大量轻质花粉，极易飘入城市。正是这些从单一树种人工林中集中释放的花粉，导致了日本大部分的季节性过敏。由于这些树木在 30 岁成熟后会释放更多的花粉，而目前几乎所有的树木都已达到这一树龄，问题变得愈发严重。
“Pollen allergies have become a national health issue in Japan,” says Sato. “Addressing this problem is urgent.” “花粉过敏已成为日本的国家健康问题，”佐藤说，“解决这一问题刻不容缓。”
In 2023, Japan declared allergies a national social problem and the central government set out an ambitious plan – reduce pollen by 50% in 30 years. As a first step, it aims to reduce the forest areas covered with high-pollen sugi trees by 20% by 2033. 2023 年，日本将过敏症列为国家社会问题，中央政府制定了一项雄心勃勃的计划：在 30 年内将花粉量减少 50%。作为第一步，政府计划到 2033 年将高花粉柳杉林的覆盖面积减少 20%。
But swapping out forests covering over 2% of Japan in 10 years is a massive endeavour. Plus, simply cutting these trees down won’t be enough – they also need to be replaced with new forests to avoid soil erosion or accidentally undercutting Japan’s own climate targets. 然而，在 10 年内替换掉覆盖日本 2% 以上国土面积的森林是一项巨大的工程。此外，仅仅砍伐这些树木是不够的——还需要补种新的森林，以避免水土流失，或意外影响日本自身的减排目标。
Return to life / 重获新生
Walking through sugi or hinoki plantation forests is eerie – all the trees are the same height and there are few birds or insects. The ground is spongy with dry needles, and there’s little light or sound. 走在柳杉或扁柏人工林中，感觉十分诡异——所有的树木高度一致，几乎没有鸟类或昆虫。地面铺满了干枯的针叶，踩上去软绵绵的，几乎没有光线，也听不到声音。
It’s a stark contrast to Japan’s natural forests, which teem with biodiversity and sound. With their diverse tree species like red pine, larch and maple, these forests support more of all kinds of wildlife. 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. 这与日本充满生物多样性和生机的天然林形成了鲜明对比。天然林拥有红松、落叶松和枫树等多种树木，能够支持各种野生动物生存。日本独特的地理环境使其成为全球生物多样性热点地区之一，但栖息地的丧失和外来物种的入侵，已使许多独特的野生动物面临日益严重的威胁。
With the monoculture plantation forests causing so many problems, it makes sense that Japan is now trying to replace them with something better. But it’s a daunting challenge. The reason? Japan has a lot of forests. 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. The US, by contrast, is 34% forested; the UK just 13%. 既然单一树种的人工林造成了如此多的问题，日本试图用更好的方式来替代它们是合乎逻辑的。但这却是一项艰巨的挑战。原因何在？日本森林覆盖率极高。事实上，它是世界上森林覆盖率最高的工业化国家之一，森林覆盖率达 68%，其中三分之一是柳杉和扁柏人工林。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. Japanese even has a word for the transition area between city and forest: satoyama. 在日本各地，城市周边随处可见森林。日语中甚至有一个专门的词汇来形容城市与森林之间的过渡地带：里山（satoyama）。
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. 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 heat for eel farms as well as chopsticks and timber. 尽管如此，早在 2023 年政府发布声明之前，一些地方组织和非营利机构就已经开始努力将这些森林转变为生物多样性的生态系统，并且已经初见成效。例如，冈山县西粟仓村围绕减少其 84% 的扁柏和柳杉纯林，建立了一套完整的经济体系，将木材转化为鳗鱼养殖场的供热能源，并生产筷子和建筑木材。
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 plan. 2020 年，日本中部的大型港口城市神户，在城市中心人口稠密且境内拥有广阔森林的情况下，启动了一项为期 15 年的计划，旨在将超过 180 公顷（445 英亩）的人工林恢复为天然阔叶林。