北京，還有蝴蝶嗎？

文/John James Wilson 譯/史聰一

如同所有初到北京的人們，我很快便意識到：從任何意義上講，北京都是一座“特大城市”。北京的人口數量在全球范圍內僅次于上海。

包括明清兩代王朝的興衰史，北京的歷史跨度長達兩萬七千余年，這也意味著北京擁有諸多文化杰作，如今，許多已列入聯合國教科文組織世界文化遺產名錄。這些藝術瑰寶與歷史院校不僅使北京成為整個中國的藝術與文化中心，還詮釋了為何包括我本人在內的許多外籍教職員工將北京視為家鄉。

盡管如此，在過去的20年時間里，與許多其他中國城市及東南亞城市如出一轍，北京的城市增長與發展速度前所未有。2000年至2009年間，北京的城市用地面積翻了兩番。而如今，“建成區”的面積已經占據了北京全市總面積的40%，并延伸到“京津冀”都市帶。放在過去，這樣的場景或許只會出現在科幻小說之中。

Like all new arrivers to Beijing, I quickly came to appreciate that Beijing is a “megacity” in every sense. The Chinese capital is the second largest city in the world by population, trailing only Shanghai.

Twenty-seven thousand years of history, including the rise and fall of the great Ming and Qing dynasties, means Beijing is home to numerous cultural masterpieces, many now recognised as UNESCO world heritage sites.The art treasures and universities have made Beijing the center of art and culture in China and explain why I, and many expatriate teaching colleagues, now call Beijing home.

Nonetheless, the speed of the urban growth and development of Beijing during the last 20 years, like many cities across China and East Asia more widely, has been unprecedented. Between 2000 and 2009, Beijing's urban land quadrupled. The “built-up” area now stretches across 40% of Beijing municipality and even further a field across the “Jing-Jin-Ji”（京津冀）metropolitan region offering an urban vastness previously only contemplated in science fiction.

自然缺失癥

對于北京居民而言，無論是世居于此，還是初來乍到，都會感受到這座世界級大都市所帶來的現代化都市便利：美味的食物、宏偉的景觀，以及無與倫比的購物體驗，但也會使人感受到遠離大自然的孤獨感。對于世界各地的城市居民而言，因與大自然的疏遠而產生的孤立感已被公認為是一種重大的全球性挑戰，這種現象則被稱為“自然缺失癥”（Nature Deficit Disorder）——該術語在理查德·勒夫（Richard Louv）2005年出版的《林中的最后一個孩子》（Last Child in The Woods）一書中被首次提出。

在日常生活中，同大自然的接觸與否影響人類對廣闊自然的感知度與鑒賞度。時常與大自然接觸的人，往往對環境問題更加敏感，并對生態系統之于人類的價值與野生動物生存的權利有更積極的看法。然而，對于我這位畢生致力于野生動物研究和保護的生物學者而言，隨著城市人口與土地面積的持續快速增長，自然缺失癥的影響將十分令人擔憂。

Nature Deficit Disorder

For residents of Beijing, lifelong and recently arrived alike, life in one of the world's largest cities provides all the conveniences of modern life: superb food,magnificent sightseeing, and great shopping, but can also trigger feelings of isolation from the natural world. The detachment from nature felt by city dwellers the world over has been recognised as a major global challenge and has become known as “Nature Deficit Disorder”,a phrase first coined by Richard Louv in his 2005 bookLast Child in the Woods.

Exposure, or lack of exposure, to nature on a day-today basis has been shown to affect people's perceptions and appreciation of the wider natural world. People regularly exposed to nature tend to be more sensitive to environmental issues and to have more positive opinions of the value of ecosystems to humans and of the right of wildlife to exist. As the urban population, as well as the urban land area, continues to increase rapidly,the implications of Nature Deficit Disorder are deeply concerning to me as a conservation biologist who has devoted my professional life to the study and protection of wildlife.

走出鋼鐵森林

我所教授本科班的學生們曾花去數周的時間對蝴蝶進行記錄，這些蝴蝶與我們同在屋檐下，共享京北的校園。這項實地作業的目的是提高學生們對環境問題的認識，解決自然缺失癥所帶來的困惑。一學期下來，學生們對多達300只蝴蝶個體進行了記錄，這些蝴蝶分屬于10種不同類別。一些學生在不斷努力地克服對昆蟲的恐懼，旁人也溫柔地提醒他們：蝴蝶對人類是無害的，它們既不會咬人，也不會傳播任何疾病。總體來講，許多學生終其一生都置身于城市的鋼鐵森林之中，對于這次經歷，他們異常珍視；正如一名學生所述：“此次蝴蝶取樣的經歷，將成為我大學生活中一段難以忘懷的記憶。”

除去課堂內應盡的職責，我還加入了一個科學家團隊：他們與我志同道合，散居于東亞與東南亞的不同城市中，對城市公園中發現的蝴蝶進行調研。同時，我們還對公園中的人群進行了采訪，以斷定其對蝴蝶的感知度與鑒賞水平。夏天，我從南走到北，從東走到西，足跡遍布整個北京，對京內十個公園內的蝴蝶進行了記錄，并對超過兩百名園內訪客進行了采訪。在此期間，兩名學生受到先前在校園記錄蝴蝶經歷的鼓舞，志愿加入此次調研任務。

盡管我不能用中文交流，但通過觀察學生們與園內人群間的對話，我對北京的生活有了更深的了解：因為大多數外籍人士通常被限于校園之內，或是朝陽區高檔住宅的門禁之中，而這一經歷使我的視野超越了上述界限。在北京，包括年輕人群與老年人群在內，公園被社會各階層所共同使用，在天氣晴朗的日子里，公園里的每一寸土地都被跳廣場舞的大媽、慢跑者、野餐者、拍婚紗照的夫婦，或是僅僅享受戶外生活的孩子們占據。

Going out of the concrete jungle

My undergraduate classes spent several weeks recording the butterflies which share our university campus in north Beijing. The objective of the assignment was to raise awareness about environmental issues and also address Nature Deficit Disorder. Throughout the semester the students recorded 300 individuals belonging to 10 butterfly species. Some students struggled to overcome their phobia of insects, and were gently reminded that butter flies are harmless to humans, they cannot bite and don't spread any diseases. Overall the students, many of whom have lived in the concrete jungle their whole lives,deeply cherished the experience； as one student put it: “this experience of butter flies sampling will be an unforgettable memory in my university life.”

In addition to my classroom duties I have been part of a team of like-minded scientists working across East and Southeast Asia surveying butterflies found in urban parks. We also have been interviewing parks users to determine their levels of perception and appreciation of butterflies. In summer I traversed Beijing from north to south and east to west to record the butter flies in ten city parks and interview more than two hundred park users.Two undergraduate students volunteered to assist in this task after being inspired by their experience recording butter flies on campus.

Although I cannot speak Chinese, observing the conversations between my students and the park users gave me an insight into life in Beijing beyond that seen by most expatriates con fined to their university campuses or gated communities in Chaoyang. Beijing parks are used by young and old alike from all sectors of the community,and on fine weather days every inch of the parks are occupied, by dancing aunties (guangchangwu), joggers,picnickers, couples taking wedding photos, or children simply enjoying being outdoors.

有蝴蝶嗎？

還是在北京的公園內，我們共記錄了31種蝴蝶，其中包括體型大而雄壯的鳳尾蝶及微小的灰蝶。在很大程度上，菜粉蝶（學名Pierisrapae）是一種最為常見的蝶種，也是我們在調查的十個公園都發現的唯一一個蝶種。這種白色的蝴蝶遍布于世界各地的城市中，在離北京8000公里的地方——我的家鄉英格蘭西北部，這種蝴蝶也隨處可見。每年2月至10月，幼年的菜粉蝶會在北京四處紛飛。而在一年之中，第一批蝴蝶的體型比后來的成年蝴蝶要小，這可能是由于蝶蛹在地下越冬的影響；這一特點是我們在校園里記錄蝴蝶發現的。

在大城市中，城市公園與大學校園擁有令人意想不到的生物多樣性，以及種類繁多的野生動物，這或許會讓許多人感到驚訝。事實上，在策劃校園蝴蝶調查時，同事們經常會發出這樣的疑問：“校園里有蝴蝶嗎?”城市里的野生動物并不總是顯而易見的，如果我們不花時間去仔細觀察，那么我們這些城市居民通常很難注意到它們。

Are There Butter flies？

We recorded thirty-one species of butterflies in Beijing parks, including large and spectacular swallowtails and teeny-tiny grass blues. The small white (known by the scientific name Pierisrapae) was the most common species by a large margin and was the only species found in all ten parks we surveyed. This white butter fly can be found in cities all over the world, and is abundant in my hometown in Northwest England, 8000 kilometres from Beijing. Adult small white butter flies can be seen flying in Beijing from February until October each year. The first butterflies of the year are of smaller size than the later adults, probably due to the effects of overwintering underground as pupae；a pattern noticed by the students recording the butter flies at our campus.

It may come as a surprise to many that the urban parks and university campuses in megacities, can host remarkable levels of biodiversity and abundant wildlife.In fact, when planning the campus butterfly survey,colleagues would frequently ask: “There are butter flies on campus?” Urban wildlife may not always be obvious, and we city dwellers often fail to notice it if we don't take the time to look carefully.

John James Wilson，英國，動物學博士學位，曾任中國農業大學國際學院生物課教師。圖為John James Wilson（前）和學生在一起（中國農業大學國際學院供圖）

“虛假的”蝴蝶展

目前，雖然北京的蝴蝶數量龐大且種類繁多，但蝴蝶在城市中仍面臨著諸多挑戰，其在城市的長期續存還遠遠沒有得到保障。在過去的50年里，英國鄉村蝴蝶的消失已讓人們扼腕嘆息。然而，最近的一項研究表明：蝴蝶在英國城市中的消失速度比在鄉村地區更加迅速。

城市化進程導致了綠地的喪失與碎片化，使得蝴蝶的覓食難度不斷增加。對于菜粉蝶這樣的蝶種而言，它們能夠以諸多不同種類的植物為食，或許可以應對此類情況，但對于那些飛行能力不強，同時又不太可能尋找到全新食物來源的蝶種而言，在城市生存中的處境正變得舉步維艱。由于城市中的熱島效應，全球變暖導致的氣溫上升在市區內尤為明顯，因而那些在寒冷的冬季處于繁盛的蝴蝶，或將會受到嚴重影響。此外，城市中密集的交通流量導致了氮沉積水平的增加，這不僅改變了植物的營養質量，還與蝴蝶的減少息息相關。

英國廣播公司（BBC）新聞網站曾有一條新聞：對于“虛假的”蝴蝶展，中國游客憤怒至極。據新聞報道，廣西的游客們期待一睹蝴蝶展，但當他們意識到自己購買了門票，卻只能看到粘在樹枝上的塑料蝴蝶時，感到失望透頂。而在我看來，這個故事表明了中國人對與蝴蝶的互動頗為重視，甚至愿意為它們埋單。也許這里的人們并沒有意識到：在城市公園內，他們很容易做到與許多美麗的蝴蝶進行互動，而這一切往往又是免費的。因此，讓我們攜起手來，提升人們保護本地野生蝴蝶的意識，讓它們與我們同處一屋檐之下，并采取措施，讓我們真正成為“一家人”。

“Fake” butter fly exhibition

While there are currently diverse and abundant assemblages of butter flies in Beijing, butter flies in urban areas face many challenges and their continued presence in the city is far from guaranteed. The disappearance of butterflies from the British countryside over the past 50 years has been well-documented, but a recent study has demonstrated that butterflies are vanishing from British cities more quickly than from rural areas.

Urbanisation causes the loss and fragmentation of green spaces which makes it harder for butterflies to find food. Species like the small white, which can feed on many different types of plants, can probably cope, but species that aren't as strong fliers and are less able to find new food sources increasingly struggle with city life.Temperature increases due to global warming are more strongly pronounced in cities due to the urban heat island effect and butter flies which thrive during cold winters are likely to be severely affected. The high volumes of traffic in cities leads to increased levels of nitrogen deposition which changes the nutritional quality of plants and has been linked to butter fly declines.

“Chinese visitors left furious by ‘fake' butter fly exhibition”was a headline on the BBC News website. According to the news report, visitors in Guangxi hoping to see an exhibition of butter flies were disappointed after realising they had bought tickets to see plastic butter flies attached to sticks. To me, this story shows that Chinese people value interactions with butterflies and are even willing to pay for them. Maybe they don't realise they can easily interact with many beautiful butter flies in their city parks,often free of charge. Let's raise awareness about the wild,native butterflies sharing our cities, and take steps to ensure they continue to have a home among us.