HISTORY ENTWINED
Illustrator SALLY GRACE BUNKER and botanist RICHARD SAUNDERS tell the story of Hong Kong’s natural history by getting to the root of its native trees. Introduction by MARK JONES插畫師Sally Grace Bunker與植物學者Richard Saunders為香港原生樹木尋根究底，細訴香港大自然的故事。撰文： Mark Jone
As a new book on Hong Kong’s trees is published, we trace the SAR’s special relationship with its roots
There aren’t many cities in the world where trees regularly make the news. But trawl the archives of the South China Morning Post and you won’t have to go back far to find stories on an arboreal theme. ‘ Time running out to save historic tree.’ ‘Axe falls on decades- old banyan trees in Hong Kong after stand- off.’ ‘ Worst post-typhoon tree situation.’
Trees – especially the historic banyans which entangle themselves with the city’s masonry – are part of Hong Kong’s fabric and consciousness. The clean- ups after the annual typhoons that threaten the island and uproot its forests are accompanied by prolonged bouts of soul-searching: are we doing enough to protect our trees? Do we care enough about this part of our natural heritage?
So it’s timely that a book celebrating Hong Kong’s 390 native tree species is about to be published.
A local botanical artist, Sally Grace Bunker, has collaborated with two botanists from The University of Hong Kong, Professor Richard Saunders and Dr Pang Chun- chiu. The result is Portraits of Trees of Hong Kong and Southern China.
The work highlights over 100 species that are illustrated in watercolours. We have chosen seven trees worth celebrating in their own right, but also because they tell us something about the natural and human history of this extraordinary place. Most of them grow widely throughout the territory, whether in the hinterland of Hong Kong’s biggest island, Lantau, or labelled and curated in Central’s Botanical Gardens.
THE SELFISH TREE (LEFT)
Acacia confusa ( Taiwan acacia) wasn’t originally a native species but has now been extensively cultivated as it grows well in degraded areas and helps to prevent soil erosion. As it’s relatively fire-resistant, it’s also widely cultivated in Hong Kong as a fire break in plantations. The tree is known to excrete toxic chemicals into the soil following the rotting of fallen leaves; these chemicals act to inhibit or suppress the growth of other plants. This phenomenon – known as allelopathy – is beneficial to the tree itself as it reduces below- ground competition for nutrients and water, but is an undesirable characteristic in a plantation species as it hinders natural regeneration and biodiversity restoration.
全球沒有多少個城市的樹木會經常成為當地報章上的新聞。只但 要翻查《南華早報》檔，必案 不 翻查年代久遠的舊報紙，很快就會找到與樹有關的新聞標題︰救「拯 古樹時間無多」、爭「議僵持不下香港百年榕樹魂斷斧下」、颱「風過後樹木遭受歷來最嚴重破壞」。
樹木與香港的面貌和保育意識密不可 分，尤其是在城中的牆石 上盤根錯節地生長的老榕樹。每年，威脅香港的颱風過後，不少樹木被連根拔起，清理工作令我們生起反思之心︰我們可有好好保護城中的樹木？我們是否有好好關心大自然送給我們的禮物？
因此，本一 以390種香港原生樹木品種為題的專書即將出版，可說是適時而至。
本物地植 藝術家Sally Grace Bunker與香港大學兩位植物者學學 桑德士教授及彭俊超博士合作，版出 了《Portraits of Trees of Hong Kong and Southern China》（香港及南中國樹木圖誌）。
這本書收錄過百幅以水彩手繪的插圖，都是香港重要的樹木品種。我們精選了當中七種樹木，它們不但各有特色，亦向我們娓娓道出香港這片非凡土地上的自然及人文歷史。書中提及的樹木大部分都可在香港的郊野找，到 例如香港最大的島嶼大嶼山。此外，位於中環的植物公園內亦種植了不少品種，而且加上標籤，容易辨識。
自私的樹
（左圖）
台相灣 思樹不是香港原生，樹 但有助防止水土流失，適合生長於土地退化的，地區 因此政府大規模種植。由於抗火功能亦較高，香港在林地間大量栽種台灣相思樹，用作防火帶。台灣相思樹的落葉在泥土中腐爛時，會釋出有毒化學物質，抑制或阻止其他植物的生長，這個現象稱為「相剋作用，」對台相灣 思樹自然有利，可藉此減少樹群之間競相吸收地下的養分和水分。但這種特性對植林樹種而言並不可取，礙會阻 自然再生及回復生物多樣性。
AN AWKWARD SYMBOL (LEFT)
Bauhinia blakeana (Hong Kong orchid tree) was first found growing in the grounds of an abandoned house near Mount Davis, Hong Kong Island, in the late 19th century and was later introduced to the Hong Kong Botanic Gardens. This individual (which survived being blown over by a severe typhoon in 1906) was propagated and became the ancestor of all specimens cultivated today.
The Bauhinia blakeana is an artificially propagated hybrid derived from interbreeding two naturally occurring species, Bauhinia purpurea and Bauhinia variegata. Bauhinia blakeana was adopted as the floral emblem of Hong Kong in 1965, and now appears, often in a stylised form, on local banknotes, coins and the SAR flag. As a sterile hybrid, this is arguably an inauspicious symbol for a city built on mixed Chinese and British heritage.
尷尬的象徵
（左圖）
19世紀末，有人在港島摩星嶺一間廢置大屋的空地上首次發現洋紫荊（又名香港蘭） ，其後移植至香港植物公園。這一棵洋紫荊捱過1906年的強烈颱風吹襲，現今所見的洋紫荊都是從它繁衍出來。
洋紫荊須由人工繁殖，紅以 花羊蹄甲和宮粉甲羊蹄 兩種自然生的成 樹種雜交而來。洋紫荊於1965年正式定為香港市，花 現時經常化身圖案，出現於香港紙、幣 硬幣及特別行政區區旗上。由於洋紫荊是不育的混種植物，有人認為，對於結合中國及英國文化傳的統 香港來說，這是不吉利的。象徵
THE TREE THAT GAVE A CITY A NAME (RIGHT)
Aquilaria sinensis (incense tree) is the source of a highly fragrant, resinous wood – known commercially as agarwood – that’s used in the manufacture of incense and as a source of Chinese medicine. The high concentration of resin develops in response to fungal infection, with uninfected trees lacking the valuable resin. Mature individuals of Aquilaria sinensis are often indiscriminately and illegally felled in Hong Kong in the hope of retrieving commercially valuable agarwood.
Hong Kong was historically an important hub in the commercial export of Aquilaria sinensis incense to other parts of Asia, with most exported via Shek Pai Wan in Aberdeen. This harbour was known as Heong Kong (meaning ‘Incense Harbour’), which was subsequently misapplied as ‘Hong Kong’ to the entire territory.
名留香江
（右圖）
土沉香（又名牙香樹或白木香）是俗稱沉的，香木 原木 這種木材的分泌 樹脂可用生於 產香料及中藥材。由於樹木受真菌感染才會分泌高濃度的，未樹脂 因此 受感染的樹木就沒有珍貴的。樹脂 香港經常見到成年土沉香樹遭人任意及非法砍伐，以盜取商業價值高的沉香木。
香港曾是將土沉香香料輸出至亞洲各地的重要樞紐，大部分香料經香港仔石排灣轉運，此港口亦被稱為「香港」（香料港口） ，這名稱後來更用被 來指稱整個地域。
THE DEVIOUS TREE (LEFT)
Adenanthera microsperma (red sandalwood) is common in feng shui woods near villages in Hong Kong. The fruit pod is large, up to 20 centimetres in length, and splits into two valves as it dries, exposing bright red glossy seeds that are suspended from the pale brown inner surface of the pod. These seeds superficially resemble fleshy berries and it has been suggested that the red colouration has evolved to mimic berries and deceive birds that normally eat fleshy fruits – a clever method of seed dispersal.
狡猾的樹
（左圖）
海紅豆又叫孔做 雀豆，常見於香港鄉村附近的風水林。樹上結出的果莢呈淺褐色而且十分碩大，可長達20厘米，乾枯後會裂開成兩瓣，露出朱紅晶瑩的種子，長得極像果肉飽的滿 莓果。相信種子是為了模仿莓果而進化成紅，色 以蒙騙平常進食漿果的雀鳥，這實在是一個傳播種子的聰明辦法。
HONG KONG WAS AN IMPORTANT HUB IN THE EXPORT OF INCENSE TO OTHER PARTS OF ASIA香港曾是將香料輸出至亞洲各地的重要樞紐
THE GREAT SURVIVOR (LEFT)
Bruguiera gymnorhiza (many-petalled mangrove) is one of only eight plant species in Hong Kong that are truly adapted to survive in mangrove habitats. Mangroves are intertidal ecosystems and, as a consequence, the high salinity of the habitat is extremely challenging for plant survival.
Many of the morphological peculiarities of mangrove trees are adaptations to surviving in these difficult conditions, including ‘prop’ roots that help support the tree on soil that is unstable because of the tides; roots with ‘knees’ that project above the ground to assist with aeration in oxygen-poor soil; and the evolution of vivipary, in which seeds germinate while still attached to the maternal plant.
偉大的倖存者
（左圖）
在香港，木欖是真正能夠適應並在紅樹林環境中生的存 八個植物品種之一。紅樹林是潮間帶生態系統，高鹽分的環境極考驗植物的生命力。
大部分紅樹林樹種的形態特徵皆是為了適應惡劣的生存環境而發展出來，如支柱根將樹木固定在受潮水沖刷而不穩固的泥土中；泥土缺乏氧氣，狀膝 根便向上屈曲來呼吸；並進化出胎生苗現象，即種子在連接母的況株 情 下發芽。
THE LEFT- BEHIND TREE (RIGHT)
Pyrenaria spectabilis (common tutcheria) is a rare local species that is now legally protected. It is dispersed by ‘scatterhoarding’ rodents that collect and store fruits to eat later. The seeds often germinate when the rodent fails to retrieve the fruit.
The bad news: these rodents no longer survive in Hong Kong and, as a consequence, tree species with this dispersal mechanism are rare and noticeably absent from secondary forests. This is in striking contrast with the closely related species, Polyspora axillaris, which produces winged seeds that hitch a ride on passing breezes. As a result, Polyspora axillaris is far more common in Hong Kong, and is regarded as a pioneer species that is able to colonise disturbed areas and often dominates early-stage secondary forests.
被遺下的樹
（右圖）
石筆木是稀有的生原 樹種，現時受到法令保護。樹木依賴收集並貯藏果子的
囓齒類動物散播種子，齒當囓 類動物忘記或找不到果子時，種子便有機會發芽。
可惜這些囓齒類動物已在香港絕跡，因此依靠這個方式傳的播 樹種異常罕有，亦不會見於次生。林 這一點與其近緣物種大存茶截然不同，者後 長出翅果，可以隨風飛散。因此大存茶在香港更加常見，更被選為整頓受破壞地區的鋒先 樹種，亦常見於早期的次林生 。
THE COLONISER (LEFT)
Pinus massoniana (Chinese red pine) is Hong Kong’s only native pine species. The British colonial government implemented several major afforestation projects (from the early 1870s until the Second World War, and again from 1953), with Pinus massoniana the most widely planted species. Concern was raised in 1978, however, by the death of many trees following the wilting and browning of needles. This was due to ‘pine wilt disease’, resulting from infestation by roundworms spread between trees by longicorn beetles originating from North America. This, in addition to a scourge of pine-needle scale insects from Taiwan, caused the widespread destruction of local Pinus massoniana populations, dramatically reducing the extent of forested land in Hong Kong.
開拓者
（左圖）馬尾松（或稱山松）是香港唯一的生原 松樹品種。英國殖民政府從1870年代初至第二次世界大戰爆發前，曾推行數次大型造林計劃，並於戰後再度於1953年展開植林工作，馬尾松是最被廣泛的。種植 樹種 1978年，由於大量馬尾松在松針枯萎後壞死而引起關注。病因是「松樹萎凋病」，由來自北美的昆蟲天牛在樹木之間散播松材線蟲造成；加上來自台的灣 松針介殼蟲肆虐，引致本地大批馬尾松死亡，大幅減少香港的林地面積。