Elephants and Monkeys Are Fighting Climate Change in Ways Humans Can't
大象和猴子正以人類做不到的方式對抗氣候變化
Marlene Cimons 馬琳·西蒙斯
Mother Nature has it figured out. She's designed a master scheme that connects plants and animals， all working in concert to keep every living thing in balance. Imagine a stack of dominoes—knock down one of them， and the rest will tumble. The same can happen in nature.
This is especially evident in places like central Africa and in South American tropical rainforests where certain animals—from the world's largest to its smallest—help keep trees safe and healthy， which is critical as trees absorb vast amounts of planet-warming carbon pollution.
Recent research warns that losing the creatures that nurture trees puts forests in danger. This， by extension，is helping to accelerate dangerous climate change.
In central Africa， for example， elephants eat fast-growing trees， making room for those that grow more slowly. The slow-growing trees—with their very dense wood—store more carbon than their thinner， faster-developing counterparts. Without elephants， more carbon would accumulate in the atmosphere， worsening climate change， according to a new study that used computer models to project what could happen if elephant populations continue to dwindle or become extinct.
“Africa may once have contained 10 million elephants from the Mediterranean to the Cape， in every habitat except extreme desert. In 1970， there may have been a million left. By the end of the 1980s， there were half that number， mostly killed for the ivory trade，”said Stephen Blake， assistant professor of biology at St. Louis University， and author of the study， which appears in the journal Nature Geoscience.
By killing elephants， poachers rob slow-growing trees of their guardian. They also slow the growth of new trees. Elephants blaze trails and disperse seeds as they forage.“Elephants are basically the gardeners of the forest，”Blake said.“They disperse over 100 species of seeds， and disperse more of them over longer distances that other dispersers.”
Similarly， some of the world's littlest creatures also help replenish forests， although they don't face the grave risks that elephants encounter. Tiny tamarins that live in Peruvian rainforests eat fruits from trees， then poop out the undigested seeds in degraded former pastures—land cleared by humans for grazing water buffalo—effectively planting trees.
Scientists showed that two types of these squirrel-sized monkeys—moustached and black-fronted tamarins—are seeding new forests. This is vital because—like the forests of central Africa—tropical rainforests also store carbon， and are home to a vast number of plants and animals.
The scientists tracked seeds from the animals' feces deposited in the new forest and identified eight different plant species found in the main rainforest.“Tamarins can play a role for the natural regeneration of disturbed areas，”said Eckhard W. Heymann， a scientist at the German Primate Center.
However， their contribution， while important， usually isn't enough to regenerate large tracts.“So it is better to protect the forests—which also protects the animals living there—than to rely on the services [of tamarins].”Moreover， climate change may be altering the plants that tamarins eat， changing when they produce leaves， flowers， and fruits. This could limit tamarins' ability to seed new forests.
Blake， who has spent nearly 20 years in Africa working in elephant research and conservation， laments their fate， describing them as “a complex society of intelligent， caring， emotional animals who respect their grandmothers and mourn their dead，” and condemns those who neglect their duty to save them.
“We will go to Mars—there is no doubt—humans are too smart not to，”he said.“Yet we do not have the wisdom to protect elephants and their forest environment that do so much for our physical， spiritual， and emotional well-being.”
大自然自有辦法。它設計了一個將植物和動物聯繫起來的卓越方案，讓它們協力保持所有生物的平衡。試想有一列多米諾骨牌，推倒其中一塊，剩下的將會倒下。同樣的情況在自然界也會發生。
這在非洲中部和南美熱帶雨林等地尤其明顯，在那些地方，某些動物幫助保持樹木的安全和健康，其中既有全世界最大的動物，也有最小的動物。這一點至關重要，因為樹木吸收大量能導致地球變暖的碳汙染。
最近的研究警告稱，失去那些能養護樹木的動物會令森林陷於危險。延伸開來說，這會加速危險的氣候變化。
例如，在非洲中部，大象會吃生長迅速的樹，從而為生長較慢的樹留出空間。那些生長緩慢的樹木的木材密度很高，相較於木材密度更小、生長更快的樹木，它們能儲存更多的碳。一項新研究利用了計算機模型來預測如果大象繼續減少或滅絕的話可能會發生什麼，該研究顯示，如果沒有大象，大氣中會累積更多的碳，從而加劇氣候變化。
聖路易斯大學的生物學助理教授、《自然·地球科學》月刊上這份研究報告的作者斯蒂芬·布萊克說：“從地中海到好望角，非洲可能曾有1000萬頭大象，它們分佈在除條件極其惡劣的沙漠之外的每處棲息地。1970年可能還有100萬頭。到上世紀80年代末，它們的數量又減少了一半，主要因為象牙貿易被殺。”
偷獵者殺死大象會令生長緩慢的樹木失去守護者。他們還令新樹生長放慢。大象覓食時會開闢小徑並傳播種子。布萊克說：“從根本上說，大象是森林的園丁。它們能傳播100多種種子，並且與其他種子傳播者相比，它們能將更多的種子傳播到更遠的地方。”
同樣，一些世界上最小的動物也能幫忙植樹造林，儘管它們並未面臨大象遭遇的那些嚴重風險。生活在秘魯熱帶雨林的小檉柳猴會吃樹上的果子，然後將未消化的種子隨糞便排到曾為牧場、後來退化的土地，從而在其上種植樹木。人類為了養水牛而清理了那些土地。
科學家表明，這些松鼠大小的猴子中有兩種——長鬚檉柳猴和黑額檉柳猴正在播種新的森林。這至關重要，因為與非洲中部的森林一樣，熱帶雨林也能儲存碳，並且是大量動植物的棲息地。
科學家們對這些動物遺留在新森林的糞便中的種子進行了追蹤，發現了存在於最大雨林中的八種植物。德國靈長類動物研究中心的科學家埃克哈德·海曼說：“檉柳猴可以對受干擾區域的自然再生髮揮一定作用。”
然而，它們的貢獻雖然重要，但通常不足以再造大片樹林。“所以，與其依靠（檉柳猴的）幫助，不如保護森林，這也能保護生活在那裡的動物。”此外，氣候變化可能正改變檉柳猴所吃的植物，改變它們長葉、開花和結果的時間。這可能會限制檉柳猴播種新林的能力。
在非洲從事大象研究和保護工作近20年的布萊克對它們的命運表示痛惜，稱它們是“一個由有智慧、有愛心、有情感的動物組成的複雜社群，它們會尊重祖母並哀悼死去的同類”，他譴責那些忽視了拯救大象責任的人。
他說：“我們會登上火星，這一點毫無疑問，人類太聰明瞭，不會做不到。但我們沒有足夠的智慧來保護大象及其森林環境，它們對我們的身體、精神和情感健康大有助益。”（李莎譯自美國《大眾科學》月刊網站8月13日文章）
閱讀更多 參考消息 的文章
