象群激增危及生態平衡 南非國家公園經營面臨兩難 | 環境資訊中心

象群激增危及生態平衡 南非國家公園經營面臨兩難

2006年07月24日
作者:Mark Schulman(WWF總編輯);莫聞、丁秋仁編譯;陳瑞賓審校

克魯格國家公園的象群(圖片來源:WWF)非洲南部平日受陽光嚴重曝曬的乾泥焦土,正度過史上最多雨水的夏季,新生嫩綠的植物隨即將這片土地點綴成綠意樂園。在南非的克魯格國家公園內,充沛的雨水不但使草木繁茂,也灌注了乾涸河床。

野生生物暫且不需再遠行尋覓食物與水源,這對生物來說是件好事;對每年逾120萬名來訪的觀光客而言倒是未必,他們一心只想著捕捉「五大」生物的鏡頭──也就是獅子、豹、大象、犀牛與水牛,若是在雨量稀少的時期,很容易可見到這些動物聚集在零零落落分布的水坑附近。

不過就算是雨水多的時期,觀光客還是很容易看到大象。世界自然基金會(WWF)非洲象專案人員史蒂文森(Dr. P.J. Stephenson)說:「畢竟,大象是那麼巨大而壯觀的動物!」「但是,為了養活自己,大象也需要非常大量的食物和廣大的空間。」象群一天可消耗掉200公斤的植物,另外國家公園的空間也很有限;在此情況下,為了爭奪稀少的資料,大象難免與其他動物產生競爭關係,就像人類和其他動物競爭一樣。

不像非洲其他的瀕危動物,多面臨盜獵和棲地流失等威脅,克魯格國家公園內的象群受到良好保護,族群數量迅速擴大。克魯格國家公園涵蓋面積2萬平方公里,約等於瑞士國土的一半,但似乎仍容納不下這些愈來愈多的象群。

10年前,當局在國際壓力下停止撲殺象群,自此象群從7,000隻增加到12,000隻。當地官員說,長期來講,公園內的棲地最多能養活7,000隻大象左右,再多的話,便會危及脆弱而必須小心呵護經營的生態環境。

大象在遷移覓食的過程中會把樹皮剝除,也因此危害到幾種極為重要的高大樹種,像是猴麵包樹、多種猛禽習慣於其中築巣的 knobthorn、以及marula果樹──果實富含維他命C,常用來製作果醬、果汁或酒精飲料,例如南非常見的利口酒Amarula。還有像棕櫚樹 lalla 等稀有植物,也會遭到破壞。

南非國家公園署(SANParks)保育局局長瑪格米(Dr. Hector Magome)就說:「我們的職責是經營管理和保育生物多樣性,我們必須對此採取一些行動,不只是為了保護生態系,也為了在公園週遭生活的住民,以及前來參觀的旅客。」

南非和其他非洲南部國家都在設法處理當地象群過多的問題,目前已提出了七種方案待考量,其中包括:透過設立跨國保護區並保護象群遷徙廊道,擴大對象群遷徙範圍的保護;將數量較少的象群搬家;幫大象結紮;甚至最受爭議的撲殺手段都列入考慮。每種方式都有其優缺點、代價與限制。

本文僅節錄部分內容,全文詳見http://ens-newswire.com/ens/jul2006/2006-07-19-03.asp

A Numbers Game: Managing Elephants in Southern Africa
KRUGER NATIONAL PARK, South Africa, July 19, 2006 (ENS); By Mark Schulman

大象太多了Southern Africa just had one of the wettest summers on record, turning its usual adobe brown sun-burnt landscapes into verdant green paradises. In South Africa's Kruger National Park, vegetation has grown thick and dried riverbeds have flooded. Wildlife haven't had to wander too far in search of food or water.

That's great for the wildlife, but not necessarily for the 1.2 million tourists who come to the world famous park each year expecting to spot the Big Five - lion, leopard, elephant, rhino and buffalo - that in leaner times are easily found congregating in the open around sparse waterholes.

But even in the best of conditions one can't miss the elephants. "Elephants are such large and magnificent creatures," said Dr. P.J. Stephenson of WWF's African Elephant Programme, "but they also need a lot of food and freedom if they are to survive."

As elephants consume up to 200 kilograms of plant matter in a single day, when space is limited, as it usually is, they often come into conflict with other animal species, as well as people, who are competing for many of the same, often scarce resources.

Kruger National Park covers an area of some 20,000 km2 - about half the size of Switzerland - but it still doesn't seem big enough to accommodate a growing elephant population. Unlike many populations in Africa which remain endangered as a result of years of poaching and habitat loss, elephants in Kruger are growing at a rapid rate.

Since the park stopped culling elephants about a decade ago as a result of international pressure, numbers have gone from 7,000 to over 12,000. According to local officials, the park's habitat can only sustain about 7,000 over a long period. Any more and it will add pressure to an already fragile and carefully managed environment.

In the course of their foraging, elephants often strip the bark of trees of such important tall tree species as ancient baobabs, knobthorns - where birds of prey often make their nests - and marulas, whose fruit has an extremely high vitamin C content and is used to make jam, juices and alcoholic beverages like the popular South African liqueur Amarula. Rare plant species, such as the lalla palm, are also being damaged.

"Our obligation is to manage and conserve biodiversity," added Dr. Magome, Conservation Services Director of South African National Parks (SANParks). "We have to do something to manage the situation, both for the ecosystem, the people who live near the park and for those who visit it."
Several options are currently being considered by South Africa and other southern African range states to tackle local over-population of elephants. These include range expansion through the establishment of cross-border protected areas and protection of migration corridors, translocation to under-populated areas, contraception, and perhaps the most controversial, culling - the intentional reduction of elephant populations. Each option has its advantages and disadvantages, each its costs and constraints.