與印度尼西亞這家棕櫚油工廠類似的生物燃料計劃將增加人類對于地球生物量的使用
（圖片提供:AFP/Getty Images）
生物谷：人類給地球留下了一道深深的傷疤，但這里提及的并非人們常說的氣候變化,。一項新的研究表明,，除了過度捕魚以及對其他資源的榨取外,，人類還攫取了全球每年將近1/4的生物量。這一發(fā)現(xiàn)意味著,，人類活動正在威脅著地球的生物多樣性,，同時讓人不禁對抑制全球變暖的一項主要策略——使用生物燃料以減少二氧化碳排放——提出了質(zhì)疑。
近幾年來,，科學(xué)家們進行了大量工作,，試圖確定有多少植被——或者說生物量——被人類占用。然而根據(jù)不同的模型以及手頭的數(shù)據(jù),，研究人員最終獲得的評估結(jié)果卻相差很大,。為了解決這個問題，由奧地利克拉根福大學(xué)的生態(tài)學(xué)家Helmut Haberl領(lǐng)導(dǎo)的一個研究小組采用了一種新的方法,。研究人員分析了來自數(shù)據(jù)庫的大量最新數(shù)據(jù),，同時考慮了人類活動對全球植物生長造成的影響。Haberl和他的同事對農(nóng)業(yè)產(chǎn)量,、森林覆蓋狀況以及人類活動導(dǎo)致的土壤退化進行了最新的統(tǒng)計學(xué)分析,，并繪制了相關(guān)的圖表。
分析表明,，僅在2000年,，人類便耗盡了當(dāng)年23.8%的生物生產(chǎn)力。研究人員發(fā)現(xiàn),，在人類占用的生物量中,，78%與農(nóng)業(yè)有關(guān)，剩下的22%則涉及林業(yè),、人類引發(fā)的火災(zāi)以及其他活動,。研究小組同時發(fā)現(xiàn)，全球各地對于生物量的使用具有顯著差異,。在這份名單中,，南亞人首當(dāng)其沖，他們占用了該地區(qū)63%的植被,，這可能是由于當(dāng)?shù)馗呙芏鹊霓r(nóng)業(yè)生產(chǎn)所致,。而北美人和中東人占用的植被僅為22%和12%。研究人員警告說,，那些大量使用來自農(nóng)業(yè)和林業(yè)產(chǎn)品的生物燃料的做法“需要進行慎重考慮”,，這是由于這些做法能夠使人類使用的生物量翻一番，同時給那些試圖分享地球植物的其他物種造成更大的壓力,。研究人員在本周的美國《國家科學(xué)院院刊》（PNAS）網(wǎng)絡(luò)版上報告了這一研究成果,。
美國東蘭辛市密歇根州立大學(xué)的地球科學(xué)家Nathan Moore表示，研究人員的分析是“合理的”，其結(jié)果“相當(dāng)令人擔(dān)憂”,。加利福尼亞州斯坦?？▋?nèi)基研究所的生態(tài)學(xué)家Christopher Field對此表示贊同。他說,，新的評估結(jié)果“基于對最佳可用信息的謹(jǐn)慎判讀”,。Field警告說：“一個物種占據(jù)了全世界陸地近1/4的生物生產(chǎn)力，而數(shù)百萬物種則只好分享剩余的生物量,，很難想象到底有多少物種被擠出了這場競賽,。”Field同樣贊成Haberl的研究小組對于生物燃料使用的關(guān)注。他說：“對人類而言,，并沒有足夠的生物生產(chǎn)力可以讓我們用生物燃料來解決21世紀(jì)的能源挑戰(zhàn),。”（援引科學(xué)網(wǎng)）
英文原文：
News
July 02, 2007
Humans Gobble One Quarter of Food Chain's Foundation
In some areas of the world, up to 63 percent of all the energy produced by plants—energy that would normally fuel native ecosystems—has been pressed into service for humankind
By David Biello
The original farmer probably did not have an outsized impact on the world. Scattering some seeds, guarding them and perhaps clearing a few other species of plants, this proto-agrarian would have been the first to harness the power of photosynthesis for humanitys benefit. Now, thousands of years later, modern agrarians—along with engineers, foresters and consumers—directly control 23.8 percent of all the world's photosynthesis, according to a new analysis.
SELFISH SPECIES?: Humans have appropriated nearly 25 percent of the energy created by photosynthesis in plants, according to a new report.
Using Food and Agriculture Organization statistics through the year 2000 on areas farmed, crops harvested and animals grazed—as well as models of the photosynthetic production of vegetation worldwide and global data on forested areas—ecologist Helmut Haberl of Klagenfurt University in Austria and his colleagues calculated the difference between the energy produced by plants in the absence of humans and the actual amount of photosynthetic energy available to ecosystems after humans have taken their share.
"We found that, due to human activities, in particular past and present land use, 23.8 percent less [photosynthetic energy] remains currently in ecosystems than would be available without human activities," Haberl says.
This affects everything from the diversity of life on Earth to desertification. More than half of the human share of photosynthetic energy comes from farming, but other forms of land use contribute 40 percent and human-caused forest fires a full 7 percent.
And the burden is not evenly spread. The human share, for example, is as high as 63 percent in southern Asia and as low as 11 percent in central Asia and Russia. Technologies such as industrial fertilizers have helped to lower the human burden by increasing harvests while limiting land area, but this increasing agricultural output has been confined to certain regions of the globe, Haberl notes.
HUMAN IMPACT: Humanity's share of worldwide photosynthetic production is not evenly distributed as shown in this map. Click on the image for a larger version.
As the human population continues to rise in coming years, Haberl and his colleagues expect the human share to eat up more and more of the available biomass."On a global scale, our preliminary—so far unpublished—results strongly indicate, in any case, that [the human share] is on the rise and has been so [for] the past 300 years," Haberl says.
And that share could rise explosively should a shift to biofuels occur on a broad scale. Such a shift might result in a doubling of crops harvested in coming decades, Haberl adds, "something that could have massive impacts on ecosystems, above all their resilience and biodiversity" as energy is shifted from feeding animals to fueling cars. Already Haberl has shown in other papers how land-use changes on a local scale undercut the complex web of life in Austria—from breeding bird species to crickets to the plants themselves—and endangered its ability to thrive.
That relationship will be explored in the much larger North and South American context next, Haberl says. Nevertheless, it is already clear that "a remarkable share of global [photosynthetic production] is used to satisfy the needs and wants of just one species on earth," as the researchers write in Proceedings of the National Academy of Sciences USA
原始出處：
PNAS, Proceedings of the National Academy of Sciences of the United States of America
"Quantifying and mapping the human appropriation of net primary production in the Earth's terrestrial ecosystems"
Helmut Haberl, K. Heinz Erb, Fridolin Krausmann, Veronika Gaube, Alberte Bondeau, Christoph Plutzar, Simone Gingrich, Wolfgang Lucht, Marina Fischer-Kowalski
http://www.pnas.org/
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