December 9,2020 (News from Science)
There’s an ecosystem beneath your feet—and it needs protection, new report says
一份新的報告稱，你腳下有一個需要保護的生態系統
Reach down and scoop up some soil. Cupped in your hands may be 5000 different kinds of creatures—and as many individual cells as there are humans on the globe. That random handful might hold microscopic fungi, decomposing plant matter, a whisker-size nematode munching on the fungi, and a predatory, pinhead-size mite about to pounce on the nematode. One bacterium may fend off another with a potent antibiotic. It’s a whole world of often overlooked biodiversity.
伸手去挖一些土。在你的手中可能有5000種不同的生物——和地球上人類的數量一樣多的個體細胞。這一小撮隨機的細菌中可能有微小的真菌，正在分解的植物物質，一隻鬍鬚般大小的線蟲正在咀嚼這些真菌，而一隻針尖大小的掠食性蟎正準備撲向這些線蟲。一種細菌可以用強效抗生素來抵禦另一種細菌。這是一個經常被忽視的生物多樣性的世界。
Today, on the eve of World Soil Day, the Food and Agriculture Organization of the United Nations has released its first ever global assessment of the biodiversity in this underground world. Some 300 experts have pooled their knowledge and data to describe the diversity of these organisms, the roles they play in both natural and agricultural environments, and the threats they face.
今天，在世界土壤日的前夕，聯合國糧食及農業組織首次發布了對這個地下世界生物多樣性的全球評估。大約300名專家匯集了他們的知識和數據，描述了這些多樣性的生物在自然環境和農業環境中扮演的角色，以及它們面臨的威脅。
「The organisms below ground are arguably just as important, if not more important, than what’s above ground,」 says Noah Fierer, a soil ecologist at the University of Colorado, Boulder, who did not contribute to the report. The report details how they boost crop growth and purify soil and water. Together with plant root systems, these organisms store more carbon, potentially for longer, than the aboveground parts of trees do. 「Depending on how we handle soil, it could become a help or a burden to face the crisis of biodiversity or climate change,」 says Francisco Pugnaire, a soil and plant ecologist at the Spanish National Research Council’s Experimental Station of Arid Zones.
科羅拉多大學博爾德分校的土壤生態學家諾亞·菲勒爾(Noah Fierer)說:「地下的生物可以說與地面上的生物同等重要。」他沒有參與該報告的撰寫。該報告詳細介紹了它們如何促進作物生長和淨化土壤和水。和植物的根系一起，這些有機體比樹木的地上部分儲存更多的碳，可能儲存的時間更長。西班牙國家研究委員會幹旱地區實驗站的土壤和植物生態學家Francisco Pugnaire說:「這取決於我們如何處理土壤，它可能成為面對生物多樣性或氣候變化危機的一種幫助，也可能成為一種負擔。」
Yet with each pass of the bulldozer or tractor, each forest fire, each oil spill, even the constant traffic of hikers along a popular trail, more and more soil organisms are being killed off. By compiling research on these subterranean ecosystems and how they affect visible ones, the report’s authors hope to convince scientists, policymakers, and the general public to take steps to slow this loss.
然而，每當推土機或者拖拉機、每個森林大火或者石油洩漏,甚至徒步旅行者沿著流行的旅遊路線來回走，越來越多的土壤生物被殺死。通過編譯這些地下生態系統以及它們是如何影響的研究，可見該報告的作者希望說服科學家、決策者和公眾採取措施減緩這種損失。
「You just can’t have a Mars-like soil and expect to maintain the food supply and forests,」 warns Diana Wall, an ecologist at Colorado State University who contributed to the report. Current conservation efforts are not helping much, she adds. For example, soil biodiversity hot spots aren’t necessarily in the same place as the biodiversity hot spots that conservationists focus on.
科羅拉多州立大學的生態學家黛安娜·沃爾(Diana Wall)對該報告作出了貢獻，她警告說:「你不能既擁有類似火星的土壤，又指望維持食物供應和森林。」她補充說，目前的保護措施收效甚微。例如，土壤生物多樣性的焦點不一定與自然資源保護論者關注的生物多樣性熱點在同一個地方。
「We are managing [conservation] by what we see above ground, which doesn’t necessarily match what’s below ground.」 In contrast, Fierer says, 「If you preserve the soil, you will likely preserve the whole ecosystem.」
「我們是根據我們在地面上看到的東西來管理[保護]的，這和我們在地下看到的東西不一定匹配。相比之下，菲爾勒說，「如果你保護了土壤，你就可能保護了整個生態系統。」
Soil is a mix of organic material, minerals, gases, and other components that provide the substrate for plants to grow. About 40% of all animals find food, shelter, or refuge in soil during part of their life cycle.
土壤是有機物質、礦物質、氣體和其他為植物生長提供基質的成分的混合物。大約40%的動物在其生命周期的一部分時間裡在土壤中尋找食物、庇護所或庇護。
Scientists have mostly focused on the largest and smallest soil creatures. For centuries, natural historians have observed ants, termites, and even earthworms and moles that chew, wiggle, and dig their way among soil’s particles, some feasting on decaying leaves and other debris and some feasting on each other. Those ecosystem engineers aerate the soil and create underground passageways that make soil more amenable for other life. And over the past several decades, microbiologists sequencing soil DNA have discovered an astonishing diversity of bacteria and fungi, which process that litter into organic material.
科學家們主要關注最大和最小的土壤生物。幾個世紀以來，自然歷史學家觀察到螞蟻、白蟻，甚至蚯蚓和鼴鼠，它們咀嚼、扭動，並在土壤顆粒中挖出自己的道路，一些以腐爛的樹葉和其他碎片為食，還有一些以彼此為食。這些生態系統的「工程師」給土壤充氣，並創造地下通道，使土壤更適合其他生物生存。在過去的幾十年裡，微生物學家對土壤DNA進行測序，發現了種類驚人的細菌和真菌，它們可以把垃圾處理成有機物質。
But in between the scales of macroscopic animals and microbes lie thousands of long-overlooked tiny creatures—the micro- and meso-fauna. Microscopic protists, nematodes, and tardigrades inhabit the watery films surrounding soil particles. Slightly larger animals up to 2 millimeters in size, such as mites, springtails, and insect larvae, live in the airy pores between those particles, helping make soil one of the most biologically diverse habitats on Earth. 「How little we know [about these creatures] is a bit overwhelming,」 Fierer says.
但在肉眼可見的動物和微生物之間，存在著成千上萬長期被忽視的微小生物——微型和中型動物。微觀原生生物、線蟲和緩步蟲棲息在土壤顆粒周圍的水膜中。稍大一些的動物，如蟎蟲、跳蟲和昆蟲幼蟲，大小可達2毫米，它們生活在這些顆粒之間的通風孔洞中，這有助於使土壤成為地球上生物最多樣化的棲息地之一。「我們(對這些生物)的了解太少了，這有點讓人難以承受，」菲勒說。
This diversity creates a rich, complex ecosystem that boosts crop growth, breaks down pollutants, and can serve as a nearly inexhaustible sink for carbon. Some soil organisms promote plant diversity and many have yielded important compounds, from antibiotics to natural pesticides. 「Without soil organisms and the activities they carry out, it would be impossible for other organisms to survive,」 says Stephen Wood, a soil ecologist at the Nature Conservancy.
這種多樣性創造了一個豐富而複雜的生態系統，促進作物生長，分解汙染物，並可以作為一個幾乎取之不盡的碳匯。一些土壤生物促進了植物多樣性，許多已經產生了重要的化合物，從抗生素到天然殺蟲劑。大自然保護協會的土壤生態學家史蒂芬·伍德說:「沒有土壤生物和它們所進行的活動，其他生物就不可能生存下來。」
Hidden below ground, these ecosystems seemed immune to aboveground disturbance, Wood says. 「For a long time, soil scientists thought that soil microorganisms were so well spread around the world that land management would not harm them,」 he explains. 「We now know that soil microorganisms can be very specific to very specific habitats and species,」 habitats that are rapidly disappearing as farms and cities expand.
伍德說，這些隱藏在地下的生態系統似乎不受地面擾動的影響。他解釋說:「很長一段時間以來，土壤科學家認為土壤微生物在世界各地廣泛傳播，土地管理不會對它們造成傷害。」「我們現在知道，土壤微生物可以針對特定的棲息地和物種，」隨著農場和城市的擴張，棲息地正在迅速消失。
The report lists a dozen human activities taking a major toll on soil organisms. They include deforestation, intense agriculture, acidification due to pollutants, salinization from improper irrigation, soil compaction, surface sealing, fire, and erosion. 「If you pave over a site, you are sealing off an entire belowground ecosystem,」 Fierer says. 「And that’s happening all over the globe.」
該報告列出了對土壤生物造成重大損失的十幾個人類活動。它們包括森林砍伐、密集的農業、汙染物導致的酸化、不適當的灌溉導致的鹽鹼化、土壤壓實、地表封閉、火災和侵蝕。「如果你在一個地點上鋪路，你就封閉了整個地下生態系統，」Fierer說。「這在全球都在發生。」
A few governments and companies are making some progress. Several states are considering legislation that would help protect soils from destructive human activities. In China, the Agricultural Green Development program works to conserve soil by avoiding tilling and by interweaving different crops to preserve biodiversity. However, 「Most organizations want to protect soil biodiversity as a means to an end—[to] the benefit of people and/or nature,」 Wood points out.
一些政府和公司正在取得一些進展。一些州正在考慮立法，以保護土壤免受人類活動的破壞。在中國，農業綠色發展計劃(Agricultural Green Development program)通過避免耕作和交叉種植不同作物來保護土壤，以保護生物多樣性。然而，伍德指出，「大多數組織希望保護土壤生物多樣性作為一種手段，以達到人類和/或自然的利益。」
Some researchers hope the report will encourage protecting soil organisms for their own sake. 「Soil biodiversity is huge, and we must not destroy it without knowing what potential there is for improving sustainability,」 says Mary Scholes, a biogeochemist at the University of the Witwatersrand.
一些研究人員希望這份報告能夠鼓勵人們為了保護土壤中的生物而保護它們。Witwatersrand大學的生物地球化學家Mary Scholes說:「土壤生物多樣性是巨大的，在不知道提高可持續性的潛力之前，我們不能破壞它。」
Fierer thinks the new assessment will also awaken a sense of wonder. 「My hope is people will look at this document and say 『Huh, I never thought about [soil organisms] and all the things they do for me.』」
菲勒認為，新的評估也將喚醒人們的好奇感。「我希望人們看到這份文件後會說，『哈，我從沒想過(土壤生物)以及它們為我做的所有事情。』」