Huge, age-old trees are of vital（至关重要的） importance for our ecosystem. They help to sustain（支撑） life on Earth. My lifelong（终身的） goal is to save big trees. They are probably the most important bar of gold on the planet. But all over the world, those big trees are under threat（威胁）. It's high time we begin saving the last remaining giants of our forests.

  The Amazon has been called South America's river of life. For a special group of visitors, it's their passageway（过道） deep into the Peruvian（秘鲁人(的)） rainforest. Meg Lauman has pioneered（拓荒者） research into forest canopies（天篷）. She's taking the amateur（业余的） researchers on an expedition to see the largest trees of the rainforest. And they're only reachable（可达成的） by water. Why, why, why did any of you come here?

  And why should you look at the Amazon? You know, truly（真实地）, this ecosystem keeps all of us alive. This Amazon is also called the Lungs of the Planet. It's the highest diversity（差异） in the world here. The American biologist（生物学家） has dedicated her life to studying the huge trees here that are hundreds of years old. They help purify the air, safeguard biodiversity（生物多样性）, and stabilize（使稳固） our climate.

  But they're in grave（严重的） danger from global warming and deforestation（砍伐森林）. New ideas are needed to protect these giants and their unique（唯一的） habitats（(动植物的)生活环境）. Meg Lauman has a clear objective（目的） to preserve（保护） the trees and make their unique（唯一的） canopy（天篷） accessible to others, including eco-tourists. Okay（好）, so follow Willie, everybody, that's ready. You go ahead and find us a sacropia tree. Ding, ding, ding, ding.

  Oh, listen. There go parrots. A whole flock of parrots. They're welcoming you. During her expeditions, tourists become researchers. They begin their study on the ground, before later taking to the treetops（树稍）.

  Together, the group examines the condition of the trees and their leaves（许可） and records the insects they find. Okay, I'm coming to answer any questions. Having extra pairs of eyes is useful for picking up all that's going on in this vibrant（ 振动的） world. Amateur researchers often notice things that a more experienced scientist might not bother with, which is why citizen（公民） science is becoming increasingly（日益） important in research. It's a tarantula hole, so I'm going to respect its space. Frank（免费邮寄特权） Laumann is considered a pioneer（拓荒者） in researching treetops（树稍）.

  In the late 1970s, she discovered a world previously unknown（未知的） to science, 35 meters above the ground. She coined the term "Arbonaut" for a biologist who explores the forest canopy. I'm just a girl from a small town. I didn't have any scientist friends, and my parents were teachers. And I sort of, I don't know, I liked nature and I went to nature, but when I finally kept studying trees, I realized everybody always studied the bottom. The only time they saw the top of the tree is if they cut it down.

  I called it sort of like if you went to the doctor and he looked at your big toe and said, you know, your brain's okay, your hearing（ 听力）'s fine, your eyesight's great. You would say, this is crazy because it's only the bottom of my whole body. So she made her way to the very top to study the canopy of these forest giants. In the process, entering a world that no researcher before her had ever seen. Then I got to the full canopy and it was like full of life. Because so many species live up there, probably 50 percent of what lives on planet Earth, I and a few others started calling it the eighth continent.

  She discovered a complex ecosystem high up in the trees where there is still a wealth（ 财富） of species that have yet to be studied. Back to the present. Eight-year-old Holden is busy discovering life on the forest floor. Leslie Johnson was keen to show her son more of the world. We live in a city and it's really important to us that he get in touch with nature. And this sounded like such a great adventure and to go with a real science, a world class scientist.

  One visitor, Alex Smith, is a biologist. So for him, the trip is also interesting from a professional viewpoint（观点）. A lot more new leaves are in the canopy, so that's the place to be. Because here there's fewer things at night here. I guess my expectations（期待） are kind of high based off what Meg has told us, like calling it the eighth continent. This is just like the real deal.

  But this ecosystem is under threat. Over the past 30 years, well over 400,000 square kilometers or forest have been cleared throughout the Amazon region. That's an area roughly（粗糙地） the size of Germany and Denmark（丹麦） combined. In my lifetime（一生）, over half of the world's primary forests have been cut down. It's a terrible track record for me and my scientific colleagues. So we need to do things differently.

  It's kind of why I'm branching out on a limb（肢）, so to speak, to go into the world of canopy walkways instead of just pure（纯粹的） research. By having special walkways built, Meg Laumann makes canopy areas accessible（易接近的） to everyone, with rope bridges connecting large old trees. They've become places of research and education, and the tour group is about to visit this one at a height of over 35 meters. Humanity（人性） was once also rich in primeval（原始的） forest. Remnants（残余） still existed into the Middle Ages. Today, commercial forests with fast-growing conifers（[植]松类） dominate（控制） the landscape（风景）.

  The Kennavat Idazi National（国民） Park is home to one of Europe's few untouched（ 未触动过的） primeval（原始的） forests. They now cover just 0.2 percent of Europe's land surface. Forest ecologist（生态学者） Pia Ivish and startup founder（铸工） Anzem Schneider want to safeguard（维护） what's left. They understand the value of these big old trees. So the surface temperature is 18.8 degrees, which is interesting. The air temperature towards the light is 23.2 degrees, so we have 5 degrees less here.

  Yeah, I would have guessed that by the feel（感觉） of this. Trees consist of 50 percent water and help cool the forest. They also absorb（吸收） CO2 and release oxygen. The bigger the tree gets, the more CO2 it can store. Up to half of the carbon（碳） that a tree can sequester（使隔绝） is absorbed（吸收） in the last quarter of its life. These old trees are invaluable（无价的） to a forest ecosystem.

  That makes it all the sadder that you only find them now in national parks or small-scale（刻度） reserves（储备(物)）. And that's because foresters（林务官） tend to say, "If a tree is 120 or 150 years old, it's time for it to go." Pia Ivish and Anzem Schneider are fighting for forests to be allowed to grow old again. After the Second World War, large areas of Germany were reforested with conifers. But these monocultures can't withstand（抵挡） climate change. Drought（干旱）, forest fires, pests and the timber（木材） industry are decimating their populations.