Rainforests, it turns out, are not created equal. Take the Amazon rainforest, an area that covers about 7 million square kilometers. But within that huge expanse are all kinds of ecological zones, and some of these zones, says Greg Asner, are a lot more crowded than others.

    “Some forests have many species of trees,” he said, “others have few. Many forests are unique from others in terms of their overall species composition…” And all of these different small areas of forest exist within the giant space that is the Amazon Rainforest.

    So Asner, using the signature technique called airborne laser-guided imaging spectroscopy, began to map these different zones from the air. “By mapping the traits of tropical forests from above,” he explains, “we are, for the first time, able to understand how forest composition varies geographically.”

    The results show up in multicolored maps, with each color representing different kinds of species, different kinds of trees, the different kinds of chemical they are producing and using, and even the amount of biodiversity, the animal and plant species that live within each zone.

    Armed with this information, Asner says decision-makers now have “a first-time way to decide whether any given forest geography is protected well enough or not. If not, then new protections can be put in place to save a given forest from destruction.”

    Asner says the information is a great way for decision-makers to develop a “cost-benefit ratio type analysis.”  Conservation efforts can be expensive, so armed with this information, government leaders can ensure they are making the most of their conservation dollars by focusing on areas that are the most biologically diverse or unique.

    The next step, Asner says, is to take his project global, and to put his eyes even higher in the sky, on orbital satellites. “The technique we developed and applied to map Peru is ready to go global.” Asner said. “We want to put the required instrumentation on an Earth-orbiting satellite, to map the planet every month, which will give the best possible view of how the world's biodiversity is changing, and where to put much needed protections.

材料一：城市和人一样，也有完整的生命历史。从其诞生至今，城市与自然环境和人文环境相互融合。一代代人创造了它之后纷纷离去，却将此转化为一条条老街道、一座座名胜古迹，还有民间手艺、历史人物等等，全都默默地记忆在它巨大的肌体里。城市文脉是一座城市的气质和精神，文物建筑是承载这种气质和精神的物质载体；如果城市文脉断裂，城市的风采、特色和精气神也将因此暗淡。

如何才能延续城市的历史文脉？学者给出的答案很简单：“尊重历史，尊重先人的智慧，尊重先人留下来的文化遗产。”

材料二：延续城市历史文脉，保护好前人留下的文化遗产，2017年9月17日，在桂林独秀峰·王城景区举行面向全球招募桂林历史文化的双语讲解志愿者启动仪式活动。希望通过发动所有热爱桂林历史文化的中外专家、大学生、市民一起为桂林历史文化传播做贡献。

这样的活动将有利于桂林的人文精神扎根在深厚的历史文化土壤中，桂林人应该为自己的文化感到骄傲自豪，更是从正能量方面树立和提升桂林人的文化自信，树立主人翁精神，捍卫自己的文化。正如桂林市市长周家斌提出，桂林要保护好珍贵的历史文物，将它与旅游结合起来，把历史文化的精髓传承下去，发扬光大。