The world’s forests are under threat. As well as being logged for timber and cleared to make way for agriculture, rising global temperatures are causing more intense wildfires. Re-forestation is essential in the fight against climate change and to protect biodiversity, but planting saplings by hand can be slow and labor-intensive. In recent years, drones have begun to be used to drop seeds onto land deforested by wildfires; a company called Mast Reforestation, formerly DroneSeed, has applied this method in the western United States and beyond, and World Wildlife Fund has used specialized drones to restore rural bushland in Australia. But for a forest to regrow, dropped seeds have to get into the soil and germinate, and that can be a challenge. Researchers from Morphing Matter Lab at Carnegie Mellon University, in Pennsylvania, might have an answer. Inspired by nature’s own design, the lab has created an “E-seed” carrier that is intended to be dropped by drones and drill into the soil. But remarkably, the carrier doesn’t need an energy source to drill into the ground — it’s made from a material that “self-drills” in response to rain. Lab director Yao Lining and her colleagues looked at erodium seeds for inspiration. The seeds of this genus of plants have a coil-like “drill” that changes shape when wet, using a “tail” to prop itself up and push more effectively into the ground. The team created a seed carrier based on the same principle, made from white oak wood that naturally responds to changes in humidity. They chemically treated the wood to make it more flexible when wet, as well as softer and denser so it expands more effectively. Erodium has a single tail, but the seed carrier has three, making it easier to drill into soil. According to research Yao published in the journal Nature, the carrier has an “80% drilling success rate on flat land,” making it more effective than erodium seeds in the same conditions. After the carrier burrows, the seed is protected from animals and the natural elements, improving its chances of germination. So far, Morphing Matter has only tested the seed carriers at sites in Pittsburgh and Changxing, China, but Yao says the lab has received interest from venture capitalists and government agencies around the world wanting to use the seed carriers in reforestation projects. But she notes that specific types of seed carriers must be developed for different locations, to accommodate different soils and humidity levels, amongst other variants. “We have to tailor the design to local conditions and the seeds of their interest,” explains Yao.(SD-Agencies) Words to Learn 相關詞匯 【砍伐森林】kǎnfá sēnlín deforest cut down or destroy trees in an area 【屬】shǔ genus biological classification ranking between family and species 除了伐木和開荒種地，全球變暖還引發更猛烈的山火，這些因素都威脅著世界上的森林。 應對氣候變化和保護生物多樣性，植樹造林至關重要，但人工植樹費時又費力。 近年來，人們開始使用無人機將種子撒到野火毀林的空地上；一家名為 “桅桿造林”（前身為“無人種子”）的公司已經在美國西部以及其他地區有過類似嘗試，世界野生動物基金會也曾使用無人機來恢復澳大利亞鄉村燒毀的林地。但是，要讓森林重新生長，播撒的種子必須鉆進土里發芽，這并不容易。 賓夕法尼亞州卡內基梅隆大學變形物質實驗室的研究人員給出了可能的答案。受大自然的啟發，該實驗室設計了一種基于橡木吸濕性的機器人（以下簡稱E-seed），由無人機投放，能自行鉆入土壤。令人稱奇的是，E-seed不需要動力就能鉆入地下，因為特別的材料在雨水作用下能“自主鉆孔”。 實驗室主任姚力寧和她的同事從牻牛兒種子中找到了靈感。這種植物的種子有一個線圈狀的 “鉆頭”，遇濕會改變形狀，用 “尾巴”把自己撐起來，更有效地鉆入地下。研究小組基于同樣的原理設計了一個種子載體，由白橡木制成。他們對木材進行了化學處理，使其遇濕時延展性更好，更柔軟、致密，能更有效地膨脹。牻牛兒只有一條尾巴，而E-seed有三條尾巴，更容易鉆入土壤。 姚力寧在《自然》雜志上發表的研究報告稱， E-seed“在平地上的鉆孔成功率高達 80%”，在相同條件下，它比牻牛兒種子更高效。鉆入地下后，種子受到保護，不會受動物和外界環境的影響，提高了發芽率。 到目前為止，變形物質實驗室只在匹茲堡和中國長興縣的一些地方對E-seed進行了測試，但姚力寧說，世界各地風投和政府機構都表示對項目感興趣，希望在植樹造林時使用種子載體。 她指出，不同地點使用的E-seed必須量身定制，以適應不同的土壤類型和大氣濕度，也要考慮其他變量。 她解釋說：“我們必須根據當地條件和對方感興趣的種子類型進行設計。” (Translated by Debra) | 