【推荐1】When lightning caused fires around California’s Big Basin Redwoods State Park north of Santa Cruz in August 2020, the fire spread quickly. Mild fires strike coastal redwood (红杉) forests about every decade. The giant trees resist burning thanks to the bark (树皮), up to about 30 centimetres thick at the base, which contains acids. Their branches and needles are normally beyond the reach of flames. But this time flames shot through the top of 100-metre-tall trees, burning the needles. “It was shocking,” says Drew Peltier, a tree expert at Northern Arizona University. “It really seemed like most of the trees were going to die.”

Yet many of them lived. In a paper published yesterday in Nature Plants, Peltier and his colleagues help explain why: The survivors use long-held energy reserves—sugars that had been made from sunlight decades earlier—and poured them into buds (芽) that had been lying dormant (休眠的) under the bar k for centuries.

“This is one of those papers that challenges our previous knowledge on tree growth,” says Adrian Rocha, an ecosystem ecologist at the University of Notre Dame. “It is amazing to learn that carbon taken up decades ago can be used to sustain its growth into the future.” The findings suggest redwoods have the tools to cope with big fires driven by climate change, Rocha says. Still, it’s unclear whether the trees could cope with the regular infernos that might occur under a warmer climate environment.

The fire in 2020 was so intense that even the top branches of many trees burned and their ability to photosynthesize (光合作用) went up in smoke along with their pine needles. Trees photosynthesize to create sugars and other carbohydrates (碳水化合物), which provide the energy they need to grow and repair tissue. Trees do store some of this energy, which they can call on during a drought or after a fire. Although the redwoods have sprouted (长出) new growth, Peltier and other forest experts wonder how the trees will cope with far less energy from photosynthesis, given that it will be years before they grow as many needles as they had before the fire. “They’re alive, but I would be a little concerned for them in the future.”

【推荐2】When talking of a typical mineral mine, people will probably think it's underground. It's unlikely that the picture of plants and soft greenery would cross their minds. Now, new explorations into phytomining may change that viewpoint. Instead of traditionally mining metals like nickel, iron or cobalt from rocks, phytomining uses plants as an alternative source (来源) for these minerals. Using plants to extract (提取) metals can have significant environmental benefits over rock mining.

Phytomining was first studied in 1983, but it hasn't yet been adopted by the metals industry. In 2004, Indonesian soil scientist Aiyen Tjoa from Tadulako University in Central Sulawesithe took her research to Sorowako, a small town in Indonesia with one of the largest nickel mining areas, to look into plants that continued to live after years of mining. She brought samples back to her lab and found that these super plants were more than just surviving—they were growing.

The plants were absorbing and storing nickel from the soil. Large quantities of metals kill most plants, but these, known as hyperaccumulators, were learning to adapt. If these plants were storing metals, that meant that science could find a way to extract the minerals for use and quite frankly, scientists easily did. When the shoots are harvested and burnt, the metals are separated from the plant material in the ashes.

Tjoa returned to Sorowako and spent years searching for new hyperaccumulator species. After a plant is considered a possibility, there's a simple test paper that turns pink when placed against the leaf of a hyperaccumulator plant. Two local Indonesian plants, sarcotheca celebica and knema matanensis, were found but there are many others still to be validated.

Tjoa's research caught the attention of Satria Bijasksana, a professor of rock magnetism. Together, they designed an experiment to understand magnetic susceptibility (磁化率) when plants accumulate more nickel. Their research led to the discovery of two new species of hyperaccumulators. Besides, this research serves as the basis for the potential that plants can give to the mining industry, offering great advantages to our ecosystem and towards building a more sustainable (可持续的) future.

【推荐3】You don’t have to use a dandelion (蒲公英) to know which way the wind blows. But it can help. Dandelion seeds fly freely in the wind. But those seeds on any given dandelion have different fates. Some are to float north when the wind blows them, while others are fated to fly east, south, west or some direction in between. “How do dandelion seeds respond to the wind depends on where they sit on the dandelion head?” says Jena Shields, a biophysicist at Cornell University in Ithaca.

One day, Jena happened to watch her little child play with dandelions. She noticed that the dandelion seeds didn’t all fall off the same. Some came loose more easily than others, but it depended on how the child blew on the seed heads. Jena got the inspiration for the research from it. So Jena set out to study what was going on.

She measured the force it takes to blow dandelion seeds away. To start with, she glued (粘贴) a wire to the different seeds. Then she pulled them at various angles. This seed-by-seed study mimicked what happens when the wind pushes them over.

The findings show that each seed falls off most easily in the wind from one direction, and seeds from one head don’t go the same way. The feathery seeds on the side facing the wind will fall off most easily. The others hold on more tightly until the wind shifts. Besides, once blown off a dandelion, a seed’s umbrella-like feather carries it on the wind that pulled it away. And it helps explain why the plants are so successful in spreading.

However, Jena also found an exception. A sudden strong blow was still able to blow all the seeds away in the same direction. So when a strong wind blows or excited children try their best to blow, all the seeds could be blown off at once.