Among the many ecological disasters that terrify us today, one that only a handful of people have considered as sufficiently terrifying is the loss of the bats in our church tower. According to “The Darkness Manifesto” (Scribner), by the Swedish ecologist Johan Eklf, most churches in southwest Sweden had bat colonies back in the nineteen-eighties, and now most of them don’t.

Light pollution, his research suggests, has been a major reason: “District after district has installed modern floodlights to show the architecture it’s proud of, all the while the animals-who have for centuries found safety in the darkness of the church towers and who have for 70 million years made the night their home-are slowly but surely vanishing from these places.”

The difference between light and dark is, in a way, arbitrary: what counts as light and what as darkness depends on what wavelengths we can make out. But the nocturnal (夜间活动的) world gives rise to creatures, equipped with large-pupilled and infrared-sensitive eyes, that see what we cannot and that, under cover of darkness, act as we can only imagine.

We learn, for instance, of the ghost moths, a species in which the adult males appear in fields in twilight, floating weirdly as they signal to the females-only to mate once and then fall to the ground dead. Though Eklf tells us that these creatures are threatened by the confusing presence of artificial light and that moths play a crucial role as pollinators (“something of invaluable importance for keeping our ecosystem undamaged and thriving”), what one recalls is the sad fate of their couplings.

Nor are bugs and birds alone affected by the light; so are plants, and so are humans. Our eyes adapt badly to darkness, and our night vision-which is activated by the pigment protein rhodopsin (视紫红质)-takes a long while to turn on. By now, cities such as Singapore and Hong Kong are so brightly lit that their inhabitants scarcely call on night vision at all, and, as their rhodopsin becomes unnecessary, they may well create people in later generations who, in even middling darkness, are as blind as bats.

Suzanne Simard, a professor of forest ecology who called herself a “forest detective”, was raised in mountains in Canada. Few scientists make much impact with their PhD thesis, but, in 1997, she did just that. Her research on the “wood wide web” made the cover of Nature and transformed our understanding of forests. What was then a challenge to traditional ideas is today widely accepted.

A mushroom is the part of a fungus (真菌) that sticks up above the ground. Thin, white threads grow from its stem deep into the soil. These threads are called hyphae (菌丝). Hyphae connect themselves to tree roots. They also stretch from root system to root system, like an underground network. This network may go for miles. Hyphae pick up nutrients and water from soil. The fungus threads that connect to tree roots share their nutrients and water with the trees. In return, they sip a bit of the sugar the trees make. Sharing helps both trees and mushrooms live. It’s also how trees communicate.

When a tree is being eaten by bugs, it makes chemicals to shoo them away, sort of like bug repellent (驱虫剂). The chemicals travel through the tree, down its roots, and into the hyphae network. Other trees connected to the network taste the chemicals. That tells them a nearby tree is under attack, so they start to make their own bug repellent. Trees do more than share warnings through the hyphae. They also help each other. In the fall, paper birch trees drop their leaves and can no longer make sugar. So, a fir tree that stays green all winter uses the network to send extra sugar to the birch until spring comes again. This system of sharing information and nutrients through the hyphae is sometimes called the “wood wide web”, because it works a bit like the Internet.

Local climate sets the stage for the wood wide web, researchers say. In cool temperature and boreal forests, where wood and organic matter decay slowly, network-building EM fungi rule. By contrast, in the warmer tropics where wood and organic matter decay quickly, AM fungi dominate. These fungi form smaller webs and do less intertree swapping, meaning the tropical wood wide web is likely more localized.

Ecologist Thomas Crowther’s results suggest that as the planet warms, about 10% of EM-associated trees could be replaced by AM-associated trees. Microbes in forests dominated by AM fungi deal with carbon-containing organic matter faster, so they could liberate lots of heat-trapping carbon dioxide quickly, potentially accelerating a climate change process that is already happening at a frightening pace.

A “superhero” moss can significantly reduce the risk and severity of flooding for communities living in downstream areas, researchers have found. Scientists from the conservation group Moors for the Future Partnership who conducted a six-year study into sphagnum moss (泥炭藓) found that planting it in upland areas could dramatically slow the rate at which water runs off the hillsides, preventing river catchments (集水处) being overwhelmed with water downstream.

The research found that the sphagnum moss reduced peak streamflow — the maximum amount of water that enters a river after a storm — by 65%. The moss was also found to increase lag time — the time taken between rainfall and the rainwater entering the river system — by 680%.

More than 50,000 individual sphagnum plants–which are about the size of a 5 0p coin — were planted on Kinder Scout, the highest point in the Peak District national park, as part of an “outdoor laboratory” for researchers to observe.

Before the moss was planted on Kinder, the hill surface consisted of bare peat, which meant that after a storm rainwater would wash straight off, leaving communities in downstream valleys more vulnerable to flooding.

The planting of sphagnum moss could therefore bring important ecological benefits. The plant is capable of absorbing up to 20 times its own weight in water, which means that more rainwater can be held upstream and enter a river catchment more gradually to prevent it from being overwhelmed. Sphagnum moss can also help protect the layers of peat underneath it, and can accumulate over time to create new layers of peat which are essential to carbon storage.

Tom Spencer, a research and monitoring officer for the Moors for the Future Partnership hailed the dramatic effects the moss has had on the river catchment. He said sphagnum planting could be “a powerful tool in minimising the risk and severity of flooding”, which would have “far-reaching benefits for communities downstream”.