Plants treated with diverse species of fungi that live on roots grew larger flowers, prompting bees to visit them more often and spend more time there.
“[These fungi] might not only have benefits for the plant itself, or for the soil, but also for the pollinators,” says Aidee Guzman at Stanford University in California.
Guzman and her colleagues grew squash plants (Cucurbita pepo) inoculated with four combinations of different species of mycorrhizal fungi. These fungi live on…
The northern pocket gopher (Thomomys talpoides) brings unexpected ecosystem benefits
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Two years after Mount St Helens erupted in 1980, a team of researchers helicoptered in a gopher to the ash-covered landscape. Decades later, the activity of that single gopher burrowing for a single day may have helped the decimated ecosystem regrow by boosting the diversity of soil fungi.
“There’s something to be said about learning lessons from the gophers,” says Mia Maltz at the University of Connecticut, who has used the eruption to understand how forests might recover from other stresses – including wildfires and…
Fibres from wet wipes can get into fertilisers if they are flushed down the toilet
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Natural fibres that are increasingly being used in wet wipes may actually do more harm to the environment than the synthetic ones they are designed to replace.
Viscose and lyocell, which are made from cellulose in wood, are commonly used in wet wipes and clothing in place of fibres such as polyester, which is primarily a byproduct of fossil fuels.
“They are in high street stores, so you can pick them up in your ethical conscience consumer section of fast fashion stores,” says Winnie Courtene-Jones at Bangor University in the UK.
But there is uncertainty about whether they are really better than the materials they replace. “There’s a bit of a knee-jerk reaction to move away from fossil fuel-based traditional, conventional plastics and substitute those with alternatives, and there hasn’t been much testing of those other materials,” says Courtene-Jones.
To learn more, she and her colleagues tested the impact of viscose, lyocell and polyester on soil and some of the animals that live in it. Wet wipes often make their way into wastewater treatment plants, along with microfibres that come off clothes in washing machines. They are then inadvertently spread on soil via the sludge from these plants that is used as fertiliser.
The team exposed a type of earthworm (Eisenia fetida) to different concentrations of viscose, lyocell and polyester in soil. Around 30 per cent of those exposed to high levels of polyester died after 72 hours – compared with nearly 60 per cent of those exposed to lyocell and 80 per cent of those exposed to viscose.
When the researchers tested lower concentrations that more commonly occur in the real world, they found that the worms exposed to viscose or lyocell reproduced less than those exposed to polyester. Why this occurs is unclear, but any fibrous material could be toxic to earthworms, regardless of its make up.
“Bio-based fibres may [be] better at production time, because they’re not based on fossil fuels, but there’s no clear vision on whether they’re better at degradation time,” says Caroline Gauchotte-Lindsay at the University of Glasgow in the UK. “They have a place, because we still need to replace the fossil fuel industry, but it’s important to know the message isn’t that they’re better once they’re in the environment.”
A bacteriophage virus can kill microbes, influencing what happens to the carbon their bodies contain
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Viruses that infect other microbes may influence the movement of more than a billion tonnes of carbon in soil, according to the first attempt at quantifying their role in one of the planet’s main carbon stores.
“While there are still gaps, we’re understanding that viruses can have a huge impact on soil carbon,” says Kirsten Hofmockel at Pacific Northwest National Laboratory in Washington state.
Climate change is raising winter temperatures faster than those of summer, especially in high-altitude areas. This “asymmetric” warming could spell trouble for the vast amount of carbon stored in soils there by altering microbial activity more than expected.
The planet’s soils store more carbon than any ecosystem other than the oceans, and could store much more if better managed. But soil carbon is threatened by climate change. Researchers expect warmer temperatures will boost the amount of soil carbon lost to the atmosphere as greenhouse gases, largely due to changes in the behaviour of soil microbes. However, the scale of this warming feedback remains uncertain.
Ning Ling at Lanzhou University in China and his colleagues heated soils in an experimental grassland on the Tibetan plateau to test how different patterns of warming might change microbial activity. Some of the soils were kept at ambient temperatures, while others were exposed to a “symmetric” warming of 2°C throughout the year. A third group was exposed to warming of 2.5 to 2.8°C during winter and 0.5 to 0.8°C during the rest of the year, a more realistic simulation of actual warming patterns.
After a decade of this treatment between 2011 and 2020, the researchers tested microbial activity of samples from the different soils. They focused on two measures in particular: growth rate and an indicator of how the organisms are using carbon, known as carbon use efficiency. This has been shown to be a major determinant of the amount of organic carbon stored in soils.
“When a microbe eats carbon, it can do one of two things with it: it can break it down for energy and breathe that carbon as CO2, or it can use it to make new body structures,” says Daniel Rath at the Natural Resources Defense Council, an environmental non-profit organisation based in New York. A higher growth rate means microbes are using more carbon, and higher carbon use efficiency means more of that carbon is being made into body structures, rather than respired as CO2, he says.
Ling and his colleagues found both warming patterns substantially reduced microbial activity. Soils under symmetric warming saw growth rate decline 31 per cent and carbon use efficiency decline 22 per cent relative to soil exposed to ambient temperatures. Under asymmetric warming, this effect was even stronger, with growth rate lowered by 58 per cent and carbon use efficiency lowered by 81 per cent relative to soils exposed to ambient temperatures. They ascribed the differences to factors including a change in the nutrients available to the microbes.
“Their findings suggest that soil carbon storage likely will decrease, reducing the capacity of terrestrial ecosystems to sequester carbon and degrading the soil’s efficacy for nature-based solutions to climate change,” says Yiqi Luo at Cornell University in New York.
Rath says the fact that current models don’t take asymmetric warming into account means we are probably underestimating soil carbon losses due to climate change. However, he says the findings may only apply to soils from frigid ecosystems, and more research is needed to understand exactly what these changes in microbial activity mean for carbon. For instance, despite the significant change in microbial activity, the total amount of carbon stored in the soil didn’t change over the course of the experiment.
