A Helpful Fungus Targets an Invasive Plant in the UK

Scientists in the United Kingdom have discovered a new species of fungus that kills a harmful invasive plant. This finding gives researchers hope that damaged natural habitats might one day be restored. The fungus targets the heath-star moss. This moss is aggressive and has been damaging the UK’s environment by pushing out native species.

Experts say this discovery represents a rare moment where the British environment is fighting back against invasive species. While fungi are often seen as harmful, this particular fungus is acting as a helper to the ecosystem.

The discovery was made by Dr. George Greiff. He is a thirty-year-old researcher. Four years ago, he was walking on the Isle of Wight. He noticed that the invasive moss on a cliffside was dead. He collected samples but could not immediately identify what killed the plant. However, he continued to see more cases of decaying moss in similar areas.

He worked with other scientists in the UK and France to solve the mystery. They identified the cause as a potent fungus that had never been seen by scientists before. They have named it "moss die-back." While people often view fungi as bad, this one is considered a "goodie." Its target, the heath-star moss, is widespread across Britain. It grows on hillsides, sand dunes, and even in pavement cracks. Dr. Greiff describes it as aggressive. He admits it looks pretty, but notes that it has caused many problems.

About two thousand non-native plants and animals have been brought to Britain from around the world. This happened either by accident or on purpose. Some of these species end up dominating the local environment. A famous example is the North American grey squirrel. This animal has nearly wiped out the native red squirrel population. In the plant world, invasive Japanese knotweed damages homes. Rhododendron leaves toxins in the soil. These are significant issues for the landscape.

Not much was known about the heath-star moss before this discovery. Scientists believe it arrived in Britain in the 1940s. It likely came from somewhere in the southern hemisphere. By 1990, it had spread everywhere. Dr. Greiff explains that the moss population had exploded. In the 1930s, native mosses would have been growing in these areas instead.

There are more than one thousand types of moss in the UK. They form the backbone of precious habitats. These include rare temperate rainforests and peatlands that store carbon. However, native mosses are threatened by non-native plants. The heath-star moss spreads spores far and wide. It reproduces quickly, making it a very successful invader. Dr. Greiff, who works at Amgueddfa Cymru museum in Cardiff, recalls his first encounter with the moss. He did not know what it was at the time and threw it in the bin.

In heathlands, such as the one where the fungus was found, native mosses have gone locally extinct or their populations have dropped significantly. Dr. Greiff is skilled at careful observation. He looks closely at plants that are not very tall. Just a few meters into a walk, he finds evidence of the fungus. He points out a brown ring of dead moss. It is about the size of his hand. The scene is not dramatic at first glance. But when viewed through a macro lens, white blobs are visible. These are suspended on the tips of the moss. The fungus is at work.

Dr. Greiff points out young heather plants nearby. These native plants are now able to grow in the gaps left by the dying moss. Now that Dr. Greiff knows what the helpful fungus does, he looks for it everywhere. He jokes that the map of where the fungus has been found is also a map of his holiday destinations.

He explains that it took a lot of DNA sequencing to fully identify the fungus. In the lab, he shows the dead moss under a microscope. The fungus clings to the moss stem. It balloons out like candy floss around a stick. It has even penetrated some of the moss cells. He has determined that the fungus is a close relative of the ash die-back fungus. That other fungus has killed up to eighty million ash trees in Britain.

A powerful fungus that destroys plants sounds like a threat to biodiversity. However, Dr. Greiff’s analysis suggests it only affects the heath-star moss. It may also affect one other type of moss to a limited extent. More work is needed to confirm these findings. He believes the fungus may have originated from a native species. Over time, that native species may have adapted to kill the heath-star moss. This could be a rare example of the British environment fighting back.

Usually, invasive species are targeted by humans. For example, there are projects to give contraceptives to grey squirrels to control their numbers. Dr. Greiff says that trying to manually collect the moss is not very effective. It is expensive and requires many resources. Having a natural biological control agent doing the work is very valuable.

In cabinet drawers, the museum holds the oldest collection of mosses in the UK. Dr. Nathan Smith, the Head of Plant and Earth Science, shows dried mosses in paper envelopes. Some samples date back to the 1880s. Scientists want to look for evidence of the moss die-back fungus on these historical samples. This will help them pinpoint exactly how and when the fungus appeared.

Dr. Smith explains that the fungus offers a chance to save unique moss landscapes. These areas are homes for insects, fungi, mollusks, and other plants. It provides a real opportunity to preserve their uniqueness and beauty. Mosses are just one part of Britain’s complex biodiversity. Nature in Britain is among the most depleted in the world. One in six species is at risk of extinction. Discovering a way to control habitat destruction is a cause for hope. Dr. Greiff finds the discovery exciting. He wishes more people would help look for the fungus.