An audit of fungi on lawns and meadows begins today as part of measures to assess the state of the nation’s soil.

Most people’s response to fungi is to avoid them or get rid of them but they are hailed by conservationists as an important indicator of the health of the environment.

Waxcap fungi, which come in a host of bright colours, have been selected for the survey because they are comparatively easy to see and identify.

The National Trust will from today ask visitors to its homes and gardens to record all sightings of waxcaps on its land. The reports will be analysed to identify where they are doing well and badly so that follow-up research can be carried out to find out why.

Sightings will also help to monitor annual changes in the time they appear at the surface. This year’s wet summer allowed them to appear early, giving them time to fruit again this autumn.

Over the next few decades summers are expected, on average, to be drier with more frequent droughts because of the effects of global warming.

Fungi could play a vital role in enabling plants to survive drier periods, particularly trees with which fungi have symbiotic relationships. The fungi take the sugar produced through photosynthesis and in return effectively extend the root network and provide extra water and nutrients.

While some fungi, such as honey-fungus, damage or kill plants, the majority benefit trees, grasses and flowers by helping to break down or supply nutrients. Waxcaps were described yesterday as the “jewels of grassland”, where they encourage the growth of grasses and wild flowers and help to keep the soil healthy.

The survey of waxcaps will last throughout the autumn and is intended to act as a pilot for annual counts in the future. David Bullock, head of nature conservation at the National Trust, said: “We know that fungi can give us lots of nasty diseases but the majority are benign.

“In general, we welcome fungi. Good, healthy soils have lots of fungi. That means good, healthy pastures and rich botanic numbers.

“Waxcaps seem to be particularly good in our grasslands. Some of the really rare ones are more frequent here in Britain than in the rest of Europe.”

There are more than 40 species of waxcap in Britain but they have been in decline over the last century because of loss of habitat.

They and most other fungi spend most of their lives underground, only coming out in the open when they fruit as mushrooms and toadstools.

For most of the year they process dead organic matter, such as leaves and wood, to produce nutrients that benefit trees and other plants. Mr Bullock said: “Fungi are mini recycling machines. These toadstools may be quite small, but they are enormously important to our planet. Without them there would be piles of rubbish everywhere.”

He added: “Although we suspect that trust land is home to a great many waxcaps, we don’t have a good picture of where they are found. We are asking our visitors to be our eyes and seek out these grassland gems. All you need is a keen pair of eyes, a pen, paper and the ability to get online. .”

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