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Once is not enough
From top: Fly agaric, mosaic puffball and parasol

Mushroom hunters have never had it so good. Picking edible, fleshy fungi may now be carried out over an extended period of time, at least in Europe, thanks to the much whipped weather monster — climate change. A team of ecologists in the UK have found that climate change, which is now blamed for every second ill on earth, may be a boon in disguise for growing mushrooms and many other members of the fungi family. The study was reported in the journal, Science, last week.

The study by Alan Gange of the Royal Holloway College, University of London, and others is significant in many ways. The researchers found that many fungal species now fruit twice a year, a response to climate change not yet seen in other organisms. It is “unheard of for an organism to start reproducing twice a year instead of once,” says Gange.

Among all organisms, fungi seem to be the most sensitive to climate changes. Other living creatures such as birds, fish, mammals and plants, too, respond to climatic aberrations. “(But) birds nest in spring and even though the climate has got warmer, they have not started to nest in autumn as well,” Gange observes.

Interestingly, the data the scientists used for the research came from the lead author’s father — Edward Gange. Though not a scientist, Gange senior has meticulously kept nearly 52,000 individual fungal fruiting records, collected from 1,400 locations in southern England over 55 years. Of these, the researchers chose 315 species, each of which had been recorded for over 20 years. Many of these fungi are edible, some decorative and some poisonous as well.

According to the researchers, the increase in overall fruiting period is dramatic. While the average fruiting period for these fungi was 33.2 days (plus or minus 1.6 days) in the 1950s, it has more than doubled to 74.8 days (plus or minus 7.6 days) in the current decade, the scientists reported. Similarly, for the species that fruit early, the first fruiting date was on an average advanced by nearly nine days per decade, whereas for those which fruit later the fruiting date was delayed by about an average of eight days per decade.

Normally, biologists measure changes in the appearance of organisms in days per decade. For example, sulphur tuft — a commonly found toxic woodland mushroom — has started to fruit twice a year. Similarly, 50 years ago mushroom hunters looking for the mosaic puffball or the delicious parasol mushroom would have gone out in September, but today they are more likely to go hunting in July.

The detailed analysis by the scientists has shown that the changes in fungal fruiting have coincided with changes in the British weather, particularly since 1975. They found that over the past 56 years, August temperatures have increased, as has October rainfall. The increase in late summer temperatures and autumnal rains has caused early season species to fruit earlier and late season species to continue to fruit even later. “Species that used to start fruiting in September now do so in July or August. The end of the season has got delayed — it used to be October, now it is December. These events have been caused by elevated temperatures in July (this makes the mushrooms start earlier) and in October (no frosts anymore, so autumn stays warmer for longer),” Gange told KnowHow.

This is also the reason why many species now fruit twice a year. Species that used to fruit only in October now do so in April too. As spring has got warmer, the fungus in the soil becomes active in February itself. Earlier, February used to be colder, and the fungi remained dormant. Activity in February means the fungus acquires sufficient nutrients to enable it to fruit within a month or two, Gange says.

This increased fungal activity has also meant increased decomposition rates. Thus, leaf litter in a forest now disappears at twice the rate it did 50 years ago, says Gange. This enhanced speed of decomposition in turn means enhanced availability of nutrients to plants. Hence, their growth rates too pick up.

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