Fungal Banking
canopic jug writes:
Doug Muir, at his blog Crooked Timber, discusses a paper about symbiotic fungal networks loaning glucose to seedlings and saplings. Of note, fungi do not produce glucose themselves, so they are extracting and storing it. The fungi connect to new seedlings and help them get started by feeding the roots micronutrients, which for some of them compensates for sunlight which they can't yet reach. Then after some time, the network cuts off the supply. If the sapling dies, the network rots it. If the sapling survives, the network extracts and caches nutrients from it.
The problem was, succession leading to forest was a bunch of observations with a big theoretical hole in the center. Imagine a mid-succession field full of tall grass and bushes and mid-sized shrubs. Okay, so... how does the seedling of a slow-growing tree species break in? It should be overshadowed by the shrubs and bushes, and die before it ever has a chance to grow above them.
And the answer is, the fungus. The forest uses the fungus to pump sugar and nutrients into those seedlings, allowing them to grow until they are overshadowing the tall grasses and shrubs, not vice versa. The fungus is a tool the forest uses to expand. Or - looked at another way - the fungus is a venture capitalist, extending startup loans so that its client base can penetrate a new market.
This also answered a bunch of other questions that have puzzled observers for generations. Like, it's long been known that certain trees are "nurse trees", with unusual numbers of seedlings and saplings growing closely nearby. Turns out: it's the fungus. Why some trees do this and not others is unclear, but the ones that do, are using the fungus. Or: there's a species of lily that likes to grow near maple trees. Turns out they're getting some energy from the maple, through the fungus. Are the lilies symbiotes, providing some unknown benefit to the maple tree? Or are they parasites, who are somehow spoofing either the maple or the fungus? Research is ongoing.
Since the slow-growing trees spend years in the shade of other foliage, the nutrient boost lent by the fungi can make the difference between survival or death.
Previously:
(2022) Mushrooms May Communicate With Each Other Using Up To 50 "Words"
(2020) Radiation-Resistant Graphite-Eating Fungus
(2018) Soil Fungi May Help Determine The Resilience Of Forests To Environmental Change
(2015) Earth Has 3,000,000,000,000 Trees and Some Resist Wildfires
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