Nature is rife with symbiotic relationships, some of which take place out of sight, like the rich underground exchange of nutrients that occurs between trees and soil fungi.
But what happens in the dark may have profound implications above ground, too: A major new study reveals that soil fungi could play a significant role in the ability of forests to adapt to environmental change.
Kai Zhu, assistant professor of environmental studies at UC Santa Cruz, took a unique "big data" approach to investigating the role of symbiotic fungi in tree migration in forests across the eastern United States.
"Our climate is rapidly changing, and our forests are responding, but in very slow motion -- it's hardly detectable," said Zhu, who wanted to identify factors that contribute to the pace of that response.
In forests, tree growth largely depends on the nutrients available in the soil, while the transfer of carbon through roots to the soil regulates ecosystem processes. Mycorrhizal ("MY-koe-RY-zull") fungi grow on the roots of most plants and drive the nutrient-carbon exchange between plants and soil: They take up carbon resources from their hosts and provide soil nutrients that plants need. The two most common fungi associated with forest trees are ectomycorrhizal (ECM), which grow on conifers, including pines, oaks, and beeches, and arbuscular (AM), which grow on most nonconifers, such as maples.
Zhu utilized data from the U.S. Department of Agriculture's Forest Inventory and Analysis program to examine how soil carbon and nitrogen levels differ across stands of forest that are characterized by "AM dominant" trees and "ECM dominant" trees. He correlated the distribution of trees with soil fungi and content, then analyzed the distribution of trees by fungus type. In the most significant finding, Zhu was able to identify distinct soil nitrogen "signatures" that impact soils and ecosystems in ways that may determine the resilience of forests to the changing climate.
[...] Zhu's study, published in the Journal of Ecology, is one of the first to use the USDA's large-scale data set to see how climate change is impacting the ecosystem, an approach known as "top down" rather than "bottom up."
[...] "We know the environment is changing, but how it impacts the Earth and its systems is a big question," he said. "As scientists, we have the responsibility to correctly work out this problem -- it's a problem that's important to scientists and the general public."
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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
(Score: 1) by cocaine overdose on Tuesday March 20 2018, @04:06PM (2 children)
I wonder why no one just downloads all their governments public data and start doing simple regression analysis. Might as well put that data to use, since it's just sitting around in poorly-managed gov't websites waiting for the few GIS guys who know how valuable it is, to rape apart their bandwidth.
(Score: 0) by Anonymous Coward on Tuesday March 20 2018, @05:47PM (1 child)
?? What are you Trying to say? Last time I looked California was still in the US and University of California Santa Cruz was still in California.
(Score: 1) by cocaine overdose on Tuesday March 20 2018, @05:56PM