Suzanne's Mom's Blog

As a kid, I was kind of creeped out by fungi, but in recent years I’ve found myself fascinated by their unexpected beauty and mystery. And I’ve taken lots of pictures, three of which are here.

In an article at the New York Times, Ferris Jabr, describing the symbiotic relationship between trees and fungi, talks to forest ecologist Suzanne Simard about what trees are communicating with one another through their subterranean networks of fungi.

“By the time she was in grad school at Oregon State University, [Simard] understood that commercial clearcutting had largely superseded the sustainable logging practices of the past. Loggers were replacing diverse forests with homogeneous plantations, evenly spaced in upturned soil stripped of most underbrush. Without any competitors, the thinking went, the newly planted trees would thrive. Instead, they were frequently more vulnerable to disease and climatic stress than trees in old-growth forests.

“In particular, Simard noticed that up to 10 percent of newly planted Douglas fir were likely to get sick and die whenever nearby aspen, paper birch and cottonwood were removed. The reasons were unclear. The planted saplings had plenty of space, and they received more light and water than trees in old, dense forests. So why were they so frail?

“Simard suspected that the answer was buried in the soil. Underground, trees and fungi form partnerships known as mycorrhizas: Threadlike fungi envelop and fuse with tree roots, helping them extract water and nutrients like phosphorus and nitrogen in exchange for some of the carbon-rich sugars the trees make through photosynthesis.

“Research had demonstrated that mycorrhizas also connected plants to one another and that these associations might be ecologically important, but most scientists had studied them in greenhouses and laboratories, not in the wild. For her doctoral thesis, Simard decided to investigate fungal links between Douglas fir and paper birch in the forests of British Columbia. …

‘The old foresters were like, Why don’t you just study growth and yield?’ Simard told me. ‘I was more interested in how these plants interact. They thought it was all very girlie.’

“Now a professor of forest ecology at the University of British Columbia, Simard, who is 60, has studied webs of root and fungi in the Arctic, temperate and coastal forests of North America for nearly three decades. Her initial inklings about the importance of mycorrhizal networks were prescient, inspiring whole new lines of research that ultimately overturned longstanding misconceptions about forest ecosystems. By analyzing the DNA in root tips and tracing the movement of molecules through underground conduits, Simard has discovered that fungal threads link nearly every tree in a forest — even trees of different species. Carbon, water, nutrients, alarm signals and hormones can pass from tree to tree through these subterranean circuits.

“Resources tend to flow from the oldest and biggest trees to the youngest and smallest. Chemical alarm signals generated by one tree prepare nearby trees for danger. Seedlings severed from the forest’s underground lifelines are much more likely to die than their networked counterparts. And if a tree is on the brink of death, it sometimes bequeaths a substantial share of its carbon to its neighbors.

“Although Simard’s peers were skeptical and sometimes even disparaging of her early work, they now generally regard her as one of the most rigorous and innovative scientists studying plant communication and behavior. … In May, Knopf will publish [her] book, Finding the Mother Tree, a vivid and compelling memoir of her lifelong quest to prove that ‘the forest was more than just a collection of trees.’ …

“Before Simard and other ecologists revealed the extent and significance of mycorrhizal networks, foresters typically regarded trees as solitary individuals that competed for space and resources and were otherwise indifferent to one another. Simard and her peers have demonstrated that this framework is far too simplistic. An old-growth forest is neither an assemblage of stoic organisms tolerating one another’s presence nor a merciless battle royale: It’s a vast, ancient and intricate society. There is conflict in a forest, but there is also negotiation, reciprocity and perhaps even selflessness. The trees, understory plants, fungi and microbes in a forest are so thoroughly connected, communicative and codependent that some scientists have described them as superorganisms. …

“Together, these symbiotic partners knit Earth’s soils into nearly contiguous living networks of unfathomable scale and complexity. ‘I was taught that you have a tree, and it’s out there to find its own way,’ Simard told me. ‘It’s not how a forest works, though.’ ”

More at the New York Times, here.

Hat tip: Hannah.