I welcome back guest blogger Emily Stone so that she may present the second part of her “Wood Wide Web” series. Her first blog , as well as this essay, focuses on the great ecological importance of the interconnected underground world of plants and forests.
Emily is an award winning writer and the Naturalist and Education Director at the Cable Museum in Northern Wisconsin . The museum characterizes “Natural Connections” between people and Nature as well as the interconnectivity between all creatures and organisms within Nature.
Emily’s wonderful writing style brings freshness to this important (but rarely emphasized) subject about connections in Nature. I particularly like her blog title, “Wood Wide Web”, which is a takeoff on the Internet expression “World Wide Web” where Dr. Suzanne Simard describes the deeply interconnected subterranean information highway of plants and trees.
I am very grateful that Emily has agreed to permit me to publish copies of her “Wood Wide Web” series. Thank you Emily for sharing this with us.
Wood Wide Web 2
By Emily Stone
Winter is coming in fits and starts. Last week, a thick, white blanket of snow separated each stoic tree trunk. Then it melted. This morning, a thin frosting of damp flakes swirled out of the sky, outlining every feature of the forest floor, highlighting the trunks and tracing the twigs. The intricate patterns, thus revealed, give us just a glimpse of the complexity that lies beneath. Yes, the roots of the trees ramble widely, and fuse with relatives to form a Wood Wide Web that shares resources, but the connections don’t stop there.
Fungi pick up where the roots leave off. Most tiny root tips are colonized by filaments of fungi, which extend the plants’ reach into the surrounding soil. Each tree species can host multiple types of fungi, and each fungus can colonize a variety of plant species. This expands the network beyond the species-specific root grafting, and creates a mycorrhizal (myco=fungus; riza=root) network that is robust and thickly woven. So thickly, in fact, that scientists say you could find seven miles of fungal hyphae in a pinch of dirt, and hundreds of miles under a single footstep.
Light snow traces the complex network of twigs in the forest.
We can imagine an even more intricate web of roots and fungi living below the surface.
Photo by Emily Stone.
When Dr. Suzanne Simard (a forest ecologist from the University of British Columbia who coined the term “wood wide web”) used DNA to identify all the individual trees and fungal strains in a forest plot, she ended up with a diagram resembling the airline route map in your seat back pocket. A big, old, well-connected white pine is like Chicago O’Hare, because it provides connections to lots of other places. Hub trees connect (through the mycorrhizal network) to other hub trees, as well as younger, more isolated trees. This pattern is incredibly efficient. The two most distant trees in her study plot only needed two “flights” to connect, and the maximum path length the researchers discovered required only three “flights.”
In addition, this pattern creates resilience. With just a few important hub trees (or airports), there is a lower likelihood that one of them will be damaged. If one of the less-connected trees dies, the impact on the ecosystem isn’t large. However, in the infrequent event that one of the few hub trees dies, the impact on the connectivity of the surrounding forest could be dire. That’s why conservationists and foresters must focus on identifying and preserving the venerable elders.
Trees and mycorrhizal fungi live in an incredible symbiosis. Trees feed the fungi sugars produced during photosynthesis, and may share up to 80% of their total production. In return, fungal hyphae increase the absorbing area of roots from 10 to 1000 times. This protects trees against drought by contributing to water uptake and storage. Fungi don’t just absorb nutrients; they actively break down tightly bound soil nutrients like phosphorous and iron and make them available to plants. Some fungi even recycle nitrogen from soil nematodes into their plant hosts. Fungi and trees feed each other, and the intricate web captures and holds nutrients before they can be lost from the system.
The benefits aren’t just food related. The sheath that a fungus forms around a root creates a physical barrier against diseases. Meanwhile, it is diverting heavy metals and excreting antibiotics designed to kill pathogens. At a community level, the fungi act like fiber optic cables. Using warning chemicals and electrical impulses, they help trees share information about insects, drought, and other threats, so that currently unaffected trees can prepare their defenses in advance of an invasion.
What’s more, the mycorrhizal fungi can facilitate nutrient sharing between trees and plants of different species. Dr. Suzanne Simard traced the flow of radioactive carbon 14 from birch to Douglas-fir trees. After only an hour, she found evidence that birches had incorporated the carbon 14 into sugars during photosynthesis, and then shared it with nearby firs (which had been shaded for the experiment). Later, after leaf-off, she found that the evergreen firs were providing sugars to the twiggy birches.
Why would the fungi benefit from distributing resources to trees in need? Their existence depends on the presence of a mature, stable forest with its humid microclimate and flow of nutrients. Tree diversity is essential, since monocultures are vulnerable to disease and disturbance. Therefore, the fungi may share resources in an effort to maintain diversity in the forest and ensure the long-term stability of the environment they enjoy. A diversity of fungi is also important, since different fungi provide different benefits to their hosts and thrive in different situations.
The Wood Wide Web, with all of its natural connections, is beautiful from many angles. Perhaps our society could do worse than trying to emulate a system that has kept forests thriving on Earth for many millennia.
Worth Your Extra Attention
Emily Stone is the author of a book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses. The book is a collection of her essays where she uses personal experiences as an entry point to teaching people about the amazing interconnectedness of life, including themselves. I own a copy of Emily’s book. Its many essays are my companions as I engage Nature on my various camping trips. Order your own copy of this wonderful book.
For over 45 years, the Cable Natural History Museum has served to connect people to the Northwoods of Wisconsin. Come visit the museum and Emily in Cable, Wisconsin! The museum’s new phenology exhibit: “Nature’s Calendar: Signs of the Seasons” is now open.
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My name is Bill Graham. As a Marine Biologist who has worked in the US and Mexico for 30 years, I am a student of Nature, a teacher, a researcher, and a nature photographer. Through my work, I have acquired an ever growing passion for how everything in Nature is connected. Today, I travel extensively contemplating about, writing about, and photographing Nature’s connections. I also work with conservation projects in the USA and Mexico and mentor talented youth.