‘Wood wide web’—the underground network of microbes that connects trees—mapped for first time

A fungus known as a Dermocybe forms part of the underground wood wide web that stitches together California’s forests.

Kabir Gabriel Peay

‘Wood wide web’—the underground network of microbes that connects trees—mapped for first time

Trees, from the mighty redwoods to slender dogwoods, would be nothing without their microbial sidekicks. Millions of species of fungi and bacteria swap nutrients between soil and the roots of trees, forming a vast, interconnected web of organisms throughout the woods. Now, for the first time, scientists have mapped this “wood wide web” on a global scale, using a database of more than 28,000 tree species living in more than 70 countries.

“I haven’t seen anybody do anything like that before,” says Kathleen Treseder, an ecologist at the University of California, Irvine. “I wish I had thought of it.”

Before scientists could map the forest’s underground ecosystem, they needed to know something more basic: where trees live. Ecologist Thomas Crowther, now at ETH Zurich in Switzerland, gathered vast amounts of data on this starting in 2012, from government agencies and individual scientists who had identified trees and measured their sizes around the world. In 2015, he mapped trees’ global distribution and reported that Earth has about 3 trillion trees.

Inspired by that paper, Kabir Peay, a biologist at Stanford University in Palo Alto, California, emailed Crowther and suggested doing the same for the web of underground organisms that connects forest trees. Each tree in Crowther’s database is closely associated with certain types of microbes. For example, oak and pine tree roots are surrounded by ectomycorrhizal (EM) fungi that can build vast underground networks in their search for nutrients. Maple and cedar trees, by contrast, prefer arbuscular mycorrhizae (AM), which burrow directly into trees’ root cells but form smaller soil webs. Still other trees, mainly in the legume family (related to crop plants such as soybeans and peanuts), associate with bacteria that turn nitrogen from the atmosphere into usable plant food, a process known as “fixing” nitrogen.

The researchers wrote a computer algorithm to search for correlations between the EM-, AM-, and nitrogen-fixer–associated trees in Crowther’s database and local environmental factors such as temperature, precipitation, soil chemistry, and topography. They then used the correlations found by the algorithm to fill in the global map and predict what kinds of fungi would live in places where they didn’t have data, which included much of Africa and Asia.

Local climate sets the stage for the wood wide web, the team reports today in Nature. In cool temperate and boreal forests, where wood and organic matter decay slowly, network-building EM fungi rule. About four in five trees in these regions associate with these fungi, the authors found, suggesting the webs found in local studies indeed permeate the soils of North America, Europe, and Asia.

By contrast, in the warmer tropics where wood and organic matter decay quickly, AM fungi dominate. These fungi form smaller webs and do less intertree swapping, meaning the tropical wood wide web is likely more localized. About 90% of all tree species associate with AM fungi; the vast majority are clustered in the hyperdiverse tropics. Nitrogen fixers were most abundant in hot, dry places such as the desert of the U.S. Southwest.

Charlie Koven, an Earth system scientist at the Lawrence Berkeley National Laboratory in California, applauds what he says is the first global forest microbe map. But he wonders whether the authors missed some important factors that also shape the underground world. Hard-to-measure processes such as nutrient and gas loss from the soil could affect where different microbes live; if so, the study’s predictions could be less accurate, he says.

Despite such uncertainties, having the first hard numbers for which tree-associated microbes live where will be “very useful,” Treseder says. The findings could, for example, help researchers build better computer models to predict how much carbon forests will squirrel away and how much they will spew into the atmosphere as the climate warms, she says.

Crowther, however, is ready to make a prediction now. His results suggest that as the planet warms, about 10% of EM-associated trees could be replaced by AM-associated trees. Microbes in forests dominated by AM fungi churn through carbon-containing organic matter faster, so they could liberate lots of heat-trapping carbon dioxide quickly, potentially accelerating a climate change process that is already happening at a frightening pace.

That argument is “a little bit more tenuous” to Treseder. She says scientists are still puzzling out how different soil fungi interact with carbon. But, she adds, “I’m willing to be convinced.”

SCOTUS Upholds Vote Rigging

In another death blow to our democracy, the United States Supreme Court ruled last Thursday that extreme gerrymandered congressional maps will no longer be reviewed nor struck down by the federal federal courts. This means that the extreme gerrymandering of states like North Carolina and Maryland – which were previously struck down by the federal courts – are now sanctioned by the highest court.

This combined with the Citizens United decision and the systematic eroding of voting rights in the U.S. has ensured that the country will continue its trajectory of replacing democracy with corporatocracy.

Grassroots Politics on the Internet

I just stumbled across this video which talks about politics on the web. Of course despite this video’s misleading inference, before there was the web, the internet existed. Before the public rollout of hypertext, i.e. the web, full blown grassroot politics had already been going on for about a decade. I know this first hand because I was the programmer and director of ECONET in the mid-eighties, a network devoted to appropriate technology and environmentalism. For all you history buffs…enjoy!

Global Earth Repair Conference

I presented at the global earth repair conference in Port Townsend, Washington earlier this month. The event was certainly groundbreaking with some six-hundred attendees and over sixty presentations. The conference was not a scientific conference and while there was a good deal of sound information based on well understood and proven practices, there was  also some information presented which was notably disturbing.

Some speakers were ridiculing current scientific consensus on the necessity of bringing down atmospheric CO2 levels and instead were advocating for altering the earth’s hydrologic cycle through ecosystem restoration as the most important task in face of the present climate emergency. This theory is controversial at best and I am not aware of any peer-reviewed science supporting this theory and in fact there exist cogent arguments disputing this notion.

This in no way is to diminish the importance of ecosystem restoration and the valuable contribution made to society by this conference. That said, I felt it was wholly irresponsible and dangerous to diminish the importance of the necessity for us to to limit GHG emissions. This for me was a blemish on what was otherwise a superb forum around a key topic.

Farallones Institute 40th Reunion

On May 9-10, 2019 I attended the 40th year reunion of the Farallones Institute seeing friends some of which I had not seen in well over thirty years. The Institute was an amazing place founded on a vision for how best to participate in the growing ecological movement of the 1970s. It’s an amazing story really, too long to tell here, but I’ll include some pics and links here so readers can get an idea.

Integral Urban House
Integral Urban House

What today is known as the Occidental Arts & Ecology Center (OAEC) in Occidental, California started out as the Farallones Institute some 40 years ago. I was fortunate to live and work at the Institute in the mid-eighties, both as the last caretaker/tour guide of their Integral Urban House on 5th street in Berkeley, California and also at what we then called ‘the rural center’ which is where OAEC now exists.

solar village at Farallones Institute

The Farallones Institute started with an idea of a few folks and for more than two decades went on to make its mark on society and the world, ranging from becoming the place where the organic vegetables for Alice Water’s Chez Panisse were first grown, to demonstrating urban-self reliance in the city, and from first using the internet to link environmental and appropriate technology organizations globally (ECONET), to training Peace Corps volunteers before their overseas assignments.

The work at the Integral Urban House became a best selling book and was for a time the appropriate technology sourcebook of its day. The house was world famous. I can vouch for this personally as I gave tours to people from all over the world who made their way there. Integral Urban House book

While working for the Farallones Institute I became head of the ECONET project which became a significant early pilot in the use of the internet, years before the invention of the web browser. Because of ECONET I had the good fortune of meeting many of the pioneers of the personal computer and internet revolution including Douglas Engelbart, Jacques Vallee, Lee Felsenstein, Stewart Brand and Tom Jennings. My work with ECONET led to a career in telecomputing which lasted many years.

The people who went through the Farallones Institute experience went on to do great work throughout the world. At the reunion a few of us discussed uniting our shared vision of an ecological world contemporary with our times and manifesting that in a meaningful way. We’ll see!