The Race to Understand the Underground: Alaska’s Fungal Networks and the Global Carbon Crisis

One Tuesday in June 2025, as the perpetual daylight of Alaska’s polar summer bathed the landscape in an unending glow, a white Chevy Suburban embarked on a critical mission down North America’s northernmost highway. For Michael Van Nuland, a biologist at the helm, the extended daylight hours belied a pressing race against time, a race to unravel the secrets held within the earth and their profound implications for global climate stability.

Packed with the essentials for four days of intensive fieldwork – waterproof boots for navigating the marshy tundra, a high-precision GPS, and a specialized steel tube designed to extract cores from permafrost – the vehicle rumbled along the Dalton Highway. This ribbon of asphalt and gravel carves a path through the vast, treeless expanse of Alaska’s northern coast. While the surface might appear stark, it is a vibrant ecosystem, supporting seasonal migrations of caribou, grizzlies, muskox, and an astonishing array of approximately 200 bird species. However, Van Nuland’s focus was not on the visible life, but on the intricate, unseen world beneath: the sprawling, interconnected networks of fungal threads.

These subterranean systems, ranging from microscopic filaments to cords as thick as yarn, extend dozens of feet horizontally, forming a dense, networked scaffold. They are the silent architects of life aboveground, connecting plant roots and facilitating the crucial circulation of nutrients. "Some people just see dirt as dirt," Van Nuland, lead data scientist for the nonprofit Society for the Protection of Underground Networks (SPUN), explained. "But it’s a living, breathing system. The complexity you see in a forest – the layers of canopy, the different species of birds and insects – you’re walking over an equally or possibly even more complex system below ground."

The architects of this hidden world are mycorrhizal fungi, a diverse group of soil-dwelling microbes. Their ever-growing appendages, known as hyphae, are adept at extracting vital nutrients and water from their surroundings. In a symbiotic exchange, they connect with plant roots, offering scarce nitrogen and phosphorus that plant roots struggle to access on their own. In return, the fungi receive carbon from the plants, fueling their own growth and expansion.

For over a century since their discovery, the scientific understanding of mycorrhizal fungi has evolved. Initially viewed as plant parasites, they were later reclassified as passive conduits serving plant interests. However, recent advancements in robotics and imaging technologies have begun to paint a different picture, revealing these fungi as active agents, controlling their own fates and significantly influencing the ecosystems they inhabit.

“You can think of fungi as sort of farming plants above ground,” stated Toby Kiers, an evolutionary biologist at Vrije Universiteit Amsterdam and co-founder of SPUN. “Fungal networks direct traffic through nutrient superhighways and restructure the soil to support life across entire ecosystems. Now, we see fungi more as really important actors in their own right. It’s flipping the way that we understand the underground.”

Despite this growing recognition, the global biodiversity and biogeography of these fungal networks remain largely uncharted, especially when compared to our understanding of plants and animals. Estimates suggest there are between 20,000 and 50,000 species of mycorrhizal fungi, each possessing unique strategies for nutrient acquisition. To address this knowledge gap, Van Nuland and his colleagues developed a sophisticated machine-learning model. Published in Nature in 2025, the model analyzed over 25,000 soil samples from around the globe, processing more than 2.8 billion fungal DNA sequences to predict the locations of mycorrhizal “hot spots” – areas characterized by both high diversity and rarity of species.

This predictive model is what drew Van Nuland to the Arctic. The analysis pointed to the Alaskan tundra, situated between the Prudhoe Bay oil fields and the Arctic National Wildlife Refuge, as a prime candidate for a mycorrhizal hot spot. Consequently, Van Nuland assembled a team of researchers to meticulously sample the soil across this remote region. Their expedition is part of a broader SPUN initiative to survey other predicted hot spots worldwide, encompassing diverse environments from tropical islands to dense forests and towering mountains. The hope is that these investigations will uncover new fungal species, particularly those with unique traits and functions.

The implications of this research extend far beyond academic curiosity. Annually, mycorrhizal fungi store an amount of carbon equivalent to over one-third of global carbon emissions. The permafrost regions, including the Alaskan tundra, hold an estimated 1 trillion metric tons of carbon in their top three meters of soil – roughly ten times the carbon content of the entire Amazon rainforest. Consequently, safeguarding these extensive fungal networks is recognized as a critical strategy in the fight against climate change.

“In the past, we’ve really neglected to map, monitor, and protect fungal systems, and now that’s changing,” Kiers emphasized. However, this awakening comes at a precarious moment. Climate change is already destabilizing these fragile Arctic environments. Rising temperatures, increased moisture, more frequent and intense wildfires, and thawing permafrost are all exerting pressure on fungal communities. Worryingly, less than 10% of SPUN’s predicted mycorrhizal hot spots lie within protected areas, and even these are not immune to the impacts of a changing climate. To advocate effectively for the protection of soil fungi, scientists like Van Nuland must gather robust, on-the-ground evidence, identifying rare and vulnerable species.

Laying the Groundwork for Discovery

The author joined the SPUN team on the third day of their four-day expedition in Deadhorse, a remote oilfield-support town on Alaska’s North Slope. The team had already sampled 24 sites, overcoming challenges including a flat tire on the first day. As they navigated the Dalton Highway, the conversation centered on the day’s objective: collecting soil cores that would offer a glimpse into the hidden biodiversity beneath the tundra.

During a short hike to the first sampling site of the day, Van Nuland paused to explain the significance of mycorrhizae. He carefully peeled back thick moss near a dwarf willow shrub, revealing a clod of soil. In his palm, small, white clumps, resembling miniature popcorn kernels, were visible. "All of these are places where the [mycorrhizal] hyphae are wrapping themselves really intensely around the fine roots," he explained, gesturing to the delicate fungal threads. "Then from this point, they’re sending out their hyphal networks." These hyphae, the individual filaments that constitute the fungal body (mycelium), are remarkably thin, often measuring only five micrometers in width – about one-tenth the diameter of a human hair. Their structure, rigid due to chitin (the same compound found in insect exoskeletons), allows them to burrow into soil crevices, access air pockets, and tap into moisture, enabling them to acquire nutrients that plant roots alone cannot reach.

For decades, scientists operated under the assumption that this was the primary function of hyphae. However, recent breakthroughs in imaging technology are revolutionizing this understanding. In February 2025, Kiers’s team collaborated with biophysicists from the AMOLF Institute in Amsterdam to use robotics to track nutrient flow within hyphae in petri dishes. The resulting time-lapse videos revealed a dynamic, two-way flow of nutrients through these fungal tunnels. As the hyphae branched and expanded, the network pulsed, efficiently absorbing nutrients. The density of these networks was crucial; too sparse, and they would be ineffective; too dense, and they would become inefficient.

“The study is phenomenal in its precision,” commented Justine Karst, a forest ecologist at the University of Alberta, who was not involved in the research but described the work as a “masterpiece.” The imaging provided unprecedented clarity on how thousands of independent fungal tips collectively form an efficient network. Hyphae actively explored empty spaces, fused upon contact, and redirected growth away from routes that yielded insufficient nourishment.

These observations, made in a controlled laboratory setting, offered a window into the complex interactions that were previously invisible. “It feels almost like you’re a primatologist hiding behind a tree,” remarked Kiers, a recent recipient of a MacArthur fellowship and the Tyler Prize for Environmental Achievement. Her hiring of Van Nuland in 2022, with his expertise in geospatial data, was a strategic move to connect these microscopic fungal exchanges to global ecological processes. “Michael is able to see this bigger picture of how all of these interactions come together to create what we see across the landscape. It’s such an incredible skill.”

Van Nuland’s prior research, conducted during his graduate and postdoctoral studies, involved extensive fieldwork and controlled laboratory experiments exploring the intricate relationships between fungi and plants. His work contributed to a growing body of evidence demonstrating that soil fungi are significant drivers of plant diversity. He has shown that when neighboring plants are similar, they must differentiate their methods of resource acquisition. Fungi play a crucial role in this differentiation, enabling plants to strategically optimize their underground resource uptake.

“Plants are competing for resources, and most of their resources are actually mediated by mycorrhizal fungi,” stated Karst, who studies similar ecological interactions. The vast diversity of mycorrhizal species, typically categorized into two main types – ectomycorrhizal fungi dominant in higher latitudes and arbuscular fungi prevalent in tropical regions – further complicates the ecological landscape. Each type possesses specialized mechanisms for nutrient exchange, with ectomycorrhizal fungi adept at delivering nitrogen and arbuscular fungi excelling in phosphorus transfer. Beyond these primary nutrients, fungi also supply plants with essential vitamins and minerals like calcium and zinc, adding another layer of complexity to their symbiotic relationships.

The cumulative evidence from these studies strongly suggests that plants and their fungal partners cannot be understood in isolation. “I cut my teeth in ecology thinking about how above- and below-ground systems interact with one another, but to me, they seem completely inseparable,” Van Nuland reflected. “A forest dominated by one mycorrhizal type has a completely different ecological flow of nutrients than a forest with another type, and a large part of that seems to be the result of how different symbioses work, and which fungi are better at doing certain things than others.”

This perspective reframes ecological competition: the competition between plants is, in essence, competition between their fungal partners. In the unique environment of the Arctic tundra, these competitive partnerships may harbor some of the planet’s rarest mycorrhizal communities.

The Carbon Bomb Ticking in the Permafrost

Van Nuland, a 36-year-old scientist with a background in competitive athletics, thrives on challenges. His drive was evident as the SPUN expedition pushed to reach a target of 60 sampled sites, surpassing a previous expedition in Kazakhstan. At one sampling site, located roughly half a mile from the highway, Jinsu Elhance, a geospatial data scientist with SPUN, carefully hammered a 7-inch metal cylinder into the ground. The resistance varied, from soft, damp soil to icy, compacted earth. Each core extracted captured a snapshot of the subterranean life – plant roots, fungi, and other soil organisms – offering a census of biodiversity at that specific location and moment.

At each site, Mario Muscarella, a collaborating microbiologist from the University of Alaska, Fairbanks, meticulously recorded precise GPS coordinates, identified surface plant species, and measured temperature and moisture levels with a probe. Later, laboratory analysis would focus on soil nutrients and DNA sequencing to identify potentially undiscovered fungal species.

The expedition continued south, traversing the North Slope towards the Brooks Range. The landscape shifted, with marshland giving way to thicker moss and more substantial shrubs. The team encountered muskoxen, vast icy ponds, and the imposing presence of Alaska’s high-pressure crude oil pipeline, a stark reminder of the region’s resource extraction history. By the end of the third day, they had reached their 39th site, leaving them 21 sites short of their goal with only one day remaining.

The final day dawned with a biting chill, a stark contrast to the June date. Despite temperatures hovering around 30 degrees Fahrenheit under a thick fog, summer was undeniably underway. The team trudged through calf-deep snowmelt to reach a drier sampling location. Piles of withered sedge from the previous summer lay scattered around them. "It’s odorless," Muscarella remarked, "but I’m sure that we’re breathing in a ton of methane right now."

This observation pointed to a critical process occurring in the thawing Arctic. Long-dead organic matter – plants, animals, and fungi – is becoming accessible to microbial decomposers. As these microbes break down complex organic material, they release greenhouse gases such as carbon dioxide, methane, and nitrous oxide. With accelerating climate change, deeper layers of permafrost are beginning to thaw, liberating carbon that has been frozen for millennia.

Microbial fungi are central to understanding the fate of this carbon. After being historically overlooked or misunderstood, the growing body of research on their functions has positioned mycorrhizal fungi as a crucial, yet often missing, piece in climate change studies. In 2023, Van Nuland and Kiers co-authored a study estimating the annual carbon storage by mycorrhizal fungi: 3.93 billion tons by arbuscular fungi and 9.07 billion tons by ectomycorrhizal fungi. Combined, this represents approximately 36% of the planet’s annual carbon dioxide emissions.

“It’s the cycle of life and death that creates a really big soil carbon influx,” Van Nuland stated. “It’s a living infrastructure and a dying infrastructure.” However, the precise role of specific fungal species within these broader groups is complex and varied. Mycologists are discovering that some fungal species are highly efficient decomposers, with some excelling at storing dead carbon while others release a significant portion into the atmosphere. “The taxonomic identity can really matter,” said Rebecca Hewitt, an ecologist at Amherst College who studies plant-microbe interactions in the Arctic. “Who is there really affects the function.”

In Alaska, the question of which fungal species – the carbon keepers or the carbon leakers – will ultimately thrive as the ground warms remains unanswered. The outcome will significantly influence whether the Arctic becomes a net source of planet-warming gases. As the team hiked back to their SUV after reaching their 54th sampling site, Van Nuland reflected on the broader implications of their work. He hypothesized that tundra fungi possess unique traits that enable them to capture carbon more efficiently. “Once we identify the unique mycorrhizal species here, we’ll be able to connect them to the carbon drawdown that we’re estimating for this area,” he said.

The pursuit of their goal continued with renewed vigor. After a lunch break, the team reached site 55, and the landscape began to change as they ascended into the foothills of the Brooks Range. Marshy terrain transitioned to thicker moss and more substantial shrubbery. The geographical features of the region – the Brooks Range to the south and the icy coastline of Prudhoe Bay to the north – have functionally isolated the tundra’s plant-fungus partnerships from the rest of Alaska.

“We know that big mountain ranges create geographic barriers and therefore lead to isolation and the evolution of unique species, and therefore unique symbiosis partnerships in that place,” Van Nuland explained. “It’s got me thinking, what’s their story going to be?”

A Stake in the Ground: Unearthing Rare Biodiversity

By 4 p.m. on the final day, the team reached their 60th sampling site, a west-facing hill carpeted in cottongrass. The familiar routine of GPS mapping, plant identification, and soil coring commenced, culminating in the extraction of the final core. In total, over four days, they collected 540 samples from 60 sites. “I’m proud of the hustle,” Van Nuland stated after the last sample was secured. “Amazing data is going to come out of this expedition.”

Four months later, in November 2025, preliminary results from the expedition provided a glimpse into the unique biodiversity of the region. Each sampling site averaged approximately 75 different species of ectomycorrhizal fungi. Crucially, the species composition shifted significantly from north to south. Of the 354 distinct species identified, an astonishing 253 were previously unknown to science.

This finding strongly suggests that the region is indeed a hot spot for rare, endemic fungi. Approximately three out of every four species detected had not been previously documented elsewhere. While it’s theoretically possible that some of these species might exist in unsampled tundra regions, such as Siberia, Van Nuland suspects that a substantial portion are endemic to this specific Alaskan locale. These plants and fungi have likely co-evolved in isolation for millions of years, geographically constrained between mountains and sea, akin to an isolated island ecosystem.

“Seeing it on a map is one thing. But being there really drove home just how unique these ecosystems are,” Van Nuland reflected. “There were a lot of unnamed species that we found.” The potential loss of these rare fungi could have cascading effects, destabilizing the ecosystem and diminishing its unique ecological roles. “People picture protecting the Amazon rainforest,” Van Nuland noted, “But for soil, it’s hard. Where are the Amazons of the soil?”

These “Amazons of the soil” may be scattered across the globe. The Alaskan North Slope represents just one of many potential fungal hot spots that SPUN researchers intend to investigate. The organization collaborates with scientists in 79 countries. Kiers herself participates in approximately five expeditions annually. In Kazakhstan, SPUN is studying how fungi assist grassland plants in resisting drought. On the Palmyra Atoll in the central Pacific, researchers are examining how trees and their fungal partners colonize coral rubble and compete with invasive coconut palms. In Lesotho, southern Africa, fungi appear to play a role in preventing erosion in agricultural lands. “Each place that we’ve gone to has a different story,” Van Nuland observed. The biodiversity data collected from each site feeds back into SPUN’s predictive model, refining its ability to identify future hot spots.

The research is ongoing, with plans for return expeditions. In the summer of 2026, Van Nuland and his team will revisit Deadhorse to measure the flux of carbon into and out of the tundra soil. The long-term impact of thawing permafrost on Earth’s carbon balance remains a significant scientific uncertainty. However, as the relentless Arctic daylight returns each year, new carbon pools become accessible to the most intrepid fungal hyphae. The scientific community eagerly awaits the answers these subterranean networks will provide to those patient enough to listen.