Plants Grow Hidden Second Root System – And It’s Helping Fight Climate Change

Scientists discovered that many plants secretly grow a second network of roots more than three feet underground, tapping hidden nutrient pockets and potentially locking away carbon where microbes can’t easily release it.

Using deep-core samples from tundra to rainforest, they found nearly one-fifth of ecosystems show this “bimodal” root pattern—upending shallow-soil assumptions and hinting that Earth’s vegetation may be a stealthier ally against climate change than we realized.

Roots Go Deeper Than Expected

Plants and trees send their roots into the ground to soak up water and nutrients from the soil. Until now, scientists believed these roots tapered off with depth. But a surprising new study reveals that many plants grow a second, much deeper layer of roots—often extending more than three feet underground—to tap into hidden resources.

Published in Nature Communications, the research uncovers a previously unknown root pattern that could reshape how we understand ecosystems. Even more exciting, the findings suggest that plants may be storing carbon much deeper in the soil than we realized. That’s a hopeful discovery, especially as global carbon dioxide levels hit an 800,000-year high, according to the World Meteorological Organization’s “State of the Global Climate Report” issued in March.

“Understanding where plants grow roots is vital, as deeper roots could mean safer and longer-term carbon storage. Harsher conditions at depth may prevent detritus-feeding microbes from releasing carbon back to the atmosphere,” says Mingzhen Lu, an assistant professor at New York University’s Department of Environmental Studies and the paper’s lead author. “Our current ecological observations and models typically stop at shallow depths; by not looking deep enough, we may have overlooked a natural carbon storage mechanism deep underground.”

Deep Roots, Deep Carbon Storage

The research team used data from the National Ecological Observatory Network (NEON) to examine rooting depth. The NEON database includes samples collected from soil 6.5 feet below the surface, far deeper than the one-foot depth of traditional ecological studies. This unprecedented depth allowed researchers to detect additional root patterns, spanning diverse climate zones and ecosystem types from the Alaskan tundra to Puerto Rico’s rainforests.

“Understanding where plants grow roots is vital, as deeper roots could mean safer and longer-term carbon storage.”

NYU Environmental Studies Professor Mingzhen Lu

The scientists’ work focused on three questions, all with the aim of better understanding plants’ resource acquisition strategies and their resilience in response to environmental change:

• How does the abundance of roots change with depth?
• What are the factors that impact the distribution of roots with depth?
• Are nutrients in deeper soils equally, under-, or over-exploited by fine roots compared with surface soil?

Bimodal Roots Rewrite Plant Strategy

The researchers found that nearly 20 percent of the studied ecosystems had roots that peaked twice across depth—a phenomenon called “bimodality.” In these cases, plants developed a second, deeper layer of roots, often more than three feet underground and aligning with nutrient-rich soil layers. This suggests that plants grew—in previously unknown ways—to exploit additional sustenance.

“The current understanding of roots is literally too shallow. Aboveground, we have eagle vision—thanks to satellites and remote sensing. But belowground, we have mole vision,” observes Lu, former Omidyar Fellow who conducted part of this research at the Sante Fe Institute and as a postdoctoral affiliate at Stanford University. “Our limited belowground vision means that we cannot estimate the full ability of plants to store carbon deep in the soil.”

“Deep plant roots may cause increased soil carbon storage in one condition or lead to losses in other conditions due to a stimulation of soil microbes,” suggests coauthor Avni Malhotra, the lead author of a companion study that investigated the connection between root distribution and soil carbon stock. “This discovery opens a new avenue of inquiry into how bimodal rooting patterns impact the dynamics of nutrient flow, water cycling, and the long-term capacity of soils to store carbon.”

Implications for Climate and Collaboration

“Scientists and policymakers need to look deeper beneath the Earth’s surface as these overlooked deep soil layers may hold critical keys for understanding and managing ecosystems in a rapidly changing climate,” concludes Lu. “The good news is plants may already be naturally mitigating climate change more actively than we’ve realized—we just need to dig deeper to fully understand their potential.”

Reference: “A continental scale analysis reveals widespread root bimodality” by Mingzhen Lu, Sili Wang, Avni Malhotra, Shersingh Joseph Tumber-Dávila, Samantha Weintraub-Leff, M. Luke McCormack, Xingchen Tony Wang and Robert B. Jackson, 17 June 2025, Nature Communications.
DOI: 10.1038/s41467-025-60055-2

The study also included researchers from Boston College, Columbia University, Dartmouth College, the Morton Arboretum, the National Ecological Observatory Network-Battelle, Pacific Northwest National Laboratory, and Stanford University.

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