Recent research led by a team of Yale University scientists has revealed the extensive and diverse microbial life thriving within the woody tissues of trees. This amazing research, published in the journal Nature, demonstrates the complex connection between trees and their microbiomes. Perhaps most importantly, it uncovers some of the hidden secrets behind the critical ecological roles these microorganisms play in our forest ecosystems.
The team includes experts in soil and ecosystem ecology, biogeochemistry, and plant physiological ecology. To get at these questions, they surveyed 150 living trees from 16 diverse species across the northeastern United States. This exploratory work was spearheaded by Mark Bradford, the E.H. Harriman Professor of Soils and Ecosystem Ecology. He partnered with Peter Raymond, the Oastler Professor of Biogeochemistry and co-director of the Yale Center for Natural Carbon Capture. Craig Brodersen, the Howard and Maryam Newman Professor of Plant Physiological Ecology, was integral to this research. Integral to this project was Marlyse Duguid, research scientist and lecturer on race, space, and data.
Exploring the Tree Microbiome
To the researchers’ amazement, they found that each of those trees hosted close to one trillion bacteria per inch within that woody tissue. Microbes flourish in two very different environments of a tree, heartwood and sapwood. Just like those coffee cherries, each region is a reflection of its own distinctive microbiome. The inner wood is literally alive with anaerobic microbes, which live without oxygen. By contrast, the exterior wood is teeming with aerobic microbes that thrive in oxygen-rich environments.
To uncover these hidden microbial communities, the team undertook an extensive process involving freezing, smashing, grinding, and beating wood samples over a year. This careful approach helped them to better assess the microbial community living inside trees.
Wyatt Arnold, one of the graduate researchers who conducted this work stated that he’s thrilled to have played a part in this work. He stated, “I was thrilled to contribute to this work given that few habitats so vast and widespread remain to be investigated, and especially one so familiar to folks as living trees.” He likened the adventure to that of a 19th-century ecologist. Picture this—finding a brand new, never before seen island of unique plants and animals!
Implications for Carbon Storage and Tree Health
The impact of this research goes far beyond microbiomes by itself. Carbon sinks Trees are the earth’s largest long-term carbon sink, storing over 300 gigatons of carbon worldwide. Understanding the dynamics of microbial life within trees can shed light on how these internal ecosystems influence broader biogeochemical functions in forests.
The implications are huge. Miyko Gewirtzman, another member of the research team, highlighted the significance of these findings in assessing tree health and growth. He remarked, “Understanding these internal ecosystems gives us insights into trees’ broader biogeochemical functions and how they might contribute to forest carbon cycling and nutrient exchange processes in ways we hadn’t fully considered before.”
Perhaps some of these microbial communities hold the key to optimizing tree growth. They could help with disease resistance, and they may create useful compounds that we don’t even know about yet. The eventual applications of this knowledge will undoubtedly reach across the globe and extend deep into forestry management and conservation efforts.
A Call for Further Exploration
The team’s findings have already led to a deeper dive into tree microbiomes, exploring different species and environments. With climate change continuing to threaten ecosystems around the globe, gaining a better understanding of the microbial diversity found within trees is more necessary than ever before. Gewirtzman said we’re sitting on a huge reservoir of undiscovered biodiversity. There are millions of microbial species that call trees home, and we’ve never catalogued them. We must catalogue and learn from these communities before climate change inevitably moves the goalposts.
A pair of recent Yale graduates—Cade Brown and Naomi Norbraten—were instrumental in making this research push a reality. Together, their contributions underscore the collaborative spirit of scientific inquiry at Yale. Their contributions are a testament to the increasing priority being placed on bringing along the next generation of scientists in cutting edge research.
