A team of researchers, including several Yale Institute for Biospheric Studies (YIBS) faculty affiliates, has uncovered a vast and previously unknown world living inside the wood of trees. Published in Nature, the study reveals that a single tree can host about one trillion bacteria within its woody tissues—forming highly specialized microbiomes that differ from those found in any other plant tissue or environmental niche.
While microbiome research has expanded rapidly in recent years, most studies have focused on environments such as soils, plant surfaces, or animal guts. The wood of living trees - the planet’s largest biomass reservoir - has remained largely unexplored. This new research changes that.
The team, which included YIBS faculty affiliates Peter Raymond, Marlyse Duguid, Craig Brodersen, Mark Bradford, and Jordan Peccia, examined more than 150 living trees from 16 species across the northeastern United States. Using newly developed methods to process woody tissue samples, they cataloged the bacterial, archaeal, and fungal communities living inside trees.
Their findings show that microbial communities in wood are distinctly partitioned between the outer sapwood and the inner heartwood. Each zone hosts unique communities with minimal similarity to other plant tissues or nearby soils. The heartwood, in particular, emerged as an entirely distinct ecological niche -an anaerobic environment rich in specialized archaea and bacteria that drive important biogeochemical processes.
This research supports the concept of trees as holobionts - integrated ecological units made up of the host and its associated microorganisms. By understanding the structure and function of these wood-inhabiting microbial communities, scientists can better explore their roles in tree health, disease resistance, and ecosystem functioning.
