Like Humans, Every Tree Has Its Own Microbiome, a New Study Has Found

Summary

A forest is a complex, dynamic ecosystem in which a rich array of living things, from old-growth trees to microscopic fungi, interact and depend on one another for survival.So is the inside of a tree, it turns out.Earlier this month, a team of scientists published the most comprehensive study of the microbiomes living inside tree trunks. Their findings suggest that the woody tissues of trees contain a trillion microbial cells above and beyond actual tree cells: communities of bacteria and single-celled organisms called archaea that have specialized to different parts of the tree and even to individual tree species.The study’s results, published in the journal Nature, reveal a vast and largely unexplored reservoir of microbial diversity. “A tree individual is sort of a complex ecosystem in and of itself,” said Jonathan Gewirtzman, an ecosystem ecologist at Yale University and an author of the study.He noted that while the research is still in its early stages, it was “sort of impossible” that some of these microbes weren’t crucial to a tree’s health, growth and immunological resilience.The team sampled more than 150 trees across 16 species in the Northeastern United States. They extracted wood cores, all thinner than a pen, from red maples, black birches, white ash trees and more. Then, the team tried out a variety of methods — grinding, blending, beating the wood samples — to extract the DNA and estimate the microbial population in the tree trunks.Microbes can live in two different parts of the tree trunk: the outer wood, known as sapwood, and the inner wood, known as heartwood. The new study found that each region has its own community of microbes. Sapwood is dominated by microbes that require oxygen, whereas heartwood is dominated by microbes that don’t. Much of the methane produced by a tree originates from the heartwood, the study found.“That’s really exciting, because it shows that the internal woody tissues are quite dynamic environments,” said James McDonald,...