There’s a thriving community of diverse microbes living in tree wood, a new study led by a Yale School of the Environment team of scientists has found. A single tree hosts about one trillion bacteria in its woody tissue. Trees are Earth’s largest biomass reservoir and store more than 300 gigatons of carbon. However, what is living in their wood has largely been unexplored. The study, published in Nature and led by YSE doctoral candidate Jonathan Gewirtzman and Wyatt Arnold ’24, establishes a new frontier for understanding tree physiology and forest ecology that can assist in forecasting forest response to future change and help trees adapt to climate change. “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,” Gewirtzman said.