The wood inside the average tree might seem barren, but it’s home to an incredibly diverse array of life. More than 1 trillion fungi, bacteria, and other microbes live inside the average trunk, according to the most comprehensive survey yet conducted, comprising unique communities specialized to various tree species. …Microbes are an important part of plant life. Fungi in the soil help roots access water and nutrients, for example, and beneficial bacteria and fungi on leaves can prevent infection by harmful fungi or bacteria. But little is known about the microbes living inside healthy wood, which makes up a huge amount of biomass. The estimated 10 trillion trees on the planet contain 450 gigatons of carbon, dwarfing the 2 gigatons found in animals. …Ultimately, researchers might find ways to adjust the microbiome in trees to help protect them from pathogens.