There is extensive evidence of tree-microbe interactions within soils, however recent research has highlighted diverse microbial communities exist within the bark of trees. For example, methane is transported from soils to the atmosphere through tree stems, and we have found active methanotroph communities within the bark of several Australian tree species. These methanotrophs are capable of reducing net methane emissions through tree stems by ~ 36%. While exploring the microbial communities within tree bark, we have also found nitrogen fixers, trace gas oxidizers and microbes usually associated with soil/sediment processes in the bark of trees. The biogeochemical cycling mediated by the diverse microbial community within the bark of trees is underexplored, but could potentially play an important role in regional and global biogeochemical cycles. This talk will cover the path the research team has taken from preliminary field-based measurements to metagenomic analysis and lab-based assays in an attempt to unravel the importance of tree bark microbial communities in forest biogeochemical cycles.