Microbiome sustains forest ecosystem functions across hierarchical scales.

Forests are highly productive ecosystems that contribute to biogeochemical cycles of carbon and nitrogen, through which it regulates climate and global change. Forests are also spatially highly heterogeneous ecosystems that comprise a multitude of microbial-mediated reactive interfaces. These are mainly the root-soil interface, litter-soil interface, root-root interface, and plant-atmosphere interface. Each of these interfaces has its own unique characteristics, e.g., specific drivers that affect the microbial abundance, nutrient availability, microbial community, and the dominance of certain microbial taxa. Here, we review the microbial-mediated reactive interfaces in forests, focusing on interrelation and dynamics of fungi and bacteria on a broad temporal scale with ecosystem processes ranging from short-term events (e.g., seasonal changes) to long-term stand development suffering a global climate change (e.g., global warming or nitrogen deposition). We argue that in-depth knowledge of forest microbiology can only be obtained by exploring the complex forest microbiome and its ecosystem functions. Underpinning the basis for individual forest variation would ultimately facilitate the formulation of microbiome-based strategies in the future.