John Davison and colleagues published a paper addressing spatial and temporal dynamics of arbuscular mycorrhizal fungi (AMF) in the soil. AMF are microbes that live in the soil and colonize plant roots, exchanging nutrients and carbon with their plant hosts. Different species of AMF coexist in soil, forming communities that interact with plants growing nearby. This study identified the AMF communities present in a primeval forest (Järvselja, Estonia) by matching the AMF DNA present in soil against that of previously recorded AMF species. Soil samples collected from different forest plots revealed different AMF communities, showing the influence of forest microhabitat and the availability of different plant hosts. However, the composition of soil AMF communities at a single location did not change throughout the plant growth season (May-September). Since the AMF colonising plant roots are believed to vary seasonally, this suggests that the AMF in soil represent a constant "pool" from which different plant-AMF associations form and disband during the year. Read the full article.