Due to their small size, microorganisms can be widely dispersed and they colonize sterilized soils fast. However, details regarding quickness and successional patterns are poorly understood. We investigated the ability of airborne microorganisms to colonize sterilized soil at different heights above ground, and at different distances to a tree. Soil below the tree was colonized by bacteria already after 1 day and the sites above and away from the tree after only 4 days. The site below the tree was the only one to be colonized by culturable protists during the 15 day experiment. Our results show a pattern of succession when sterile soils are colonized by bacteria and protists. The tree was found to have a substantial impact on the recruitment of microorganisms.