UV-B-MEDIATED CHANGES ON BELOWGROUND COMMUNITIES ASSOCIATED WITH THE ROOTS OF ACER-SACCHARUM

1. Little is known about how exposure to UV-B radiation affects rhizos phere microbes. Rhizosphere organisms are fed primarily by root-derive d substrates and fulfil functions such as mineralization, immobilizati on, decomposition, pathogeneity and improvement of plant nutrition; th ey form the base of the below-ground food web. 2. In this study, we ex posed Sugar Maple (Acer saccharum) seedlings to UV-B radiation in orde r to determine if UV-B influences the activities of mycorrhizal and no n-mycorrhizal fungi, bacteria and microbe-feeding arthropods in the rh izosphere. 3. Below-ground organisms are greatly affected by UV-B radi ation. Overall, carbon-flow in the plant soil system was shifted from a mutualistic-closed, mycorrhizal-dominated system to an opportunist-o pen, saprobe/pathogen-dominated one.