We have conducted a mesocosm long time experiment to inspect the bacterial community dynamic on one kind of refractory organic matter that are woods pieces. Oaks and Pine woods pieces were used and sampled 5 times during a 10 months incubation, and for each time point the bark, the wood surface and the center were taken. During the same periods an in situ experiment was set up in a Mediterranean canyon, which is one of the way of terrestrial organic matter transportation to the deep sea