on a molecular level, all sorts of possiblities arise when a vibration is constant upon organic matter. noticing any difference is always the culprit, as in this case.
That's testable. Put sample of wood on a vibrating test pad. Vibrate for a year or something, analyse, and analyse control sample from same block of wood left in same climatic conditions. I am sure it has been done by someone given that wood is used as a structural element in buildings.