Year Rings

The age of this allod can be calculated not only from its minerals, but also from its flora. Something tells me that the results of this research will be even more surprising.
However, let's not jump into conclusions. First, we need to study some tree cuts. If they indeed had been created with magic, as my furry friend supposes, than they will look rather differently from those grown naturally.

Here's your saw, there are the trees - come on, we have much work to do!

Very interesting... The trees look old, but they all have from one to three year rings, and the rings that are closer to the center are much thicker than the outer ones. I have a conjecture about how it all could happen, and I need you to help me prove it!