Tree rings

Not only beavers cut trees, humans too. In the nearby woods a lot of cut trees are waiting to be brought away. It gives me the possibility to have a look at the rings.
In the area where I took this picture most of the felled trees had the chance to turn 50 before someone thought that that was enough.
I no not so much about the tree rings, but as far as I know they can tell you the age (one per year in a climate like ours). But also how well they did in each year.
All of the trees seem to have suffered of drought the last 20 years. The first 20-30 years were good, but then the rings started to become very small. And the last 10 years are in general very meager.