Appropos of nothing in particular I was wondering what factors cause the notable changes in the way a tree grows rings.
Obviously climate differences, the cycles used to calibrate tree ring dating.
Local water table changes as would probably occur in an area where the ground is heaved up or down.
Local building and water abstraction requirements.
Felling other trees; planting other things.
Balance of the tree, as mentioned, the tree lost branches. Gravity will affect the way the tree needs to produce branches. (Note the shapes of trees growing on hills vs those on flat land.)
Covered in the above but not normally noticed even by tree huggers is the effect of aerodynamics.
Trees and bushes in an untended coppice will form an overall curve to minimise the effects that gales will have on a tree. The same way that the individual trees grow out to maximise the light available to them.
Remove some and the environment is either better or worse, depending on the competiton.
Have you got a full picture of the cross section and can you highlight the rings involved please?
I believe (I can't back it up but) the way a tree pumps up water depends on the twisting motion imparted by the wind on its branches.