Quiver tree trunk height before branching is quite variable. Widening at the base comes with age to many of them; some starting early, others waiting long. Smoothness of the bark is not relinquished in the same stage on all trees.
Not all parts of the forest have high percentages of aged trees.
The steepness of the slope in the bare, stony terrain does not seem to affect tree growth. Hardship endured in the past is reflected in the limited spread of or thinning and pronounced elongation of branches in some old crowns.