We have not burned the trunks. They can be cut into lengths and burned in the stove over the winter. Ash doesn't need to season to burn well, as we found even with the small branches and green leaves,
though I did help the fire along with some of the rhododendron and snowberry twigs that I cut in spring last year. It went well even with the finest of fine mizzle in the air.
The yellow beyond the fire, in what was an area full of meadow buttercups, is now that of greater bird's-foot trefoil. As the buttercups lost their petals and began to make seed the trefoil flowers began to open so we have had weeks and weeks of yellow meadowy lawn down in this bottom part of the garden.