What got damaged, large trees, shrub or mixed.
A weed whacked with a disc saves the back when cutting at low level,
chainsaw with solid nose bar and tungsten tipped chain, slow saw with oiler
opened up in full.
If you can find pressurised water or air that is mobile, use it to keep blowing the
ash from the saw, and in around the bar drive and clutch area, I would get
a cheap saw rather than use a very expensive one.
Put everything of no good in piles and if law permits burn it.
Otherwise pile everything in the worst spot on the plot, and let it rot,
when It starts to rot depending on how thick it is, a rotovator will break
it down further, you can of course be planting or otherwise preparing the
rest of the plot leaving the bad patch to rot.