I harvest firewood from a small woodlot behind my house. I almost exclusively cut "culls" -- dead, dying, or diseased trees that aren't going to yield much additional wood in the future anyway.
My current strategy for figuring out which trees to cull is to walk around during the summer when the trees are in full leaf and flag those that:
- have portions of the crown with no leaves (i.e. bare, dead branches),
- have obvious beech bark disease (scale and then fungus; obviously only useful on beeches),
- have obvious damage (e.g. lightning or small birches that have bent from wind/ice storms).
My primary goal is firewood. Main species are beech, birch, fir (or hemlock, I might be mis-identifying the fir), with some maple, ash, cherry, and spruce. These are 60-90 foot tall trees, perhaps 50-80 years old on the high side.
Are there alternative methods I could or should be using to identify which trees to cull?
I'm especially interested in strategies that would be useful in fall/winter when the leaves are gone. Last year I was too busy during the summer and missed my chance to check the crowns and flag while leaves were out.