Crazy off-in-another-direction suggestion: If you have the iron, consider replacing your arboretum/logger combos with a Steve's Cart using the Wood Cutter tool, a Coal Engine, and a lot of storage. Once you've gotten one (or more) of these set up, the most difficulty you'll have in maintenance will be the logistics of ferrying over the materials for processing, as it'll run infinitum off of a small amount of the wood it harvests.
No more angsting over having to supply dirt again, although if you do the logistics right and also run a farmer (that can use a Solar Engine instead and just run during the day as wheat doesn't exactly get in the way like leaves/branches do) you can use the wheat to handle the other side of your supply chain in making biomass (wheat->plantball->(macerator)->dirt+more wheat=compost). As for all the wood... consider if you might find running some high pressure steam boilers useful, with a nice handy supply of charcoal right there. =)
Just a thought if you were interested in diverging from the Forestry method and maintenance.
(Additionally, if you didn't want to bother with the wheat farm at all, if you're using Oak you could run all the apples through the Squeezer for juice and mulch for the biomass process instead... juice produces 50% more biomass per sapling... I'm just not certain if this will have an appropriate equilibrium state doing it that way as I haven't tried it out myself yet).