As noted in my post below...

British Columbia already harvests the timber equivalent of 33,000,000 Douglas firs annually. This figure is less than 1% of the provincial resource base and a tiny fraction of the beetle-infested timber that surrounds the under-utilized infrastructure already in place.

The BC and Quebec governments are transitioning both the infrastructure and resource base away from traditional pulp-paper and construction industry support programs (i.e. US housing) to Bioenergy initiatives.

That said, Robert's Douglas fir analogy, albeit effective, is misleading.

Coskata Michigan is certainly not going to be harvesting Douglas fir but rather (in a perfect world) organically grown, nitrogenous fixing perennial Dedicated Energy Crops (DECs) such as hemp - a plant that maintains a higher biomass/btu ratio, higher biomass/acre ratio, not to mention an easier and more frequent harvesting profile.

They'd be better off rotting in place to help grow future trees.

As someone who's had to deal with them, if you leave them as you are suggesting, they spread to other trees.

Thus the normal method is to remove the infested trees in the cold weather and 'process' the trees.