I'm aware of the potential of making the soil sterile but I figure I have boatloads of compost and other organic material to revitalize it afterwards. There's a portion of one bed where there are wood chips at least 12", deep and it doesn't phase the comfrey. If I were an earthworm, sow bug, millipede, or other relatively mobile creature I'd be certain to find another domain to inhabit as the temperature increased. I don't know about all the other tiny critters like nematodes, bacteria, etc. But I would think that the soil would repopulate with those also eventually. The problem with chop & drop is I have way too much of that to do in other areas and I just can't seem to keep up with it.