Earthworms have transformed the Isle of Rum's landscape

> They found that the presence of earthworms increased nitrous oxide emissions from soil by 42 percent and carbon dioxide emissions from soil by 33 percent. But they found no indications that earthworms affect soil organic carbon stocks — the carbon stored within the soil.

I'm not actually sure what to make of that statement. It seems like they're claiming worms disturb "not yet sunk" nitrogen and carbon dioxide but don't really affect anything deep in the soil. That tracks for what I know about what worms prefer compaction and temperature wise. That said, there are other organisms like mites that are far more efficient than worms - they just don't produce compost. I guess my naive question here is wouldn't that nitrogen and carbon already have high potential for release?