>Even if that’s true, what bearing does it have on the effect of plant growth on the triggering of microbial activity?

Possibly if there is too much CO2, plants might flip switches and reduce growth/size, as happened in the radiation case and therefore reduce the upcoming cycles of CO2 generation. So they might grow like crazy but smaller plants.

Therefore the article is missing a huge consideration, in other words one cannot make inferences about more CO2 release or microbial activity unless genetics considered as was the case with radiation as we have learned recently from nuclear accidents.