I don’t think it’s that the plants are controlling the ratio. I think it’s that more C14 is being made all the time. And it only gets mixed into plants when they are living. Specifically it looks like C14 based CO2 is made in the atmosphere and then consumed by plants.
I see! If so, that makes sense, but the mechanics of C14 accumulation would be curious to see.
I don’t think it’s that the plants are controlling the ratio. I think it’s that more C14 is being made all the time. And it only gets mixed into plants when they are living. Specifically it looks like C14 based CO2 is made in the atmosphere and then consumed by plants.