New plants will replace the dead plants and utilize the replaced CO2. Binding CO2 to the soil would be optimal, but I fail to see how the lifespan of plants is relevant here.
Because plants are subject to changing climate too. If regions get drier then all that CO2 will get released in a short amount of time. This is like technical debt. It's released CO2 that does not affect the climate yet but could do so in the future due to feedback loops.
And even if that doesn't happen, it's only 25% of the released CO2. 50% are still warming the climate and another 25% are still acidifying the oceans. So that's a pretty high cost for a few greener forests.
And then there is the issue that increased CO2 levels mostly increase the complex carbohydrate contents in plants. They do not produce more proteins since they need nitrogen for that. Which may actually make things worse for the foodchain. E.g. it decreases the nutritional value of pollen, which is a problem for bees.
So there is really not much positive value in there.
