Un-managed forests do not provide CO₂ relief

Left to it's natural life cycle, a forest will reach a climax stage where growth is dependent upon death.  This cycle creates a carbon balance where the CO₂ sequestered from new tree growth is matched by the CO₂ emitted by the decaying or burnt trees.

Not all trees decay from old age death.  An un-managed forest is susceptible to disease and fire contributing to the death part of the climax stage.

All over the world, non-native plants and animals strain resources for native species.  In Europe things are no different.  Non-native trees are common to un-managed forests.  With the controlled growth of managed forestry, non-native species are eliminated.