It may not always be the case that natural regeneration is the best option on a particular site, this depends on the management objectives of the forest to be established and any environmental sensitivities that may need to be taken into consideration. In time, pioneer species such as willow and birch will establish themselves on bogs - however, afforestation of these site types may offer an opportunity to introduce trees of superior genetic quality in a shorter space of time.
For these reasons, the suitability of natural regeneration on reforestation sites is made by my Department on a case-by-case basis.