Natural reformation means that the reformation is done by spreading the seeds from different seeding trees inside the forest. Sometimes this can also be done by planting tree sprouts (mainly aspen). Most of the lands forests are born naturally.
Artificial reformation is used in situations like: there is no way to naturally reform a forest, a different species is wanted, the speed of the reformation process has to increase, a swamp must be turned into a forest.
Pine is seeded in rough areas where the ground vegetation doesn’t bother the development of sprouts. A successful seeding process can be ensured by breaking the surface of the seeded ground.
Afforesting a lush forest is usually done by planting. Sprouts that are grown in nursery gardens are different aged and sized. The main rule of thumb is that the lusher the reformation area is the bigger sprouts must be used. Breaking the surface of the ground is mostly always necessary.