I would say both. The book describes how crops grew overnight, and even animals (like stionoirs) became mature quickly (in a matter of hours or days, I can't find the exact reference right now). I suppose it would be the same for trees.
But of which forests are you thinking? I thought that the center of Cyradon was mostly plains. In the map I have, the closest forests are quite far (sic). The Ritual was able to heal only a small portion of the Devastation. I assumed that when other Rituals would be perfomed, it will be at the top of Belynar, in line with the "heart" of the land.