In a vaguely fantasy renaissance world threatened by monsters, certain reclusive tribal spellcasters follow religious traditions giving them nature based spells. Specifically one spell who's limits are such: the caster picks a point at an area near him (within 150 ft from him), and cast this spell over 8 hours, enriching the land. All plants in a half-mile radius centered on a point within range become enriched for 1 year. The plants yield twice the normal amount of food when harvested.
If he cast it immediately instead, it only effects an area of 100ft radius centered on where he pointed, and all plants in that area become thick and overgrown, where even humans have trouble walking through grass. The process takes 6 seconds.
The magic uses matter manipulation to create the plants instead of relying on nutrients from the ground. As long as there's plants present in radius, the spell works.
They can cast this spell twice a day. What would be the societal impacts of this spell, and how would it effect how people lived in communities with these casters?
These casters dwell in forests and other secluded wilderness locations, where they protect the natural world from monsters and the encroachment of civilization. Some are tribal shamans who heal the sick, pray to animal spirits, and provide spiritual guidance. They’d sooner offer their services to farmers who needed to grow crops to survive rather than the expansion of the agricultural industry.
The society of this world is economically and technologically comparable to Western Europe during the late Middle Ages - early Renaissance. Gunpowder is rare in use, but most weapons are bows, spears, swords, etc. Five other types of spell casters exist, but they cannot use nature magic. Roughly 1/20 of the population can use magic.
