Even for the collection of herbs, the Elves had their own set of rules. Different sets of restrictions had limited the annual production. In fact, it was precisely the presence of the Elves that allowed the Emerald Forest to continue producing precious herbs 1,000 years after the end of the Dark Age. Without the Elves' protection, a forest 10 times bigger than the Emerald Forest would have been completely exploited by greedy humans.
Actually, Elves weren't the first inhabitants of the Emerald Forest. During the Dark Age, Elves lived as the slaves of the High Elves. Though Elves were similar to the High Elves in almost every aspect, even the names of their race, these names were only used by humans and other non-elven races. During that time, Elves had a status even lower than humans, who were also controlled by the High Elves.