The role of the Forest of Arden is to serve as the pastoral setting needed to make the play satrical of pastoral literature. The plot of As You Like It was borrowed from a popular pastoral novel published in Shakespeare's time, Rosalynde, by Thomas Lodge. Pastoral literature is a genre of literature stemming all the way back to Ancient Greece and Rome that idealized a shepherd's country life in contrast with corrupt city life. In As You Like It, the Forest of Arden represents the country life and an escape from corruption while the Duke's court represents corrupted city life.
Literary critic Kenneth Muir points out several pastoral conventions Shakespeare uses to illustrate the pastoral genre he is satirizing. One pastoral convention found in the play is a rejected shepherd being sick in love with a shepherd who continues to refuse him. Shakespeare used the shepherd Silvius and his love for Phebe to represent this convention. However, Shakespeare takes the convention one step further by critiquing this type of convention through exposing the wrongfulness of Phebe's "vanity and pride" by having her tricked into marrying Silvius at the end of the play (Muir, "As You Like It"). We see Phebe being tricked in the final scene when Rosalind, still posing as Ganymede, asks Phebe, "But if you do refuse to marry me, You'll [promise to] give yourself to tihs most faithful shepherd [Silvius]" (V.iv.13-14). Having Phebe being tricked into marrying Silvius is a way of exposing Phebe's conventional reaction to Silvius's love as vain and prideful, and exposing her vanity and pride is certainly also a means of satirizing this pastoral convention, as well as pastoral literature as a whole.
Audrey, whom Touchstone marries, and William, who was in love with Audrey, represent a second pastoral convention (Muir). True to convention, both are uneducated, dimwitted country bumpkins. Touchstone stages a temporary marriage to her, but Audrey insists on a real marriage, showing us that in some ways, Audrey is morally above Touchstone, who claims that courtly manners are superior to country manners (Muir). Presenting Audrey as morally above Touchstone further serves to satirize the pastoral convention of idealizing the mindless, simple stupidity of a country bumpkin above the educated but corrupt city dweller.
A final pastoral convention seen in the play is the sudden transformation in the villain (Muir). In a split second, Oliver changes from being a murderer in pursuit of his brother Orlando in Arden to being a "pleasant and acceptable husband for Celia" (Muir). Since the transformation is so sudden, it is also comic, and the comedy helps to show exactly how Shakespeare is satirizing the conventions found in the pastoral literary genre.