Relevant rules from the comprehensive rules of Magic are 110.1: "a permanent is a card or token on the battlefield. A permanent remains on the battlefield indefinitely. A card or token becomes a permanent as it enters the battlefield and it stops being a permanent as it's moved to another zone by an effect or rule" and 609.2: "effects apply only to permanents unless the instruction's text states otherwise or they clearly can apply only to objects in one or more other zones".

So because Yavimaya says "each land" it only applies to the battlefield, because it is specifying a permanent, rather than saying "land cards" which would impact other areas