A forest represents an area of woodlands that are harvested to gain magical materials. It shouldn't be a farm or a garden - if that is what you want to take then we would recommend you choose the farm resource or a herb garden resource instead.
Upon taking a forest, you must choose one of ambergelt, beggar's Lye, dragonbone or iridescent gloaming. A forest produces 12 measures of the chosen material.
It is possible to harvest additional materials from a forest during any given season. You may spend 6 crowns to have the forest produce an additional 5 measures of the same material as it would naturally produce.
A forest can be upgraded using white granite obtained from the Bourse. Each time a forest is upgraded, the owner receives an additional 2 measures from then on.
To upgrade a forest requires Imperial wains of white granite equal to the level the forest is being upgraded to. So the first upgrade of a starting level 1 forest costs 2 Imperial wains of white granite, from 2 to 3 costs 3 Imperial wains, etc.
A forest can be diversified to sacrifice production of one material for another. To diversify a forest requires one Imperial wain of mithril and one Imperial wain of weirwood. Each time a forest diversifies, the owner chooses a different resource from the list for forests; the forest produces 2 measures of the new material at the expense of 2 less of the original material.