the topics o f ecosystem management (em) and ecological classification systems (ecs) are appearing more frequently in forest management literature. these systems facilitate our understanding, not only o f forests from a tree standpoint, but also by the associations o f shrubs, plants, soils, climatic and geological influences considered when describing a forest community for which a stand of trees is a component. this paper specifically describes the ecs commonly used by the minnesota department of natural resources (mn dnr) as well as the u.s. forest service. terminology associated with the description o f ecological units is listed and field techniques used by entry-level resource technicians are provided to help understand and utilize the ecs.