Five major subunits, or habitat segments, were recognized in the lodgepole pine (Pinus contorta) ecosystem in northeastern Utah [USA]. Tame mule deer (Odocoileus hemionus hemionus) obtained significantly greater dry-weight consumption per unit time spent feeding on natural and created openings compared to forested segments. Ranking in descending order as forage sources for deer were: clearcut forest, dry and wet meadows, mature forest and stagnated forest. Forbs were the most important forage class in diets from all habitats, but especially nonforested ones where forbs averaged 91% compared to 61% on forested segments. The difference in forb production on the same comparison was great, 533 and 22 kg/ha, respectively.