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Structural analysis of the subalpine forest in southern Alberta shows that the old—growth Picea—Abies forest has succeeded even—aged stands of Pinus contorta var. latifolia Engelm. that became established after fire 150—200 or more years ago. Because P. Contorta regeneration fails beneath its own canopy, an irregular— to uneven—aged understory of Picea engelmannii Parry x P. glaca (Moench) Voss. and Abies lasiocarpa (Hook) Nutt. becomes established. As the even—aged P. contorta overstory ages, sporadic death of overmature trees permits an irregular— to all—aged Picea—Abies forest to emerge and dominate, unless fire reinitiates the succession to even—aged P. contorta. Extensive and frequent fires in the past, mainly initiated by "dry" electrical storms, have prevented long—term successional development and have maintained most of the forest in the early P. contorta—dominated phase of the succession. Introduction of effective fire protection is now permitting progress toward the late successional phases. Widespread development of the Picea—Abies phase and the decadent Abies—Picea phase that follows are forecast. The ecological effects of such fire—protection policies are questioned. A silvicultural program of fire prescription is suggested for the maintenance of the fauna and wilderness value of the mountain national parks. Silvicultural alternatives in harmony with the ecology of the forest are suggested for the implementation of multiple—use policies in the Rocky Mountain Reserve.