ill. (some color), col. map; Includes bibliographic references (p. 19-23 and 27-28)
SUMMARY Whitebark pine (Pinus albicaulis) is an ecologically significant component of high elevation forest and woodland ecosystems in the Cascade Mountain Range of Oregon and Washington. Its importance is noted as whitebark pine is recognized as a keystone species. The objectives of this study are to 1) gain an understanding of fire frequency and severity associated with whitebark pine forests, and 2) describe historic and current stand conditions and estimate potential ecological effects of fire exclusion policies. By applying standard field techniques (scar and core sampling) we compiled a dataset that describes fire's role in these timberline forests. We report on 55 fire history sites located in the Cascade Range. Incidence of fire was documented throughout the whitebark pine ecosystem in the Cascades, indicating that fire is a significant disturbance agent. Whitebark pine ecosystems appear to burn in a broad spectrum of severity and frequency. Fire return intervals ranged from 9 to 314 years. This broad range indicates that fire regimes in whitebark pine forests are site-specific more than species-specific. From stand reconstruction techniques, we estimate that since the 1920s, volume for all tree species including whitebark pine began to increase dramatically. Late-seral species have increased at greater rates, indicating fire exclusion as a causal agent facilitating and possibly driving changing forest conditions. Managers can reintroduce fire as a natural element of Cascadian whitebark pine forests. Because fire regimes vary greatly among these forests, it's recommended that site-specific targets for severity and frequency, rather than general range wide prescriptions be incorporated into burn plans. We provide guidelines for each of three study units with the goal to achieve burning conditions which are within the natural and historic regimes of these unique and threatened forests. IV
SUMMARY Whitebark pine (Pinus albicaulis) is an ecologically significant component of high elevation forest and woodland ecosystems in the Cascade Mountain Range of Oregon and Washington. Its importance is noted as whitebark pine is recognized as a keystone species. The objectives of this study are to 1) gain an understanding of fire frequency and severity associated with whitebark pine forests, and 2) describe historic and current stand conditions and estimate potential ecological effects of fire exclusion policies. By applying standard field techniques (scar and core sampling) we compiled a dataset that describes fire's role in these timberline forests. We report on 55 fire history sites located in the Cascade Range. Incidence of fire was documented throughout the whitebark pine ecosystem in the Cascades, indicating that fire is a significant disturbance agent. Whitebark pine ecosystems appear to burn in a broad spectrum of severity and frequency. Fire return intervals ranged from 9 to 314 years. This broad range indicates that fire regimes in whitebark pine forests are site-specific more than species-specific. From stand reconstruction techniques, we estimate that since the 1920s, volume for all tree species including whitebark pine began to increase dramatically. Late-seral species have increased at greater rates, indicating fire exclusion as a causal agent facilitating and possibly driving changing forest conditions. Managers can reintroduce fire as a natural element of Cascadian whitebark pine forests. Because fire regimes vary greatly among these forests, it's recommended that site-specific targets for severity and frequency, rather than general range wide prescriptions be incorporated into burn plans. We provide guidelines for each of three study units with the goal to achieve burning conditions which are within the natural and historic regimes of these unique and threatened forests. IV