Effect of prior disturbances on the extent and severity of wildfire in Colorado subalpine forests.

Disturbances are important in creating spatial heterogeneity of vegetation patterns that in turn may affect the spread and severity of subsequent disturbances. Between 1997 and 2002 extensive areas of subalpine forests in northwestern Colorado were affected by a blowdown of trees, bark beetle outbreaks, and salvage logging. Some of these stands were also affected by severe fires in the late 19th century. During a severe drought in 2002, fires affected extensive areas of these subalpine forests. We evaluated and modeled the extent and severity of the 2002 fires in relation to these disturbances that occurred over the five years prior to the fires and in relation to late 19th century stand-replacing fires. Occurrence of disturbances prior to 2002 was reconstructed using a combination of tree-ring methods, aerial photograph interpretation, field surveys, and geographic information systems (GIS). The extent and severity of the 2002 fires were based on the normalized difference burn ratio (NDBR) derived from satellite imagery. GIS and classification trees were used to analyze the effects of prefire conditions on the 2002 fires. Previous disturbance history had a significant influence on the severity of the 2002 fires. Stands that were severely blown down (> 66% trees down) in 1997 burned more severely than other stands, and young (approximately 120 year old) postfire stands burned less severely than older stands. In contrast, prefire disturbances were poor predictors of fire extent, except that young (approximately 120 years old) postfire stands were less extensively burned than older stands. Salvage logging and bark beetle outbreaks that followed the 1997 blowdown (within the blowdown as well as in adjacent forest that was not blown down) did not appear to affect fire extent or severity. Conclusions regarding the influence of the beetle outbreaks on fire extent and severity are limited, however, by spatial and temporal limitations associated with aerial detection surveys of beetle activity. Thus, fire extent in these forests is largely independent of prefire disturbance history and vegetation conditions. In contrast, fire severity, even during extreme fire weather and in conjunction with a multiyear drought, is influenced by prefire stand conditions, including the history of previous disturbances.

[1]  Dominik Kulakowski,et al.  Influences of fire history and topography on the pattern of a severe wind blowdown in a Colorado subalpine forest , 2002 .

[2]  Christof Bigler,et al.  MULTIPLE DISTURBANCE INTERACTIONS AND DROUGHT INFLUENCE FIRE SEVERITY IN ROCKY MOUNTAIN SUBALPINE FORESTS , 2005 .

[3]  William L. Baker,et al.  Effect of vegetation on the impact of a severe blowdown in the southern Rocky Mountains, USA , 2002 .

[4]  P. White,et al.  Natural disturbance and patch dynamics: an introduction. , 1985 .

[5]  D. Kulakowski,et al.  INTERACTIONS BETWEEN FIRE AND SPRUCE BEETLES IN A SUBALPINE ROCKY MOUNTAIN FOREST LANDSCAPE , 2003 .

[6]  Jacob Cohen.  A Coefficient of Agreement for Nominal Scales , 1960 .

[7]  Richard A. Minnich,et al.  Wildland Fire Patch Dynamics in the Chaparral of Southern California and Northern Baja California , 1997 .

[8]  D. Kulakowski,et al.  Effects of fire and spruce beetle outbreak legacies on the disturbance regime of a subalpine forest in Colorado , 2003 .

[9]  R. Werner,et al.  Fire and insects in northern and boreal forest ecosystems of North America. , 1998, Annual review of entomology.

[10]  Jeff S. Glitzenstein,et al.  Effects of the December 1983 tornado on forest vegetation of the Big Thicket, southeast Texas, U.S.A. , 1988 .

[11]  B. Stocks.  Fire Potential in the Spruce Budworm-damaged Forests of Ontario , 1987 .

[12]  O. Loucks,et al.  From Balance of Nature to Hierarchical Patch Dynamics: A Paradigm Shift in Ecology , 1995, The Quarterly Review of Biology.

[13]  W. Baker,et al.  A fire history from tree rings in a high-elevation forest of Rocky Mountain National Park , 2004 .

[14]  F. W. Smith,et al.  Disturbance patterns in southern Rocky Mountain forests , 2000 .

[15]  G. Malanson.  Intensity as a Third Factor of Disturbance Regime and Its Effect on Species Diversity , 1984 .

[16]  G. De’ath,et al.  CLASSIFICATION AND REGRESSION TREES: A POWERFUL YET SIMPLE TECHNIQUE FOR ECOLOGICAL DATA ANALYSIS , 2000 .

[17]  K. Elliott,et al.  Vegetation response to large scale disturbance in a southern Appalachian forest: Hurricane Opal and salvage logging , 2002 .

[18]  Range Experiment Station,et al.  Strategy for reducing mountain pine beetle infestations with ponderosa pine trap logs , 1983 .

[19]  Francis E. Putz,et al.  Hurricane damage to old growth forest in Congaree Swamp National Monument, South Carolina, USA , 1991 .

[20]  Monica G. Turner,et al.  Predicting the spread of disturbance across heterogeneous landscapes , 1989 .

[21]  J. M. Schmid,et al.  Spruce beetle in the Rockies. , 1977 .

[22]  D. H. Knight.  Parasites, Lightning, and the Vegetation Mosaic in Wilderness Landscapes , 1987 .

[23]  Jason S. Sibold,et al.  Spatial and temporal variation in historic fire regimes in subalpine forests across the Colorado Front Range in Rocky Mountain National Park, Colorado, USA , 2006 .

[24]  W. Hargrove,et al.  Effects of fire on landscape heterogeneity in Yellowstone National Park, Wyoming , 1994 .

[25]  D. H. Knight,et al.  Fire Frequency and Subalpine Forest Succession Along a Topographic Gradient in Wyoming , 1981 .

[26]  Anke Jentsch,et al.  The Search for Generality in Studies of Disturbance and Ecosystem Dynamics , 2001 .

[27]  R. Wein,et al.  Biotic and abiotic regulation of lightning fire initiation in the mixedwood boreal forest. , 2006, Ecology.

[28]  B. Law,et al.  Post-Wildfire Logging Hinders Regeneration and Increases Fire Risk , 2006, Science.

[29]  D. Despain,et al.  Natural Fire in Yellowstone National Park , 1977 .

[30]  E. Johnson,et al.  The Relative Importance of Fuels and Weather on Fire Behavior in Subalpine Forests , 1995 .

[31]  C. E. Van Wagner,et al.  Conditions for the start and spread of crown fire , 1977 .

[32]  D. V. Lear,et al.  Hurricane-fire interactions in coastal forests of the south: a review and hypothesis , 1998 .

[33]  Leo Breiman,et al.  Classification and Regression Trees , 1984 .

[34]  M. Turner,et al.  Landscape dynamics in crown fire ecosystems , 1994, Landscape Ecology.

[35]  Edwin M. Everham,et al.  Forest damage and recovery from catastrophic wind , 1996, The Botanical Review.

[36]  R. Paine,et al.  Compounded Perturbations Yield Ecological Surprises , 1998, Ecosystems.

[37]  G. Robinson,et al.  Conservation Policy in Time and Space: Lessons from Divergent Approaches to Salvage Logging on Public Lands , 1999 .

[38]  Thomas Kitzberger,et al.  Disturbance regime and disturbance interactions in a Rocky Mountain subalpine forest , 1994 .

[39]  Kate Lajtha,et al.  The Ecology of Natural Disturbance and Patch Dynamics , 1987 .

[40]  Charles W. McHugh,et al.  Fire behavior, fuel treatments, and fire suppression on the Hayman Fire - Part 4: Relation of roads to burn severity , 2003 .

[41]  W. Baker,et al.  A fire history of a subalpine forest in south‐eastern Wyoming, USA , 2000 .

[42]  G. Gruell,et al.  The Ecological Role of Fire in the Jackson Hole area, Northwestern Wyoming , 1973, Quaternary Research.

[43]  W. Romme,et al.  FIRE AND LANDSCAPE DIVERSITY IN SUBALPINE FORESTS OF YELLOWSTONE NATIONAL PARK , 1982 .

[44]  Richard A. Fleming,et al.  Landscape-Scale Analysis of Interactions between Insect Defoliation and Forest Fire in Central Canada , 2002 .

[45]  S. Manel,et al.  Evaluating presence-absence models in ecology: the need to account for prevalence , 2001 .