Data from: Multi-temporal analysis reveals that predictors of mountain pine beetle infestation change during outbreak cycles

Over the past two decades, severe mountain pine beetle (MPB) outbreaks have affected several million hectares of forest in western North America. The extensive ecological and economic damage caused by widespread insect infestations make understanding the development and spread of MPB outbreaks critical. This study uses a time series of Landsat5 TM and Landsat7 ETM + images to map the spread of mortality due to MPB infestation in Arapaho–Roosevelt National Forest, Colorado, between 2003 and 2010. The Normalized Difference Vegetation Index (NDVI) and change in the Normalized Difference Moisture Index (NDMI) were used to classify red attack and non-red attack stands based on a maximum likelihood algorithm with manually selected training classes. The classification was validated by comparison with independent interpretations of aerial photography and high-resolution satellite imagery. The classification had good agreement (84.5–90.5% total accuracy). Cluster analysis for time series showed infestations originating in several different locations on the landscape early in the time series and subsequent infestations likely represent a combination of dispersal from outbreak populations and independent population growth. Analysis using conditional inference trees suggested that a combination of forest composition, topography, and dispersal predicted the distribution of MPB infestation on the landscape and that the importance of these variables changed as the outbreak developed. In early years, red attack was associated with forest and topographic characteristics known to influence susceptibility to MPB. Over time, beetle pressure became an increasingly important predictor of red attack, but in later years host tree availability played an important role in outbreak spread. If this pattern occurs consistently in MPB outbreaks, knowledge of these patterns could aid managers in targeting their efforts to reduce damage resulting from MPB outbreaks.mpb_outbreak_mapsThese files represent maps of mountain pine beetle infestation in Arapaho and Roosevelt National Forests, Colorado, for the years 2003, 2005, 2006, 2009, and 2010. They are identical in their format and methods of preparation, with the exception that they represent different time periods. They were developed from Landsat5 (2005, 2006, 2009, 2010) or a combination of Landsat5 and Landsat7 (pre-scan line corrector failure) imagery (2003) (path 32 row 34). All images were atmospherically corrected and converted to reflectance. Cloud cover was manually removed, with areas obscured by cloud cover in one year removed from all images. The study area was masked to include only forested areas in Arapaho and Roosevelt National Forests. The images were classified using a supervised maximum-likelihood algorithm in ENVI v.4.8 with training classes selected based on initial NDVI and change in NDMI between images. The training classes were hand selected so that Red Attack was represented by pixels having high initial NDVI and declining NDMI between image pairs. The classification was validated by comparison with high-resolution orthoimagery. In each file, 2 represents the binary class "Red Attack," and 1 represents "Non-Red Attack." Files use the UTM Zone 13 N projection based on the WGS 1984 geographic coordinate system.point_dataThis is a spreadsheet data set containing data on infestation status (from outbreak maps) forest composition and structure, topography, and outbreak spatial relationships for 2000 randomly-generated points. These data were used to create conditional inference tree models analyzing how predictors of MPB spread change during outbreak cycle