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.