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    Author(s): Charlie Schrader-Patton; Nancy E. Grulke; Melissa E. Dressen
    Date: 2016
    Source: Gen. Tech. Rep. PNW-GTR-940e. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p.
    Publication Series: General Technical Report (GTR)
    Station: Pacific Northwest Research Station
    PDF: View PDF  (1.0 MB)


    Forest disturbances are increasing in extent and intensity, annually altering the structure and function of affected systems across millions of acres. Land managers need rapid assessment tools that can be used to characterize disturbance events across space and to meet forest planning needs. Unlike vegetation management projects and wildfire events, which typically are well documented, there is often insufficient data on the extent and intensity of insect and disease outbreaks during periods between intensive inventories. This report describes a rapid assessment approach using normalized difference vegetation index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor at a resolution of 250 m to survey within-year forest damage from insect outbreaks. We aggregated the mean biennial NDVI loss (ratio of NDVI values in the target year and NDVI values in the baseline year) for vegetation polygons (stands) in a study area within the Medicine Bow-Routt National Forest in north-central Colorado and classified these stands to produce tabular summaries of NDVI loss by stand species composition, canopy cover, and tree size. NDVI loss by species class corresponds well at the regional scale with trends in forest health aerial detection survey estimates of trees killed by damage agents. However, our results were confounded by drought response and scale/aggregation issues at the stand level. The methods presented here show promise and can be quickly applied to any forested landscape with spatially explicit stand information. Stand-level data produced with these techniques can be used to characterize vegetation for stand reassessments, forest planning efforts, as well as to study insect and disease activity across a range of spatial and temporal scales.

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    Schrader-Patton, Charlie; Grulke, Nancy E.; Dressen, Melissa E. 2016. Characterizing a forest insect outbreak in Colorado by using MODIS NDVI phenology data and aerial detection survey data. Gen. Tech. Rep. PNW-GTR-940e. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p.


    Aerial detection survey, NDVI, forest health, disturbance, MODIS.

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