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Statistical Prediction of Tree Mortality in California

Photo of An aerial view of tree mortality on the Sierra National Forest, California. Steve Dunsky, U.S. Department of Agriculture Forest Service.An aerial view of tree mortality on the Sierra National Forest, California. Steve Dunsky, U.S. Department of Agriculture Forest Service.Snapshot : Large parts of California are currently experiencing dramatic levels of tree loss due to a combination of drought and bark beetles. Forest Service scientists developed forecasts of bark beetle locations and intensity of tree damage 6 months prior to completion of aerial surveys, enabling land managers to identify areas in need of spot treatment. California’s Department of Forestry and Fire Protection (CalFire) also used the forecasts to as a warning system for increased fire risk.

Principal Investigators(s) :
Grulke, Nancy E.Preisler, Haiganoush K.
Research Location : California
Research Station : Pacific Northwest Research Station (PNW)
Year : 2016
Highlight ID : 1189

Summary

The Forest Service Forest Health Protection staff conducts aerial surveys to collect data and map the extent and severity of tree mortality. The surveys are compiled and finalized across the summer months, but prediction of the mortality earlier in the year, such as April, would be highly useful because there would be more time to assign personnel and contracting for its management. Forest Service scientists developed forecasts of bark beetle location and intensity for California 6 months prior to the completion of aerial survey. Historical aerial survey data and weather variables known to influence bark beetle success, such as precipitation, maximum minimum winter temperature, and growing degree days were used in the predictions. Comparison of the 2015 forecast with the 2015 survey data showed only 2 percent of the forecast fell outside the expected range of mortality.

Forest Service Partners

External Partners

  • Forest Health Protection
  • Pacific Southwest Region
  • Pacific Southwest Research Station