Assessing the Impact of a Mountain Pine Beetle Infestation on Stand Structure of Lodgepole Pine Forests in Colorado Using the Forest Inventory and Analysis Annual Forest Inventory

The Forest Inventory and Analysis (FIA) annual inventory system began in Colorado in 2002, which coincided with the onset of a major mountain pine beetle (Dendroctonus ponderosae) epidemic. The mortality event, coupled with 11 years of annual inventory data, provided an opportunity to assess the usefulness of the FIA annual inventory system for quantifying the effects of the beetle epidemic on the numbers and distribution of lodgepole pines (Pinus contorta) in Colorado before, during, and after the infestation. Mortality of lodgepole pine peaked around 2007, averaging 38 million trees annually. The structure of existing lodgepole pine forests underwent a significant change after the beetle epidemic. The proportion of large-diameter live lodgepole pines dropped from an average of 37% over the years spanning 2003–2005 period to an average of 25% over the years spanning 2010 –2012.