Reference data for this project came from two sources including: 1) Forest Service and RedCastle Resources field crews collecting vegetation information specific to this project in 2021-2022 (695 total); 2) legacy survey plots from the Forest Inventory and Analysis (FIA) program (21 total) (this data set does not contain FIA data); and 3) image interpreted sites (229 total).

Chugach National Forest and RedCastle personnel collected most of the ground data for this mapping effort using a variety of access means—such as, by helicopter, floatplane, boat, or by foot from existing trail and road infrastructure. The FIA data were cross-referenced with the classification key to label each plot with a vegetation type class. Image interpretation was used to bolster the number of reference sites. Reference data was consolidated into a single database and reviewed within the context of their corresponding mapping segment using high-resolution imagery.

For more detailed information on reference data methodology please see the Ketchikan-Misty Existing Vegetation Project Report.