Model Notifications

Error in VDDT model for biophysical setting 1080 in mapping zone 33: The "time since disturbance" function in the VDDT model for BpS 1080 was not attributed appropriately.

Background & Advice:

As a result of final quality control procedures for LANDFIRE (LF) National, it was noticed that the "time since disturbance" function in the VDDT model for BpS 1080 was not attributed appropriately. According to LF rules, time since disturbance should be set to less than or equal to one less than the class duration. This ensures that the time since disturbance function occurs before a deterministic transition shifts pixels to another class. In the case of BpS 1080 in mapping zone 33, time since disturbance in Class C was set to 49, although, according to LF rules, it should have been set less than or equal to 33 because the duration of Class C was 34 years. When time since disturbance is set to 49 in Class C as originally modeled, the percent of the landscape in classes A-D are 15, 30, 25 and 30, respectively. When time since disturbance is set to 33 in Class C, as it should have been attributed according to LF rules, the percent of the landscape in classes A-D changes to 15, 45, 20 and 25, respectively. Based on the assumption that the modelers achieved the results they wanted with the time since disturbance function set to 49 in Class C, it was decided to leave it as is. For future use, this model should be reassessed. Individuals intending to use this model locally may need to re-parameterize the model.