The authors suggest that fire severity varied greatly across most of these forests, and that high severity fires were common and burned thousands of hectares at a time. High severity fire typically varied along elevation and moisture gradients, so that areas with increased dominance of Douglas fire typically burned at higher severities while xeric sites dominated by ponderosa pine typically burned at low-severities consistently. However, periods of drought or wind events can override fuel conditions leading to higher fire severities and variation from year to year. Furthermore, under a more variable-severity fire regime, fuel loads tend to be more spatially heterogeneous which is consistent with fuel data from the US Rocky Mountains.

Finally, the authors found that tree regeneration was abundant after, and even enhanced by, high severity fire.