The 2018 National Insect and Disease Risk Map (NIDRM) developed by USFS-FHAAST indicates locations where forests are stressed and susceptible to outbreaks of native and non-native insects and diseases. These include forests with overly high stand densities, and where soil/site conditions contribute to drought. The basis for assigning risk is the expectation that 25% or more of live basal area (three times the natural background rate of mortality) will die over the next 15 years due to insects and diseases.