Hazard and risk assessments provide a reasonable level of guidance as to what to expect on various sites. Hazard rating of stands is used for establishing priorities to undertake surveys, treatments, and for developing silviculture prescriptions. Stand risk refers to the proximity of a current outbreak and the likelihood that the insects will infest a particular stand. Stand risk can be determined by the density, extent, and proximity of a defoliator population, as well as through predictive sampling methods which will estimate the coming years' population and expected defoliation. Determine stage of outbreak Population and defoliation predictions.
Risk increases with increasing historical occurrence of outbreaks.
Defoliator impact is a function of severity and duration of defoliation, the species and age of trees attacked, tree spacing, and site quality. Figures 7 and 8 illustrate two methods of estimating overall and current defoliation of attacked trees respectively. Cumulative damage to a stand may have an effect on a variety of resources. However, negative impacts to wildlife may result from the loss of winter forage and thermal cover.