Mapping Risk from Forest Insects and Diseases

Joseph W. Lewis (Presenter), Washington Office, USDA Forest Service

Background: This paper describes an effort undertaken to provide managers at the national level with the best currently available information on broad scale risks pertinent to the health of our nation's forests.  From a strategic standpoint, there is a need to identify where the highest potentials for forest health problems exist.  This information is needed for long range planning, and is essential for identifying priorities when developing policy for the Forest Service.

Purpose: The purpose of the risk mapping effort is to develop a geographic information system (GIS) database containing information needed for a strategic evaluation of forest health risk on all forested lands in the United States.  Development of this database, and corresponding coarse filter maps, is the first step in an analysis process designed to help set priorities for addressing forest health problems.  We used empirical data, models, and expert judgment to make projections of risks of tree mortality and/or growth loss from insects and diseases.  The insect and disease risk projections can be combined with other forest health-related risk estimates to provide much-needed help to policy makers at the national level.  Our estimates will be modified as more and better information becomes available through the long-term Forest Health Monitoring program and other information sources.  

It is understood that the terms "risk" and "forest health" may be expressed in a variety of ways, depending on one’s perspective regarding natural resources and natural resource management.  For this risk mapping effort, we try to be as precise as possible in defining risk from insects and diseases, so there can be no ambiguity in what is being depicted on the maps.  We do not, however, attempt to define "forest health".  Past attempts at defining forest health have resulted in statements that are complex, vague, and controversial.  For purposes of identifying risk from insects and diseases, we identify areas where substantial tree mortality and/or growth loss are expected to occur in the near future. 

Workshop II: Monitoring Forest Changes

Sustaining
Southern
Forests

a conference sponsored by the Southern Forest Resource Assessment