now includes 19 states. Oregon and Washington 

 established and measured 25 plots in 1994 as a 

 pilot project (see chapter 5 for results of the pilot 

 project). The two states are scheduled to fully 

 implement the program in 1997. The purpose of 

 the Forest Health Monitoring program is to deter- 

 mine the condition of forests over large areas, such 

 as the West or the entire United States, and to de- 

 tect changes in forest health at a broad scale. 



technology is the global positioning system 

 (GPS). Using signals from several satellites, a 

 portable GPS unit can calculate the precise lo- 

 cation of a field plot. Currently, GPS units are 

 taken to each forest inventory plot to record 

 plot location. The location can then be entered 

 on a GIS, and the inventory data for that plot 

 can be related to other data for that particular 

 location. 



New Monitoring Technology 



The launching of satellites and the explosive 

 growth in computer technology have created 

 many possible applications of new technolo- 

 gies to forest monitoring. Commercially avail- 

 able satellite imagery of forested land can be 

 sorted and classified to identify species com- 

 position, tree size, and canopy density for any 

 given area of forest. Changes in vegetation can 

 be detected by periodic comparisons of satel- 

 lite images. In Oregon and Washington, satel- 

 lite imagery of the National Forests is being 

 purchased, classified, and used by the Forests. 



Geographic information systems (GIS) cire 

 used extensively to store and retrieve aerial 

 survey and other monitoring data. These sys- 

 tems geographically reference each piece of in- 

 formation and allow maps to be made that in- 

 clude many layers of data. Another new 



Risl< Rating 



Monitoring susceptibility, or risk to distur- 

 bance agents, is another way of monitoring for- 

 est health. Using stand examination data from 

 site visits, inventory data, aerial photography, 

 and knowledge of forest conditions conducive 

 to insects, disease, and fire, forested areas can 

 be assigned a rating of current risk to a par- 

 ticular disturbance agent. Over time, risk can 

 change through "natural" maturing of the for- 

 est, removal of some trees by a disturbance, 

 or management activities such as thinning, 

 prescribed fire, or harvest. Subsequent risk 

 ratings using updated information can show 

 these changes in risk. Several computer pro- 

 grams for risk rating stands and watersheds 

 are being used by National Forests to assist 

 them in watershed analysis. 



Overview — 23 



