(70%), followed by hemlock-spruce (17%); some 

 plots had small amounts (about 4% each) of 

 fir-spruce, mixed conifer, or other softwoods. 



Stand Characteristics 



Each forest stand has unique understory 

 and overstory traits distinguishing it from other 

 stands with similar or different species. To- 

 gether, these traits are called stand character- 



Azimuth I -2 360° 



Azimuth 1-3 120° 

 Azimuth I -4 240° 



\ 



Hectare Plot 

 185.1' radius (5i.4m) 



National FHM plot layout is designed 

 around four points (subplot centers) 



Forest Health Monitoring field plot layout. 



istics. Tree and seedling characteristics at 

 Pilot Study sites were measured in four circu- 

 lar microplots and subplots of known size, 

 permitting results to be calculated per unit 

 area. Economic, scenic, and biodiversity val- 

 ues can then be attributed to larger landscape- 

 sized areas, allowing resource managers to 

 decide between different management options. 



Understory Vegetati o n 



Presence and abundance of understory 

 cover indicate status of seedling regeneration, 

 percentages of various vegetation ground cover, 

 and which ground cover may be competing 

 with new or established seedlings for soil mois- 

 ture and nutrients. Understory measurements 

 were taken in small microplots, at right angles 



to each subplot. Ground-cover percentages for 

 Pilot Study sites are shown in the figure above. 

 Pilot Study plots had about the same per- 

 centage cover for herbs, lichens, and seedlings 

 as did the 1992-95 California plots. Shrub 

 cover was twice, fern cover was nine times, and 

 moss cover was ten times higher in Pilot Study 

 plots. Pilot Study seedlings seem to face 

 greater competition from shrubs and ferns 

 than do plot seedlings in California, probably 

 because of wetter growing conditions. 



Overstory Vegetation 



Forest managers commonly summarize 

 characteristics of small and large trees — sap- 

 lings, poles, and sawtimber — growing above the 

 forest floor and having similar height and di- 

 ameter limits (table 5-2). Seedlings and sap- 

 lings were recorded within microplots and pole 

 and sawtimber-sized trees within subplots. 

 Field tallies showed 79 sapling, 448 pole, and 

 275 sawtimber trees. 



Table 5-2 — Size classes of forest ecosystem 

 components 



Class Range limit 



Understory seedling 



Seedlings 



Saplings 



Poles 



Sawtimber 



< I ft tall 



> I ft tall & < 1 .0 inch diameter 



> 1.0 to 4.99 inch diameter 

 5.0 to 10.99 inch diameter 



(hardwood and softwood) at least I 1.0 inch diameter 



Monitoring — 68 



