Crown Density 

 for All Species 



d Average 



Crown Density Class 



Hardwood/Softwood 

 Crown Density 



Poor 



Good Average 



Crown Density Class 

 (trees 5.0 in. DBH and larger) 



Crown Densities in 

 Oregon and Washington 



60 



O 

 S 50 



§•40 



Q- 



o 30 

 g 20 



Good Average Poor 



Crown Density Class 

 (trees 5.0 in. DBH and larger) 



Crown Dieback 

 for All Species 



Crown Dieback 



Crown dieback is the total percentage of 

 branch tips dying back from the crown 

 perimeter, except dieback caused by shading 

 and competition from neighboring trees. Die- 

 back is caused by severe shock to root systems 



from drought 

 or disease. 

 Some species 

 also will show 

 light dieback 

 as part of 

 their normal 

 growth, but 

 too much die- 

 back reduces 

 foliage area 

 available for 

 photosynthe- 

 sis. No crown 

 dieback was detected on 95% of Northwest Pi- 

 lot Study trees. The no-damage class was split 

 about equally between hardwoods and soft- 

 woods. By state, percentages 

 of trees with none, light, mod- 

 erate, and severe ratings were 

 almost identical to those rat- 

 ings when all Pilot Study trees 

 were combined. 



In the Pilot Study, western 

 hemlock comprised 1% of the 

 total population's severe die- 

 back and the "Other Hard- 

 woods" class had 6% severe 

 dieback. In the 1992-95 Cali- 

 fornia data, oaks comprised 



Normal Light Moderate Severe 



Crown Dieback Class 

 (trees 5.0 in. DBH and larger) 



about 1% and fir-spruce about 1.5% of plot 

 trees with severe dieback. Severe dieback was 

 noted for all major species groups in the 4 

 years of California data, but some species were 

 affected more in certain years. For example, 

 Douglas-fir, oak, redwood-sequoia, and true fir 

 all had severe dieback in 1 992 — the end of a 

 7-year drought. Only oaks in 1993 and 1994 

 and only oaks and pine in 1995 had severe die- 

 back. 



Foliage Transparency 



Foliage transparency measures light filter- 

 ing through needles and leaves in the crown. 

 Transparency values differ by species and de- 

 pend on natural branching habit and foliage 

 orientation. High transparency values indicate 

 unhealthy crown conditions because less foli- 

 age area is available for photosynthesis. Re- 

 duced foliage area can be caused by insects, 

 disease, and other stressors. In Pilot Study 

 plots, 98% of all trees had normal (0-30%) 

 transparency ratings. A slightly higher per- 



Foliage Transparency 

 for All Species 



Normal Moderate Severe 



Foliage Transparency Class 



(trees 5.0 in. DBH and larger) 



Hardwood/Softwood 

 Foliage Transparency 



t Hardwoods 

 I Softwoods 



Normal Moderate Severe 



Foliage Transparency Class 



(trees 5.0 in. DBH and larger) 



Monitoring- 



