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Decays and Defects Affecting Timber Values
and Safety
Timber Measurements Society
April 2019
Dan MillerPrecision Forestry LLC
Moscow, ID
Wood Decays
•Structurally weaken trees – Danger tree•$$ Loss of merchantable volume•Much less common in younger forests•Break down dead material•Recycle nutrients
Wood Decays
Grey-Brown Sap Rot(Pouch Fungus)
◼ Usually spread by bark beetles
◼ Appear in spring a year following beetle attack
◼ Rapid decay
Grey-Brown Sap Rot(Pouch Fungus)
Sapwood Decays
◼ Begin with beetle attacks or tree death
◼ Continues in dead trees and after trees are cut and hauled
◼ Decay rate & amount varies by tree species
◼ Value loss depends on amount of sapwood in the log – varies by species & growth rate
Sap Rot Defect:Merchantable volume loss
Diameter cut from 20” to 16” = 43% scale volume loss
20” to 18” = 25% loss
Deterioration Study
◼ Evaluated trees for losses due to:◼ Stain
◼ Char
◼ Decay
◼ Cracks◼ Reported cubic feet not
board feet
Fire-killed Trees◼ Often attacked by
bark beetles & borers
◼ Begin to dry out ◼ Dry rapidly if bark
scorched
◼ and surrounding trees are killed – no shade
◼ Char
Deterioration = Loss of Value
◼ Rate is Affected by:◼ Tree species
◼ Cause of death
◼ Time since death
◼ Tree size
Blue Stain
◼ Only affects sapwood
◼ Lodgepole pine 100% infected 1 year after burn
◼ Ponderosa pine 95% infected by year 1, 100% by year 2
Douglas-fir Volume Loss
Year 1 Year 2 Year 3 Year 4 Year 5
Decay % 0 1 3 6 16
Cracks % 7 19 29 31 40
Decay
Cracks0
10
20
30
40
Year 1 Year 2Year 3
Year 4Year 5
Decay
Cracks
Grand Fir Volume Loss %
Ponderosa Pine Volume Loss %
Top Logs Deteriorate Faster from Cracks
Douglas-fir (%)
Decay Loss Ranking
◼ Volume lost to sap rots proportional to sapwood thickness
◼ Ranking (high to low):◼ Ponderosa pine
◼ Grand fir
◼ Douglas-fir
◼ Western larch
◼ Lodgepole pine
Cracking Loss Ranking
◼ Volume lost to cracks related to bark thickness
◼ Ranking (high to low):◼ Lodgepole pine
◼ Western larch
◼ Grand fir
◼ Ponderosa pine
◼ Douglas-fir
Conclusions
◼ Thick-barked trees rapidly attacked by insects = decayed more quickly
◼ Thin-barked trees dried more quickly higher loss to cracking
◼ Top logs deteriorated more quickly◼ Smaller diameter
◼ Higher % of sapwood – decay
◼ Thinner bark - cracking
Indian Paint Heart rot
◼ Hosts:◼ Grand fir
◼ Subalpine fir
◼ Western hemlock
◼ Mountain hemlock
Indian Paint Conks
Indian Paint Defect
◼ IDL Scale Manual◼ 4ft. Up and 6 ft.
down from conk or punk knot
◼ Standing timber (U. of I. report)◼ 1 conk = 16 ft. up &
down, 2-3 conks = total cull
◼ Top log usually sound
Often causes breakage
Especially after partial harvests
Advance Regeneration?
Closely spaced dead branches indicate suppressed growth in the past
Red-Brown Root & Butt RotPhaeolus schweinitzii
◼ Hosts = All Idaho conifers, especially;◼ larch
◼ The pines
◼ Douglas-fir
◼ Defect◼ Heartwood 2-24 ft. up from
the butt
Cow Pie Fungus
New
Old
Red Ring Rot(pini)
Early & Advanced DecayRed Ring Rot (pini)
I
A
Red Ring Rot Hosts
◼ Hosts:◼ Common
◼ Western larch
◼ Pines
◼ Occasional◼ Most other species
◼ Defect◼ 4 ft. up and 6 ft. down from conk or
punk knot
◼ Several conks = total cull
Cedar Laminated Butt Rot
Laminated Butt Rot
Defect:Conk
indicates up to 18 ft. of cull in cedar
Cedar Brown Pocket RotPostia sericeomollis
Red Belt FungusThe recycler
Sapwood Width
◼ Sapwood width varies by species.
◼ Width also varies by growth rate
◼ Deterioration study – maybe drier sites, slower growth?
Larch Deterioration %
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