The spatial distribution of Armillaria root disease in an uneven-aged, spatially clumped Douglas-fir stand

1995 ◽  
Vol 25 (6) ◽  
pp. 1008-1016 ◽  
Author(s):  
Bart J. Van Der Kamp
Keyword(s):  
Root Systems ◽  
Douglas Fir ◽  
Root Disease ◽  
Inoculum Potential ◽  
Partial Cutting ◽  
Infected Tree ◽  
Tree Removal ◽  
Spatial Domains ◽  
Armillaria Root Disease ◽  
Distributed Analysis

The location, species, and infection status of all trees and stumps in nine 40 by 40 m plots located in a single large Armillaria root disease (caused by Armillariaostoyae (Romagnesi) Herink) infested area in the Interior Douglas-fir Zone in British Columbia were recorded. The area was logged to a diameter limit in 1963 and then left undisturbed. Spatial analysis using variance over mean ratios of number of trees per grid square for a series of grid sizes showed that stumps were randomly distributed, trees were strongly clumped, and infected trees occurred in small clumps that were themselves randomly distributed. Analysis of intertree distances showed that clumps of infected trees ranged from 1 to 29 trees (average 3.2 trees). Incidence of infection did not decline with distance from old stumps. Infection incidence in spatial domains surrounding each stump ranged from 0 to 100%. Nevertheless, variation in incidence among stump domains could not be attributed to variation in inoculum potential at the time of logging. It is concluded that in the experimental area, 30 years after the last major disturbance by partial cutting, Armillaria occurs in small domains, largely on the root systems of trees regenerated since logging. In these circumstances, bridge tree removal spacing, which removes all trees from a band around each infected tree, may isolate most of the viable Armillaria inoculum colonies from the remainder of the stand.

Allometries of coarse tree, stem, and crown measures in Douglas-fir are altered by Armillaria root disease

Botany ◽  
2012 ◽  
Vol 90 (8) ◽  
pp. 711-721 ◽  
Author(s):  
M.G. Cruickshank ◽  
C.N. Filipescu
Keyword(s):  
Wood Quality ◽  
Douglas Fir ◽  
Root Disease ◽  
Stem Diameter ◽  
Light Competition ◽  
Sapwood Area ◽  
Crown Diameter ◽  
Crown Length ◽  
Light Requirements ◽  
Armillaria Root Disease

We used allometric relationships to quantify Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) stem and crown adaptation to Armillaria root disease (caused by Armillaria ostoyae (Romagn.) Herink). At four sites, we measured height, diameter, height to live crown, crown width and length, sapwood area at base of live crown, and infection duration for healthy and infected Douglas-fir trees. Diseased trees were on average smaller than healthy trees for all measured variables, but there were also proportional changes between tree parts suggesting allocation shifts to disease. Infected trees were shorter in relation to stem diameter compared with healthy trees by 4% on average. Crown diameter was positively related to stem diameter (0.24 m·cm–1) but not to disease or competition. Diseased tree crown lengths were on average 0.5 m shorter for a given crown diameter than healthy trees—akin to response to light competition except this also occurred in the upper canopy. Prolonged infection reduced crown length probably through shedding of lower branches and by reducing stem apical growth, possibly related to changed hydraulic architecture or light requirements. Crown surface area was related to stem sapwood area (0.81 m2·cm–2) but unaffected by disease or competition. We discuss how shifting allocation could reveal important implications for life strategies involving whole tree adaptations to disease and tree to tree interactions, and for wood quality and forest inventory.

Effects of selective cutting on the epidemiology of armillaria root disease in the southern interior of British Columbia

2001 ◽  
Vol 31 (1) ◽  
pp. 59-70 ◽  
Author(s):  
D J Morrison ◽  
K W Pellow ◽  
A FL Nemec ◽  
D J Norris ◽  
P Semenoff
Keyword(s):  
Host Response ◽  
Root Systems ◽  
Root Disease ◽  
Selective Cutting ◽  
Tree Diameter ◽  
Armillaria Ostoyae ◽  
Primary Roots ◽  
Armillaria Root Disease ◽  
Mature Stands ◽  
Tree Condition

In selectively cut and undisturbed parts of four mature stands, five 0.04-ha plots were established, and trees were measured, mapped, and examined for aboveground symptoms of armillaria root disease. Trees were felled, and stumps and their root systems were removed by an excavator and were measured and examined for Armillaria lesions. Isolates from root lesions, rhizomorphs associated with lesions, and basidiomes collected in or adjacent to plots were of Armillaria ostoyae (Romagn.) Herink. All trees were assigned to one of five tree condition classes based on the location of lesions and host response. The merchantable volume in each class was calculated. In undisturbed plots, incidence of trees with A. ostoyae lesions on roots was about 10% in the dry climatic region compared with about 75% in the moist region and 35% in the wet region. In plots in the selectively cut parts of the stands, 50-100% of stumps were colonized by A. ostoyae. Results of a logistic regression analysis showed that selective cutting was associated with a statistically significant increase in the probability of a tree having A. ostoyae lesions, where the magnitude of the increase depended on tree diameter. The increase in the probability of a tree being diseased was accompanied by an increase in the proportion of primary roots with lesions and the average number of lesions per diseased tree; however, the increases in disease intensity were statistically significant at only two (one dry and one moist) of the four sites. The percentage of merchantable volume threatened or killed by A. ostoyae was usually higher in cutover than undisturbed plots.

Effect of Armillaria root disease on quality and value of green Douglas-fir lumber

2010 ◽  
Vol 86 (2) ◽  
pp. 263-266 ◽  
Author(s):  
M G Cruickshank
Keyword(s):  
Tree Species ◽  
Wood Quality ◽  
Douglas Fir ◽  
Root Disease ◽  
Tree Level ◽  
Stem Taper ◽  
Negative Effect ◽  
Key Words Disease ◽  
Armillaria Root Disease ◽  
The Impact

For a few tree species, scattered accounts of impact caused by root disease exist in the literature mainly at the tree level. No product quality impacts have ever been measured or properly costed. To provide some information on value impacts, green rough-sawn Douglas-fir lumber was cut from trees with and without Armillaria root disease. This produced 80 boards from six trees in two planted stands. Fewer boards came from living diseased trees compared to healthy trees of similar diameter (1.3 m) at both sites, suggesting that disease may affect stem taper or form. Lumber from diseased trees was affected most often by warp and for healthy trees by knots, but warp affected value the most. Disease appears to have at best no effect, and at worst, a negative effect on lumber value but is not likely to increase value. This is the first report of the impact of a root disease on lumber quality and value, but further work would be required to properly assess this. Key words: disease, Armillaria root disease, conifer, Douglas-fir, wood quality, lumber warping, lumber value, lumber grading

scholarly journals An exploration of ringbarking to reduce the severity of Armillaria root disease in logged areas in British Columbia

2015 ◽  
Vol 45 (12) ◽  
pp. 1803-1805 ◽  
Author(s):  
Bill Chapman ◽  
Bruce Schellenberg
Keyword(s):  
British Columbia ◽  
Pseudotsuga Menziesii ◽  
Tree Mortality ◽  
Timber Harvesting ◽  
Douglas Fir ◽  
Root Disease ◽  
The World ◽  
Armillaria Root Disease ◽  
Severity Of The Disease

Ringbarking is a girdling technique that is used prior to timber harvesting to reduce losses to Armillaria root disease in some parts of the world. The technique had not previously been evaluated in British Columbia, Canada. Small plots of primarily Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees that were ringbarked prior to timber harvesting had approximately 50% lower levels of Armillaria root disease caused tree mortality in young trees after 15 years than plots of trees that were not ringbarked. Ringbarking did not reduce Armillaria root disease in this trial as much as has been reported in other research. This could be attributable to the centre of the small plots being within 5–10 m of live and dead Armillaria-infected trees in the surrounding forest. The treatment did reduce the severity of the disease by both statistically and biologically significant amounts and, therefore, warrants further investigation as a possible treatment where timber harvesting is conducted in Armillaria root disease affected stands.

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