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The behaviour and impacts of Armillaria ostoyae in mature stands and plantations in the Shuswap region of British Columbia Woods, Alex J.
Abstract
Armillaria ostoyae causes considerable loss in forest productivity in both immature and mature stands within the Interior Cedar Hemlock (ICR) and the Interior Douglas-fir (IDF) zones of the southern interior of British Columbia. Two studies concerning the impacts of this pathogen where conducted near Salmon Arm, B.C.; one was within four plantations age ten to twenty-five years on Larch Hills, and the other was within mature stands on Hunter’s Range and Larch Hills. In the plantation study the relationship between the levels of A. ostoyae infection in mature tree stumps and the regeneration was examined. The evidence of past A. ostoyae infection in stumps remains visible on the inner bark for at least thirty years. This evidence may be used to estimate the extent of the disease in the former stand. The relationship between A. ostoyae in stumps and A. ostoyae-caused mortality in regeneration was significant, though not strongly. Three measures of stump inoculum were compared: the proportion of stumps infected, the number of stumps infected, and the basal area of stumps infected. The number of stumps infected was most closely associated with the proportion of regeneration infected. The relative rates of infection incidence were compared among the eight regeneration species present in the four plantations. A quantitative means of comparing the incidence of infection among species was developed. The number of infected Douglas-fir trees was chosen as a standard measure of disease incidence for each plantation. The incidence of infection in the other seven species were then compared to the Douglas-fir standard. The probability of a young tree becoming infected with A. ostoyae did not increase as the distance from an infected stump was reduced. Brushing in one of the twenty-five year old plantations significantly increased the mortality caused by A. ostoyae. The second study was concerned with the impacts of A. ostoyae in mature stands approximately 120 years old. The relative rates of incidence of A. ostoyae infection were compared between species. The incidence of infection for Western larch (Larix occidentalis) was no less than that for Douglas-fir (Pseudotsuga menziesii). The ranking of tree species susceptibility may depend more on site than on inherent differences among species. An A. ostoyae severity rating system was developed. This system assigned plots a rating based on the proportion of conifer trees infected out of the total number of conifers in the plot. This severity rating was then used in analyses to test the relationship between A. ostoyae severity and a variety of site characteristics, including elevation, logging disturbance, site index, and biogeoclimatic site classification. Of these characteristics, past logging disturbance was mostly closely associated with high levels A. ostoyae severity. The relationship between the biogeoclimatic ecological classification system and A. ostoyae incidence and severity was examined. The ICR zone had significantly more A. ostoyae infection than the IDF zone. More detailed analyses using site units within both the ICH and IDF zones did not indicate any significant relationships. The A. ostoyae severity rating was also compared to timber volumes. There was a significant relationship between A. ostoyae severity and conifer volume in 120 year old stands in the ICH zone. The most severely infected plots had significantly less conifer volume than the less heavily infected areas. There was no significant relationship between A. ostoyae severity and conifer volume in the IDF zone. However, there was a clear trend towards lower conifer volumes with increasing A. ostoyae severity.
Item Metadata
Title |
The behaviour and impacts of Armillaria ostoyae in mature stands and plantations in the Shuswap region of British Columbia
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
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Description |
Armillaria ostoyae causes considerable loss in forest productivity in both
immature and mature stands within the Interior Cedar Hemlock (ICR) and the Interior
Douglas-fir (IDF) zones of the southern interior of British Columbia. Two studies
concerning the impacts of this pathogen where conducted near Salmon Arm, B.C.; one
was within four plantations age ten to twenty-five years on Larch Hills, and the other
was within mature stands on Hunter’s Range and Larch Hills.
In the plantation study the relationship between the levels of A. ostoyae
infection in mature tree stumps and the regeneration was examined. The evidence of
past A. ostoyae infection in stumps remains visible on the inner bark for at least thirty
years. This evidence may be used to estimate the extent of the disease in the former
stand. The relationship between A. ostoyae in stumps and A. ostoyae-caused mortality
in regeneration was significant, though not strongly. Three measures of stump
inoculum were compared: the proportion of stumps infected, the number of stumps
infected, and the basal area of stumps infected. The number of stumps infected was
most closely associated with the proportion of regeneration infected. The relative rates
of infection incidence were compared among the eight regeneration species present in
the four plantations. A quantitative means of comparing the incidence of infection
among species was developed. The number of infected Douglas-fir trees was chosen as
a standard measure of disease incidence for each plantation. The incidence of infection
in the other seven species were then compared to the Douglas-fir standard. The
probability of a young tree becoming infected with A. ostoyae did not increase as the
distance from an infected stump was reduced. Brushing in one of the twenty-five year
old plantations significantly increased the mortality caused by A. ostoyae.
The second study was concerned with the impacts of A. ostoyae in mature
stands approximately 120 years old. The relative rates of incidence of A. ostoyae infection were compared between species. The incidence of infection for Western larch
(Larix occidentalis) was no less than that for Douglas-fir (Pseudotsuga menziesii). The
ranking of tree species susceptibility may depend more on site than on inherent
differences among species. An A. ostoyae severity rating system was developed. This
system assigned plots a rating based on the proportion of conifer trees infected out of
the total number of conifers in the plot. This severity rating was then used in analyses
to test the relationship between A. ostoyae severity and a variety of site characteristics,
including elevation, logging disturbance, site index, and biogeoclimatic site
classification. Of these characteristics, past logging disturbance was mostly closely
associated with high levels A. ostoyae severity. The relationship between the
biogeoclimatic ecological classification system and A. ostoyae incidence and severity
was examined. The ICR zone had significantly more A. ostoyae infection than the IDF
zone. More detailed analyses using site units within both the ICH and IDF zones did
not indicate any significant relationships. The A. ostoyae severity rating was also
compared to timber volumes. There was a significant relationship between A. ostoyae
severity and conifer volume in 120 year old stands in the ICH zone. The most severely
infected plots had significantly less conifer volume than the less heavily infected areas.
There was no significant relationship between A. ostoyae severity and conifer volume
in the IDF zone. However, there was a clear trend towards lower conifer volumes with
increasing A. ostoyae severity.
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Extent |
3553709 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-02-28
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0103805
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.