Forest Pest Management
Worldview
“The genus Pinus : feeding insects
since the Mesozoic”
...Laura Merrill
Forest Entomologist
Forest Ecologist Worldview
“The Phylum Arthropoda: Recycling
carbon since the Paleozoic”
...Nancy Gillette
Nouvelle Entomologist
Current research directions
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Forest Health Protection
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Beetle pheromone development, especially
microencapsulated pheromones
Geographical variation in beetle behavioral
chemistry (beetle “dialects”)
Role of beneficial insects in soil processes
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Effect of disturbance (fire, herbicides, thinning)
on forest floor arthropods
Biodiversity conservation of soil and CWD
decomposing fauna (NWFP)
Potential directions
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Forest health protection
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Global warming as disturbance
Effect of global warming on pest population
dynamics and insect/host interactions
Soil processes
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Effect of global warming on soil processes
mediated by arthropods (belowground food web)
Potential changes in range, rate of development,
rate of reproduction by poikilotherms
Potential for positive feedback loop, increasing
rate of carbon release from soils
Responses of forest soil
microarthropods to
prescribed fire in the
southern Cascade Range
Nancy Gillette
USDA Forest Service,
Michael Camann, Karen Lamoncha, and Neil Plant
Humboldt State University
Crucial functions of soil
arthropods:
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Soils = global storage site for carbon
Below-ground biomass equal to above ground
Arthropods fragment and decompose litter
Arthropods enhance nutrient mineralization
Feeding changes fungal/bacterial ratios
Optimizes release rate of nitrogen
Effects of fire on forest soils
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Massive shift in inputs from above ground to
below ground
Rapid flush of nitrogen (leached)
Direct incineration of soil fauna
Changes in soil fauna habitat (litter
consumed)
Increase in soil temperature (insolation)
Increase in soil moisture (evapotranspiration)
20th Century = Fire Exclusion
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Smokey the Bear campaign successful
Fire exclusion changed stand structure
(shift in tree species, fuel buildup,
increased litter)
Fire exclusion created very firesusceptible forests, huge wildfire
problem
Solution: reintroduce fire
Questions
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How severe are effects of fire on
forest floor arthropods?
How long-lasting are effects of fire?
What is effect of habitat patchiness
(refugia) on soil fauna?
How many mites are “enough”?
How many species are “enough”?
Does diversity confer stability?
Blacks Mt. Experimental Forest
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Lassen National Forest, Southern Cascade
Range, California
Interdisciplinary (wildlife biology, entomology,
botany)
Stand structure (high/low diversity + RNAs)
Each plot split into burned and unburned
splitplots
Low-intensity prescribed burn applied in 1997
Stand
structure
treatments:
• high diversity
•RNA
• low diversity
Microarthropod responses to
prescribed fire at BMEF
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multi-year study
stand structure
alteration
low intensity fire
Acari from 600
samples
600
800
1000
1200
B: October 1998
0
200
400
Mean abundance +- 1.0 SE
800
600
400
200
Prostig
Hypopi
Oribatids
600
800
1000
Unburned
Burned
400
Mean abundance +- 1.0 SE
Mesostig
C: June 1999
1200
Mesostig
200
Oribatids
0
Mean abundance +- 1.0 SE
1000
1200
A: June 1998
0
Acarine
suborder
responses:
Oribatids
Mesostig
Prostig
Hypopi
Prostig
Hypopi
1000
800
400
600
Mean abundance +- 1.0 SE
0
200
Oribatid
assemblage
responses:
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
June 1998
• mean abundance
October 1998
June 1999
25
Sample dates
15
10
0
5
Mean richness +- 1.0 SE
• 500,000 individuals
20
• 72 Oribatei species
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
• mean species richness
June 1998
October 1998
Sample dates
June 1999
2.5
2.0
1.5
1.0
Mean Brillouin index +- 1.0 SE
0.5
0.0
Oribatid
assemblage
responses:
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
June 1998
• mean species diversity
October 1998
June 1999
0.2
0.4
0.6
0.8
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
0.0
Mean Camargo index +- 1.0 SE
1.0
Sample dates
June 1998
• mean assemblage evenness
October 1998
Sample dates
June 1999
250
200
150
100
Mean abundance +- 1.0 SE
50
0
Collembola
assemblage
responses:
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
June 1998
October 1998
• mean abundance
June 1999
August 1999
October 1999
12
Sample dates
8
6
4
0
2
Mean richness +- 1.0 SE
10
• 44 Collembola species
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
June 1998
• mean species richness
October 1998
June 1999
Sample dates
August 1999
October 1999
0.5
1.0
1.5
HSD unburned
HSD burned
LSD unburned
LSD burned
RNA unburned
RNA burned
0.0
Mean Brillouin index +- 1.0 SE
2.0
Collembola
assemblage
responses:
June 1998
• mean diversity
October 1998
June 1999
Sample dates
August 1999
October 1999
Soil microarthropod responses
to prescribed fire at BMEF:
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Fire consumed litter, but was patchy
Profound effects on mite community structure:
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decreased abundance, richness, diversity
increased evenness and alteration of dominance
relationships
Prostigmatids recovered quickly and dramatically;
other mites and Collembola declined
Oribatei were excellent bioindicators
Fire effects lasted at least two years
Specific questions answered
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Fire effects drastic, even with cool
burn
Abundance, species richness, and
diversity continue to decline two years
post-treatment
Stand structural complexity mitigated
effects of fire (RNA>HD>LD)
No sign of recovery yet
Questions unanswered
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How long will recovery take?
Is the decline in mite populations of
real concern (how many mites are
enough)?
Is the decline in mite diversity of
concern (how many species are enough)?
Are these results generalizable to
other sites?
Where are we now?
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Documented intermediate-term effects
Described nine new arthropod species
(two of them named for BMEF…B.
montanus and B. blacksensis)
Started a catalog of oribatid mites of
PNW
Identified a trend of concern for mites
The End