effects of climatic variability and change on forest resources: a scale- based framework for...
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Effects of Climatic Variability and Change on Forest Resources: A
Scale-based Framework for Analysis
David L. PetersonUSDA Forest Service, PNW StationUW College of Forest Resources
UW Climate Impacts Group
Temperature varies over time
Forest vegetation varies over time
PDO affects tree growth Subalpine fir in the Cascade and Olympic Mountains
From Peterson et al. (2002)
1920 1930 1940 1950 1960 1970 1980 1990
Low elevation forest
Summer precipitationSummer temperaturePDSIPDO
Summer soil moisture
YEAR
PC
Va
lue
3
2
1
0
-1
-2
WINTSMTH
PC3HIGHS
PC3MIDS
PC3LOWS
PC2STEPS
PDO affects growth of semi-arid tree species
Ponderosa pine in the Cascade Range
Data from G. Ettl
1900 1920 1940 1960 1980 2000
Subalpine conifer regeneration
warm, cool,dry wet
Limiting factors in forest ecosystems
High-elevation forests• Duration of growing season at treeline• Summer soil moisture at lower and drier locations
Low-elevation forests• Summer soil moisture
Semi-arid forests• Summer soil moisture
How does climatic variability affect wildfire?
Years with fire area > 80,000 hectares
National Forest data, 1916-2002
Warm-phase PDO Cool-phase PDO
Idaho 14 7
Oregon 14 5
Washington 10 2
TOTAL 38 (73%) 14 (27%)
Climatology affects wildfire in the Pacific Northwest
Extreme wildfire years are forced at least in part by antecedent drought and summer blocking in the 500 hPa height field.
From Gedalof et al. (2004)
M ay
Septem ber
August
July
June
Climatic change effects
From McKenzie et al. (2004)
Temperature (oC)
Pre
cipit
ati
on
(%
)
Fire areaOregon1916-2002
Stress Interactions, Disturbance
Increased fire risk• Higher fire frequency• Higher fire intensity, esp. eastside where fuel hazard is high
Increased insect outbreaks, esp. eastside• Postfire stress• Low vigor stands with high stem density
Forest Carbon Budgets
Storage (quantity) vs. uptake (rate)
Young forest Storage Uptake Mg/ha
Mg/ha/yr
50-100 5-10
Old forest 400-1000+ + 1.0?
(600?)
Local (small watershed)
Subregional (large watershed, national forest)
Regional
Paleoecology Low Moderate Low
Growth and productivity
High Moderate Moderate, depends on ecosystem
Carbon Moderate Low Low
Regeneration Moderate Low Low
Genetics Low Low Low
Disturbance ecology
High Moderate Moderate, mostly for fire
Scale-based framework: knowledge base
Management authority
Federal• Forest Service• Bureau of Land Management
State• WA Department of Natural Resources• OR Department of Forestry
Private• Industrial forest• Nonindustrial forest
Response capacity
FederalCarbon management (storage, LCA)Altered planting strategiesFire mitigation
StateCarbon management (storage)
PrivateIndustrial forest -- Genotype management -- Carbon management (storage, LCA)Nonindustrial forest -- None; default carbon storage?
