vegetation distribution and climate change in the west · 2010. 7. 29. · future woody and grass...
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Ronald P. NeilsonUSDA Forest Service
Pacific Northwest Research Station
Corvallis, OR, USA
(and a cast of many)
Vegetation Distribution
and Climate Change in
the West
Challenges for Restoration
Under Rapid Climate Change
• Function – Services?– Wetter or Drier?
• Woody Expansion?
• Dieback?
• Infestation
• Loss of Water Resources
• Diversity – Services?– A Superstructure to maintain Function
– Functional Types – Functional Groups
– Species and Community Assembly Rules
– Migration• Invasion
• Establishment
Source: OSTP
Ocean-Climate Regime Shifts
1972-77
1988-89
1940-47
Variations of the Earth’s Surface Temperature:
1000 to 2100
• 1000 to 1861, N.
Hemisphere, proxy data;
• 1861 to 2000 Global,
Instrumental;
• 2000 to 2100, SRES
projections
High Warming
Moderate Warming
Small Warming
Similar to Glacial –
Interglacial
Temperature Change
CSIRO
MIROC
HAD
A2 A1B B1
Change in Mean Monthly Temperature
(Degrees C)
2070-2099 vs 1961-1990
Climate Scenario UncertaintiesModel Uncertainty versus Emissions Uncertainty
(IPCC – Fourth Assessment Report Scenarios)
A2 A1B B1
CSIRO
HAD
MIROC
Percent Change in Precipitation
2070-2099 vs 1961-1990
Regional Precipitation Uncertainty:
North Wetter, South Drier
Long-Term
Changes in Distribution
and
Structure
Communities and Ecosystems:
MacMillan
RH Whittaker - New York, 1975
Major Biome BoundariesEcotones in Space – Ecotones in Time (Threshold, Tipping Point)
Water Limited
Leaf Area
Carrying Capacity
All else follows!
Future Thermal Impacts
• Longer Growing Season
• Migration
• Natives Invade Natives
• Release of Frost Limitations
• Loss of Alpine
• Expansion of Subtropics
• Great Basin Thresholds
• Expansion of Tropics
Current Climate
GFDL Future Climate
Thermal ZonesMAPSS Simulations Boreal
Temperate
Subtropical
Tropical
MAPSS Simulated Vegetation Distribution
Ecotones in Space
Emergent Properties LAI, Ecotones, Runoff
Neilson,R.P. 1995. A model for predicting continental-scale vegetation
distribution and water balance. Ecological Applications 5:362-385.
Water LimitedLeaf Area
Carrying Capacity
All else follows!
To my Knowledge
Only three
Process-based
Biogeography
Models Published!
DGVM (Full Structure)
MAPSS MC1, BIOMAP
DOLY SDGVM
BIOME LPJ
Current Climate Future Climate(CGCM1)
Future Woody and Grass Expansion in the West
Enhance Carbon Storage, and
Catastrophic Wildfire, But…
Woodland ExpansionMAPSS Simulation
Bachelet,D., R.P.Neilson, J.M.Lenihan, and R.J.Drapek. 2001. Climate change effects on
vegetation distribution and carbon budget in the U.S. Ecosystems 4:164-185.
Desert
Forest
(Green)
Woodland
Savanna
(Brown)Shrubland
Grassland
Natives Invading NativesMAPSS Simulation
Current Climate
Explosive Great Basin Diversity
Future Climate(CGCM1)
Bachelet,D., R.P.Neilson, J.M.Lenihan, and R.J.Drapek. 2001. Climate change effects on
vegetation distribution and carbon budget in the U.S. Ecosystems 4:164-185.
MC1 Simulate Historical Vegetation Distribution
Mode Vegetation Type (1961 -1990)
MC1 Simulate Future Vegetation Distribution
Mode Vegetation Type CSIRO_a2
MC1 Simulate Future Vegetation Distribution
Mode Vegetation Type HADLEY_a2
MC1 Simulate Future Vegetation Distribution
Mode Vegetation Type MIROC_a2
Vegetation Carbon (Percent Change) CSIRO_a2
Vegetation Carbon (Percent Change) HADCM3_a2
Vegetation Carbon (Percent Change) MIROC_a2
Biomass Consumed by Fire (Percent Change) CSIRO_a2
Biomass Consumed by Fire (Percent Change) HADCM3_a2
Biomass Consumed by Fire (Percent Change) MIROC_a2
Near -Term
Changes in Variability
and
Disturbance
Some areas are projected to become wetter,
others drier with an overall increase projected
Annual mean precipitation change: 2071 to 2100 Relative to 1990
The Water Cycle moves most of the energy from the Tropics to the Poles!
August 6, 2008
September 14, 2008
The Water Cycle moves most of the energy from the Tropics to the Poles!
The Water Cycle moves most of the energy from the Tropics to the Poles!
June 4, 2009
The Water Cycle moves most of the energy from the Tropics to the Poles!
June 6, 2009
July 12, 2009
The Water Cycle moves most of the energy from the Tropics to the Poles!
Western Regions
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Wet
P
DS
I
D
ry
-4
-2
0
2
4 Sim
ula
ted
Are
a B
urn
ed(m
illi
on
s o
f a
cres
)
0
10
20
30
40
50
60
Palmer Drought Severity Index (5 year running average)
Simulated Area Burned (MC1 Model) (5 year running average)
Spearman Rank Correlation Coefficient -0.59***
J LENIHAN 9/11/03
El Niño
1983 1998
Drought and Fire in the West(Simulated Fire, no Fire Suppression)
The MAPSS Team, unpublished
Summer
Humidity
Gradient
Arizona Monsoon
(July – August
Polar Front
Wet vs. Dry Winter
Moisture Zones
Mitchell,V.L. 1976. Journal of Applied Meteorology 15:920-927.
Neilson & Wullstein. 1983. Journal of Biogeography 10:275-297.
Precipitation (Red Transect)
Tentative Changes
• Winter Cyclonic Storms
• Wetter North, Drier South
• Seasonality Shifts
•Expansion of Arizona Monsoon
Global Cooling
Global Warming
Global Cooling
Global Warming
-100
-50
0
50
100
150
2001
89
0
19
00
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21
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Variation in Leaf Carbon (g/m2)
OR / WA / ID (SRES A2 Scenarios)
4K-hist 8K-hist 8K-Miroc 8K-Had 8K-CSIRO
-25
0
25
501
89
0
19
00
19
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20
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Variation in Leaf Carbon (g/m2)
CA / NV / UT (SRES A2 Scenarios)
4K-hist 8K-hist 8K-Miroc 8K-Had 8K-CSIRO
-25
0
25
501
89
0
19
00
19
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Variation in Leaf Carbon (g/m2)
AZ / NM / CO (SRES A2 Scenarios)
4K-hist 8K-hist 8K-Miroc 8K-Had 8K-CSIRO
Summary
• Warmer temperatures will push alpine and subalpine communities off the tops of the mountains
• Wetter winters in the north, drier in the south with great uncertainty and variability inbetween
• The Arizona Monsoon will very likely be enhanced, although the GCMs are very weak in simulating this
• Thus, lower elevational forest ecotones could go down at southern latitudes (within the Monsoon region), even while deserts could become hotter and either more or less xeric.
• Huge Uncertainties:
– CO2 effect on enhanced woody expansion.
– Near-Term Variability, Establishment and Disturbance
Management Implications(personal musings)
• Management Goals face an uncertain Future
– The Future will NOT echo the Past
• Instead,… Manage Change, per se
– Desired function may supercede ‘Desired future condition’
• Improve resilience of ecosystems to rapid change,
e.g.
– Keep forest density below water-limited carrying capacity
– Plant diversity rather than homogeneous monocultures
• Restoration efforts confront:
– a) establishment bottlenecks,
– b) invasions,
– c) functional communities
Acknowledgements
Pacific Northwest Research Station
Managing Disturbance Regimes Program
Oregon State University
Colorado State University
University of Montana
National Center for Atmospheric Research
IRI, International Research Institute for
Climate Prediction
CEFA/DRI Program for Climate, Ecosystem
And Fire Applications
National Fire Plan
USFS Climate Change Program
NSF, EPA, DOE, EPRI, USGS-BRD
-25
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Variation in Leaf Carbon (g/m2)
Western States (SRES A2 Scenarios)
4K-hist 8K-hist 8K-Miroc 8K-Had 8K-CSIRO
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