Transcript Climatic limitations on Douglas

Climatic gradients and Douglas-fir growth:
Water limits growth from stand to region
Jeremy Littell
JISAO CSES Climate Impacts Group
UW College of Forest Resources
David L. Peterson, USFS PWFSL
Michael Tjoelker, UW College of Forest
Resources
Douglas-fir and climate
• Bio-climatic range of Douglas-fir fairly
well understood
• But presence/absence ≠ life history growth is also important
• Climatic limitations on growth should
vary substantially across range
Thompson et al.
High elevation / northern mountain hemlock
Photo: J. Littell
Low elevation / southern mountain hemlock
Photo: C. Webber
Interior ponderosa pine
Photo: C. Woodhouse
Why an emphasis on tree growth?
•
Compared to biogeography, we know relatively little
about long-term, broad-scale climatic controls on lifehistory processes of trees
•
Especially true in non-plantation, mountain
ecosystem settings where topography, soils, etc.
interact with climate
•
Establishment, growth, and mortality are the
mechanisms of species’ range changes and are tied
to climate; these are the ecological mechanisms
behind productivity, carbon sequestration, and
ecohydrology
Scales of Climatic Influence
• Global - hemispheric:
climate change
• Hemispheric to regional:
climatic variability
• Regional to local:
physiographic
• Local: topographic
• Goal: exploit network of
tree ring chronologies to
understand local vs. large
scale controls on growth
CLIMET (Climate-Landscape Interactions on a Mountain Ecosystem
Transect)
Highest
Elevation
Climate Change
Local climate
Climate Variability Physiography
North
Topography
Lowest Elevation
South
411 cm
Quinault North (ONP)
121cm
Trout Ck. North (IPNF)
199 cm
Gray Wolf South (ONP)
72 cm
Robinson South (IPNF)
219cm
Thornton North (NCNP)
118cm
Park Ck. North (GNP)
115cm
Stehekin South (NCNP)
170cm
Belly River South (GNP)
Climate Dimensions of the Sample Transect
First Detrending: Negative exponential, negative linear, or zero slope fit
Mean Detrending:
standardizedCubic
chronology
Second
smoothing spline (preserves 50% variance at 128yr
frequency, 99% at 41 yr)
Standard Chronology (mod. Z index)
ONP
NCNP
IPNF
GNP
Within each park,
the variability in
tree-growth is
similar across low,
middle, and high
elevations.
Main differences
between west and
east (note 2000s
drought)
Correlating Tree-growth and Climate
• Two scales of monthly climate data:
“Climatological”: divisional climate (1895-2002)
•
•
Year-of-growth and year-prior PPT, Avg. T, PDSI + calculated water balance deficit
“Biological”: (1/8° x 1/8 °) VIC climate (1915-2002)
•
•
Year-of-growth and year-prior PPT, T (Avg., Max., Min.), Soil Moisture, ET, SWE
• Seasonal climate variables
•
•
Climate division: ANN, H2OANN, NDJFM, AMJ, MJJAS, JJA, JA for all
PPT, T, PDSI
VIC: Selected combinations of months for different variables
• Water balance deficit
•
•
•
•
Gridded Bouwman 30cm field capacity data set: 50 and 100mm
Assumed non-linear declining availability function
Estimated PET - AET = deficit
Milne et al. surplus water: PPT- ET / PPT
General patterns of growth-climate correlations are similar for divisional and
VIC PPT and T climate.
•PPT
(M) JJ Year-of
JA (S) Year-prior
ONP relationship
stronger
• Avg. T
-JJ Year of, JA prior
+ Apr and Nov prior
Important differences:
• VIC precipitation and
divisional temperature are
better correlates in most
chronologies.
GNP relationship
stronger
• Seasonality
relationships different: VIC
captures a longer season
of sensitivity to
precipitation.
Prior JS results similar to
divisional average T
JJ results weak
in other analyses
Nov. results similar to VIC
and divisional average T
VIC allows separation of the influence of minimum and maximum
temperature
VIC Min/Max T
-JJ year of (esp. GNP and ONP), - JA year prior for maximum
temperature (esp. IPNF and NCNP) (hot summers)
+ON year prior for minimum temperature (warmer autumns)
Deficit (Div.)
-JJ year of growth
-JAS year prior
PDSI (Div.)
+May.-Sep
+ASO year prior
Soil Moisture (VIC)
Entire year prior
Evapotransp. (VIC)
Mixed (AET context
varies with PET)
Seasonal Aggregation
Divisional Climate
•Prior JA temperature
•Prior JA precipitation
VIC Climate
•Prior JA precipitation
•Prior JJAS max. temp.
• current AMJJ precip.
• current AMJJ max. temp.
•Prior ANN. soil moisture
The magnitude of the correlation between seasonal
hydrological variables and tree-growth depends on the
position of the plot along a gradient of surplus water in the
environment.
The portion of the tree-growth signal
that is common to all plots is closely
related to independent
reconstructions of PDSI.
However, there are differences
across the transect in fidelity to that
signal.
Summary: Growth-Climate Relationships
•
•
•
Most frequent patterns of
correlations point to
combined influence of (-)
temperature and (+)
precipitation during summer
Underscored by PDSI (+)
and water balance deficit (-),
esp. in IPNF and GNP.
Some cool season (+) temp.
and (-) snow relationships,
primarily in ONP and NCNP.
Bonsai PSME, Saint Mary, Glacier National Park
Melissa Hornbein
Spencer Wood
Mike Case, Mike Tjoelker,
Sarah Gobbs, Sean Hill
2003-2004
Field Crews
Carson Sprenger
Alex Karpoff
Greg
Pederson
Sam Cushman