seeing the forest for the tree(ring)s
DESCRIPTION
Every year, trees in temperate and boreal forests go through a cycle of dormancy and activity that produces a new layer of tracheids, fibers and other woody cells around their stem. The end result of this process - a tree ring - is one of the most obvious signs in nature documenting the passage of time and the character of that year’s weather. Measurements of tree-ring widths are the most widely-distributed and best replicated source of surrogate environmental information on the planet and are one of the main archives used to estimate changes in regional and global climate during the past several centuries or millennia. In this lecture, I describe the structure and characteristics of the Northern Hemisphere tree-ring width network, and outline how these data are linked with key aspects of local climate and the global climate system. More generally, by describing the characteristics of the Northern Hemisphere tree-ring width network and the diversity of its relations with varying aspects of the global climate system, this presentation highlights the breadth and quality of environmental information that may be recovered from the width of annual growth layers in temperate and boreal trees.TRANSCRIPT
SEEINGTHEFORESTFOR THETREE(RING)S
An overview of tree-ring width records across the Northern Hemisphere
University of North Carolina | Department of Geography | October 24, 2014
Andrew Douglass Flagstaff 1898
Hal Fri"s 1964
Large sets of ring-width data have provided the foundation for many proxy estimates of regional or global surface temperature.
Source: Intergovernmental Panel on Climate Change, AR5, Working Group 1
Source: Cook et al., Science, 2010
The Monsoon Asia Drought Atlas generated yearly maps of drought severity based on ring-width and other tree-ring measurements.
Source: Meko et al., Geophysical Research Le!ers, 2007
Surrogate estimates of discharge have been used to produce ‘worst-case’ scenarios for water supplies in major western rivers, including the Colorado.
TREE-RING
MYTHS
“ ”IF NO RING WAS FORMED IN A GIVEN YEAR, THAT CREATES A FURTHER COMPLICATION,
INTRODUCING AN ERROR IN THE CHRONOLOGY ESTABLISHED BY
COUNTING RINGS BACK IN TIME.
Dr. Michael Mann Penn State News, February 6, 2012
MANY HIGH-RESOLUTION PALEOCLIMATE RECORDS, SUCH AS THOSE BASED ON TREE RINGS,
ARE BIASED TOWARDS RECORDING CLIMATE CONDITIONS DURING THE SUMMER SEASON, THE CRITICAL PERIOD FOR PLANT GROWTH.
“ ”Ersek et al., Nature Communications, 2012
CONVERSELY, GROWTH RATES IN DROUGHT SENSITIVE TREES
ARE PRIMARILY CONTROLLED BY SOIL MOISTURE CONTENT
DURING THE GROWING SEASON (I.E., SPRING AND SUMMER)…
“ ”Steinman et al., Proceedings of the National Academy of Sciences, 2012
Source: Erika Wise
1 Despite their simplicity, the millions of observations that make up the global tree-ring network provide us with a powerful and flexible tool to study forest vigor and climate.
2 The climate ‘filtering’ conducted by individual trees creates major regional differences in information that may be recovered from the hemispheric network.
3 Because the Northern Hemisphere ring-width network is now so large, our understanding of tree-environment relations must not be influenced by decisions to include or exclude certain records.
Dr. Toby Ault Cornell University
MILLIONSOFRINGS
SIMPLE NOT ‘EASY’
How many tree rings can you count?
Source: Peter Brown
Sarah Appleton Crater Lake, Oregon
Source: Sarah Appleton
1809 1811 1812 181318081807
Source: Sarah Appleton
Source: Sarah Appleton
A. E. Douglass University of Arizona
The trees composing the forest rejoice and lament with its successes and failures and carry year by year something of its story in their annual rings.”“
Source: Baillie (1982)
Source: Phil Camill
Source: Uday Kunwar Thapa
PinusPicea
QuercusPseudotsuga
Larix
NothofagusAustrocedrisPhyllocladus
Agathis
Source: St. George, PAGES News, 2014
The International Tree-Ring Database holds more than 3,200 records from every continent except Antarctica.
1 Despite their simplicity, the millions of observations that make up the global tree-ring network provide us with a powerful and flexible tool to study forest vigor and climate.
THEIMPRINTOFCLIMATE
Tree-ring display at elementary school
Photograph: Tom Swetnam
Dr. Hal Fri"s University of Arizona
Fri"s, H.C. Growth-rings of trees: their correlation with climate. Science 154, 973-975 (1966).
“ ”THROUGH SEVERAL DIFFERENT STUDIES MY ASSOCIATES AND I HAVE ACCUMULATED
MORE THAN 40 REPLICATED SAMPLES OF TREE RINGS FROM A VARIETY OF SPECIES AND SITES
NEAR WEATHER STATIONS HAVING RELATIVELY LONG AND CONTINUOUS RECORDS,
IN ARIZONA, COLORADO, CALIFORNIA, AND ILLINOIS.
Dr. Hal Fri"s Science, 1966
LOW-ELEVATION FORESTS IN SEMI-ARID REGIONS
carry-over effects from wintertime climate
HIGH-ELEVATION OR HIGH-LATITUDE FORESTS
climate during the growing season
PiceaPinus
PseudotsugaQuercusLarix
A
C
# re
cord
s
% re
cord
sB
18ºN
36ºN
54ºN
72ºN90ºN
120ºW 60ºW 0º 60ºE 120ºE 180ºW180ºW
1000 20001200 1400 1600 1800
2000
1000
0 0%
12%
6%
1000 20001200 1400 1600 1800Year Year
0º
Source: St. George et al., Geophysical Research Le!ers, 2013
The principles outlined by Fri"s have guided the collection of tree-ring records at thousands of locations around the planet since the 1970s.
-0.8 -0.6 -0.4 -0.2 +0.2 +0.4 +0.6 +0.8
correlation coefficient (ring-width vs. local climate)
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
WINTER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
WINTER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
WINTER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER PRECIPITATION
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER TEMPERATURE
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER TEMPERATURE
Source: St. George, Quaternary Science Reviews, 2014
(a) Winter precipitation
(b) Summer precipitation
(c) Summer temperature
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
SUMMER TEMPERATURE
Source: St. George, Quaternary Science Reviews, 2014
Fri"s, H.C. Growth-rings of trees: their correlation with climate. Science 154, 973-975 (1966).
summertemperature
winter
precipitation
summer
precipitation
summertemperature
winter
precipitation
summer
precipitation
summertemperature
winter
precipitation
summer
precipitation
summertemperature
winter
precipitation
summer
precipitation
summertemperature
winter
precipitation
summer
precipitation
GEOGRAPHICBIASES
Angiosperms (including Quercus) diverged from the gymnosperms at least 140 mya.
Xiaolu (Grace) Li Cornell University
Vaganov et al., In Dendroclimatology, 2010
180oW 120oW 60oW 0o 60oE 120oE 180oW
15oN
30oN
45oN
60oN
75oN
90oN
180oW 120oW 60oW 0o 60oE 120oE 180oW
15oN
30oN
45oN
60oN
75oN
90oN 1.00.80.60.40.20.0
Synthetic tree-ring records generated by a forward model (and modern climate data) exhibit the same spatial pa"erns in climate response as do real trees.
SOIL MOISTURE : TEMPERATURE
Source: LI et al., in preparation
2 The climate ‘filtering’ conducted by individual trees creates major regional differences in information that may be recovered from the hemispheric network.
Cook et al., Earth Science Reviews, 2007
PLANETARYDENDROCLIMATOLOGY
PinusPicea
QuercusPseudotsuga
Larix
NothofagusAustrocedrisPhyllocladus
Agathis
Source: St. George, PAGES News, 2014
The International Tree-Ring Database holds more than 3,200 records from every continent except Antarctica.
improve the accuracy of paleoclimate reconstructions
assign more weight to behavior exhibited by many records and tree species
reduce emphasis given to unusual records that may be dominated by non-climatic noise
BENEFITS OF LARGE NETWORKS
Source: Meko et al., Journal of Climate, 1993
Source: Wise and Dannenberg, Nature Communication, 2014
Climate field reconstructions can only be produced through analysis of large arrays of proxy data.
ENSOEl Niño-Southern Oscillation
PDOPacific Decadal Oscillation
PACIFIC WARM POOL
H H
Source: Wise, Geophysical Research Le!ers, 2010
“El Niño-Southern Oscillation-related hydroclimatic variability in the western
United States is characterized by a north–south dipole pa"ern of precipitation
anomalies with opposing signs.”
EL NIÑOenhances tree growth
LA NIÑAsuppresses tree growth
(a) El Niño-Southern Oscillation
(b) Pacific Decadal Oscillation
(c) Atlantic Multidecadal Oscillation
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
ENSO
Source: St. George, Quaternary Science Reviews, 2014
PACIFIC DECADAL
OSCILLATION
... the use of high-resolution paleoclimate proxy data should be expanded because the short observational record and model uncertainty are unable to simulate [Decadal Climate Variability]...
“ ”Mehta et al., 2011
Bulletin of the American Meteorological Society
(a) El Niño-Southern Oscillation
(b) Pacific Decadal Oscillation
(c) Atlantic Multidecadal Oscillation
-0.8 +0.8-0.6 -0.4 -0.2 +0.2 +0.4 +0.6
PDO
Source: St. George, Quaternary Science Reviews, 2014
Source: Kipfmeuller et al, Geophysical Research Le!ers, 2012
There are several proxy estimates of the PDO index during the past several centuries, each developed from different sets of tree-ring data
and a variety of reconstruction approaches.
Dr. Kurt Kipfmueller University of Minnesota
ANY CONCLUSION THAT EXTENSIVE WILDFIRES ARE
MORE OR LESS COMMON WHEN THE PDO IS IN ONE PHASE OR THE OTHER
DEPENDS ENTIRELY ON THE CHOICE OF PDO RECONSTRUCTION.
“ ”Kipfmueller et al., Geophysical Research Le!ers, 2012
PinusPicea
QuercusPseudotsuga
Larix
NothofagusAustrocedrisPhyllocladus
Agathis
Source: St. George, PAGES News, 2014
The International Tree-Ring Database holds more than 3,200 records from every continent except Antarctica.
TYPE 1 ERROR
LARGE POOL OF POTENTIAL CANDIDATES
SMALL NUMBER OF PREDICTORS
3 Because the Northern Hemisphere ring-width network is now so large, our understanding of tree-environment relations must not be influenced by decisions to include or exclude certain records.
PinusPicea
QuercusPseudotsuga
Larix
NothofagusAustrocedrisPhyllocladus
Agathis
Source: St. George, PAGES News, 2014
The International Tree-Ring Database holds more than 3,200 records from every continent except Antarctica.
