What is Dendroclimatology? What can students do?
Andreas J. Kirchhefer Tromsø, Norway What is dendroclimatology?
”The tree as a weather station”
Aims: • Understanding the trees responses to climate • Reconstructing climate • Understanding modern climate
• Simple basic steps, but increasingly sophisticated methods Principals and concepts of dendrochronology
• Prerequisit: An annual ring • Limiting factors & ecological amplitude • Crossdating
• Aggregate tree growth model • Standardisation • Autocorrelation • Replication • Site selection • Uniformitarianism Tree rings
• Seasonal climate with one dormant season – Too cold – Too dry
• Challenging: mediterranean climates • Extremely difficult: tropical climate Wood structure: conifers Wood structure: conifers Wood structure: conifers Wood structure: broadleaved trees Wood structure: broadleaved trees Wood structure Think three-dimensional !
Auxin model of tree growth => Partial missing rings Limiting factors - Liebig’s Law of the Minimum -
Droughts Cross-dating Dendrochronology Dating of wood by means of tree-rings 80 yrs Living pines 300 yrs
>680 yrs Dead pines Down wood: Snag: AD 984-1180 AD 1291-1461 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 Tree-ring series
n = 212 trees
800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 year AD Brennskogtjern, 311 m Aggregate model of tree growth
Ring width is function of • Age related growth trend • Climate • Endogeneous disturbance (within stand) • Exogeneous disturbance (from outside) • error Standardisation – removing age trend
single core
2
1
0 2
1
0 2
tree-ring index index width ring (mm) tree-ring 1
0 values raw STANDARD RESIDUAL 1800 1900 year Autocorrelation
single core
2
1
0 2
1
0 2
tree-ring index index width ring (mm) tree-ring 1
0 values raw STANDARD RESIDUAL 1800 1900 year Replication
single core multiple cores chronology
2
1
0 2
1
0 2
tree-ring index index width ring (mm) tree-ring 1
0 values raw STANDARD RESIDUAL 1800 1900 1800 1900 1800 1900 2000 year Site selection Uniformitarianism
• The present is the key to the past
2 Forfjord-Dividalen mean 1
0
-1 ring-width index ring-width
-2 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 year AD Dendroclimatology
• Stabile chronology • Climate data • Climate-response analysis • Calibration / verification • Reconstruction North Cape
Tromsø sites Narvik
Rovaniemi 1850 1900 1950 2000
1.2 1 S1a 0.8 Standard chronologies 1.2 1 S1b 0.8 1850-1992 1.2 1 S2 0.8 1.8 1.2 1.6 1 S3 0.8 1.4 1.2 1 S4 0.8 1.2
1.2 1 S5a 1.0 0.8 0.8 1.2 S5b
1 index tree-ring
x 0.8 0.6 e d n
i 1.2 S6a g 1 0.4 n i r
- 0.8 e e r t 1.2 0.2 S6b 1 0.8 1850 1900 1950 2000
1.2 1.4 S7a 1 0.8 1.3 1.2 S7b 1 1.2 0.8
1.2 1.1 S7c 1 0.8 1.0 1.2 S8 1 0.9 0.8 tree-ring index tree-ring 1.2 S9a 0.8 1 0.8 0.7 1.2 S9b 1 0.6 0.8 1.2 1850 1900 1950 2000 S9c 1 0.8
1850 1900 1950 2000 year AD Regional standard S-PC1 2 chronologies 1 0 1850-1992 -1 ring index -2
2 S-COA 1 0 -1 ring index ring -2
2 S-ALP 1 0 coast -1 inland ring index ring -2
2 S-INL 1 0 -1 ring index ring -2
1850 1900 1950 2000 year AD General growth response (PC1)
From standard chronologies From residual chronologies correlations response function 0.8 0.8 t n
e 0.6 i 0.6 c i f
f 0.4 0.4 e
o 0.2 c 0.2
n
o 0.0 0 i t a l -0.2 -0.2 e r r -0.4 o -0.4 c regression coefficient regression -0.6 -0.6 asondJFMAMJJA asondJFMAMJJA months months Tree-growth from July temperatures 1875-1992 (1895-1992), standard chronologies 1900 1950 2000
S-PC1 from T7 2 s e r
o 0 c s - z -2 2 R adj = 45.5 % (44.3 %)
S-PC (1+2+3) ⇐ T7 2 s e r o 0 c s - z -2 2 R adj = 55.1 % (55.7 %)
S-PC (1+2+3) ⇐ T7 (t-4, t-3, t, t+1) 2 s e r
o 0 c s - z
-2 2 R adj = 69.8 % (75.0 %)
1900 1950 2000 A mid-20th century response shift
1930 1950 1970 1990 1930 1950 1970 1990 1930 1950 1970 1990
NN - June NN - July NN - August 0.8 0.4
0 -0.4
-0.8 correlation coeff. r coeff. correlation 1930 1950 1970 1990 1930 1950 1970 1990 1930 1950 1970 1990
Last year of 30-yr windows Temperature Precipitation Multiproxy dendroclimatology
• Ring width • Early- and latewood width • Latewood density • Stabile isotopes • Cell morphology • Other high-resolution climate archives: – Ice cores, speleotems, sediments – Corals, molluscs temp prec cloud Growth responses: 0.4 0.3 RW 0.2 0.1 - temperature (left) 0.0 -0.1 - precipitation (mid) -0.2
mult. regr. mult. coeff. regr. -0.3 - cloud cover (right) -0.4 FMAMJJA FMAMJJ A FMAMJJA 0.4 0.3 MXD 0.2 0.1 0.0 -0.1 Tromsø -0.2
mult. regr. coeff. regr. mult. -0.3 Andenes -0.4 Forfjorddalen FMAMJJA FMAMJJ A FMAMJJA 0.4 0.3 d13C 0.2 Svolvær/Skrova 0.1 0.0 -0.1 -0.2
mult. regr. mult. coeff. regr. -0.3 Glomfjord -0.4 FMAMJJA FMAMJJ A FMAMJJA JA-temperatures from RW JA-temperatures from d 13 C 3 3 2 2 1 1 0 0
z-scores -1 z-scores -1 -2 -2 -3 -3 1890 1910 1930 1950 1970 1990 2010 1890 1910 1930 1950 1970 1990 2010
JA-temperatures from MXD JA-cloudiness from d 13 C 3 3 2 2 1 1 0 0
z-scores -1 z-scores -1 -2 -2 -3 -3 1890 1910 1930 1950 1970 1990 2010 1890 1910 1930 1950 1970 1990 2010 Calibration statistics RE: Reduction of Error, CE: Coefficient of Efficiency
2 Target <= predictor (model) Calibration n r R adj Verification RE CE
JA temp <= RW (t-1,t,t+1) 1890-2005 116 .58 .319 1890-1947 58 .73 .502 1948-2005 -.095 -.136 1948-2005 58 .57 .286 1890-1947 .177 .151 JA temp <= RW (t-1,t,t+1) 1890-2002 113 .65 .401 1890-1947 58 .73 .502 1948-2002 .171 .156 1948-2002 55 .63 .363 1890-1947 .325 .314 JA temp <= MXD (t) 1890-2005 116 .76 .567 1890-1947 58 .78 .594 1948-2005 .541 .524 1948-2005 58 .73 .525 1890-1947 .606 .593 JA temp <= δ13 C (t,t+1,t+2) 1890-2003 114 .74 .540 1890-1947 58 .69 .441 1948-2003 .624 .615 1948-2003 56 .82 .654 1890-1947 .432 .420 JA cloudiness <= δ13 C (t,t+1) 1890-2001 112 .69 .460 1890-1947 58 .73 .515 1948-2001 .209 .207 1948-2001 54 .66 .412 1890-1947 .415 .415 July-August climate from tree-rings
A) Temperatures from RW, MXD and d13C 0.9
0.0 z-scores
-0.9 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
B) Temperatures (RW, MXD) vs . near-ground solar radiation (d13C) 1.2 0.8 0.4 0.0 -0.4 z-scores -0.8 -1.2 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
sunshine temp. Synoptic dendroclimatology
• Large-scale networks – Atmospheric circulation – Teleconnections CRU TS3
Forfjord 3-proxy JA temp. What can students do? - basics -
• Where do we find tree-rings? How do they look? • Tree species, circumference, height, state? • Site geology, slope aspect, soil moisture, vegetation type - what influences tree growth? • Preparation: http://web.utk.edu/~grissino/ , http://www.rmtrr.org/ • Tree-ring counts – On discs or cores – How old is the tree (vs. DBH & height, stand structure)? What can students do? - basics (2) -
• Tree-ring patterns on discs – From pith to bark – Concentric? – Growth discontinuities? • Young conifers branch whirl count & height increment vs. TR What can students do? - ring widths - • Single-year analysis: – skeleton plotting • exteme rings, abrupt changes • particular characteristics: frost rings, resin ducts – Cross-dating (pointer years) – Comparison with climate What can students do? - ring widths (2) - • Ring-width series: – Measuring (measuring scale, scan, digital photography – depending on RW) – Cross-dating and chronology – Dealing with age trends – Comparison with climate – Reconstruction excercise? What can students do? - dating excercises -
• Stumps? • Recently died trees? • Buildings?