Transcript Telling time and climate using tree rings

Day 3
Driving Questions
1. Why do we need to study past climate?
2. How can we reconstruct past climate?
Agenda
Morning
1. Observing tree cookies.
2. Tree rings: How can trees tell us about climate?
3. Tree coring (10 oak trees)
4. Tree as proxy data: Tree core analysis and finding
correlations with climate.
Afternoon
5. Classroom Activities for teaching climate using tree rings
6. Presentation (Emi Ito): Climate change in Earth history
and Human history
7. Manoomin Project (Holly Pellerin)
8. Medicine Wheel (Daiana, Dwight, Younkyeong)
Telling time and climate using
tree rings
Tree cookies?
Observation of a tree cookie – What did you find about the tree?
How do trees grow?
In order to move water and nutrients
efficiently within themselves, woody
plants had to develop a plumbing
system. Just underneath the bark is a
layer of plant tissues that serves this
function. This is actually the only part
of the trunk that is alive. It is called
the Cambial Layer (red arrow). Within
the cambial layer, one kind of tissue
transports liquids from the roots to the
leaves. This is called
the Xylem. Another transports liquids
from the leaves to the roots and also
laterally above ground. This is called
the Phloem. As the plant grows it
constantly renews both of these. Only
the new xylem and phloem transport
water and nutrients. The old xylem
tissue becomes the wood and the old
phloem tissue becomes the bark.
What is a tree ring?
• A tree ring is really an expression of the
seasonality of climate
Late Wood
Early Wood
(Summer Wood)
(Spring Wood)
Width
Chemical/Isotopic
Composition
(Climate change,
pollution tracking,
precipitation sources,
tropical dendro)
Tree-ring Density
(X-Ray Densitometry;
temperature variability)
Annual Ring
Center
Oak
Maple
Bark
Tree coring
and making
tree cores
How do scientist study trees?
Biological Growth Curve:
The average radial growth of as tree as measured over time.
Standardization: The process by which the biological
growth curve is removed from the individual raw ring width
measurements producing a new time series of index values(indices).
The Principle of Crossdating
• Ring counting ≠ crossdating.
• Crossdating: The procedure of matching
ring-width variations among many trees
from nearby areas allowing the
identification of the precise year in which
each ring was formed (Fritts 1976).
– Absolutely essential in applications that make
comparisons with time-dependent phenomena (e.g.,
interannual climate variability).
Crossdating: Temporal Control and
Chronology Extension
Very Old Dwelling
Dead Tree
Living Tree
Chronology Extension
The Importance of Chronology Extension
Living trees only
extend to 1675
Remnants
Remnant materials
extend chronology to
1197
>470 year difference!
Living
Trees
Cross-dating in Practice: Skeleton Plotting
The narrowest ring is connected (blue line) with the longest skeleton mark.
The widest ring is connected (green line) with a "b" mark.
Note the red line:
1.Points to a ring of average width, but it seems narrow compared to the preceding ring
2.Perhaps it merits a small mark because of the large year-to-year difference
Dendrochronologists can make
skeleton plots to standardise scales:
Note the three skeleton plots of the figure above:
Have the same relative scale making them
easy to compare to one another while
clearly showing the same pattern of ring width variation
in each sample
Mud River Tree rings and Precipitation (Minnesota)
30
25
20
15
10
5
0
1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980
Tree Ring width(mm) *10
Precipitation (inch)
Full ring
False ring
Morrison Lake, Beaverhead Mountains, MT
About 25cm
Fig. 4. A composite CO2 record over six and a half ice age cycles, back to 650,000
years B.P. The record results from the combination of CO2 data from three Antarctic
ice cores: Dome C (black), 0 to 22 kyr B.P. (9, 11) and 390 to 650 kyr B.P.; Vostok
(blue), 0 to 420 kyr B.P. (5, 7), and Taylor Dome (light green), 20 to 62 yr B.P.
U. Siegenthaler et al., Science 310, 1313 -1317 (2005)
Published by AAAS
Warm
~70% of variation continental ice volume 1.5‰
Cold
Variation relative to a nominal mean value per core
Karner et al. Paleoceanography, 2002
Antarctic Dome C ice core record
warmer
Thousands of years ago
Lüthi et al. 2008, Nature
2010
2009
2008
20
15
10
5
0
Steel Lake core image
(scale in cm; this section represents ~100 years)
oak savanna
pine savanna
pine
spruce
Prairie Period
pine/birch/aspen
Moody Lake C, Cental Core
1620±120
1350±30
2510±35
3770±40
12000±290* rejected
(8000- Steel L.)
10550±35
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Pollen Diadram of Selected Taxa
Analisys: Jacqueline van Leeuwen
470
510
550
590
630
670
710
750
790
830
870
910
950
990
1030
1070
1110
1150
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Prairie period
40
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Trees+Shrubs/Herbs
20 40 60
20 40 60
20 40 60 80
%Pollen Sum=AP+NAP
50
20
20 40 60
20 40 60
20