Transcript Intro. to Stems and Dendrochronology

STEMS
SO WHAT DO
WE ALREADY
KNOW?????
Stems exist for three reasons
•To produce leaves, branches and flowers
•To hold leaves up to the sunlight
•To transport substances between roots
Stem Basics
1. Stems develop from the embryonic
hypocotyl
2. We call the stem and the leaves the
shoot
3. Stems can present a variety of
forms some typical some not so
much. Consider the stem of a carrot.
Where is it????
4. Stems contain the apical meristem.
What’s that?
a) Shoot apical meristem
(b) Leaf primordial
(c) Axillary bud primordium
(d) leaf
(e) Stem tissue
Growth of Stems
In the spring, the shoot lengthens rapidly
from the elongation of cells below the
apex similar to the “extension of a
telescope”
Will produce two patterns of growth in
stems
1. Apical Dominance- excurrent growth
pattern
2. Lack of Apical Dominance- deliquescent
growth pattern
Apical Dominance or
Excurrent Growth
AUXIN!
Apical Dominance
Excurrent Growth Pattern
Effects of Pruning
Deliquescent Growth
External
Stem
Features
External
Stem
Features
How is a stem ‘put together’?
Function of…
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CorkCortexPhloemVascular cambiumXylemPith-
DENDROCHRONOLOGY
Dendron= tree
+
Chronos= time
+
Logos= word= the study of
_____________________
DENDROCHRONOLOGY
DEPENDENT ON THE PRINCIPLE OF
“UNIFORMITY IN THE ORDER OF NATURE”
OR
The concept that the present is the
key to the past.
but it’s a whole lot more than that…
• DENDROARCHAEOLOGY- uses tree rings to date when
timber was felled, transported, processed or used for
construction of wooden artifacts
• DENDROCLIMATOLOGY-uses tree rings to study climate
and reconstruct past climate
• DENDROECOLOGY- uses tree rings to study factors that
affect earth’s ecosystems
AND AT LEAST 5 MORE “DENDROS”
SEAHENGE at Holme-next-the-Sea
WHY RINGS???
• EARLY IN THE GROWING SEASON
TREES PRODUCE THIN-WALLED
CELLS REFERRED TO AS
SPRINGWOOD OR EARLYWOOD.
• LATER IN THE GROWING SEASON
WHEN CONDITIONS ARE LESS THAN
OPTIMUM, TREES PRODUCE
THICKER-WALLED CELLS CALLED
SUMMERWOOD ORLATEWOOD.
• TOGETHER, THESE MAKE WHAT WE
REFER TO AS AN ANNUAL RING.
Factors that affect the appearance of
annual rings include the following.
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RAINFALL
PHYSIOLOGY
SLOPE GRADIENT
SUN
WIND
SOIL PROPERTIES
TEMPERATURE
SNOW ACCUMULATION
Annual Rings can be compared and
matched with trees growing in the
same geographical zone and under
similar climatic conditions to produce
CHRONOLOGIES.
The
Increment
Borer
CHRONOLOGIES
• The Bristlecone Pine which
can live for thousands of
years has produced tree
ring records that travel
9000 years into the past.
• River Oaks growing near the
Main and Rhine Rivers
provide records from over
10,000 years ago