Tree Rings

Colin Bielby, SAPS and MMU. All photos copyrighted. Contact author on 0161 247 2307 or docbielby@hotmail.com

Starter• Can you, in groups of 4, find the value of

Pi?• You have 4 pieces of string (20, 30, 40

and 50 cm in length), a piece of graph paper and a ruler.

Go!!!

Dendrochronology? It’s all

greek to me!

DendrochronologyPronounced

den – dro - kron – o - la – gee

Word roots•dendro (from dendros, greek for tree)•chrono (from chronos, greek for time or past events)•logy (from logos, greek for reason or word. “ology” indicates a study or theory)

What are tree rings?• Growth – varies throughout year in

our climate• Late Spring/Summer – wide light

coloured ring (lots of growth)• Late summer/autumn – narrow

darker ring (little growth)• Winter – dormant (no growth)

From LTTR, Arizona

• So one year’s growth is a dark and light ring together = annual growth ring = X

X

From LTTR, Arizona

• Earlywood – appears light in colour – cells are thin walled and large in diameter

• Latewood – appears dark in colour – cells have thick walls and are small in diameter

• Total ring width = a light and dark band

Photos by Grassino-Mayer at UTK (see web address)

X

An aerial photo of the wooded area before the felling in 2002. X marks the area where the felled trees came from at grid

reference 832396

Courtesy of Multimap

x

Courtesy of Multimap

An area of pine trees showing how close together they are as they grow

The area after the trees were felled in autumn 2002

Young pine trees ready to plant in the cleared area in 2004

A pupil, Bielby junior, collecting measurements from felled pines

Task 1. Is there a relationship between the age (number of

rings) and the diameter of the tree?

Stop here to do task

Tree Rings Tree Diameter(cm)

5 6

6 7

7 7

7 7

8 8

11 12

14 11

14 12

14 12

18 17

18 16

18 16

19 16

19 17

19 18

20 19

20 20

22 14

25 18

26 18

27 21

27 23

28 23

29 21

30 23

30 28

30 26

31 28

32 18

32 30

32 25

32 35

35 33

36 33

36 33

36 31

38 26

38 32

38 35

39 40

39 31

39 31

40 24

40 21

41 27

41 29

41 34

42 31

42 29

42 40

42 32

43 36

44 24

44 36

44 52

45 34

47 42

47 44

49 32

49 48

50 51

51 39

53 26

Tree Diameter(cm) with age

0102030

405060

0 20 40 60

Age (tree rings) years

Tree

dia

met

er (c

m)

TreeDiameter(cm)Linear (TreeDiameter(cm))

Diameter of tree (cm) Number of tree rings7 812 11

15.5 1818 17

18.5 2220 1924 2725 2730 4533 3534 3340 37

Tree ring graph

05

10152025

3035404550

0 20 40

Diameter of the tree (cm)

Tree

ring

s (a

ge in

yea

rs)

Task 2. Marking off actual years and events on a tree

section

2002

The year England won the world cup?

The new millenium?

? When were you born?

Put in some important dates

Task 3. Is there a relationship between the shape of the tree section

and where it grew?

Look at the shape of this cross section of a tree trunk.What is unusual about the shape?Think about how it has grownThink about where it might have been in the group of trees that were cut down (go back to the photo and map on slides 9 and 10)

Task 4. Is there a relationship between the width of the summer ring

and the weather that year?

See slide 6

Current Useful Websites about Tree Rings and Dendrochronology

• Sites for primary pupils

• http://www.safetreekids.net/index.html

• A public education programme of the Pacific Gas and Electric Company. It has a section on tree rings and an activity to draw rings on downloadable cartoon tree sections.

• Sites for secondary pupils

• Tree Rings: A Study of Climate Change

• http://vathena.arc.nasa.gov/curric/land/global/treestel.html

• A very comprehensive site that has a glossary, very readable text and a series of activities to help pupils understand the relationship between tree ring growth and climate.

Sites for teachersHenri D. Grissino-Mayer's Ultimate Tree-Ring Web Pageshttp://web.utk.edu/~grissino/principles.htm and ............/gallery.htm• Ideal for a teacher who wants to know a little more about the subject. There is an extensive gallery

that has some very clear images of tree rings in a variety of species that could be used to help pupils understand the principle of tree aging.

Oxford Dendrochronology LaboratoryDaniel Miles, Michael Worthington, and Dr Martin Bridgehttp://www.dendrochronology.com/• Technical site that would be useful for background information for the teacher.

The University of Arizona. The Laboratory of Tree-Ring Research Dendrochronologyhttp://www.ltrr.arizona.edu/dendrochronology.html• A very detailed site with clear explanations about tree rings supported with comprehensive

illustrations.

Title: Tree Rings - Dendrochronology (2 Lessons)Prepared by: Claudia Marosz, Garden Grove Unified School District, Westminster, CA, USAhttp://www-sci.lib.uci.edu/SEP/CTS/TreeRing.html• A rather complex site but there is an excellent description of tree rings by Bruce Palmer (very

readable for secondary pupils) if you scroll to the bottom of the page.

Tree Rings. A cursory look at these well known features by Paul James, UK• Published in the  January 2002 edition of Micscape Magazine the on-line monthly magazine of the

Microscopy UK web. http://www.microscopy-uk.org.uk/mag/artjan02/treering.html • An excellent gallery of sections of a variety of trees.