e-binder for 2014 CEETEP workshop
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Activity—Dendrochronology
In this activity, students will use pre-marked paper strips to simulate tree-ring core samples to
help them understand that data for past climate changes can be gathered from sources beyond
long-term weather observations. Students will be able to recognize the direct impact of climate
on annual tree growth patterns.
Trees are some of nature’s most accurate timekeepers.
Their growth layers, appearing as rings in the cross section
of the tree trunk, record evidence of oods, droughts, insect
attacks, lightning strikes, and even earthquakes.
Tree growth depends on local conditions, which include
the availability of water. Because the water cycle, or
hydrologic cycle, is uneven, that is, the amount of water
in the environment varies from year to year, scientists
use tree-ring patterns to reconstruct regional patterns of
drought and climatic change. This eld of study, known
as dendrochronology, was begun in the early 1900’s by an
American astronomer named Andrew Ellicott Douglass.
While working at an observatory in his native Arizona,
Douglass began to collect pine trunk cross sections to
study their annual growth rings. He thought there might be
a connection between sunspot activity and drought. Such
a connection could be established, he believed, through
natural records of vegetation growth.
Douglass was not the rst to notice that some growth
rings in trees are thicker than others. In the climate where
Douglass was working, the varying widths clearly resulted
from varying amounts of rainfall. In drier growing seasons
narrow rings were formed, and in growing seasons in which
water was more plentiful, wide rings occurred.
(from USGS student activity page:
Global Change — Time and Cycles:
Logs of Straws: — Dendrochronology
Activity not done in the workshop, but discussed on Tsunami eld trip.
Science Standards
(NGSS; pg. 287)
From Molecules to Organisms—Structures •
and Processes: MS-LS1-8
Ecosystems—Interactions, Energy, and •
Dynamics: MS-LS2-1, MS-LS2-4
Earth’s Place in the Universe: HS-ESS1-5•
Earth’s Systems: HS-ESS2-1, MS-ESS2-2, •
HS-ESS2-2, MS-ESS2-3
Earth and Human Activity: HS-ESS3-1, •
MS-ESS3-2
Learning Goals
1. Students will understand that data for
past climate changes can be gathered
from sources beyond long-term weather
observations.
2. Students will recognize the direct impact of
climate on annual tree growth patterns.
Grade Level/Time
• Grade level: 6 to 8
• Time:
• Preparing the paper strip samples: 15
minutes
• Lesson background: 20 minutes
• Student activity: 45 minutes
• Class discussion: 20 minutes