This document provides an overview of dendrochronology, which is the scientific method of dating tree rings to the exact year of formation. It discusses key researchers in the field like Andrew Douglass and Edward Cook. Dendrochronology allows researchers to reconstruct past climate conditions like drought. It has applications for dating wood artifacts and understanding natural hazards. The document outlines current research projects using dendrochronology to study topics like changes in lake hydrology, climate impacts on forests, and flood frequency.

3. Bachelor of Science Master of Science Doctor of Philosophy
University of Winnipeg University of Western Ontario University of Arizona

6. Source: Dave Sauchyn

7. Behold, there comes seven years of great plenty
throughout all the land of Egypt: And there shall
arise a er them seven years of famine; and all the
plenty shall be forgo en in the land of Egypt; and
the famine shall consume the land;
Genesis 41, 29-30

8. ENVIRONMENTAL HISTORY

10. Tree-ring display at elementary school
Source: Tom Swetnam

11. DENDROCHRONOLOGY IS
MUCH MORE
THAN JUST
COUNTING TREE RINGS.

12. “ RINGS
”
IN THE BRANCHES OF
SAWED TREES SHOW
THE NUMBER OF YEARS
AND, ACCORDING TO THEIR
THICKNESS,
THE YEARS WHICH WERE
MORE OR LESS
DRY.
Leonardo da Vinci

14. Andrew Douglass University of Arizona

15. “ Crossdating is the recognition of the same ring pa ern in
different trees, so that the actual growth date of any one ring
of the pa ern is the same in the different trees and one may
carry a chronology across from tree to tree.
”
A.E. Douglass
Journal of Forestry, 1941

16. Pueblo Bonito New Mexico (before it was excavated)

17. Source: Stones 55

19. Source: mlhradio

20. Source: Alan Stark

21. Tree-ring display at elementary school
Photograph:Tom Swetnam

22. “ Tree-ring analysis is one of the most powerful tools available
for the study of environmental change and the identification of
fundamental relationships between tree growth and climate.
Edward Cook and Neil Pederson
”
Uncertainty, Emergence, and Statistics in Dendrochronology

25. WHAT ARCHEOLOGISTS
NEED TO KNOW ABOUT
DENDRO-
CHRONOLOGY
IN MINNESOTA

26. How old is the oldest tree in Minnesota?

27. The Seward oak 330 yr?
Source: Ralph Sievert

28. Bur oak >450 yr
Source: Joe Zeleznik NDSU

31. White pine 1714
Source: Kurt Kipfmueller

32. White cedar 1452
Source: Danny Margoles

37. Source: Robert Simon, NASA and the Woods Hole Research Center

38. Source: Jonathan Frazier

41. Source: Erik Nielsen

42. 42
Source: Erik Nielsen

44. Source: Baillie (1982)

46. APPLICATION
Dating wood artifacts

47. Source: Pearce Paul Creasman

49. ‘Rat River’ House 1859
Source: Erik Nielsen

50. THREE
MAIN REQUIREMENTS
FOR TREE-RING DATING
WOOD ARTIFACTS

51. 1 Specimens should have enough rings to describe
the unique sequence of growth (generally, more
than 80 years).

52. 2 The ring sequence should exhibit a high degree of
year-to-year variability (in other words, each ring
should not look like every other ring).

53. 3 The artifact should have been constructed from local
trees, with the wood transported not more than a
few hundred kilometers from its cu ing location.

55. Dugout canoe McLoud County Historical Museum, Minnesota

56. APPLICATION
Reconstructing past droughts

57. “
The growth of trees is undoubtably controlled
more by the movement of water than by the
movement of any other single substance.”
Hal Fri s
Tree Rings and Climate

58. water stress
narrow ring reduced photosynthesis
less cell expansion
reduced cell division

59. Tree rings provide the long perspective on drought severity
Drought severity
Weather measurements
Estimated from tree rings
Source: St. George et al., Journal of Climate, 2009

60. NORTH AMERICAN
DROUGHT ATLAS
Cook et al., 2007, Earth Science Reviews

61. Tree-ring estimates of summer drought across North America
AD 1452
Source: Cook and Krusic, 2004

63. Drought (and tree growth) can be ‘tuned’ to different seasons
St. George et al., The Holocene, 2010

64. APPLICATION
Understanding natural hazards

65. floods
climate landscape change
forest dynamics
ecology

67. AP Photo/U.S. Coast Guard, Lt. Brendan Evans

69. 69
St.. George and Nielsen, The Holocene, 2003

74. Source: Lane Johnson

76. 1875
1653
Source: Lane Johnson

77. DENDROCHRONOLOGY IS
MUCH MORE
THAN JUST
COUNTING TREE RINGS.

78. Kurt Kipfmueller University of Minnesota
Photo: Calvin Ferris

79. CURRENT PROJECTS
How has the hydrology of Lake Winnipeg
changed during the late Holocene?
How has climate and human activity affected
forest fires in the Boundary Waters?
How is the snowpack in the
central Rockies changing?
How o en do severe floods occur
on the Red River, and why?
Does decadal climate variability affect
forest ecology and wildfire risks?

80. INTRODUCTION TO DENDROCHRONOLOGY

81. CLIMATE VARIATIONS

83. National Geographic ‘Beam Expeditions’ 1920s

84. Social Sciences
Tower