Data Home | Math Topics | Environment Topics | Topics Matrix | Master List | Help

Download the Data

PDF

Excel File

Text File

Minitab File

Data Set #056

About the Data
View the Data
Help with Using Data
Play with the data on StatCrunch
 

  Go to Top  

About the Data

    As trees grow in age a layer of wood cells are produced each year that usually extends around the entire perimeter of the tree. This annual ring of growth consists of thin-walled cells formed early in the growing season (earlywood) and thicker-walled cells produced later in the growing season (latewood).  From the start of earlywood growth to the end of the latewood growth constitutes one annual tree ring.  Because new wood is also added upwards, the number of rings through cross sections of the trunk will decrease with height.  Thus to determine the age of the tree, a tree ring researcher (dendrochronologist) typically counts the number of annual rings near the base or at "belt height".  Ideally, to determine the age of a tree a researcher will saw through the tree to get a cross section.  To preserve living trees, researchers use an increment borer, which is a hollow auger-like device that is twisted into the trunk.  When the borer, about a centimeter in diameter, reaches the center of the tree, the interior plug or core of wood is removed.  The core is then taken to the lab where tree wood and rings are analyzed.  In practice, at least 2 samples are usually taken from the same tree to reduce the amount of variability in the tree ring data.

    It's a general rule that tree ring widths decrease as the tree ages.  This fact is well supported by the data, especially in the first 100 years of growth. Overall we see annual fluctuations in tree growth most likely due to seasonal differences in climate variables such as temperature and precipitation.  What's really interesting is the periodic fluctuations beginning around 1650 and continuing through 3-4 cycles into the mid 1800's.  Are these an indication that there were 50-year fluctuations in climate in the Pacific Northwest during this period? If so, what climate variables were limiting factors during periods of slow growth?  An excellent exercise for the student is to determine the best fitting curve through the time series or analyze the differences in variation between the two samples.

    The study that uses tree rings to reconstruct the past climate of an area is called dendroclimatology, a subfield of dendrochronology -- the science of using tree ring dating to analyze patterns in physical and social sciences.  Other subfields of dendrochronology include dendroarchaelogy (using tree rings to date wooden artifacts), dendrohydrology (using tree rings to study changes in river flow, surface runoff, and lake levels), and dendropyrochronology (using uses tree rings to study past and present changes in wildfires).  An excellent source on dendrochronology is Henri D. Grissino-Mayer's Ultimate Tree Ring Web Pages.

Source of the data:  Earle, C.J., Brubaker, L.B., Segura, G., International Tree Ring Data Base, NOAA/NGDC Paleoclimatology Program, Boulder, Colorado, USA.  http://www.ngdc.noaa.gov/paleo/ftp-treering.html
 
 

     
  Go to Top  
View the Data


Douglas Fir Ring Widths
Silver Creek, Washington State

source: Earle, C.J., Brubaker, L.B., Segura, G. 
International Tree Ring Data Base

Tree: Sil159    
Elevation: 900m 
Lat/Long: 46N/121W

year

mean width 
(x .01mm)

1565

258

1566

210

1567

265

1568

299

1569

274

1570

319

1571

357

1572

324

1573

263

1574

280

1575

299

1576

195

1577

245

1578

208

1579

240

1580

255

1581

201

1582

216

1583

235

1584

223

1585

169

1586

186

1587

150

1588

183

1589

185

1590

177

1591

152

1592

154

1593

114

1594

115

1595

123

1596

137

1597

146

1598

155

1599

208

1600

151

1601

144

1602

125

1603

99

1604

135

1605

93

1606

94

1607

95

1608

76

1609

96

1610

105

1611

135

1612

128

1613

138

1614

154

1615

137

1616

103

1617

103

1618

80

1619

52

1620

51

1621

71

1622

84

1623

85

1624

100

1625

85

1626

71

1627

65

1628

68

1629

85

1630

83

1631

70

1632

70

1633

75

1634

68

1635

56

1636

45

1637

60

1638

51.5

1639

44.5

1640

53.5

1641

53.5

1642

52.5

1643

50.5

1644

48

1645

39

1646

38

1647

38.5

1648

55.5

1649

29.5

1650

30

1651

36.5

1652

41

1653

26

1654

31.5

1655

34.5

1656

50.5

1657

59

1658

67.5

1659

68

1660

61

1661

61.5

1662

58

1663

54.5

1664

69.5

1665

48.5

1666

55

1667

69

1668

73.5

1669

83.5

1670

86

1671

79

1672

92

1673

77.5

1674

89

1675

92

1676

76

1677

75

1678

102

1679

85

1680

76.5

1681

104.5

1682

121

1683

103.5

1684

84

1685

98

1686

109

1687

108.5

1688

87

1689

87

1690

89.5

1691

96.5

1692

91

1693

95

1694

107.5

1695

96.5

1696

112.5

1697

102.5

1698

87

1699

106

1700

83.5

1701

70.5

1702

80

1703

94

1704

79

1705

58

1706

55

1707

41.5

1708

38.5

1709

49

1710

66.5

1711

74

1712

65.5

1713

59

1714

66.5

1715

76

1716

87.5

1717

69.5

1718

70.5

1719

79.5

1720

81.5

1721

77

1722

78.5

1723

85

1724

86

1725

82.5

1726

72

1727

78

1728

76.5

1729

92.5

1730

98.5

1731

66

1732

91

1733

76.5

1734

66.5

1735

79.5

1736

60

1737

71.5

1738

95.5

1739

71.5

1740

59.5

1741

46

1742

53

1743

44.5

1744

36

1745

38

1746

35.5

1747

49.5

1748

38.5

1749

37.5

1750

49

1751

50

1752

51.5

1753

54.5

1754

37

1755

54

1756

49

1757

57

1758

46

1759

48.5

1760

57

1761

58

1762

61

1763

67

1764

50.5

1765

55.5

1766

50.5

1767

53

1768

42.5

1769

44

1770

64.5

1771

69.5

1772

58

1773

100

1774

93.5

1775

77.5

1776

60

1777

74

1778

77

1779

82.5

1780

79.5

1781

72.5

1782

65

1783

69

1784

79

1785

89.5

1786

89.5

1787

68.5

1788

99

1789

96.5

1790

83

1791

76

1792

77

1793

89

1794

75

1795

58

1796

50

1797

41.5

1798

54.5

1799

42.5

1800

49.5

1801

73

1802

70.5

1803

59.5

1804

74

1805

70.5

1806

64

1807

64

1808

55

1809

45.5

1810

54.5

1811

41

1812

56

1813

56

1814

75

1815

72

1816

82

1817

75.5

1818

71.5

1819

79.5

1820

72

1821

55.5

1822

76.5

1823

51

1824

51

1825

75

1826

66

1827

47.5

1828

46

1829

62.5

1830

44.5

1831

31

1832

49.5

1833

68.5

1834

64.5

1835

57.5

1836

35

1837

39.5

1838

47.5

1839

51.5

1840

38

1841

44

1842

38

1843

47.5

1844

47.5

1845

59

1846

56

1847

36

1848

38

1849

33

1850

33

1851

48

1852

44

1853

41

1854

37.5

1855

52.5

1856

49

1857

45

1858

48.5

1859

46

1860

56.5

1861

58.5

1862

47

1863

56

1864

41.5

1865

45

1866

52.5

1867

55

1868

54.5

1869

41

1870

52

1871

48

1872

49.5

1873

50

1874

55

1875

60

1876

53

1877

69.5

1878

64

1879

57.5

1880

54.5

1881

48.5

1882

58.5

1883

50

1884

47.5

1885

41.5

1886

39.5

1887

39

1888

46

1889

32

1890

27.5

1891

44

1892

52.5

1893

47.5

1894

46.5

1895

34.5

1896

47.5

1897

35

1898

39

1899

40

1900

47.5

1901

46.5

1902

47.5

1903

43.5

1904

55

1905

31

1906

34

1907

35

1908

37.5

1909

40

1910

35

1911

39

1912

41.5

1913

47.5

1914

50.5

1915

36

1916

41

1917

44.5

1918

37.5

1919

45.5

1920

46.5

1921

47.5

1922

32.5

1923

31

1924

32.5

1925

39.5

1926

33

1927

33

1928

35

1929

37.5

1930

38

1931

58

1932

54

1933

31

1934

23

1935

24.5

1936

16.5

1937

19.5

1938

33

1939

21.5

1940

30

1941

29

1942

41

1943

32.5

1944

33

1945

32.5

1946

24.5

1947

31.5

1948

43.5

1949

29.5

1950

33.5

1951

21

1952

29

1953

34

1954

39

1955

49

1956

32.5

1957

32.5

1958

40

1959

27.5

1960

35

1961

47.5

1962

31.5

1963

33

1964

35.5

1965

32

1966

24

1967

34.5

1968

27

1969

33

1970

38

1971

33

1972

29

1973

34.5

1974

33.5

1975

27

1976

43

1977

39.5

1978

40.5

1979

36

1980

37

1981

51

1982

36

1983

49

1984

50

1985

41

1986

45

1987

39.5

Go to Top