The University of Arizona

The Laboratory of Tree-Ring Research

History of LTRR

LTRR logo
Dendrochronology was founded at the University of Arizona by A.E. Douglass at the turn of the century. The Laboratory was approved as a University department on December 4, 1937, and it came into operation on 1st July 1938. The Arizona Board of Regents established the Laboratory "to promote teaching and research in dendrochronology", and it is the oldest, largest and most comprehensive dendrochronology program in the world.

Originally, the Director of the Laboratory reported directly to the President of the University, and then successively to the Dean of the Graduate College (1958-9), the Provost (1966), the Director of the School of Earth Sciences (1967) the Dean of the College of Earth Sciences (1971-1982), and the Dean of first the Faculty of Science and then the College of Science (1982-present). This administrative history may be seen as a result of the interaction between the multidisciplinary nature of the Laboratory's work and a large modern university's need to impose administrative structures that may not reflect academic reality.

The Laboratory's directors have come from a variety of academic backgrounds:

This also demonstrates the breadth of the Laboratory's work. A period of great scientific success commencing in the 1960s culminated in the mid-1980s, largely from significant faculty turnover. Since that time, a vigorous new group of faculty has been hired.

In addition to the hundreds of scientific publications of dendrochronology that have emanated from the Laboratory of Tree-Ring Research (click here to see a list of recent publications by subdiscipline), two exceptional publication events have occurred. Both events involved a prominent dendrochronologist of the Laboratory as well as The National Geographic Magazine:

  1. Andrew Ellicott Douglass. 1929. The secret of the Southwest solved by talkative tree rings. The National Geographic Magazine, v. LVI, no. 6 (December).
    • Demonstrated that crossdating of tree rings works
    • Established absolute dates of construction, occupation, and abandonment of many of the famous ancient pueblos and cliff dwellings of the American Southwest
  2. Edmund Schulman. 1958. Bristlecone pine, oldest known living thing. The National Geographic Magazine, v. CXIII, no. 3 (March).
    • Demonstrated the great ages of many bristlecone pines
    • Considered the scientific importance of these old trees for learning about environmental change through long time periods

Laboratory of Tree-Ring Research, The University of Arizona
Tucson, Arizona 85721 USA
Main Office: (520) 621-1608, Fax: (520) 621-8229
Comments to Paul Sheppard: