Ring-Growth Anomalies


Question: If one tree ring is grown each year ("annual rings"), why not just count the rings?
Answer: Ring growth is not always annual:
Single Locally Absent Ring:
  • Bottom part of this photo has 4 full rings
  • Top part of this photo has only 3 full rings
  • Wedging ring is "locally absent" from that part of the sample
  • This sample is crossdateable, but not by mere ring counting
two wedging rings on BCP
Photo provided by P.R. Sheppard
 
Many Locally Absent Rings:
  • This photo of a coast redwood sample has many rings that are wedging out
  • This sample probably is not crossdateable
  • Important Point: Not all tree-ring samples are crossdateable
many wedging rings on BCP
Photo provided by H.C. Fritts
 
Easy False Ring Example:
  • This photo has 2 full rings -- left-most ring has a false band
  • The false band of dark latewood cells fades back to earlywood
  • This sample is crossdateable, but not by mere ring counting
easy false ring
Photo provided by C.H. Baisan
 
Difficult False Ring Example:
  • This photo has 2 full rings -- right-most ring has a false band
  • The false band appears to go through the resin duct
  • This sample is crossdateable, but not by mere ring counting
hard false rings
Photo provided by C.H. Baisan


Introduction | Dendrochronology Applications | Crossdating Application | Ring-Growth Anomalies
Sensitivity-Complacency | Skeleton Plotting | Relative Scale | Master Chronology
Pattern Matching | Finding the Dates | Absent/False Rings | Try Skeleton Plotting for Yourself!
Laboratory of Tree-Ring Research

Paul R. Sheppard
Laboratory of Tree-Ring Research, The University of Arizona
Tucson, Arizona 85721 USA
office: (520) 621-6474, fax: (520) 621-8229
Comments to: sheppard@ltrr.arizona.edu

Copyright © 1998, Laboratory of Tree-Ring Research, The University of Arizona
Revised -- December, 1998
URL: http://tree.ltrr.arizona.edu/skeletonplot/ringanomalies.htm