WNTS Maximum Ages for Western Trees

The oldest official counts for ages of western trees are posted on the OLDLIST maintained by Rocky Mountain Tree Ring Research  Of the hundreds species listed in western  US (Audubon Field Guide), only a handful have "official" cross-dated ages.


For the most part dendrochronologists focus on collecting samples from long lived trees in order to create long histories of environmental, fire, archaeological events and sequences. For this reason there are only a few species that are heavily sampled. For other species there may be a few samples taken here or there as part of a larger study. The results of these often are not published or compiled in any systematic way as they are not the focus of the research. Until recently the International Tree Ring database http://www.ncdc.noaa.gov/paleo/treering.html  would not even accept dendro sequences less than 200 years old. Check on the current age listings on the OLDLIST  website: http://www.rmtrr.org/oldlist.htm   for the most detailed information.

In the face of this lack of published information the maximum ages that hundreds of species of trees and shrubs may reach is virtually unknown, and often misrepresented in various popular media and field guides. We can help remedy this situation.  I want to collect ages from as many of the other species as possible from ring counts on stumps and cores. So I am asking WNTS members count everything you find, write down your information on where, when, who, and how and send them to me.  At this stage the primary goal is to collect ring count ages from trees, shrubs and vines in western United, Canada, and Mexico.

To be included are:

  1. Any ages from species not currently on the OLDLIST
  2.  Ages that exceed or approach the ages for the species on the OLDLIST
  3. Ages that represent great age for the species.

There are some inherent inaccuracies with ring counts. There may be false rings or missing rings, but these limitations are understood within the context of the methodology. They are trivial compared to the degree of error in field guides. Better age range information will be valuable when considering the ecology and history of the small patches of old growth we are finding and documenting.

For foresters and field people there will be a tenancy to not count rings on some stumps because you "know" there are older examples out there that you have seen. However at this point, there is such a paucity of good numbers, I would encourage you to count what you find. If we get older counts later so much the better, but the goal now is to get something more reasonable. Along access roads there may be shrub-sized species, like witch hazel for example, cut that are not normally harvested. Numbers for these species would be useful also.

A next step for the project, and one that can begin simultaneously, is the use of all collected data, both for "new" species and for old, to plot the ages known for various forests, and forest sections. This will allow a development of a beginning geographic data base of the age of various forests, and allow us to better understand and investigate the age structure of forest we are visiting and investigating.

Edward Frank


WNTS Maximum Tree Ages List              
Last Revised 7/9/2009                
Name Species Age Count OLDLIST Age Age Category Location Sample Type Date Counted Collector Comments
Poison Oak Rhus diversilobum 70       ring count   M. Vaden Cut poison-oak vine on a fallen tree. Almost 70 growth rings: near 2" in diameter.

WNTS Maximum Ages Spreadsheet .xls


Collection Information:

The following information would be needed:
1) Species name:
2) Location: Include name of forest, address (if applicable) county, state, GPS (if known):
3) Date of field sampling/counting:
4) Type of sampling;
a) Field count of tree stump or log
b) Field count of increment borer core
c) laboratory count of tree cross-section
d) laboratory count of increment borer core
e) Other method - please describe
5) Was a sample collected and if so, what is its disposition?
6) Diameter of tree:
7) Is the sample complete or partial:
6) Collector Name and address, phone, email:
7) Is the tree still alive or is it dead? (Living, Snag, Stump, Log, Remnant)
8) Description of the site, associated trees, land use history, etc.
9) Site Code (if applicable)
10) Photographs of the sample/sample area: yes or no.
11) Age character/category:

.Age Category Definitions

This category deals with the apparent age of the specimen as interpreted by the collector. There are three
broad categories of age information that might be obtained from stumps or dendro cores. I would leave it up
to the person doing the collecting or counting to provide a judgment of which category in which to place the sample

1) Late Mature: This specimen represents an old tree, but trees in this age range are not uncommon.
2) Old tree: This specimen represents a tree that is uncommonly old for the species.
3) Very old: This specimen may be approaching the maximum age possible for the species.
4) Not categorized / Unknown