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Logging releases seen in spruce cores from the Hubbard Brook Valley plots


  Contact Info:
  Tom Siccama
School of Forestry and Environmental Studies
Yale University
Greeley Memorial Laboratory
370 Prospect Street
New Haven, CT 06511
phone: 203-432-5140
Ellen Denny
USDA Forest Service
271 Mast Road
Durham, NH 03824
phone: (603) 868-7683

Some examples of logging releases
Many of the cores we’ve examined have clear releases. The most common dates seem to be from 1875-1889 and 1908-1914. Some trees have releases in both time periods, and some only in one. For some cores the release is very clear and can be attributed to a single year. In others, the release is gradual, the rings slowly getting wider over several years. All cores were taken during 1995.

  Spruce tree core


The upper core in the image above is from plot 156, transect 775N, 17m out of plot at 48 ° from center. Dbh is 27.9. There is a very clear release in 1879, and perhaps one in 1922, although this second one is not very clear. The lower core is from plot 157, same transect, 20m out of plot at 244 ° from center. Dbh is 39.2. This tree has a clear release in 1915. (Note: Heavy "magic marker" marks 2 to 4 cm in from the bark indicate the sapwood boundary. The boundary is only visible on the fresh core and is marked when the core is taken.)

  Spruce tree core


The upper core in the image above is from plot 159, out of plot 25m at 236 ° from center. Dbh is 37.4. Rings go back to 1891, but there is no clear release here. It may be possible to show release on this type of core if it were cored lower to the ground. The lower core is plot 158, tree #5674, dbh 39.3. There is no release in the 1870s, but a gradual one starting in 1907 with rings much larger by 1909. Some cores have a much more subtle release spanning closer to ten years.

A very old spruce tree
The lower core in the image below is from a tree that was 1.3 meters tall around the year 1600 (the core missed the center but we counted rings back to 1606!!) So it may very well be 425 years old!!!

  Spruce tree core


Lower core is from plot 250 on transect 760, 45m out of the plot at 194 ° from center. Dbh is 53.2 cm.