Bighorn Mountains Dendrochronology

In August and September of 1998 we collected increment cores from 30-45 of the oldest trees at each of 3 sites along the western base of the Bighorn Mountains, WY, and the Pryor Mountains, MT (table below). Each of these sites is a canyon draining the western side of the mountains and is near the lower elevational limit of conifer forest and the upper elevational limit of Utah juniper. The three sites span about 150 km of the eastern edge of the Bighorn Basin. The oldest trees sampled are of a different species at each of the 3 sites, although at least 2 of the 3 species are present at each site. At each site we found a concentration of mature trees along the upper rim of the canyon. These trees are apparently protected from fire, harvesting, and possibly from disturbance by livestock grazing. Most of the cored trees were live, but a few dead trees were sampled to determine the potential for extending the chronology by collecting cross sections of dead trees.

We also sampled a few limber pines at 4 other sites (Alkali Creek, Webber Canyon, John Dent Ranch, and Copper Mountain).

Utah juniper project home page

Number of trees and increment cores of 3 species sampled at the 3 major study sites in 1998.

 

 

 Limber Pine

Douglas Fir

 Ponderosa Pine

  Site

 Elevation (m)

 trees

cores

trees

cores

trees

cores

Inferno Canyon, MT 

  1600-1800

 36

42

3

2

2

2

Trapper Creek Canyon, WY

 2000-2200

 13

16

33

50

0

 0

Tensleep Preserve, WY

 1600-1900

1

2

1

1

28

43