Juniperus occidentalis of the Yolla Bolly Explored | Papers w/ Robert Adams

Original Publication DATE: 9/3/2010 1:26:00 PM

Late in the summer of 2009 I re-visited an isolated population of junipers in the Yolla Bolly-Middle Eel Wilderness. The visit was inspired by Robert Adams after he read a blog post of my first visit to the trees. At the time, the population was believed to be Juniperus grandis based on habitat type and other morphological characteristics. After collecting the specimens and sending them to Baylor University for study Dr. Adams published two papers last month on these populations and their relationship to other junipers of the west. He graciously named me as a co-author for my collecting and final editing skills–otherwise the work was all his.

The papers are:

  1. Geographic variation in the leaf essential oils of Juniperus grandis and comparison with J. occidentalis and J. osteosperma. Phytologia 92(2):167-185. 
  2. Geographic variation in nrDNA and cp DNA of Juniperus californica, J. grandis, J. occidentalis and J. osteosperma (Cupressaceae). Phytologia 92(2):266-276.

While the DNA and essential oil comparisons verified the Yolla Bolly junipers are Juniper occidentalis they did not clarify the relationship of Juniperus occidentalis to Juniperus grandis. Unusual similarities were found between occidentalis populations of Oregon and Northern California and grandis populations of the San Bernardino Mountains. As Dr. Adams states in his conclusions, some questions were answered with the research but more questions remain–further study is needed.

I created this range map after visiting the Yolla Bolly and observing several new, undocumented populations.
As viewed from the ridgeline west of Mount Linn looking northward the populations of western juniper generally grow just east of the ridgelines on sandy soil. Notice the image names the trees as Sierra juniper, which Dr. Adams proved to be wrong.

Other Resources:

  1. Junipers of the World

AUTHOR: Jeffrey Kane
DATE: 9/6/2010 12:36:05 AM
yo dude. congrats on the pub(s).
AUTHOR: Dewey Robbins
DATE: 5/24/2014 5:10:10 PM
This population extends from Low Gap southwesterly along Jones Ridge nearly to Hayden Roughs as isolated individual. Most of the trees my forestry crew and I found were young regeneration; however, there are a few gnarled fire-scarred relics that are more like shrubs than trees.
AUTHOR: Michael E Kauffmann
DATE: 5/26/2014 2:58:05 PM
Dewey– thanks for the note. I’ve never been to that area of the Yolla-Bolly, but want to get there. It looks like they extend even further west to the Eaton Roughs. It is private property, but I’d love to get there too.

3 Replies to “Juniperus occidentalis of the Yolla Bolly Explored | Papers w/ Robert Adams”

  1. I’ve also found Juniper on the ridge trail to the south of Shell Mountain and Cherry Camp.

Comments are closed.