Skip to Main Content
Characteristics of western juniper encroachment into sagebrush communities in central OregonAuthor(s): Mary M. Rowland; Lowell H. Suring; Robin J. Tausch; Susan Geer; Michael J. Wisdom
Source: La Grande, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, La Grande Forestry and Range Sciences Laboratory. 23 p.
Publication Series: Miscellaneous
Station: Pacific Southwest Research Station
PDF: View PDF (1.13 MB)
DescriptionWestern juniper (Juniperus occidentalis) woodlands in Oregon have expanded four-fold from 600,000 ha in 1930 to > 2.6 million ha, often resulting in the reduction and fragmentation of sagebrush (Artemisia spp.) communities. We documented dynamics of western juniper across the John Day Ecological Province in central Oregon by recording size class and growth form at 178 sites. We used stratified random sampling, with strata based on vegetation association (sagebrush, juniper, other) and distance from juniper stands. Only 26% of sites contained pre-settlement trees (i.e., > 140 years old), and < 5% of the 2,254 junipers tallied were pre-settlement trees. Mean densities of pre-settlement trees by stratum ranged from 0 to 18 trees/ha, suggesting that historically, juniper was widely scattered across the landscape. Current densities of post-settlement trees ranged from 75 to 211 trees/ha in non-woodland strata to 457 trees/ha in the juniper stratum. Juniper in non-woodland strata was most abundant in sites adjacent to juniper stands and in sagebrush communities. Mean densities of post-settlement trees were greatest in the > 2.0-m tall size class (82 trees/ha), followed by the 0.3-1-m tall size class (52 trees/ha). These densities pose substantial risk to sagebrush communities in central Oregon. Questions remain about the extent of western juniper woodlands across the species' range that have replaced or are expanding into sagebrush communities versus sites that historically supported woodlands. However, our findings suggest that within sagebrush communities of the John Day province, intensive management through removal of western juniper may be prudent, while retaining pre-settlement trees.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationRowland, Mary M.; Suring, Lowell H.; Tausch, Robin J.; Geer, Susan; Wisdom, Michael J. 2008. Characteristics of western juniper encroachment into sagebrush communities in central Oregon. La Grande, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, La Grande Forestry and Range Sciences Laboratory. 23 p.
KeywordsArtemisia spp., encroachment, Juniperus occidentalis, Oregon, sagebrush, western juniper
- Dynamics of western juniper woodland expansion into sagebrush communities in central Oregon
- Performance of finishes on western juniper lumber and particleboard during outdoor exposure
- Benjamin Research Natural Area: guidebook supplement 36
XML: View XML