Impact of Western Juniper on
Hillslope Hydrology:
Steens Mountain, OR
Eastern Oregon Agricultural Research Center
Burns, OR
Northwest Watershed Research Center
Boise, Idaho
Background
• 8.5 million acres in western juniper woodland
• 95% of the woodlands are 100 years old or
less
• Juniper invasion results in
 Significant reductions in shrub/understory
production and cover
 Reduced plant diversity
 Loss of wildlife habitat
 Increased erosion potential
Project Info
Rainfall simulation plots were run on eight
replicates of cut and uncut treatments.
Vegetation Response
Cut plot
Un-cut plot
Trough Water
Cut plot
Un-cut plot
Removing Juniper increases infiltration and
decreases overland flow
Removing Juniper decreases runoff volume
Removing Juniper reduces sheet erosion
Removing Juniper decreases rilling
Junipers increase runoff and erosion
Conclusion
• Juniper invasion can result in a dramatic
increase in runoff and erosion. The severity
of erosion will likely be related to the loss of
understory cover and the erosion potential of
a site.
Questions?
For more information contact:
Jon Bates or Tony Svejcar
(541) 573-8900
or
Fred Pierson
(208) 422-0700.