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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #233138

Title: Response of Two Sagebrush Sites to Low-Disturbance, Mechanical Removal of Piñyon and Juniper

Author
item BAUGHMAN, CARSON
item De Queiroz, Tara
item PROVENCHER, LOUIS

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2010
Publication Date: 9/15/2010
Citation: Baughman, C., Forbis, T.A., Provencher, L. 2010. Response of Two Sagebrush Sites to Low-Disturbance, Mechanical Removal of Piñyon and Juniper. Journal of Invasive Plant Science and Management. 3(2):122-129.

Interpretive Summary: The spread of trees into shrublands and grasslands is occurring across the globe and prompting land management agencies to deal with the ecological results. In North America, invasion of shrublands by pinyon pine and juniper has been observed throughout the 11 western states and has been the focus of management efforts for decades. Our study examined effects of removal of trees by mechanical means in two sites with different degrees of pinyon-juniper invasion. Located in eastern Nevada, near the center of the Great Basin, the Ely site was moderately invaded but retained a significant understory component. The Mt. Wilson site was heavily invaded and had a depleted understory. We hypothesized that restoration efforts would be most effective (increasing percent cover of grass, and forbs) on the Ely site and least effective at Mt. Wilson. Both sites showed a decrease in percent cover of trees and an increase in percent cover of forbs. Ultimately, the Ely site had a greater percentage of treated plots transition to earlier stages of succession and Mt. Wilson had a greater increase in invasive species cover. These results support our hypothesis and could guide land managing agencies in determining which sites are ecologically and economically suitable for restoration efforts.

Technical Abstract: Encroachment of shrubland communities by woody species is occurring across the globe and prompting land management agencies to deal with the ecological results. In North America, invasion by Pinus monophylla (pinyon pine) and Juniperus osteosperma (Utah juniper) into Artemisia spp. (sagebrush) communities has been observed throughout the 11 western states and has been the focus of management efforts for decades. One such effort is shrubland restoration where the goal of management is to remove encroaching trees from areas that were historically shrubland. Our study examined effects of tree thinning in two sites located in eastern Nevada, near the center of the Great Basin. Such projects can be controversial, so our goal was to estimate and document the ecological effects of tree thinning at these two sites. Pre-treatment site characteristics were similar with two exceptions. Tree cover was 29.4% at the Mount Wilson site compared to 14.3% at the Ely site. The Ely site possessed a greater grass and shrub component; 8.1% and 22.9% vs. Mount Wilson’s 2.2% and 8.9% respectively. Both sites were mechanically thinned of trees and aerially seeded. After 3 growing seasons both sites significantly increased in percent cover of forbs while Mt. Wilson saw a significant increase in invasive species cover and Ely saw a significant increase in grass cover. There was no significant change in shrubs, litter cover, or biotic crust at either site.