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Comparing Mechanical Treatments for Pinyon-Juniper Removal
Comparing Mechanical Treatments for Pinyon-Juniper Removal

​​​​Personnel 

  • ​​Danielle Bilyeu Johnston​
  • Mark Paschke and Jayne Jonas, Colorado State University
  • Garrett Stephens, Colorado State University student for first phase

Study Area: Piceance Basin 

​​Project Status: First phase completed, data collection underway for second phase

Research Objectives

  • Compare understory response to three different mechanical methods of pinyon-juniper removal: hydro-axing, ship anchor chaining, and rollerchopping.

  • Compare the effectiveness of seeding desirable forage species, especially shrubs, when applied with the above three tree removal methods.

​Project Description

Pinyon-juniper habitat has increased throughout the western United States over the past century. While this increase is not necessarily unnatural or detrimental, managers often convert pinyon-juniper stands to sagebrush ecosystems in an effort to increase forage for big game, especially elk and mule deer.

This can be accomplished by fire, however using prescribed fire as a management tool is often difficult to implement due to safety concerns.

Therefore, several mechanical methods of removing pinyon and juniper trees have been developed:

  • Ship Anchor Chaining - This is the oldest method and entails dragging a ship anchor chain between two bulldozers in order to pull over and uproot trees. This is generally the least expensive method, although it causes soil disturbance and large tree skeletons remain behind after treatments.

  • Roller Chopping – This method entails dragging a rotating drum with protruding plates behind a bulldozer. Trees are knocked over by the bulldozer and chopped into pieces by the rotating drum.

  • Hydro Axing - This is the most recent and expensive method. It uses a rubber-tired loader with a mulching head to grind trees into a fine mulch. This method causes the least amount of soil disturbance of the three described here.

To determine which of these three treatments produces the most favorable plant community, we initiated a field study in the Magnolia region of the Piceance Basin in fall 2011. Each treatment was applied to a 0.8-hectare parcel in each of 7 replications. Initially, we saw higher incidence of exotic species with rollerchopping than with chaining or hydroaxing, and a benefit of hydroaxing in establishing native annual species. After 5 years, differenc​​es among treatment types were minimal, but all treated areas differed greatly from controls. ​Perennial grass cover and cheatgrass cover were higher in treated areas. Perennial forb cover and cover of bitterbrush (Purshia tridentata) were higher in seeded areas.​

Associated Publications