Friends of Northern Arizona Forests

Browse-resistant Aspen

While FoNAF is dedicated to building fences, or exclosures, to protect young aspen from elk and deer that would browse them to oblivion, a research project was conducted to identify strains of aspen that are not tasty to the animals.  

Under the leadership of volunteer Ralph Baierlein, FoNAF embarked on locating these promising aspen, harvesting them, and nurturing them prior to relocation to "ideal" sections of the Coconino Forest.  These new areas include sites where old aspen stands have since declined or new locations where conditions are conducive for aspen growing strong and thriving. 

The project concluded in 2016 and the results are described in three documents prepared by Ralph.  The first is a one page overall summary, the second is a comprehensive report of just the 2016 planting in three exclosures along Highway 180, and the third is a comprehensive report on the total project and an analysis of the results. Links to all three are listed below:  

Summary of Browse Resistant Aspen 

Executive and narrative summary Fall 2016


Initial Description of Project with Links to Annual Reports
During the past two decades, aspen have been dying in alarming numbers on the Coconino National Forest.  To be sure, the roots remain alive for several years, and they send up suckers.  This regeneration, however, is being browsed to oblivion by elk, deer, and livestock.  What can we do to keep aspen on the landscape?

We can build fences around the aspen stands, and this has been done for decades.


The big problem with this route is a disparity in scale.  The Coconino National Forest once held some 10,000 acres of aspen.  Most were on the Flagstaff Ranger District, where exclosures now protect some 250 acres of young aspen.  Extension to thousands of acres is neither fiscally possible nor aesthetically desirable.

What other route might work?

Here and there on the national forest, young aspen continue to flourish--without any fencing.


The photo above shows young growth of various ages on the “Weatherford plateau,” a relatively flat area of the San Francisco Peaks between the eastern end of the Freidlein Prairie Road and the Weatherford Trail.  Scat and tracks show that elk and deer frequent the area. 

High concentrations of natural chemicals (such as tremulacin) are known to deter browsing by elk.  Because of genetic variation, the concentrations differ from one clone to another.  Perhaps the aspen above “taste bad” to elk and deer.

Other such flourishing stands exist.  FoNAF has embarked on a project to collect roots from such stands and to ascertain whether the aspen really are browse-resistant when placed in other locations.

The roots that FoNAF collects go to the NAU Research Greenhouse for incubation under the careful eye of Phil Patterson.  After the suckers have grown to 4-6 inches in height, Phil cuts the suckers from the roots and nurtures them into saplings, roughly a meter high.  Then FoNAF and a crew from the Coconino Rural Environmental Corps or American Conservation Experience plant the saplings in test plots on the forest: some saplings exposed to browsers; others protected within an exclosure as controls.

Here’s a synopsis of the project.

To read the progress during the past few years, click on the reports listed below.

If all goes well, FoNAFand the Forest Service will plant aspen on a landscape scale.

     Year-end report December 2011

     Year-end report December 2012

     Year-end report December 2013

     Year-end report December 2014

     Year-end report December 2015

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