Ponderosa Pine forest with lupine

PostHeaderIcon Mount Trumbull Study Area

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Mount Trumbull from the north

Mount Trumbull seen from the north in spring–photo by Mark Daniels.

 

Cooperating Agencies:

Location:

Approximately 60 miles (100 km) southwest of Fredonia, in the Uinkaret Mountains of the Arizona Strip.

Date Initiated:

1995

Description:

The Uinkaret Mountains of northwestern Arizona form an island of forested uplands among the arid woodlands, shrublands and sandy deserts north of the Grand Canyon and west of the Kaibab Plateau. Despite their remoteness, the forests of these mountains have been heavily impacted by over a century of logging, grazing, and fire exclusion, and have become densely overgrown with young trees like most of the ponderosa pine forests around the Southwest.

In 1995 the Ecological Restoration Institute, along with the Bureau of Land Management and the Arizona Game and Fish Department, initiated a project to apply ecological restoration treatments across portions of a large (approximately 4000 acres) landscape between Mount Trumbull and Mount Logan, and to measure the effects of the treatments on associated plant and animal species.  The ERI installed over 250 ecosystem monitoring plots across the entire landscape, to measure pre-treatment forest conditions and monitor changes as the treatments were completed incrementally over a series of years. Nested within the larger landscape, a series of four intensively studied, replicated experimental blocks were installed with paired treated and control units to quantify and statistically compare the effects of restoration treatments under carefully controlled conditions.

Landscape view with treated and untreated forest

Landscape view including treated forest in the mid-ground and untreated forest in the background—photo by John Paul Roccaforte.

 

ERI researchers travel to the Mount Trumbull study area periodically to remeasure our monitoring plots and assess the response of forest trees and understory plants to the restoration treatments. Numerous other scientists have ongoing research projects within the area as well. Arizona Game and Fish researchers have studied the response to restoration treatments of various animal species including deer, small mammals, reptiles, and songbirds (more on AGFD research at Mount Trumbull). Researchers from the Forestry, Biology, and Environmental Science departments at Northern Arizona University, as well as graduate and undergraduate students affiliated with the ERI, have also conducted research at Mount Trumbull, with projects ranging from songbird, small mammal, beetle and butterfly surveys to understory vegetation soil seedbank studies, monitoring the fate of forest snags after restoration treatments, and experimenting with different methods of reducing logging slash (branches and small trees) left over from thinning operations.

Researchers collecting soil samples

Field researchers collecting soil samples for seedbank analysis—photo by Judy Springer.

 

 

Project Status:

At present, over half of the 4000 acres in the study area have been treated (thinned and/or burned), and the rest are in control units which are not currently scheduled for treatment. A subset of the ecosystem monitoring plots were remeasured in the summer of 2003 to track changes across the landscape as treatments have progressed, and assess the current crown fire vulnerability. In the course of the 2003 remeasurements, field crews noticed a marked increase in the abundance of cheatgrass, an invasive exotic species.  A new study was initiated to examine the causes of the cheatgrass outbreak, and to look for ways to slow its spread at the Mt. Trumbull study site and elsewhere. For an update on the status of this study, please refer to the Mount Trumbull Ecosystem Restoration Final Report 2006 document below.

The experimental blocks were treated in 1999, and were remeasured in the summer of 2005 to assess changes in overstory tree structure and understory vegetation composition after five growing seasons.

For More Information:

 

Pre- and post-treatment views from the same photopoint

Pre- and post-treatment views from the same photopoint on an ecosystem monitoring plot— photos by ERI)

 

Pinyon-Juniper Restoration at Mt. Trumbull:

Southwestern pinyon-juniper woodlands have undergone many of the same changes since Euro-American settlement as ponderosa pine forests, including increased tree density and decreased understory vegetation cover, with a resulting loss of soil through increased erosion.  In 2002 the ERI and the BLM initiated a small-scale demonstration project to explore the feasibility of applying ecological-based restoration treatments to the pinyon-juniper woodland type, with the goals of halting ecosystem degradation and reestablishing woodland structure and ecological function more consistent with conditions that prevailed prior to intensive land management practices and fire regime disruption.  A modification of the experimental block method employed in the ponderosa pine restoration project was implemented, with two blocks of paired control and treatment units, and six monitoring plots in each unit.

The two blocks were thinned in 2003, utilizing an approach similar to that used in ponderosa pine restoration, with all mature trees retained and a proportion of the younger trees left to replace old stumps and snags.  In addition, slash from the thinning operations was scattered about the interspaces between retained trees, with the goal of stabilizing the soil and creating safe sites for herbaceous plant establishment.  In spring of 2004 the sites were seeded with native understory species, and later in the year the first round of remeasurements were conducted by ERI field crews. Monitoring will continue in this ongoing project, with the results helping to inform future management decisions in southwestern pinyon-juniper woodlands. For more information on the Mt. Trumbull pinyon-juniper restoration project, download the project proposal or the project update from early 2004, or refer to the Mount Trumbull Ecosystem Restoration Final Report 2006 document above.

Researcher Mike Stoddard seeding the pinyon-juniper demonstration unit

ERI researcher Mike Stoddard seeding the pinyon-juniper demonstration unit—photo by ERI.

 

Publications:

Peer reviewed:

Not peer-reviewed:

Theses:

  • Roccaforte, J.P. (2005). Monitoring Landscape-Scale Forest Structure and Potential Fire Behavior Changes Following Ponderosa Pine Restoration Treatments. Master's Thesis, Northern Arizona University, Flagstaff, Arizona. 102 p.
  • Stoddard, M.T. (2006). Slash Additions: A Tool For Restoring Herbaceous Communities In Degraded Pinyon-Juniper Woodlands. Master's Thesis, Northern Arizona University, Flagstaff, Arizona. 108 p.

View southeast from summit of Mt. Logan

View southeast from the summit of Mt. Logan—photo by Mark Daniels.


Last updated:

November 20, 2009

 

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Ecological Restoration Institute
P.O. Box 15017, Flagstaff, AZ 86011
Phone: (928)523-7182, Fax: (928)523-0296