Cooperating Agencies:

• NAU School of Forestry


• Arizona State Land Department

Location:

Approximately 3-9 miles (5-15 km) southwest of Flagstaff, Arizona, on the southern half of the Centennial Forest.

Date Initiated:

2001

Description:

The Centennial Forest is the result of a collaboration between the Arizona State Lands Department and the NAU School of Forestry to create a “living laboratory” where researchers and students from NAU can study examples of forest, woodland, and grassland ecosystems around Flagstaff to learn about ecosystem dynamics, test ecological hypotheses, and conduct ecological restoration experiments. The Centennial Forest is divided roughly in half into a unit north of the San Francisco Peaks in pinyon-juniper woodland and grassland ecosystems, and a checkerboard of southern units in the ponderosa pine forest southwest of Flagstaff.

On some of these units southwest of Flagstaff, the ERI established an ecological restoration experiment with four restoration treatment units and adjacent control (untreated) units, and installed 160 permanent monitoring plots to measure ecosystem response to the treatments. These treatments are integrated into a large-scale project, entitled Stand Treatment Impacts on Forest Health (STIFH), established by several School of Forestry researchers to study the effects of different forest management practices on various biotic and abiotic ecosystem components.

Associated Projects:

Former ERI graduate student, Megan Van Horne, conducted a research project for her master’s degree looking at fire-scarred ponderosa pine trees on a part of the Centennial Forest study site. The following is a summary of her study (from her publication, listed below):

Fire scars have been used to understand the historical role of fire in ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) ecosystems, but sampling methods and interpretation of results have been criticized for being statistically invalid and biased, and for leading to exaggerated estimates of fire frequency. Megan compared “targeted” sampling, random sampling, and grid-based sampling to a census of all 1,479 fire-scarred trees in a 1-km2 study site in northern Arizona. Of these trees, 1,246 were sufficiently intact to collect cross-sections; of these, 648 had fire scars that could be cross-dated to the year of occurrence in the 200-year analysis period. Given a sufficient sample size (approximately n ≥ 50), she concluded that all tested sampling methods resulted in accurate estimates of the census fire frequency, with mean fire intervals within one year of the census mean. She also assessed three analytical techniques: (1) fire intervals from individual trees, (2) the interval between the tree origin and the first scar, and (3) proportional filtering. “Bracketing” fire regime statistics to account for purported uncertainty associated with targeted sampling was not useful. Quantifying differences in sampling approaches cannot resolve all the limitations of fire-scar methods, but does strengthen interpretation of these data.

Project Status:

Thinning has been completed on the treatment units in the Centennial Forest, and we will return to remeasure the site once the site is burned.

For More Information:

• Contact Joe Crouse, at This e-mail address is being protected from spambots. You need JavaScript enabled to view it
• See the Centennial Forest Website

Publications:

• Abella, S.R., and J.D. Springer. 2009. Planting trials in northern Arizona ponderosa pine forests. Ecological Restoration 27(3):290-299.
• Laughlin, D.C., S.R. Abella, W.W. Covington, and J.B. Grace. 2007. Species richness and soil properties in Pinus ponderosa forests: a structural equation modeling analysis. Journal of Vegetation Science 18:229-240.
• Van Horne, M.L. and P.Z. Fulé. 2006. Comparing methods of reconstructing fire history using fire scars in a southwestern United States ponderosa pine forest. Canadian Journal of Forest Research 36:855-867.

Last updated:

November 20, 2009