| Gus Pearson Natural Area Restoration |
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The Gus Pearson Natural Area approximately 5 years after
restoration treatments—photo by Doc Smith Cooperating Agencies:Location:Approximately 12 miles (20 km) northwest of Flagstaff, AZ. Date Initiated:1992 Description:The Gus Pearson Natural Area (GPNA) is located within the Fort Valley Experimental Forest, the oldest experimental forest in the United States (established in 1908). GPNA is also the site of the ERI’s oldest ecological restoration treatments utilizing thinning of small trees to emulate presettlement forest structure prior to reintroducing low-intensity fire (though the study site itself had to be decommissioned as a part of the GPNA to allow for cutting trees). Aside from some light logging in 1894, the site has never been commercially harvested, and so retains its complement of mature ponderosa pines, as well as a dense growth of young pines originating from the seed crop of 1919. The National Science Foundation funded the initial experiment to compare three treatments: 1) tree thinning to emulate predisruption forest structure, followed by fuel reduction and prescribed burning (composite); 2) tree thinning only, without fire (thinning); and 3) control. The study also attempted to examine the response of the treatments to different “patch types” at the site, including presettlement stands, postsettlement stands, and remnant grassy patches.
Map of the GPNA study site after restoration treatments,
showing the different treatment areas. The circles on the map represent tree canopies The goal of the composite treatment was to recreate as closely as possible the structure and function of a ponderosa pine forest prior to Euro-American settlement and the initiation of fire exclusion (about 1876), and the small size of the project area allowed for the use of relatively labor-intensive methods to effect this result. First most of the small, postsettlement trees were cut and removed from the site, with some left to replace trees which had died or been cut since 1876. Recent leaf litter (from the last few seasons) was raked aside, and the accumulated duff from the past century was removed, then the recent litter was replaced. Finally, to replicate the composition of fine fuels which would have been in place in presettlement times, native grass hay from nearby Hart Prairie was collected and scattered across the site before burning. The composite units were burned in the fall of 1994, and have since been repeatedly burned on a four-year rotation. The thinning units received the same level of tree thinning, but had none of the forest floor manipulation, and of course were not burned.
Prescribed fire at GPNA. Mature ponderosa pines have thick, fire resistant bark that allows them to survive low-intensity fires such as this—photo by ERI Now, more than a decade after the treatments were completed, the composite and thinning treatments appear to have made substantial recovery towards the structure and functioning of an undisturbed presettlement ponderosa pine forest. The mixture of large, yellow-bark pines and young, vigorous blackjacks in clumps across the site approximates the structure of the original forest, and the open spaces between clumps are dense with native grasses (including squirreltail, mountain muhly, Arizona fescue, and pine dropseed) and forbs (such as American vetch, Wheeler’s thistle, and silvery lupine). The strongest response in the understory vegetation was seen in the patches where all the young postsettlement trees were removed.
Pre- (1992) and post- (2005) treatment photos from a
permanent photopoint at Gus Pearson Natural Area—photos by ERI As the first ecologically based ponderosa pine forest restoration experiment in the Southwest, the Gus Pearson site has been intensively studied since the project’s inception by a variety of researchers from the ERI and the NAU School of Forestry, including both professors and a number of graduate students. Studies which have been conducted at the GPNA include measurement of tree growth and ecophysiological response to the treatments, nutrient cycling, fungal mutualists, microbial communities, plant phenology, and above- and below-ground biomass. Project status:Research at the GPNA is ongoing, and the composite treatments continue to be burned every four years to replicate the presettlement fire regime of frequent, low-intensity burns. A number of scientific papers have been published on research from the site, and results of the experiment have informed decisions made on numerous subsequent restoration projects. As the forest develops over time we expect to continue learning from this very special research site. For More Information:
Publications:Peer-reviewed
Non peer-reviewed:
Last updated: February 6, 2008 |
