Land and Ecosystem Management
Pringle Falls Experimental Forest
Pringle Falls Experimental Forest is within the Deschutes National Forest in central Oregon southwest of Bend, Oregon, and was established in May 1931 as a center for silviculture, forest management, and insect and disease research in ponderosa pine forests east of the Oregon Cascade Range. Early research objectives of the Pringle Falls Experimental Forest focused primarily on silvicultural methods for harvesting mature and improving immature ponderosa pine stands for commercial production, converting lower value to higher value forest types, protecting forests from insects and fire; and integrating silviculture and range management methods to improve forage resources. These early objectives evolved over time to what became a “mission” statement in 1954 that, if slightly modified, still remains largely relevant today.
Pringle Falls Experimental Forest on the Deschutes National Forest.
The mission of the Pringle Falls Experimental Forest is to supply facts, through research, to aid in the management of forest land resources, both public and private. More specifically, the objective is to learn basic silvicultural and ecological facts about central Oregon’s forests and develop and demonstrate better methods for protecting, harvesting, reproducing and managing for optimum sustained condition, function, and ecological and social values.
A bibliography of research conducted at Pringle Falls Experimental Forest listed 119 items of scientific literature published between 1930 and 1993. Early research included studies on the susceptibility of ponderosa pine to western pine beetle attack, age-class distribution in ponderosa pine, silvicultural cutting methods with different intensities of selection; stand structure and growth for suppressed and released ponderosa pine seedlings, and sanitation and salvage of insect-susceptible ponderosa pine with the objective of fuel and fire hazard reduction. Contributions such as these added greatly to management of ponderosa pine throughout east-side forests of Oregon and Washington at a time when vast segments of these forests were being harvested to meet society’s increasing demands for lumber products.
Later studies concentrated on determining the competitive effect of shrubs growing with ponderosa pine; the soil thermal properties, surface temperatures, and seedbed characteristics required for lodgepole and ponderosa pine regeneration from natural seedfall; the biology of dwarf mistletoe in ponderosa pine, its spread, and subsequent damage it has caused in understory pine; and the effect of underburning on dwarf mistletoe in ponderosa pine.
Long-term or permanent research plots were established to study the response of ponderosa pine to fertilization and the release and subsequent growth of ponderosa pine at various tree densities. Periodic evaluation of these stands added to understanding of structural changes occurring in natural and managed stands. Work extending through the 1990s emphasized the relationship between ponderosa pine vigor and mountain pine beetle attacks; the effect of fire on root decay in ponderosa pine and the occurrence of fungal microflora on burned and unburned sites; and the cyclic population dynamics of pandora moth, a defoliator of ponderosa pine.
Relatively young (110 years) even-aged stands of ponderosa pine on the
lower slope of Lookout Mountain in Pringle Falls Experimental Forest.
For much of its existence, Pringle Falls served as a primary research platform because of proximity to the Bend Silvicultural Laboratory of the Pacific Northwest Research Station. The Bend Silvicultural Lab closed in 1996, and long-term research studies either were retained by the lead scientist employed elsewhere, were transferred to other federal or university scientists, or were terminated. Although much of the long-term research in applied forestry has continued, other topics have increased in importance.
The long-term research at Pringle Falls is important for continued understanding of the dynamics of managed and unmanaged interior northwestern forests. These studies provide a baseline for assessing different management strategies for commodity and amenity values, for identifying the effects of changing climate on disturbance agents and stand dynamics, and evaluating interactions of overstory and understory vegetation. Current long-term research in Pringle Falls is designed to increase understanding of the processes that regulate or influence the structure, composition, and pattern of forests and are critical for the maintenance of diverse, healthy, productive, and sustainable forest ecosystems. Specific examples include quantification of stand structure in old-growth ponderosa pine, the role of repeated fire in regulating forest structure and forest health, and the effect of species composition in overall stand production and development.
Facilities and infrastructure
The administration site at Pringle Falls consists of 25 acres on the north bank of the Deschutes River. Original headquarters buildings consist of a three-story administration building and a single-story cottage constructed between 1932 and 1934 by Works Progress Administration craftsman. These buildings are excellent examples of the period architecture and rustic rock, log, and frame construction. Later, an additional two-story dormitory, a garage/shop complex, and various outbuildings were added. This infrastructure provides seasonal living and working facilities for about 20 people. The entire administration site is on the National Register of Historic Sites. Researchers and field crews working at Pringle Falls use the Administration Building, Dormitory, and Cottage during the summer field season. All buildings are seasonally closed from November through April. University use and conservation education activities are compatible uses for the Dormitory, Administration, and Cottage.
Old-growth ponderosa pine stand in Pringle Falls Experimental Forest
restored to reference conditions (pre-1900s).
The administration site at Pringle Falls has special value. The ponderosa pine stand surrounding the historical buildings include 700-year-old trees, providing a direct link to establishment of the Pringle Falls and initial functioning of the administration site as a Works Progress Administrationand The Civilian Conservation Corps-era work camp. A well-developed road system currently exists for both the Pringle Butte and Lookout Mountain units of Pringle Falls. With the exception of the Forest Road 43 (Burgess Road) that crosses the northern portion of the Pringle Butte unit, all roads are gravel or cinder roads. Locked gates are in place on the east and west side of the Pringle Butte Research Natural Area and near the top of Lookout Mountain.
Youngblood, A. 1995. Research publications of the Pringle Falls Experimental Forest, central Oregon Cascade Range, 1930 to 1993. Gen. Tech. Rep. PNW-GTR-347.Portland, Oregon. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 45 p.
Speer, J.H.; Swetnam, T.W.; Wickman, B.E.; Youngblood, A. 2001. Changes in pandora moth outbreak dynamics during the past 622 years. Ecology. 82: 679-697.
Administration site in Pringle Falls Experimental Forest.
Youngblood, A.; Johnson, K.; Schlaich, J.; Wickman, B. 2004. Silvicultural activities for special places in Pringle Falls Experimental Forest, central Oregon. In: Shepperd, W.D., Eskew, L.G., comps. Silviculture in special places: Proceedings of the national silviculture workshop;Proceedings. Granby, CO. U.S. Department of Agriculture, Forest Service, Rockey Mountain Research Station. RMRS-P-34: pp. 31-48.
O’Hara, K.L.; Youngblood, A.; Waring, K.M. 2010. Maturity selection vs. Improvement selection: lessons from a mid-20th century controversy in the silviculture of ponderosa pine. Journal of Forestry. 108(8): 397-407.
Youngblood, A. 2011. Ecological lessons from long-term studies in experimental forests: ponderosa pine silviculture at Pringle Falls Experimental Forest, central Oregon. Special Issue. Forest Ecology and Management. 261(5): 937-947. (doi:10.1016/j.foreco.2009.11.025).
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