La Grande Forestry and Range Sciences Laboratory

Background and Establishment

The Pringle Falls Experimental Forest is one of 14 experimental areas associated with the Pacific Northwest Research Station. These experimental areas represent important forest and range types and provide opportunity for short- and long-term field study and demonstration. The areas are part of the National Forest System and represent the partnership between Research and National Forest System branches of the Forest Service.

Pringle Falls Experimental Forest is a diverse natural laboratory within the Deschutes National Forest in central Oregon. It was formally established on May 20, 1931, as a center for silviculture, forest management, and insect and disease research in ponderosa pine forests east of the Oregon Cascade Range. The Experimental Forest is maintained by the U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station for research and education in ecosystem structure and function, and demonstration of forest management techniques. It provides outstanding examples of undisturbed and managed ponderosa pine, lodgepole pine, and higher elevation mixed conifer forests occurring on 6,600-year-old aerially-deposited Mount Mazama pumice and ash common throughout central and south-central Oregon.

Pringle Falls Experimental Forest was the first Experimental Forest to be established and was the site of some of the earliest forest management and silviculture research in the Pacific Northwest. Thornton T. Munger, first Director of the Pacific Northwest Research Station (then Experiment Station), selected the 7,520 acre site of the Pringle Butte unit in 1914. Munger was a colleague and long-time friend of Gifford Pinchot, first Chief of the Forest Service. Existing headquarters buildings were constructed between 1932 and 1934. The 3,535-acre Lookout Mountain unit was added in 1936 for a total of 11,055 acres. Pringle Falls Research Natural Area, within the Pringle Butte unit of the experimental forest, provides a protected area for nondestructive research.

Environment

Pringle Falls Experimental Forest and Research Natural Area, southwest of Bend, Oregon (see inside map), are characteristic of low elevation forests within the High Cascades physiographic province. The Experimental Forest has two separate units, each named for the dominant volcanic feature in the unit. Terrain is generally flat or gently rolling, dotted with small volcanic peaks and cinder cones. Pringle Butte, the oldest known geologic formation in the area, is a 5-million-year-old shield volcano rising nearly 1,000 feet above the surrounding basin. More recent deposits are sand and silt sediments of the La Pine basin, overlain with sands and gravels deposited by glacial outwash from the Cascade Range. Lookout Mountain, the highest point in the Experimental Forest (5,223 feet), is a 300-thousand-year-old shield volcano resting on La Pine sediments. Overlaying the entire area is 1.5 to 6 feet of dacite pumice and ash resulting from the explosion of Mount Mazama (now Crater Lake) nearly 6,600 years ago.

Soils derived from Mazama pumice and ash have only a thin weathered surface layer. Most of the soil profile is undeveloped, with low organic matter content, low nitrogen, sulfur, and phosphorus content, and high porosity. Daytime to nighttime temperature variation within the soil profile can be extreme.

The climate is continental, modified by proximity of the Cascade Range to the west and the Great Basin desert to the east. Most precipitation occurs as snowfall. Annual precipitation averages 24 inches on Pringle Butte and over 40 inches on Lookout Mountain. Daytime high temperatures in the summer range between 70 and 90 degrees. Summer nights are cool and frosts can occur throughout the growing season.

Forest types

Forest communities within Pringle Falls Experimental Forest are representative of low- and mid-elevation regional landscapes. Ecological site differences such as aspect and elevation, and past disturbance events, especially fires, insects, and disease, and more recent timber harvesting, have created a mosaic of rich biological diversity.

Ponderosa pine is the dominant conifer through most of the experimental forest. Shrub layers include bitterbrush, ceanothus, greenleaf manzanita, golden chinkapin, and bearberry. A fire regime of low-intensity burns every 7 to 20 years, coupled with infrequent large and more intense fires, was common prior to the advent of modern fire suppression efforts.

Dense lodgepole pine stands with bitterbrush, Idaho fescue, western needlegrass and bearberry occur on flats and basin bottoms that are slow to drain in the spring and, because of topography, are prone to frequent frosts that kill ponderosa pine seedlings. The risk of stand-replacement fire increases in these stands as woody fuel accumulates, often the result of insect-caused mortality.

In the mixed-conifer forest type at higher elevations, stands may contain ponderosa pine, grand fir, Shasta red fir, sugar pine, western white pine, whitebark pine, and mountain hemlock.

Research Opportunities

Some of the earliest forestry research in central Oregon occurred within Pringle Falls Experimental Forest. In 1936, F. Paul Keen published a rating system for determining the susceptibility of ponderosa pine trees to western pine beetle attack, based on a west-wide study and monitoring effort which included ponderosa pine stands in Pringle Falls Experimental Forest. In 1950, Edwin L. Mowat described the stand structure and analyzed periodic growth measurements resulting from a study in which suppressed ponderosa pine seedlings were released from a lodgepole pine canopy. The stand of lodgepole had been removed by Civilian Conservation Corps 16 years earlier, in 1934.

During the next several decades, research concentrated on determining the competitive effect of shrubs growing with ponderosa pine; use of prescribed fire to control competing shrubs; and the soil thermal properties, surface temperatures, and seed bed characteristics required for lodgepole and ponderosa pine regeneration from natural seedfall. Also during this time, logging methods that ensured survival of existing seedlings and saplings were developed, thus reducing future reforestation efforts and costs.

During the 1970's, permanent research plots were used to study the response of ponderosa pine to fertilization, and the release and subsequent growth of ponderosa and lodgepole pine and grand fir at various tree densities. Periodic evaluation of these stands adds to our understanding of structural changes occurring in natural and managed stands. During this time, the frequency, intensity, and spatial patterns of wildfire in old-growth ponderosa pine stands were examined, and the genetic characteristics of ponderosa pine were described.

Work beginning in the 1980's and extending up through the early 1990's emphasized the response of dwarf mistletoe-infected pine to thinning, interactions between fire and dwarf mistletoe, and development of stands in response to various silvicultural practices.

Although much of the long-term research in applied forestry has continued over the years, other topics have increased in importance. Much of the current research in Pringle Falls Experimental Forest is designed to increase our understanding of the processes that regulate or influence the structure, composition, and pattern of forests and that are critical for the maintenance of diverse, healthy, productive, and sustainable forest ecosystems. 

An annotated bibliography of publications resulting from research at the Pringle Falls Experimental Forest from 1930 to 1993 was published in 1995.  It is available from the PNW Station Director's Office as General Technical Report PNW-GTR-347.  The address is located in "Further Information," below.

Requests for approval of research sites within the Experimental Forest should be addressed to:

Andrew Youngblood

La Grande Forestry and Range Sciences Lab

1401 Gekeler Lane

La Grande, OR 97850

(541) 962-6530

ayoungblood@fs.fed.us

Pringle Falls RNA

Research Natural Area (RNA) is a classification used by Federal land management agencies to designate lands where natural ecosystems are preserved in an undisturbed state solely for research and education. The Pringle Falls RNA, jointly managed by the Pacific Northwest Research Station and the Pacific Northwest Region, USDA Forest Service, was established in 1936 to preserve and protect plant communities typical of the northern Mount Mazama pumice area in central Oregon. A total of 1,160 acres are contained in two units. The western unit is nearly flat and supports lodgepole pine, bitterbrush, western needlegrass, Ross's sedge, Idaho fescue, and bearberry. The eastern unit has flat or rolling topography and steep slopes near the tops of Cruiser, Wampus, and South Buttes, and supports ponderosa pine, sugar pine, grand fir, bitterbrush, manzanita, ceanothus, and western needlegrass. Together, these two units provide unique opportunities for nondestructive, nonmanipulative research and education in the natural sciences. Fire scars on ponderosa pine throughout the eastern unit of the RNA indicate ground fires periodically burned the area before effective fire suppression programs began in about 1910; four fires are known to have occurred during the 1800's. Current management of the RNA includes efforts to return fire to apparent pre-1900 intervals. Permission to visit or use the RNA may be obtained by contacting the Pacific Northwest Research Station RNA Coordinator:

Sarah Greene

Corvallis Forestry Sciences Laboratory

3200 SW Jefferson Way

Corvallis OR 97331

541-750-7360

Getting There

Click on the map to see a full-size version

The Experimental Forest and Research Natural Area are about 1 hour south of Bend, Oregon, and are easily accessed from U.S. Highway 97.

Restaurants and motel accommodations are readily available in Bend, Sunriver, La Pine, and Cresent.

Facilities for camping are available within the Deschutes National Forest at numerous locations near the Pringle Falls unit of the Experimental Forest, and in the vicinity of Wickiup and Crane Prairie Reservoirs.

Scientific Facilities

Housing at the Experimental Forest is limited to people involved in on-site research or educational activities. Researchers may request use of the lodging at the Experimental Forest headquarters by contacting:

Administrative Officer

Bend/Fort Rock Ranger District

1230 NE Third Street, Suite A-262

Bend, OR 97701

541-383-4747

mcarpenter@fs.fed.us

For Further Information or Maps, Contact:

Pacific Northwest Research Station

333 S.W. First Avenue

P.O. Box 3890

Portland, OR 97208

(503) 808-2592

La Grande Forestry and Range Sciences Lab

1401 Gekeler Lane

La Grande, OR 97850

(541) 963-7122

Bend/Fort Rock Ranger District, Deschutes National Forest

1230 NE 3rd St. Suite A-262

Bend, OR 97701

(503) 388-5664

Deschutes National Forest maps are available from the Bend/Fort Rock Ranger District or the Deschutes Supervisor's Office in Bend, Oregon. 

US Forest Service - La Grande Forestry and Range Sciences Laboratory
Last Modified: Sunday, 10 April 2005 at 12:28:43 EDT