North Central Research Station - Experimental Forests

Sinkin Experimental Forest Mark Twain National Forest, MO 4,116 acres, Est. 1951 Contact: Frank Thompson Silviculture and ecology of oak-hickory ecosystems, with an emphasis on shortleaf pine and oak reproduction.

Brief introduction

In 1950, the lands (Township 32N Range 3W) that make up the Sinkin Experimental Forest were withdrawn from the national forest system for the purpose of implementing forestry research studies. The headwaters of Sinking Creek originate in the general vicinity of the experimental forest, hence the name “Sinkin”. The forest is 4,116 acres and is in southeastern Dent County, Missouri. It is also a compartment within the Salem Ranger District of the Mark Twain National Forest. The town of Salem is approximately 25 miles northwest of the experimental forest. The forest is operated and maintained cooperatively by the North Central Research Station and Mark Twain National Forest.

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Climate

Weather data have been collected from 1950 to the present. Most of the average annual precipitation of 44 inches falls in the form of rain, with occasional freezing rain, sleet and snow during the winter months. Winter snowfall averages 10 inches. The coldest month is January and the warmest is July or August. Within the data set, the lowest temperature recorded is 20°F below zero and the warmest is 112°F. It is not uncommon during the winter months for temperatures to hit 50-60°F, this is known locally as the January thaw. Temperatures of 90°F or higher have been recorded in April and October. The wettest months are April, May, and June; the driest months are December, January and February.

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Soil types

Most of the ridge tops and steep side slopes on the experimental forest are comprised of Clarksville stony loam or gravelly loam. The surface layer is about 13 inches thick, and consists of cherty silt loam. The subsoil is about 7 inches thick, reddish yellow, and contains very cherty loam. From 40-90% of the soil profile contains pieces of chert from ¼ inch to 6 inches or more in size. These soils originate from Cambrian Age dolomite and sandstone in the Roubidoux and Gascanade formations. Since these soils have a low moisture storage capability, droughty conditions develop quickly when there is a lack of precipitation.

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Vegetation types

Approximately 3000 acres of the Sinkin are dominated by the red oak and white oak groups. Black (Quercus velutina) and scarlet oak (Q. coccinea) are the most numerous species in the red oak group with some northern red oak (Q. rubra). The most numerous and largest trees in the white oak group are white oak (Q. alba) and post oak (Q. stellata). Growing in association with both groups are species of hickory (Carya spp.), black gum (Nyssa sylvatica), sassafras (Sassafras albidium), shortleaf pine (Pinus echinata), black cherry (Prunus serotina), maple (Acer spp.), dogwood (Cornus spp.), and some black walnut (Juglans nigra). The youngest stands are 3 years of age, and the oldest exceed 100 years. The understory usually consists of the species mentioned above, plus elm (Ulmus spp.), ash (Fraxinus spp.), various brush species, woody vines, and numerous herbaceous plants.

About 540 acres of the Sinkin contain pure stands of shortleaf pine. Most of this is at least 70 years old. The understory is composed of hardwood species and shade tolerant herbaceous plants.

The remaining 460 acres is the oak-shortleaf pine timber type. The overstory and understory will consist of varying amounts of hardwood species and shortleaf pine. Herbaceous plants, which do well on acidic and dryer sites, will be found on these sites.

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Long-term data bases

• Sinkin weather data, origin 1950
• Pine Stocking Study, origin 1950, (growth and yield)
• Oak Stocking Study, origin 1962, (growth and yield)
• Spatial Distribution Study, origin 1978
• Shelterwood Study, origin 1979
• Sinkin Experimental Forest, Continuous Forest Inventory (CFI), origin 1992.

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Research – past and current

Initial research concentrated on solving management and reproduction problems of shortleaf pine. Planting techniques, prescribed fire, use of herbicides to control competition, and thinning methods were developed to address these problems. Later research confronted the silvicultural issues with the management and reproduction of oak stands. Studies were established to answer questions about natural and artificial oak regeneration. Current research involves monitoring the long-term studies, savanna demonstration areas, joint fire-science projects with Missouri Department of Conservation and U.S. Geological Survey, and administrative studies on uneven-aged management with the Mark Twain National Forest.

Some research conducted on the Sinkin:

• Oak and shortleaf pine stocking studies.
• Oak shelterwood and oak clearcut regeneration studies.
• Selection silviculture demonstration project.
• Northen red oak and white oak underplanting studies.
• English oak and loblolly pine planting trials.
• Oak fertilization studies (effects on growth and groundwater).
• Diameter growth patterns of black and scarlet oaks and short-leaf pine.
• Field trial of rule thinning in natural oak stands.
• Oak wilt tree wounding study.
• Root grafting in oaks, an exploratory isotope study.
• Planting trials of chestnut. Shortleaf pine seed source study.
• Weather observations (precipitation, temperature, and humidity) since early 1950's.
• Down deadwood decomposition demonstration project.
• CMU (herbicide) study for regeneration release.

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Major research accomplishments

In the 52 years that the Sinkin has been an experimental forest, over 200 research projects have been established. Numerous shortleaf pine management guides have been written by project scientists. The silvicultural techniques used by foresters for pine management in Missouri were developed on the experimental forest. The success of oak underplanting was developed and refined by Dr. Paul Johnson on the Sinkin and surrounding national forest lands. Information gained from research conducted on the Sinkin contributed significantly to the text book “The Ecology and Silviculture of Oaks” by Dr. Paul S. Johnson, Dr. Stephen R. Shifley, and Dr. Robert Rogers.

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Collaborators

Mark Twain National Forest, Missouri Department of Conservation, University of Missouri, U.S. Geological Survey, Southern Illinois University, and others.

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Research opportunities

Ecology and silviculture of central hardwood forests, oak decline, drought related stress on tree growth and yield, insect pest and drought relations, and savanna development.

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Facilities, contact address, location

The technical staff for the experimental forest consist of 3 full-time technicians. An office is located at the Salem Ranger District office. The Sinkin Experimental Forest has an automated weather station that is satellite/cell phone accessible.

Contact information:
Dr. Frank Thompson
North Central Research Station
202 Natural Resources Bldg.
University of Missouri
Columbia, MO, 65211
phone: 573-875-5341
e-mail: Frank Thompson

or
Ken Davidson, Lead Technician (Superintendent)
phone: 573-729-6656
e-mail: Ken Davidson

USDA Forest Service - North Central Research Station
Last Modified: Thursday, 19 February 2004