Shelterwood-Planted Northern Red Oaks: Integrated Costs and Options

Rather than evaluate only planting costs, we estimate the cost of producing a successful seedling (i.e., one that is likely to attain a dominant or codominant crown position by stand age 11). This provides a more realistic cost estimate, since the objective is to obtain a given number of competitively successful trees. Thus, the cost of trees that are likely to die or not attain a competitively successful crown position (dominant or codominant) is added to the cost per successful seeding. This provides a more inclusive approach to accounting for costs by integrating the outcome of the competitive struggle between planted trees and other vegetation, the relative cost of the various underplanting treatments, and effects that environmental site quality have on planted tree success. The Underplanting Study: Sites The study was located in the Boston Mountains of Arkansas, in the southern lobe of the Central Hardwood Region (Merritt 1980). The Boston Mountains are the highest and most southern member of the Ozark Plateau physiographic province. They form a band 30–40 miles wide and 200 miles long from north central Arkansas westward into eastern Oklahoma. Elevations range from about 900 ft in the valley bottoms to 2,500 ft at the highest point. The plateau is sharply dissected. Most ridges are flat to gently rolling and are generally less than 0.5 mile wide. Mountainsides consist of alternating steep simple slopes and gently sloping benches. Site index for red oaks (northern red and black oaks [Quercus velutina Lam.]) on study sites ranged from 60 to 79 ft at 50 years (where site index is a measure of site quality). Soils on mountaintops and slopes are usually of shallow to medium depth and are represented by medium-textured members of the Hartsells, Linker, and Enders series (Typic Hapludults). They are derived from sandstone or shale residuum, and their productivity ranges from medium to low. In contrast, soils on mountain benches are deep, well-drained members of the Nella and Leesburg series (Typic Paleudults). They developed from sandstone and shale colluvium, and their productivity is medium to high. Rocks in the area are alternating horizontal beds of Pennsylvanian shales and sandstones. Annual precipitation averages 46–48 in., and March, April, and May are the wettest months. Extended summer dry periods are common, and autumn is usually dry. The frost-free period is normally 180–200 days long.