Author ORCID Identifier

https://orcid.org/0009-0006-8633-9751

Semester

Spring

Date of Graduation

2025

Document Type

Thesis

Required Additional Files
Solar position calculator JOF_030525.xlsm (16 kB)

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Forestry and Natural Resources

Committee Chair

Jamie Schuler

Committee Co-Chair

Kirsten Stephan

Committee Member

Kirsten Stephan

Committee Member

Melissa Thomas-Van Gundy

Abstract

There are well-known difficulties associated with regenerating oak stands throughout the Central Hardwoods region. To successfully regenerate oak, competitive sources of advance reproduction are required ahead of harvesting—a condition that is rarely present, especially on productive sites. While treatments that enhance seedling competitiveness (e.g., midstory removals, burning, vegetation control) are available, in practice, these are rarely implemented and/or effective because of large treatment costs and/or because they require delaying harvest.

As a potential alternative practice, we report the 10-yr results of a strip clearcut regeneration method. This method removes alternating 45-m wide strips across a mixed Appalachian hardwood forest, where the initially harvested strips provide timber revenue while simultaneously elevating understory light levels to increase oak seedling size within the residual strips. Additionally, we investigated the shade patterns of strip clearcuttings with varying strip width layouts for the purpose of informing a more appropriate strip width to regenerate oak.

Ten years after strip clearcutting, I found competitive, natural oak advance reproduction within the residual strips. Natural northern red oak (Quercus rubra L.) seedling densities (>10000 stem ha-1) were greater than densities of any other species. Northern red oak seedlings were most competitive one-quarter of the way into the residual strips from either edge. While large densities of competitive northern red oak seedlings occurred along the edges of the residual strips, the edges were also associated with competitive black birch (Betula lenta L.) and black cherry (Prunus serotina Ehrh.) reproduction. By contrast, in the cut strips, black birch and yellow-poplar (Liriodendron tulipifera L.) were the dominant stems and oaks were almost nonexistent. Using dominance probabilities to model regeneration success I found that the oak reproduction within the residual strips and along strip edges was sufficient to regenerate those areas to 20% northern red oak overstory dominance.

In addition to the natural reproduction, we planted and measured northern red oak seedlings across the same cut and residual strip positions. Nine years after planting, seedling survival was greatest within residual strips, and lowest within cut strips, although average growth was greater in the cut strips. Planted seedlings along strip edges had the best combination of survival (about 70%) and growth with the average height of edge seedlings exceeding competitive size in 2024. I also used dominance probabilities to calculate the required planting density to regenerate 20% stocking of dominant and codominant oaks 20 years after harvest. Ten years following the initial strip harvests, based on the survival and growth of planted seedlings, the required planting density ranged from 2500-4500 trees/ha to meet a 20% stocking goal.

In order to better understand the shading associated with this and other variations of strip widths I used calculations of solar position to determine theoretical shade patterns for three different arrangements of strip clearcut harvests. Strip clearcut combinations comprised 75-ft-wide (0.625 × tree height) residual and cut strips (H1), 150-ft-wide (1.25 × tree height) residual and cut strips (H2), and 75-ft-wide residual strips and 150-ft-wide cut strips (H3). Harvest H3 had the greatest amount of light hitting the forest floor within residual strips, along strip edges, and within cut strips. Harvest H1 had a greater amount of light hitting the forest floor in the center of residual strips than in harvest H2; however, H1 had a lesser amount of light in all other portions of the strip pairings. I conclude that harvest H1 or H3 would provide a better understory light regime for oak seedling development within residual strips than harvest H2.

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