Seeing past the green: Characterization, modeling, and management of high graded forests
Open Access
- Author:
- Curtze, Alexander
- Graduate Program:
- Forest Resources
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- May 27, 2021
- Committee Members:
- Bradley Cardinale, Program Head/Chair
Laura P Leites, Thesis Advisor/Co-Advisor
Kimberly Bohn, Committee Member
Allyson Muth, Committee Member
Jeffery L Larkin, Committee Member - Keywords:
- high grading
silviculture
mixed-oak
forest management
forest degradation
partial harvest
hardwood
temperate forest
high grading
silviculture
mixed-oak
forest management
forest degradation
partial harvest
hardwood
temperate forest
decision support tools
SILVAH
rehabilitation - Abstract:
- Forests are a prominent feature of the landscape in the eastern United States (US), covering nearly half of the land area. A substantial portion of eastern forests have been degraded due to past methods of harvesting timber. High grading is one of the most commonly used methods of harvesting timber and involves the removal of the largest and most valuable trees with no consideration for residual forest composition and structure. High grading is generally understood to degrade forest composition and structure and limit the application of standard forest management practices. Since high grading is frequently used to harvest timber in the eastern US, being able to quantitatively describe, recognize, and manage these forests is essential to ensure the conservation of the eastern US’s vast forest resources. In Chapter 1, we quantify the characteristics of high graded forests and evaluate the consequences of high grading as compared to a well-established silvicultural treatment that follows ecological principles to control for species composition, spacing, and tree health/form in the mixed-oak (mixed-Quercus spp.) forests of Pennsylvania. We found that the high graded forests contained larger numbers of unhealthy and/or poorly-formed trees, more small-diameter trees, less oak (Quercus spp.) in the overstory canopy, fewer total tree seedlings, and stored less aboveground woody biomass and carbon per hectare than the silvicultural treatment. We also confirm that tree diameter is not always a reliable predictor of tree age and conclude that it should not be used as the sole criterion to select trees for removal. In Chapter 2, we focus on the identification and management of previously high graded forests by 1) developing a model that can quantitatively identify whether a forest has been high graded based on current forest conditions, 2) demonstrating an application of the classification model, and 3) evaluating silvicultural prescriptions provided by the popular decision support tool, SILVAH. Our classification model uses standard forest inventory measurements, predicts the past harvest type with moderate to high accuracy, and provides users with a level of certainty for a particular timber harvest type classification. Lastly, our study identified points that have the potential to improve the ability of SILVAH to prescribe silvicultural treatments for high graded mixed-oak forests of the eastern US. The results of this thesis highlight the degrading effects of high grading and provide tools that can be used by forestry professionals and landowners to support forest management practices aimed at returning high graded forests to healthier and more productive states.