MODELING DIAMETER DISTRIBUTION OF LOBLOLLY PINE PLANTATIONS IN RESPONSE TO MID-ROTATION THINNING TREATMENTS AND ASSING THE ECONOMIC RETURNS IN WESTERN GULF COASTAL PLAIN

<p>The influence of thinning regimes incorporating row thinning on diameter distribution and timber product allocation is of considerable importance in the management of loblolly pine (<em>Pinus taeda</em>) plantations within the Western Gulf Coastal Plain. This study utilized data from a thinning study plots established by the East Texas Pine Plantation Research Project across East Texas and Western Louisiana. A two-parameter Weibull distribution was used to model diameter distributions under varying thinning intensities, with parameter estimation conducted using both parameter prediction (PPM) and percentile-based (PRM) methods. The PRM approach demonstrated excellent model performance, with coefficients of determination (R²) ranging from 0.94 to 0.99 and root mean square error (RMSE) values remaining below 2% of the mean for DBH percentiles. The PPM method yielded high accuracy for the scale parameter (R² = 0.99) but exhibited lower predictive strength for the shape parameter (R² = 0.53). Model validation against both 9th-year post-thinning and independent datasets confirmed strong predictive capability. Thinning intensity significantly altered stand structure and product distribution, with moderate to heavy thinning increasing the proportion of sawtimber and overall financial returns, particularly on higher-quality sites. An analysis of variance revealed statistically significant effects of both site quality and timber product class on revenue outcomes (p < 0.001). These findings highlight the importance of aligning thinning intensity with site productivity to optimize structural and economic outcomes in loblolly pine plantations.</p>

Name thesis:degree_name

Master of Science - Forestry

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Forestry

Year dc:date.available

2025

Authors dc:creator

• Rijal, Pragya
• Weng, Yuhui
• Shrestha, Anusha
• Grogan, Jason

Contributors dc:contributor

• Dr. Yuhui Weng
• Dr. Anusha Shrestha
• Mr. ason Grogan

• Loblolly Pine
• Mid-Rotation
• Thinning
• Weibull
• Diameter Distribution
• Forest Management

Repository record dc:identifier

https://scholarworks.sfasu.edu/etds/651

OAI identifier oai:identifier

oai:scholarworks.sfasu.edu:etds-1680