Date of Award

Fall 2023

Project Type


Program or Major

Natural Resources

Degree Name

Master of Science

First Advisor

Mark Ducey

Second Advisor

Olivia Fraser

Third Advisor

John Gunn


Forest structural complexity (FSC) is an informative characteristic in forest management due to its connections to ecosystem resilience, biodiversity, and carbon sequestration. Despite its widespread use, quantifying FSC remains a challenge because of the many attributes that can comprise an assessment of FSC and ambiguity around what exactly is meant by “complexity.” Many assessments of FSC involve metrics derived from lidar data, yet there is not a clear understanding of how spatial extent impacts metrics of FSC. This thesis investigates the influence of spatial extent on FSC metrics and metric relationships in the context of New England mixed hardwood forests. Chapter 1 examines the role of spatial extent in FSC metrics. Analysis of correlations between FSC metrics across a range of plot sizes revealed relationships that suggest smaller plot sizes, with a radius of 10 meters or smaller, can be adequately representative of larger areas. This observation has implications for lidar data processing efficiency and cost-effectiveness. Chapter 2 explores the relationships between field-derived and lidar-derived metrics of FSC. Some noteworthy patterns emerged, emphasizing the significance of several classes of FSC characteristics, including size-related and canopy-related variables. The alignment of field-based and lidar-derived metrics underscores their complementarity in characterizing forest structure. This research elucidates some of the intricacies of quantifying FSC and identifies categories for comprehensive assessments of FSC, using canopy height, height diversity, canopy cover, outer canopy complexity, and diameter diversity. This should provide a useful framework for future studies involving FSC assessments.