Keywords: Forest structure, phylogenetic diversity, species diversity, data science, size class distribution
Forest ecosystems are constantly changing due to factors such as climate change, invasive species, and management. Traditionally, changes to forest ecosystems are described by shifts in species composition, successional stage, or phylogenetic diversity. Recent advancements in remote sensing, particularly LiDAR, have revealed the importance of stand structure (the arrangement of trunks, branches, and leaves in 3-dimensional space) on forest dynamics. However, the limited availability of LiDAR data at a continental scale prevents the analysis of forest structure across the United States. In this exploratory analysis, we compiled data from the U.S. Forest Inventory and Analysis (FIA) Program from over 120,000 plots. We computed a suite of metrics related to the distribution of tree size classes, species diversity, and phylogenetic diversity in FIA plots and mapped the resulting metrics across the U.S. using R programming. In addition, we subsetted our data by ecoregion and assessed the relationships between these metrics. We found a positive relationship between forest structural diversity and both species and phylogenetic diversity at low levels of structural diversity, but the relationships tend to flatten out or become negative in areas with higher levels of structural diversity. These relationships also varied in strength between ecoregions which may be related to the regional variability in the species pool. Moving forward, we plan to explore the relationship between forest structure and ecosystem functions using data science technologies to implement a number of statistical analyses, which will help broaden our understanding of forest structural dynamics in a changing global environment.