Method Step Description:
Data Acquisition:
Current inventory data was obtained from the USDA Forest Service's Forest Inventory and Analysis (FIA) program, spanning from 1999 to 2022.
Filtered the dataset to include records from 2009 to 2019 to focus on recent data.
Geographic and Data Filtering:
The dataset was restricted to nine southeastern US states: Alabama, Mississippi, Florida, Georgia, North Carolina, South Carolina, Texas, Louisiana, and Virginia.
Data was processed using R, including filtering and preparation.
Data Conversion:
Aboveground biomass (AGB) was converted from pounds per acre to kilograms per hectare.
Tree height data was converted from feet to meters.
Diameter at breast height (DBH) was converted from inches to centimeters.
Structural Diversity Calculation:
Structural diversity was calculated for tree height and diameter using predefined height and diameter classes (5 cm for smaller trees and 10 cm for larger trees).
Shannon diversity index was used to quantify the structural diversity.
Climate Data Integration:
Climate data from PRISM was integrated with the FIA data using nearest-neighbor spatial join techniques via the sf package in R.
Data Standardization:
The combined dataset was standardized to prepare for Structural Equation Modeling (SEM) analysis.
Instrumentation and Data Sources:
USDA Forest Service FIA Data:
Source: USDA Forest Service FIA
Time Range: 1999 to 2022
Filtered for: 2009 to 2019
Climate Data:
Source: PRISM Climate Group
Software:
R: Used for data filtering, conversion, and integration.
sf Package in R: Utilized for spatial joining of climate data with FIA data.
Data Processing:
Data conversions and calculations were performed using R scripts to ensure consistency with the metric system and prepare the data for analysis.