Leveraging ecological monitoring programs to collect soil and geomorphology data across the western United States

Abstract

Ecological site information is essential to interpreting monitoring data and guiding site-specific management of ecosystem functions and services. Ecological information includes soil properties (e.g., texture class), geomorphology characteristics (e.g., slope aspect), and ecosystem dynamics (e.g., plant succession), which are critical covariates in rangeland monitoring programs such as the Assessment, Inventory, and Monitoring (AIM) strategy conducted by the Bureau of Land Management (BLM). Based on field observations, AIM identifies ecological sites according to ecological site concepts uniquely developed within individual Major Land Resource Areas (MLRA). Here, we present and evaluate the availability of ecological site identification, soil observations, and geomorphology characteristics determined by AIM data collectors between 2012 and 2021 in 14 states of the western United States. There are 31,267 monitoring plots (79% of plots) with identified ecological sites and 29,228 plots (74% of plots) containing soil morphology descriptions of soil horizons examined in excavated pits. While soil texture class is observed in most soil horizons (98%), rock fragment volume is the soil property with the least data availability (75%). The consistency of soil data (e.g., clay content observations within the ranges of texture classes) increases as a function of time following guidance in soil profile description training for AIM data collectors. Nearly 47% of AIM plots are found on gentle slopes of 0% to 5% steepness and on Flat/Plain and Hill/Mountain landscape types. We confirmed that the AIM database is a robust source of georeferenced soil and geomorphology information that can be used for land management and research on land potential, soil geography, and assessment of soil health indicators across the western United States.