L. Scott Baggett | Search USGS

USGS2026

A picture is worth a thousand plants: Using historic and repeat photography to quantify long-term change in drylands on the Colorado Plateau

This study analyzes over a century of plant community change on the Colorado Plateau (CP) using repeat photography (1910–2016) and various GIS (Geographic Information Systems) data. We examined 338 repeat photo pairs across three dominant vegetation communities: CP Blackbrush-Mormon-tea Shrubland (CP Blackbrush), Inter-Mountain Basins Semi-Desert Grassland and Big Sagebrush Shrubland (IM grasslands) and CP Pinyon-Juniper Woodland/Shrubland (PJ Woodland). Vegetation changes, including plant counts, plant size, patch shifts, patch size and live plant cover, were evaluated against photo pair time span and spatial covariates, including climate, topography, soil characteristics and land-use history using logistic regression. Responses varied significantly by community type, driven by interacting factors such as time since domestic grazing cessation, climate conditions, and geomorphic setting. CP Blackbrush and IM grasslands showed recovery with longer time since grazing cessation, with increases in plant numbers, patch size, and cover. PJ Woodlands showed mixed, context dependent responses. All communities exhibited increased growth on alluvial landforms, likely from deeper soils and better water availability. Human disturbances lead to a higher probability of patch shifts in CP Blackbrush and IM grasslands. These findings underscore utility of long-term datasets for understanding dryland ecosystem dynamics and highlight how land-use history, climate and geomorphology can inform conservation efforts on dryland ecosystems.

Colorado, Utah↗

USGS2025

Evaluating a simulation-based wildfire burn probability map for the conterminous US

Background Wildfire simulation models are used to derive maps of burn probability (BP) based on fuels, weather, topography and ignition locations, and BP maps are key components of wildfire risk assessments. Aims Few studies have compared BP maps with real-world fires to evaluate their suitability for near-future risk assessment. Here, we evaluated a BP map for the conterminous US based on the large fire simulation model FSim. Methods We compared BP with observed wildfires from 2016 to 2022 across 128 regions representing similar fire regimes (‘pyromes’). We evaluated the distribution of burned areas across BP values, and compared burned area distributions among fire size classes. Key results Across all pyromes, mean BP was moderately correlated with observed burned area. An average of 71% of burned area occurred in higher-BP classes, vs 79% expected. BP underpredicted burned area in the Mountain West, especially for extremely large fires. Conclusions The FSim BP map was useful for estimating subsequent wildfire hazard, but may have underestimated burned areas where input data did not reflect recent climate change, vegetation change or human ignition patterns. Implications Our evaluations indicate that caution is needed when relying on simulation-based BP maps to inform management decisions. Our results also highlight potential opportunities to improve model estimates.

Conterminous United States↗