Early Estimates of Exotic Annual Grass (EAG) in the Sagebrush Biome, USA, 2025

We provide fractional cover estimates for exotic annual grass (EAG) species and one native perennial grass species on a weekly basis from mid-April to late June 2025. The cover estimates reflect actual conditions of the previous week and are released in an expedited manner, within 7-13 days of the latest satellite observation used for that weekly prediction. Each weekly release contains five fractional cover maps along with their corresponding confidence maps. The following 16 species are included in the overall EAG cover estimate (species followed by * indicate specific maps for that species); field brome* (Bromus arvensis), rattlesnake brome (Bromus briziformis), rescuegrass (Bromus catharticus) Bald brome (Bromus commutatus and Bromus racemosus), ripgut brome (Bromus diandrus), soft brome (Bromus hordeaceus and Bromus hordeaceus spp. hordeaceus), Japanese brome (Bromus japonicus), compact brome (Bromus madritensis and Bromus madritensis ssp. Rubens), red brome (Bromus rubens), rye brome (Bromus secalinus), cheatgrass* (Bromus tectorum), Texas brome (Bromus texensis), medusahead* (Taeniatherum caput-medusae). Sandberg blue grass (Poa secunda) is not considered an EAG by this project or included in the EAG layer. We map Poa secunda separately as it can have similar phenology to many invasive grasses such as cheatgrass.

These datasets were generated leveraging field observations from Bureau of Land Management (BLM) Assessment, Inventory, and Monitoring (AIM) data plots; Harmonized Landsat and Sentinel-2 (HLS) based Normalized Difference Vegetation Index (NDVI); other relevant environmental, vegetation, remotely sensed, and geophysical drivers; and artificial intelligence/machine learning techniques. A total of 40,154 AIM plots from years 2016–2024 were used to train an ensemble of five-fold regression-tree models using a cross-validation approach (each observation was used as test data once and as training data four times) that developed all the fractional cover maps. The geographic coverage includes arid and semi-arid rangelands in the western U.S classified as shrubs or grassland/herbaceous by the 2023 Land Cover product from Annual National Land Cover Database (NLCD) CONUS Collection 1.0 at or below 2350-m elevation.

Note: Maps of April 18th, 2025, were developed using satellite observation data no later than April 12. Maps of April 25th, 2025, were developed using satellite observation data no later than April 19. Maps of May 2nd, 2025, were developed using satellite observation data no later than April 26. Maps of May 9th, 2025, were developed using satellite observation data no later than May 3. Maps of May 16th, 2025, were developed using satellite observation data no later than May 10. Maps of May 22th, 2025, were developed using satellite observation data no later than May 17. Maps of May 30th, 2025, were developed using satellite observation data no later than May 24. Maps of June 6th, 2025, were developed using satellite observation data no later than May 30.

Releases: First Release: April 18, 2025 (ver. 1.0)
Revision: April 25, 2025 (ver. 2.0)
Revision: May 2, 2025 (ver. 3.0)
Revision: May 9, 2025 (ver. 4.0)
Revision: May 16, 2025 (ver. 5.0)
Revision: May 22, 2025 (ver. 6.0)
Revision: May 30, 2025 (ver. 7.0)
Revision: June 6, 2025 (ver. 8.0)