The introduction of exotic plant species into the western United States has caused substantial changes to rangeland disturbance regimes and ecosystem structure and function. For example, exotic annual grass (EAG) invasion in western rangelands has increased wildfire frequency, which greatly reduces rangeland ecosystem diversity and leads to single-species dominance in many areas. Rangeland monocultures do not provide optimal carbon sequestration and other environmental processes necessary to sustain historically normal ecosystem structure, including the ecological diversity needed to support sagebrush obligates like Greater Sagegrouse, pygmy rabbit, and pronghorn. These obligates, as well as others, require contiguous, large mosaics [...]
Summary
The introduction of exotic plant species into the western United States has caused substantial changes to rangeland disturbance regimes and ecosystem structure and function. For example, exotic annual grass (EAG) invasion in western rangelands has increased wildfire frequency, which greatly reduces rangeland ecosystem diversity and leads to single-species dominance in many areas. Rangeland monocultures do not provide optimal carbon sequestration and other environmental processes necessary to sustain historically normal ecosystem structure, including the ecological diversity needed to support sagebrush obligates like Greater Sagegrouse, pygmy rabbit, and pronghorn. These obligates, as well as others, require contiguous, large mosaics of native sagebrush to survive. The dominance of invasive plants (e.g. cheatgrass, western juniper) in these ecosystems considerably reduces the distribution of healthy sagebrush and, therefore, jeopardizes obligates’ survival.
Spatially explicit data sets that provide information on invasive plant abundance can help land managers more effectively manage for wildfire threats, ecosystem conditions and processes, and the survival of wildlife species. The U.S. Geological Survey Rangeland Exotic Plant Monitoring System was developed to construct timely, accurate, and spatially explicit maps of exotic plant abundance at various spatial and temporal resolutions in the western U.S. Since 2015, the U.S. Geological Survey Earth Resources Observation and Science (EROS) Center has developed and publicly released data sets that provide historical, rapid (i.e. early growing season), and future estimates of EAG abundance in the sagebrush biome of the western U.S. These data sets were developed by integrating field observations, satellite imagery, and other geospatial data with machine-learning techniques. Initially, the historical (2000 – 2016) and rapid (2015 – 2019) EAG data sets were developed using enhanced Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) satellite data at a 250-m spatial resolution. Starting in 2020, estimates of historical (1985 – 2019), recent historical (2016 – 2019), rapid (2020), and future (2025 – 2040) EAG data sets were developed using field observations (e.g. BLM Assessment Inventory and Monitoring [AIM]) and weekly, cloud-free composites of Harmonized Landsat 8 and Sentinel-2 (HLS) imagery at a 30-m spatial resolution. The 30-m EAG data sets provide more information and offer greater interpretive value to users in many circumstances than do the 250-m data sets. The development of rapid 30-m HLS data continued in 2021, but the study area expanded almost three times during this year, covering all or parts of 17 states in the western U.S., from the Canadian to the Mexican borders. With a greatly expanded study area, we incorporated the use of high-performance computers to develop EAG data sets and maintain our established release schedule for our user community. The full suite of EAG products with varying spatial resolutions and extents can be accessed using the links below.
