Congress directed the Bureau of Land Management (BLM) to manage public rangelands for multiple uses and the sustained yield of renewable resources in the Federal Land Policy and Management Act (FLPMA) of 1976. As a way to determine if the BLM was achieving sustained yield, Congress directed the agency to periodically and systematically inventory the public rangelands, identify current public rangeland conditions and trends, and report this information to Congress and the public. The 2011 Rangeland Resource Assessment (RRA) is the first of its kind to report on the status and condition of renewable resources on federal rangelands managed by the BLM. Read more...
The 2011 RRA is in the process of being edited and will be available to the public in the very near future. Meanwhile, here are some initial results:
There were several indicators summarized for the 2011 RRA and will continue to be analyzed for future years. These included percent bare ground, soil aggregate stability, intercanopy gaps, non-native invasive plant species, and interpreting indicators of rangeland health (IIRH).
Figure 2 shows the ecoregions with at least 30% bare ground coverage. The very southernmost ecoregion (Warm Deserts) has the highest percentage while the South Central Semi-Arid Prairies has the least. Bare ground refers to bare mineral soil with no vegetation, rocks, litter, or other cover above it. Greater amounts of bare ground suggest an increased risk of soil erosion.
Figure 3 shows the ecoregions with the presence of non-native invasive plant species within ecoregions and depicts that the Northern Cold Deserts and Central Basin and Range ecoregions have the most BLM land within the corresponding ecoregions that have a presence of non-native invasive plant species. Nonnative invasive plant species had colonized nearly all of the rangelands within the Northern Cold Deserts ecoregion, on average btween 77% and 88%. Nonnative invasive plant species often out compete native species for growin space, causing a decline in abundance of native plant species. This decline in turn causes changes in wildlife habitat availability, wildfire frequency and severity, and susceptibility of soil to erosion. Only BLM rangelands in the Central Basin and Range had as high a proportion of colonization and abundance of nonnative invasive plant species as those in the Northern Cold Deserts.
The Western Rivers and Streams Assessment’s (WRSA) provides the first statistically valid assessment of the chemical, physical, and biological condition of streams and rivers on BLM-managed lands throughout the contiguous western United States. Initial results showed that biological condition significantly differs among ecoregions. Read more...
The target population were all National Hydrography Dataset (NHD) streams and rivers on BLM lands within the lower 48 (both wadeable and non-wadeable). About 350 sites were selected after being stratified by hybrid Level III ecoregions. All AIM aquatic indicators were collected at each site (see the Intro to AIM site here for a list of aquatic indicators) from 2013 to 2015. Results showed that biological condition significantly differs among ecoregions (Figure 5).