Source: US Geological Survey
The sagebrush biome is one of the most intact and least modified ecosystems in the world covering more than 165 million acres, on par with the Amazon or the Serengeti. It’s also the largest contiguous open space in the Lower 48. But we are losing 1.3 million acres — an area slightly larger than Rhode Island — on average each year.
In 2022, a group of scientists and managers with expertise in sagebrush biome conservation came together to publish the Sagebrush Conservation Design, an effort to provide a common basis for understanding this iconic landscape through time. The SCD used new remote sensing technologies like the Rangeland Condition Monitoring Assessment and Projection dataset and the Rangelands Analysis Platform, to map the entire sagebrush biome and categorize it into Core Sagebrush Areas, Growth Opportunity Areas, and Other Rangeland Areas. It also evaluated the different threats facing the biome and showed that more than 90% of degradation across the biome stems from three main threats: invasive annual grasses, conifer encroachment, and land-use modification. These losses impact livelihoods and reduce important ecosystem services like water availability, wildlife habitat, forage for livestock, carbon storage and more.
To continue moving sagebrush conservation forward and to best leverage the SCD’s insights and map products, a diverse group of researchers, land management professionals, federal agencies, and non-governmental organizations came together for this Special Issue of Rangeland Ecology and Management to identify research opportunities and answer other questions that complicate sagebrush conservation.
The USGS has been a leader in sagebrush ecosystem research, working with management agencies to bring together the breadth of science information and data across the biome to meet management needs. Below are the USGS contributions to Special Issue.
Understanding how climate change will contribute to ongoing declines in sagebrush ecological integrity is critical for informing natural resource management, yet complicated by interactions with wildfire and biological invasions. Here, researchers assessed potential future changes in sagebrush ecological integrity under a range of scenarios using an individual plant-based simulation model, integrated with remotely sensed estimates of current sagebrush ecological integrity. The simulation model allowed researchers to estimate how climate change, wildfire, and invasive annuals interact to alter the potential abundance of key plant functional types that influence sagebrush ecological integrity: sagebrush, perennial grasses, and annual grasses. Results of this study provide a long-term perspective on the vulnerability of sagebrush ecosystems to climate change and may inform geographic prioritization of conservation and restoration investments.
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Sagebrush ecosystems support a suite of unique species such as the emblematic greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) but are under increasing pressure from anthropogenic stressors such as annual grass invasion, conifer encroachment, altered wildfire regimes, and land use change. In this study, researchers examined the ability of an ecosystem-based framework for sagebrush conservation, the sagebrush conservation design (SCD) strategy, and the associated model of Sagebrush Ecological Integrity (SEI), to identify and rank priority habitats for sage-grouse, a sagebrush indicator species. Researchers compared sage-grouse population trends from 1996–2022 across the three categories that characterize integrity of sagebrush ecosystems (core, growth opportunity, and other rangelands) and then generated a parallel categorical model of sage-grouse population trends, based on the same landcover variables that comprise the SEI. Researchers then compared the sage-grouse condition categories to trends derived from population count data.
In all, they found that the SCD and SEI were effective tools for identifying and ranking priority habitats for sage-grouse. Their analysis demonstrates that proactive ecosystem-based approaches to the conservation of the sagebrush biome can help optimize the return on limited conservation resources and benefits for sagebrush obligate species, and help reduce some of the real and perceived conflicts inherent in single-species management
High-quality Core Sagebrush Areas, as delineated by the Sagebrush Conservation Design, continue to decline despite conservation and restoration investments. The increasing recognition of the scale of threats and the pace of ecosystem degradation has led to a shift towards threats-based ecosystem management. To this end, researchers quantified the acres of conservation implementation relative to the rate of loss from specific threats to the sagebrush biome and assessed how much additional action may be needed to stop Core Sagebrush Area loss.
They found that current rates of conservation are markedly lower than rates of Core Sagebrush Area loss (~10% of average annual loss). Furthermore, most conservation actions, ~90% for some treatment types, occurred outside of Core Sagebrush Areas, likely reducing the efficacy of these conservation actions at retaining and restoring intact sagebrush rangelands. Additionally, they found that conservation efforts will need to increase ten times its current annual rate to halt declines. However, through better spatial targeting of conservation actions, the increase in conservation needed to stop Core Sagebrush Area loss could be substantially reduced. This analysis demonstrates the divergent futures that may await the sagebrush biome pending key decisions regarding conservation targeting, stakeholder cooperation, and the strategic addition of resources.
