COS 16-3 - Choosing from divergent futures for the sagebrush biome

Abstract: Drylands systems around the world are experiencing degradation and declines in ecological integrity at rates unprecedented in modern history. This is true in the sagebrush biome of the western United States, where threats including invasive annual grasses, conifer encroachment, and anthropogenic land use change have caused widespread biome declines that may be exacerbated by climate change. Mitigating large-scale degradation in this system has been a central conservation challenge that requires a shift from traditional species-specific interventions to holistic, cross-boundary conservation initiatives. Following significant investments in sagebrush biome conservation across federal and state agencies and NGO partners, questions have emerged about how and where to direct resource capacity, funding, and management efforts to yield the greatest benefit, and whether current rates of conservation are sufficient to stop further biome decline. To address these questions, we leveraged biome-wide, high resolution, spatiotemporally explicit maps of sagebrush rangeland condition to track habitat dynamics from 2001 to 2020 and compare rates of change in high integrity core habitat for sagebrush obligates to the volume and location of conservation actions implemented. We found that despite increases in conservation implementation over time, 1.3 million acres of sagebrush habitat have transitioned to degraded rangeland areas annually, a 1.34% loss of the biome each year. We then projected the outcomes of several future conservation scenarios in the sagebrush biome and compared relative cost and the time to biome recovery (or loss). These scenarios included: 1) business-as-usual rates of conservation, 2) increasing total conservation while maintaining the current proportion of conservation occurring in core sagebrush habitat vs. degraded rangelands, 3) maintaining the current rate of conservation but concentrating conservation in core habitat areas, and 4) increasing the rate of conservation and increasing the proportion of conservation occurring in core sagebrush habitat. We found that increased rates of conservation will be required to halt biome degradation and that shifting even 25% of future conservation efforts from other rangelands to core habitat was enough to drastically reduce the amount of total conservation, time, and cost required to reverse biome decline. Ultimately, we hope this work helps to substantiate the need for outcome-oriented planning, and catalyzes a shift towards more strategically implemented conservation to stem the tide of loss and support ecosystem recovery in the sagebrush biome.