Considering the Resistance and Resilience Framework as a Tool for Building Site-Appropriate Restoration Seed Mixes

Successfully restoring rangelands hinges on the design of site-appropriate seed mixes that enhance species establishment and persistence. There is a need for tools to facilitate the design process, particularly in regions like the Intermountain West, USA, where restoration occurs across vast extents of rangeland. The Resistance and Resilience (R&R) framework offers a way to classify sites based on soil moisture and temperature regimes and assess their capacity to resist invasion (e.g., cheatgrass Bromus tectorum L.) and recover from stress and disturbance (e.g., drought, fire). However, the utility of R&R for restoration seed mix design, including the extent to which site-appropriate species selection is consistent with the framework, is unclear. We investigated how species-selection patterns of seedings in Utah, USA, aligned with the R&R framework, as well as the correspondence of those patterns with seed cost and traditionally used elevation and precipitation guidelines found in agency technical documents and tools. We found that species selection was consistent with elevation and precipitation guidelines. Species selection frequency also declined with increasing seed cost, despite the ecological importance of some high-priced species. Selection patterns for many species were distinguishable according to the R&R framework, indicative of being treated as “specialists” for certain R&R categories. High R&R (cold, moist) specialist species were mostly native, while low R&R (warm, dry) species were a mixture of native species and high-performing non-native grasses, such as crested wheatgrass ( Agropyron cristatum L. Gaertn.). We advocate for developing plant material (e.g., increase seed collections, production, and supply) to reduce costs of ecologically valuable species. Depending on the field performance of R&R-informed mixes, the framework could be used to create robust, customizable tools for restoration planning.