Sagebrush ecosystems are more than Artemisia: The complex issue of degraded understories in the Great Basin

Authors: Copeland, Stella; Davies, Kirk; Boyd, Chad

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2024
Publication Date: 4/11/2024
Citation: Copeland, S.M., Davies, K.W., Boyd, C.S. 2024. Sagebrush ecosystems are more than Artemisia: The complex issue of degraded understories in the Great Basin. Rangeland Ecology and Management. 94:184-194. https://doi.org/10.1016/j.rama.2024.03.007.
DOI: https://doi.org/10.1016/j.rama.2024.03.007

Interpretive Summary: Degraded sagebrush steppe understory plant communities are a major management and restoration challenge in the Great Basin. Understory plants are diverse and abundant in intact sagebrush communities and provide key elements of wildlife habitat as well as livestock forage. Large areas of sagebrush steppe appear to meet definitions for degraded understory communities, though these definitions require careful comparisons with appropriate benchmarks for intact sagebrush communities in similar sites. Several mechanisms likely contribute to creating degraded understory communities, both alone and in combination, including the legacy effects of historic land-uses. Understory recovery may be limited by a number of factors, suggesting that simple restoration approaches may be ineffective. Additional knowledge and improved restoration methods are urgently needed to avoid additional degradation and effectively restore degraded understories in sagebrush steppe.

Technical Abstract: Plant communities in a stable, long-term state with high sagebrush cover and low desirable perennial herbaceous cover and/or relatively high invasive annual cover are widespread across the Great Basin and distinct from areas affected by wildfire. Restoring these areas, collectively called “degraded sagebrush understories,”and preventing future degradation are management challenges that require maintaining desirable levels of sagebrush cover while simultaneously increasing understory perennial abundance and diversity. Defining degradation based on a firm grasp of current and potential vegetation composition is a fundamental aspect of setting restoration goals and selecting methods. Assigning degraded status to any given site is also a considerable challenge in many sagebrush landscapes due to widespread (and long-standing) lack of intact herbaceous plant communities in some landscapes, as well as high interan- nual variation in herbaceous community composition (particularly cover). In this manuscript, we provide a workflow for defining degraded understories and present a framework for identifying restoration ap- proaches emphasizing the pathways (causes) of degradation in this system, such as historical cultivation, inappropriate grazing, invasive species, and drought, as well as the size and extent of degraded areas. We also describe the relative paucity of well-documented successful restoration approaches for degraded understories, particularly for one-time restoration treatments. This lack of success may be due to lack of propagules, potential competition from sagebrush, invasive species, and/or altered soil conditions. Mul- tiple restoration treatments in specific sequences and/or years may increase success; however, the ef- fectiveness of these techniques is uncertain due to infrequent implementation and rigorous evaluation across a range of environmental conditions. Due to the extent of degraded understories in Great Basin sagebrush ecosystems, meeting biome-level conservation goals will likely require additional research to characterize the types and development pathways of the degraded understories, spatiotemporal recovery or ongoing degradation patterns, and targeted restoration techniques.