COS 159-2 - Barriers and Opportunities for Pre-emptive Restoration of At-Risk Sagebrush Communities

Abstract: The sagebrush-dominated cold deserts of western North America are susceptible to invasion by non-native grasses, e.g., cheatgrass (Bromus tectorum), leading to conversion to annual grasslands maintained by frequent wildfire. A typical strategy to prevent this transition is to seed native species within a few months after a fire, but this approach is not reliably successful. Our proposed alternative is to pre-emptively - before a plant community has burned - transplant native grasses and forbs into sagebrush communities at risk of conversion to an annual grass understory. By attempting to restore a plant community before it shifts to a virtually permanent alternative state, practitioners may achieve higher restoration success, reduce the likelihood of annual grass invasion, and increase resistance to wildfire-driven community shifts. We tested the potential effectiveness of pre-emptive restoration, focusing on environmental factors influencing survival of out-planted herbaceous species as well as social factors influencing implementation of novel restoration practices. We out-planted greenhouse-grown seedlings of two native forbs (Sphaeralcea munroana, Achillea millefolium) and two native perennial bunchgrasses (Elymus elymoides, Pseudoroegneria spicata) at six sagebrush community sites in the Intermountain West, USA, representing a range of elevations, temperature, and precipitation. Interviews (N=12) and surveys (N=138) were used to understand agency- and individual-level factors influencing the feasibility of a pre-emptive approach. At all experimental field sites, ~100 individuals of each species were planted in 2018, a relatively wet year, and 2019, a much drier year. Year 1 survival rates ranged from 1%-45% in 2018 and 0-69% in 2019, with the highest survival in both years at the site that was warmest and driest and experienced the least disturbance (frost heaving, herbivory, trampling, etc.). In 2018, seedling survival was highly correlated with disturbance (R=-0.77). Forb (but not grass) survival was highest in microsites that occurred midway between the edge of sagebrush canopies and the center of the interspace and covaried with biocrust cover. In-depth interviews revealed influences upon restoration decisions at multiple layers, from variable contexts such as staffing and budget to deep-seated beliefs about when it is ethical to intervene in natural processes. Practitioners strongly preferred proactive to reactive approaches (90% vs 10%) but tended to believe seeding would be more effective and easier to implement, especially at management-relevant scales. We conclude that pre-emptive planting may be useful in some situations, but care must be taken with planting microsites and seedling protection.