Managing to survive despite the weather: Seeding decisions affecting simulated dryland restoration outcomes

Authors: Copeland, Stella; BAUGHMAN, OWEN - The Nature Conservancy; BRADFORD, JOHN - Us Geological Survey (USGS); Hardegree, Stuart; Larson, Julie Elizab; SCHLAEPFER, DANIEL - Us Geological Survey (USGS); BADIK, KEVIN - The Nature Conservancy

Submitted to: Restoration Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2024
Publication Date: 8/5/2025
Citation: Copeland, S.M., Baughman, O.W., Bradford, J.B., Hardegree, S.P., Larson, J.J., Schlaepfer, D.R., Badik, K.J. 2025. Managing to survive despite the weather: Seeding decisions affecting simulated dryland restoration outcomes. Restoration Ecology. Vol. 33, No.6, Article e14362. https://doi.org/10.1111/rec.14362.
DOI: https://doi.org/10.1111/rec.14362

Interpretive Summary: Dryland seed-based restoration often fails due to poor weather for early seedling survival. We examined whether post-fire seeding decisions could increase restoration success using a simulation approach for several thousand sites and multiple 5-year post-fire periods in cold desert sagebrush ecosystems in western North America. We asked how seeding success was influenced by a) seeding in different years, b) delaying seeding or germination within years (e.g., via seed coating technologies), or c) selecting different seed sources from 10 common native perennial grasses with variable germination behavior. Our results suggested the seeding the first year post-fire with a mean seed source generally led to much poorer outcomes that seeding the best year of 5 or the best source of 10. Emergence was generally higher in sites with higher mean precipitation regardless of seeding decisions. However, mean precipitation also altered the effects of some seeding decisions on restoration outcomes. For example, delaying seeding until later in the fall or winter was more likely to lead to higher emergence in sites with higher mean precipitation compared to sites in drier climates. Seeding decisions had greater effects on outcomes for slower-germinating seed, and when longer emergence windows were assumed, highlighting the sensitivity of our results to germination and emergence rate. Our results are dependent upon the limitations of our simulations including the data available for germination and assumptions related to emergence response for these specific seed sources, and require testing in field settings. However, these results do broadly suggest that approaches linked to germination behavior and weather variability could improve restoration success rates in variable drylands like the Great Basin.

Technical Abstract: Limited favorable weather windows for post-germination early seedling survival are associated with low restoration success in drylands. We examined whether post-fire seeding decisions could alter early seedling emergence and restoration success across western North American sagebrush ecosystems with a simulation approach. Seedling emergence estimates were based on germination of a specified percentile of sown seeds followed by favorable conditions for seedling development. We asked how three categories of seeding decisions affected emergence: post-fire seeding year, seasonal seeding delay (via seed coating technologies or later seeding timing), or native perennial grass seed source (via differing germination behavior). We also tested potential effects of mean annual precipitation on seeding decision outcomes (interactive effect) and included topographic microclimate and site (random effect) in models. Emergence was highest when the best seed source (of 10) was seeded in the best post-fire year (of 5). High emergence also resulted from seeding in the best post-fire year with an average seed source or seeding with the best source in the first post-fire year. Emergence was higher overall with higher mean precipitation. Seeding decision outcomes were sensitive to annual mean precipitation, with greater differences observed due to decisions at lower precipitation levels. While sensitive to assumptions related to seedling development and germination speed, these results suggest that restoration approaches linked to germination behavior and weather variability could improve restoration success rates in variable drylands like sagebrush ecosystems.