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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Research Project #439222

Research Project: Are Good Intentions Enough? Post-Wildfire Seed Mix Performance in Sagebrush Rangelands

Location: Forage and Range Research

Project Number: 2080-21000-018-038-N
Project Type: Non-Funded Cooperative Agreement

Start Date: Jul 1, 2021
End Date: Jun 30, 2024

Test how different seed mixes perform across a range of restoration sites and how they respond to modified seeding practices. Test seed mixes currently being used in large-scale restoration projects in Utah, as well as mixes that have been modified based on current research (i.e., removal of highly competitive species to promote establishment of a greater diversity species). Specific objectives include: 1) evaluating the composition (relative frequencies of species) of seed mixes currently being used in post-fire restoration efforts across projects with different restoration objectives (e.g., forage provision, sage-grouse habitat.), and 2) establishing a controlled experiment across a range of restoration sites to assess potential of current Watershed Restoration Initiative (WRI) seed mixes to establish diverse plant communities with strong forb components. The second objective will establish long-term field plots that will be used in the future to test complementary questions, such as long-term plant persistence and resilience of seeded communities to future fire or potential for seeding or planting additional species into established seeded communities.

Objective 1 Characterize seed mixes developed and used for post-fire rehabilitation in sagebrush communities in Utah. Summarize information in useful ways, such as tallying the frequency and number of species in seed mixes currently being used for restoration projects, along with relevant project information. These data will be used to identify broad trends in seed mix composition and help guide objective 2. Objective 2 Test how different seed mixes perform in each of two plant community types (Wyoming big sagebrush and mountain big sagebrush) in each of three Wildlife Management Areas (WMAs). Within each of these six sites, seed mixes will be subject to factorial combinations of seeding method (drill, broadcast, drill+broadcast), and post-seeding treatment (imprinter vs. none). The “drill+broadcast” treatment will seed species by either drill or broadcast, depending on which is most appropriate according to each species’ biology. Initiation of all seeding treatments will be repeated in each of two years. At each of the six sites we will establish fifteen 20m x 36m plots that will be randomly-assigned to one of the three seeding treatments (n = 5 for each seeding treatment). Plots will be divided into twelve 3-m strips, and in each of two planting years, half of each plot will be harrowed and disked to prepare a suitable seedbed. Strips will be assigned to receive one of six seed mixes in Year 1, and the other half will receive the same seed mixes in Year 2. Half of each strip will then be treated with an imprinter to pack loose seedbeds and increase seed-to-soil contact (total of twenty-four 10m x 3m half-strips). The six seed mixes will include: 1) three mixes developed for typical post-fire rehabilitation goals (e.g., livestock forage production, sage-grouse habitat), and 2) the same three mixes, but with removal of competitive dominants. Harrowing/disking will occur in August in order to allow loose soils to settle using either a Dixie Harrow or offset disk plow. Seeding will occur later the same fall. Sites will be fenced to exclude large ungulates if needed. Prior to establishment of the 20m x 36m plots at each of the six study sites, we will characterize soils and make visual estimates of plant cover in 20 randomly-placed 50cm x 50cm quadrats within each 20 x 36 m plot. Following seeding of our experiment plots we will evaluate emergence, establishment and persistence of all species, as well as species richness/diversity, at the peak and end of the growing season. Within each 10m x 3m half-strip we will place 18 nested frequency frames on a 2x9 one-meter grid, in which we will assess nested frequency of all species each year following planting. Beginning in year two post-planting we will measure cover of all species, as well as density by size class (basal widths, heights), and reproduction (yes/no) of perennial bunchgrasses and woody species. Data will be analyzed using mixed-effect ANOVA models and split-split-split-plot designs. Site and replicate (block) will be considered random effects, and community and treatment combinations will be considered fixed effects.