Project Number: 2070-21630-003-024-I
Project Type: Interagency Reimbursable Agreement
Start Date: Aug 1, 2023
End Date: Sep 30, 2025
The objective and purpose of this project is to determine if two types of salicylic acid (acetylsalicylic acid and sodium salicylate) applied through an imbibition process to help desired species overcome environmental stressors (e.g. heat and drought stress) and result in higher total survival rates of seeded species.
Two studies will be conducted with this project: a field study and a lab study. The field study for this project will be implemented at two post-fire sites that were previously seeded with desired species that failed to establish and invasive exotic species reinvaded (Miller and Stewart fire complexes in southern Nevada). The two sites were sprayed with herbicide one year ago and new seeding treatments will be applied between Oct-Dec 2023. Three seed treatments will be applied through aerial seeding: 1. seed treated with acetylsalicylic acid imbibition, 2. seed treated with sodium salicylate imbibition, and 3. untreated bare seed. Aerial applications will be made along elevational strips (e.g. flight paths for each treatment will go from low to high elevation). Each flight path will have a >100 m strip area. Three elevations (low, mid and high elevation) will be selected for plots and there will be five replicates for each elevation and seed treatment (2 sites x 3 seed treatments x 3 elevations x 5 replicates = 90 total plots). All plots will be installed in the center of each >100 m strip. Plots will be surveyed prior to seeding to quantify existing vegetation and soil conditions. Similarly, TMS-4 probes that quantify ecologically relevant weather data will be installed at every plot prior to seeding. At the time of aerial application, open and closed germination bags will be installed with camera traps to quantify whether granivorous species such as kangaroo rats and small birds, have higher predation rates on the different seed treatments. Four temporal replicates of germination bags will be installed at each plot to quantify granivory in the fall (2 weeks after seeding, Oct-Nov 2023), winter (3 months after seeding, Jan 2024), early spring (when snow melts, March 2024) and late spring (peak seedling emergence, May-June 2024). Monitoring of emergent seedlings will be made in spring (May-June) 2024, end of summer 2024 and end of summer 2025. The lab study for this project will test 10 of the grass species and the same 3 seed treatments that were applied in the field study to test emergence under varying water potential profiles. Each species x seed treatment combination will have 100 seeds planted in a plastic container (11 × 11 × 4 cm [L ×W ×H]) filled with 50 g of the two most common surface soils at the two sites (2 soils x 3 seed treatments x 10 species x 5 replicates = 300 total containers). Variation in soil water holding capacity will be quantified in tandem with seedling emergence, which is difficult to capture and measure in field studies. Containers will be prepared and unsealed containers placed in a growth chamber with onboard environmental controls (model PGW132, IntellusUltra C8T, Percival, Perry, IA) for photosynthetically active radiation (PAR), air temperature, and relative humidity (RH %). The chamber will be set to a 12:12 h day:night regime, and temperature and RH values will be chosen to mimic a springtime regimes for the study area. Seedling emergence and soil water content will be checked daily for a month.