Reestablishing native perennial vegetation in annual grass-invaded rangelands is critical to restoring ecosystems. Control of exotics, often achieved with preemergent herbicides, is essential for successful restoration of invaded rangelands. Unfortunately, desirable species cannot be seeded simultaneously with preemergent herbicide application due to nontarget damage. To avoid this, seeding is commonly delayed at least 1 year. Delaying seeding increases the likelihood that annual grasses will begin reestablishing and compete with seeded species. Activated carbon (AC) can provide preemergent herbicide protection for seeded species because it adsorbs and deactivates herbicides. Previous studies suggest that a cylindrical herbicide protection pod (HPP), containing AC and seeds, allows desired species to be seeded simultaneously with the application of the preemergent herbicide imazapic. Unfortunately, imazapic is only effective at controlling annual grasses for 1-2 years. Indaziflam is a new preemergent herbicide which exhibits longer soil activity, with which HPPs may be useful. To assess this possibility, we evaluated seeding two native species (Wyoming big sagebrush [Artemisia tridentata Nutt ssp. wyomingensis] and bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Á. Löve]), both incorporated into HPPs and as bare seed, at four application rates of indaziflam in a grow room study. HPPs protected seeded species at low, mid, and high rates of indaziflam. The abundance and size of plants was greater in HPPs compared to bare seed treatments. These results suggest that HPPs can be used to seed native grasses and shrubs simultaneously with indaziflam application.

Pre-emergent herbicides are frequently used to control exotic annual plants prior to seed-based restoration, but seeding must generally wait until herbicide toxicity has waned. The emerging seed-enhancement technology of herbicide protection pods (HPP) allows for simultaneous seeding and herbicide application by protecting desirable seeds inside pods or pellets containing activated carbon, allowing for single-entry and potentially cost-saving wildland restoration approaches. This technology has shown promise in multiple recent lab and field experiments. However, the effect of pod size on efficacy has not been formally investigated, and important small-seeded species have either not been tested or have shown less-promising results when used with this technology. Using emergence trials in two different laboratory environments with two small-seeded species important to restoration in the semi-arid western United States (Wyoming big sagebrush [Artemisia tridentata Nutt ssp. wyomingensis] and Sandberg bluegrass [Poa secunda J Presl]), we investigated if HPP size affected early performance and protection from herbicide (imazapic), as well as how different sizes of HPPs compared to bare seed. For both species, smaller HPP sizes selected to match optimal seeding depths showed up to twofold higher emergence and aboveground biomass than larger pellets and still maintained protection from herbicide toxicity. Both species also showed 50-90% reductions in emergence and aboveground biomass due to incorporation into HPPs in general, resulting in only one species (bluegrass) showing the desired effect of HPPs: higher success than bare seed in the presence of herbicide. We suggest that additional experimentation to improve this promising technology is warranted.

No abstract

Post‐fire restoration of foundation plant species, particularly non‐sprouting shrubs, is critically needed in arid and semi‐arid rangeland, but is hampered by low success. Expensive and labor‐intensive methods, including planting seedlings, can improve restoration success. Prioritizing where these more intensive methods are applied may improve restoration efficiency. Shrubs in arid and semi‐arid environments can create resource islands under their canopies that may remain after fire. Seedlings planted post‐fire in former canopy and between canopies (interspace) may have different survival and growth. We compared planting Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) seedlings post‐fire in former sagebrush canopy and interspace microsites at five locations. Four growing seasons after planting, seedling survival was 46 and 7% in canopy and interspace microsites, respectively. Sagebrush cover was 5.8 times greater in canopy compared to interspace microsites. Sagebrush survival and cover were likely greater because of less competition from herbaceous vegetation as well as benefiting from resource island effects in canopy microsites. Initially, post‐fire abundance of exotic annual grasses was less in canopy microsites, but by the third year post‐fire it was substantially greater in canopy microsites, indicating that resource availability to seedlings was greater, at least initially, in canopy microsites. These results suggest microsites with greater likelihood of success should be identified and then utilized to improve restoration success and efficiency. This is important as the need for restoration greatly exceeds resources available for restoration.