Seed-based Restoration of Native Plant Communities Following Phragmites Control in Great Salt Lake Wetlands
Abstract
While many strategies exist to reestablish wetland plants, seeding offers the advantage of being cheaper and less labor intensive to install. This is true when restoring large wetlands, such as around Utah’s Great Salt Lake (GSL). The GSL is threatened by Phragmites australis, an aggressive invasive species. Research has highlighted effective control techniques for Phragmites; however, natural recolonization of native vegetation is limited. Four potential factors that may limit seed-based revegetation are: 1) dense Phragmites litter, 2) buoyant seeds floating away from the site, and 3/4) unfavorable moisture and temperature conditions. Tackifier has been proposed as a solution to seed buoyancy, and mulch can potentially retain early spring moisture, but their application in wetlands has not been rigorously evaluated. Similarly, few studies have evaluated how different Phragmites litter removal techniques or the timing of seed addition impact seedling recruitment. Therefore, we evaluated the effects of tackifier, mulch addition, litter removal, and seed sowing timing on establishment. We conducted a field experiment with five replicates containing two 10m x 30m subplots. In subplot 1, Phragmites litter was mowed and removed from site. In subplot 2, Phragmites litter was rolled and left on site. Within each subplot, five seed treatments were applied at various times: one control (no seeds), and factorial combinations of mulch (+/-), and sowing times (early/late spring). Tackifier was applied in each of the seeding treatments. Percent cover and stem density data were collected throughout the growing season. We found that tackifier was successful at keeping seeds in place, while the mulch addition did not enhance native cover or density. The most important treatment driving plant recovery was the litter treatment—there was higher seedling recruitment in the mow and remove plots. Our findings provide strategies that land managers can use to enhance seedling recruitment.
Seed-based Restoration of Native Plant Communities Following Phragmites Control in Great Salt Lake Wetlands
The North Atrium
While many strategies exist to reestablish wetland plants, seeding offers the advantage of being cheaper and less labor intensive to install. This is true when restoring large wetlands, such as around Utah’s Great Salt Lake (GSL). The GSL is threatened by Phragmites australis, an aggressive invasive species. Research has highlighted effective control techniques for Phragmites; however, natural recolonization of native vegetation is limited. Four potential factors that may limit seed-based revegetation are: 1) dense Phragmites litter, 2) buoyant seeds floating away from the site, and 3/4) unfavorable moisture and temperature conditions. Tackifier has been proposed as a solution to seed buoyancy, and mulch can potentially retain early spring moisture, but their application in wetlands has not been rigorously evaluated. Similarly, few studies have evaluated how different Phragmites litter removal techniques or the timing of seed addition impact seedling recruitment. Therefore, we evaluated the effects of tackifier, mulch addition, litter removal, and seed sowing timing on establishment. We conducted a field experiment with five replicates containing two 10m x 30m subplots. In subplot 1, Phragmites litter was mowed and removed from site. In subplot 2, Phragmites litter was rolled and left on site. Within each subplot, five seed treatments were applied at various times: one control (no seeds), and factorial combinations of mulch (+/-), and sowing times (early/late spring). Tackifier was applied in each of the seeding treatments. Percent cover and stem density data were collected throughout the growing season. We found that tackifier was successful at keeping seeds in place, while the mulch addition did not enhance native cover or density. The most important treatment driving plant recovery was the litter treatment—there was higher seedling recruitment in the mow and remove plots. Our findings provide strategies that land managers can use to enhance seedling recruitment.