Date of Award:
Master of Science (MS)
Wetlands are important ecosystems that improve water quality, prevent floods, and provide wildlife habitat. As such, restoring native plants that promote wetland health is a high priority for land managers. However, there are many challenges to the restoration of native plants. In our study system (Great Salt Lake wetlands), many areas are invaded by the European grass, Phragmites australis. Phragmites grows in dense stands and displaces native plants. The reduction of native plant communities in Great Salt Lake wetlands is a major concern because these ecosystems provide habitat for millions of native birds. Managers have made successful efforts to reduce large stands of Phragmites, but native plant communities do not often return on their own. To address this issue, seeding wetlands with native species is a promising strategy due to the large scale of restoration needed. Seeding is challenging because water levels can be unpredictable in wetlands, and invasive species can spread to restoration sites. To improve seeding success, we investigated several restoration strategies novel to our system. Our first strategy was to identify native species that could establish in a broader range of environmental conditions (particularly soil moisture). These species included perennial grasses and bulrushes that provide high quality avian habitat and forbs that were expected to germinate and establish faster than bulrushes and sedges. We also tested different compositions of species in seed mixes. We found two annual species, Bidens cernua (nodding beggartick) and Rumex maritimus (goldendock), established across a range of moisture conditions and out-performed other natives when sown in a mix. Distichlis spicata (saltgrass) had the greatest success of all perennial graminoids (grasslike species) and established at higher rates than other natives in a field setting. Our final restoration strategy was to implement artificial microtopography (elevation change at the scale of individual plants <1m). Microtopography is an important feature in wetlands because it affects soil moisture, water levels, soil properties, and the distribution of plants. We found some evidence from a single experiment to support the use of microtopography as a restoration intervention. Given the vast evidence for the importance of wetland microtopography, we also sought to explore the relationship between microtopography, wetland types (emergent marsh, wet meadow, playa), and plant communities. We found microtopography was more abundant in marshes (as opposed to playas and wet meadows) that had not been grazed by cattle.
Hebert, Coryna, "The Effect of Species Choice, Seed Mix Composition, and Microtopography on Native Plant Restoration in Great Salt Lake Wetlands" (2022). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 8547.
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