Date of Award:

5-2026

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Committee Chair(s)

Karin M. Kettenring

Committee

Karin M. Kettenring

Committee

Kari E. Veblen

Committee

Scott Hotaling

Abstract

Wetlands are declining worldwide, and those in arid regions are especially vulnerable to climate change, drought, water diversions, and other human pressures. As a result, land managers increasingly rely on active revegetation to re-establish native plant communities and their associated ecosystem functions. Restoration that utilizes seeds as the propagule source is often the most cost-effective way to revegetate large areas, but in highly variable environments such as exist at Great Salt Lake, Utah, drought and flooding regularly limit plant establishment. Restoration practitioners require science-informed strategies to reach their goal of establishing diverse native plant communities with high native species cover.

Improving outcomes in hydrologically extreme wetland systems requires practical guidance in two areas: (1) how to prepare seeds of previously underutilized or unused species so they germinate reliably, and (2) how to time seeding in relation to annual water availability. Managers also need to know whether incorporating more drought-tolerant species or adjusting seeding timing can improve establishment under increasingly dry summer conditions. This thesis presents two experiments designed to explore these areas. A growth chamber study tested how germination response varies among ten drought-tolerant wetland species following treatments to break seed dormancy and incubation under three germination temperatures in light and darkness. Germination responses varied widely by species, indicating that dormancy break treatments must be tailored to individual species rather than applied uniformly across seed mixes. A field experiment at two sites with contrasting water conditions evaluated the effects of three seeding timings (June, August, and September) across two growing seasons. At a consistently moist or shallowly inundated site, June seeding produced the highest native species cover over both years and reduced invasive species cover by the end of the experiment. At a site which experienced summer drought but which was otherwise inundated, plant establishment was limited across all treatments, but one native grass (Puccinellia nuttalliana) established when seeded in August and September. The August seeding also limited invasive species cover by the end of the experiment.

These results suggest that successful restoration in hydrologically extreme wetland systems depends on selecting species based on their germination requirements and natural establishment timing and on matching seeding windows to site-specific hydrology. Practitioners should apply species-specific dormancy break treatments prior to seeding, and use species that have germination phenology in line with expected site-specific water conditions to successfully establish native plants.

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