Date of Award:

8-2013

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Advisor/Chair:

Karin Kettenring

Abstract

Revegetation projects in wetlands are challenging due to questions surrounding where to obtain plant materials and how hydrologic conditions, which are often unpredictable at restoration sites, may impact restoration success. We used a two-pronged approach to inform decisions on seed sourcing. Our study species, Schoenoplectus maritimus (alkali bulrush), is a widely distributed wetland plant. First, we investigated how genetic diversity was partitioned within and among populations of S. maritimus. We found five weakly differentiated populations and one distinct population. We found high levels of genetic diversity with the majority (92%) of diversity found within rather than among sites (8%). Also, the proportion of viable seed produced was surprisingly high within stands (mean = 0.64 ± 0.02) given the supposed prevalence of asexual reproduction in the species. Second, we conducted two studies to look at the influence of hydrology, population of origin, and genetic diversity of seeds on the productivity of S. maritimus. In a field survey we measured environmental variables and productivity within established S. maritimus stands. In a greenhouse experiment we determined how source population identity and the genetic diversity of seeds impacted emergence and productivity under different hydrologic conditions. We found that stands of S. maritimus differed in proportion of time with water present, mean water level, and soil conditions. Productivity also differed, with 3-fold differences in stem density and biomass among sites. In the greenhouse experiment, we found that water treatment impacted all productivity measures; source population impacted seedling emergence and biomass allocation; and, number of source populations impacted sensitivity to drought. Advice for future restoration projects includes (1) limiting translocation of seeds among populations to conserve historic lineages, (2) when it is necessary to translocate seeds, collect seeds from many parent plants within populations that are in close geographic proximity to the restoration site, and (3) water level management is extremely important at all life stages of S. maritimus and should be an important consideration in wetland restoration and management in this water-limited region.

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