AbstractsBiology & Animal Science

Changes in Wetland Conditions and Wetland Plant Communities in the Prairie Pothole Region After 50 Years

by Ryann Cressey

Institution: South Dakota State University
Year: 2016
Keywords: climate; Prairie Pothole Region; water chemistry; wet-dry cycle; wetlands; Natural Resources and Conservation; Other Life Sciences
Posted: 02/05/2017
Record ID: 2134358
Full text PDF: http://openprairie.sdstate.edu/etd/1001


Wetlands in Stutsman County, North Dakota were revisited after 50 years to assess changes in wetland conditions and plant communities within wetland zones in the Prairie Pothole Region. In 1961-1966, Robert E. Stewart and Harold A. Kantrud conducted a study to investigate the relationship of wetland plant communities to variations of water permanence and chemistry on three study areas: Crystal Springs, Cottonwood, and Mt. Moriah. Within in this region, a severe drought occurred in 1988- 1992 followed by the longest deluge starting in 1993 with wetlands still impacted today. In 2013 and 2014, I revisited 80 of the original wetlands measuring water depths and specific conductivity as well as measuring wetland size from aerial imagery. Additionally, I conducted quadrat-based vegetation surveys within 4 wetland zones (i.e., wet meadow, shallow marsh, deep marsh, and open water) to examine changes in species composition, frequency, abundance, and to document progression of invasive plant species (e.g., Typha, Phalaris arundinacea, Poa pratensis, and Bromus inermis). Wetlands at the three study areas responded to the excess water from the deluge in unique ways. Wetlands at Crystal Springs were larger, deeper, and fresher in 2013-14 compared to the 1960s. Wetlands at Cottonwood were slightly larger, deeper, and more saline in 2013-14. Wetlands at Mt. Moriah had subtle, almost negligible changes in depth, size, and salinity from the 1960s study to the 2013-14 study. Although wetlands across the study areas responded to deluge conditions differently, plant communities within wetland zones on average were only 25 % similar in species composition across all study areas from the 1960s to 2013-14, but changes within each wetland zone were unique. Across all study areas, the deluge conditions left most wetlands dominated by open water and with more deep marsh zones. Excess water at Crystal Springs caused merging of wetlands to the extent that a large portion of wetland vegetation and wetland zones have been lost since the 1960s. Some merging occurred at Cottonwood but expansion of invasive plant species caused more wetland zone loss (i.e., reduction or removal of zonal plant communities) at this study area and at Mt. Moriah than did high water conditions. Species richness increased in all zones, but at least 50% of species changed minimally in abundance (i.e., ± 5%) within each zone except open water. Open water zones had 43% of species change by >10% abundance and had less submerged aquatic vegetation overall due to increased wetland depths. Deep marsh zones were mostly monotypic stands of Typha in 2013-14, and shallow marsh zones surrounding these monotypic stands were not present or dominated by Phalaris arundinacea. Shallow marsh zones in wetlands without Typha had Carex atherodes, Polygonum amphibian var. emersum, Scolochloa festucacea, and Phalaris arundinacea as the most abundant species in 2013-14. Wet meadow zones consisted of several traditional wet meadow species with the addition of traditional low prairie zone and… Advisors/Committee Members: Joshua D. Stafford, Jane E. Austin.