Botanical Assessment of Remnant Floodplain Habitats Along Plaster Creek, Kent County, Michigan: Assessing Changes Since the 1890s

Abstract

Plaster Creek, a tributary of the Grand River, drains a 58-square mile watershed in Kent County, Michigan. Its headwaters originate in the agriculturally dominated southwestern portion of the county, and then it meanders through residential, commercial, and urban areas of Kentwood and Grand Rapids before it empties into the Grand River about one mile south of downtown Grand Rapids. Much of Plaster Creek’s original floodplain, like the rest of its watershed, has been drastically altered and degraded over time due to the development of residential neighborhoods, commercial properties, agriculture, and industrial zones. Floodplains house unique assemblages of Michigan’s native biodiversity and sustain stream and watershed health, warranting their preservation and restoration. Over several seasons, Calvin University Herbarium’s Emma Cole Grand Rapids Flora Project inventoried seven remnant floodplain sites along Plaster Creek from near its source in Gaines Township to downstream areas within the City of Grand Rapids. A total of 438 species of vascular plants were documented for the combined seven floodplains, of which 341 (77.9%) are native. Floristic Quality Assessments were calculated for each of the sites with values ranging from a Total Floristic Quality Index (FQI) of 30.4 (Total Mean C = 2.8) at the smallest site with only 93 native species (78.7%), to a Total FQI of 52.7 (Total Mean C = 3.6) at the Ken-O-Sha Park floodplain, with 176 (82.2%) native species. The Stanaback Park floodplain had a similar number of native species, 174 (80.9%), and a Total FQI of 48.4 (Total Mean C = 3.3). In order to make comparisons with floristic information compiled by Emma Cole in the 1890s, a Floristic Quality Assessment was calculated based on 65 species (98.5% native) collected and reported by Cole (1901) as occurring along Plaster Creek. The Total FQI of Cole’s list was 48.4 (Total Mean C = 6.0), and 27 of her species have a high level of fidelity to a narrow range of ecological conditions, five of which today hold Special Concern, Threatened, or Endangered status in Michigan. By comparing our inventory findings with the floristic information gathered by Cole, this study highlights changes that have taken place in the Plaster Creek floodplain over the past 120+ years, describes the present-day condition of Plaster Creek’s floodplains, and can be used to inform future ecological restoration efforts along this and other local creeks.