CHARACTERIZATION OF SEDIMENT AND ORGANIC MATTER IN A UNIQUE NATURAL WETLAND SYSTEM IN SOUTHWEST MICHIGAN

The Hultmark Preserve in Van Buren County, Michigan, is a protected wetland that provides habitat for many native plants, including wild rice. This unique geomorphic setting, influenced by Michigan’s glacial and agricultural past, is being evaluated to serve as an example of the types of conditions in which native plants thrive. For this study, 40 sediment cores were taken from 4 transects across the Hultmark Preserve in Fall of 2018. The cores were halved-lengthwise, measured, photographed, and lithologically described. In addition, sub-samples from different horizons were collected for loss-on-ignition (LOI) analysis for the determination of percent organic matter. With these data, we concluded that the northwest corner of the wetland contained 4.51% organics at a depth of 12cm and the southwest corner contained 9.2% of organic matter at a depth of 5cm. These data were compared to higher organics found on the eastside of the wetland. The southeast corner was found to contain 53.4% organics at a depth of 5cm, while the core sample site east of the southwest corner was found to have 19.4% organics. From these data, we concluded that the wetland soil located on the westside of the wetland contained less organics and a higher percentage of porous sand compared to the eastside. This outcome was interpreted to affect the flow of water to and from the wetland as well as biogeochemical processes (ex. sulfate-reduction) known to affect the growth conditions of native wild rice. Less organics and more sand found on the westside of the wetland, coincided with visual observations of water flowing from east to west. Results from the characterization of this unique preserve provides a case study of what a wetland system should emulate in order to allow native plants, like endangered wild rice, to thrive in Southwest Michigan.