Nitrogen-15 uptake by Typha x glauca and Scirpus lacustris in Cheboygan marsh and Cheboygan State Park marsh.

Abstract

Typha x glauca is an invasive plant species growing in Cheboygan Marsh, which is located downstream from the Cheboygan Wastewater Treatment Facility. Its establishment in the marsh has been attributed to the deposition of excess nutrients from the treated water from the treatment facility, specifically deposition of Nitroge15-N (15-N). Given that previous research has shown T. x glauca’s ability to displace native plants, we are interested in seeing if T. x glauca provides any ecosystem services, such as ameliorating the effects of eutrophication by taking up more 15-N than native plant species. We hypothesized that T. x glauca takes up more 15-N than Scirpus lacustris, a native bulrush. To test our hypothesis we collected soil and leaf samples of juvenile T. x glauca and S. lacustris from Cheboygan Marsh, our experimental site, and Cheboygan State Park, our control site. Stable isotope analysis was performed using a mass spectrometer to obtain 15-N to 14-N ratios; the results did not support our hypothesis and showed that S. lacustris took up more 15-N than T. x glauca in the Cheboygan Marsh. Our findings suggest that S. lacustris may be a better denitrifier than T. x glauca. Given that we faced some limitations to our study, we recommend that further research includes more plant and soil samples and that comparative research be done comparing lifetime uptake of 15-N between T. x glauca and S. lacustris.