Plant invasions in Great Lakes wetlands are strongly influenced by nitrogen loading. The invaders Phragmites australis and Typha x glauca are often managed with varying degrees of long-term success, in part due to the persistence of N loading. However, even if N loading were decreased, the wetland ecosystem could potentially stay in an invaded state because of a regime shift to higher plant-sediment N cycling, maintaining invader dominance. We studied this using the Mondrian model, a wetland community-ecosystem model. In our simulations, even after a major reduction in N loading, in flooded conditions, these invasive species continued to dominate the community and did not return to pre-invasion levels. However, lower water levels allowed N cycling to return to nearly pre-invasion levels, partially reducing the dominance of the invaders.
Lead Author: Jason P. Martina, Texas A&M University
Additional Contributors: Kenneth J. Elgersma, University of Northern Iowa & Deborah E. Goldberg, University of Michigan