Sediment excavation as a wetland restoration technique had early effects on the developing vegetation community
Excavating agriculturally-accrued sediment from wetland basins is an increasingly common restoration technique worldwide, but the impacts on recruiting native plant communities are unknown. Multiple agencies developed a wetland monitoring protocol to document how restoring hydrology and removing excess sediment impacted hydrology and plant assemblages both before and up to 6 years after wetland restorations in North American prairie potholes. Our results indicated that the excavated basins had marginally greater probabilities of increased total standing water, habitat interspersion, and relative plant diversity, as well as lower probabilities of having invasive plants and hybrid cattails (Typha × glauca), when compared to unexcavated basins. By year 4, the excavated basins had 50% probability of extensive cattail invasion, whereas the unexcavated basins had 85% probability of cattails. However, the benefits from excavation were typically negated by invasive species and cattail encroachment within 3–6 years of post-restoration. Therefore, the vegetation communities may benefit from sediment excavations that are also coupled with targeted management within the first few years to combat invasion. This long-term monitoring program could be continued and revised to include post-restoration management activities (e.g., seeding, invasive species control techniques, and prescribed fire) using an adaptive management framework to provide prompt feedback to managers regarding the relative efficacy of alternative post-restoration management.
KeywordsHybrid cattail Prairie Pothole Region Sediment removal Waterfowl Wetland Wetland vegetation Typha × glauca
We thank the U.S. Fish and Wildlife Service’s Partners for Fish and Wildlife Program and the National Wildlife Refuge System, Midwest Region, Division of Natural Resources and Conservation Planning for funding this long-term monitoring program, and the Minnesota Department of Natural Resources for funding data analyses, presentations, and publication. We acknowledge Lori Stevenson for her efforts that established and provided project coordination during the early years of the project and the photos in Fig. 1; Todd Sutherland, Vicky Hunt, Sarah Jacobi, and Aaron Griffith for management of the original databases; Eric Lonsdorf for concept development and annual reporting; Christina Hargiss for protocol development; Wayne Thogmartin for preliminary analyses; Veronique St.-Louis for guidance on data analyses; Patricia Heglund for long-term program support and thoughtful manuscript review; Andrew Allstadt, Ben Walker, and Alex Galt for manuscript review; and the many people who enrolled sites, performed the restorations and site assessments, and collected and entered monitoring data. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service or the Minnesota Department of Natural Resources. The authors do not have conflicts of interest to declare.
JR, SM, MK, SP, SV conceived and designed research; SM, SP, SV, SW, JR collected field data; DL, MP, JG analyzed the data; DL, MP, JG, SW, SM, SV, JR, MK, SP wrote and edited the manuscript.
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