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Wetland Management for Sedimentation and Invasive Cattail Expansion

Sedimentation and invasive cattail impact waterbird habitat at Agassiz National Wildlife Refuge. How can we improve waterbird habitat and identify better ways to manage invasive cattail?

Established in 1937, Agassiz National Wildlife Refuge in northwest Minnesota is a 61,500 acre wetland complex that drains thousands of acres of industrialized agricultural land. The Refuge is home to many breeding and nesting waterbirds, including what was once the largest breeding colony of Franklin's gulls in North America. Due to upstream hydrologic alteration and erosion, the Refuge is experiencing significant sedimentation.

As sediment is deposited in the wetlands, soil surface elevation increases and water depth decreases, leading to expansion of invasive cattail into shallow areas and changing habitat for waterbirds.

This study focused on cataloging past cattail management practices and understanding how elevation is changing in Refuge wetlands to identify adaptive ways to manage invasive cattail and improve waterbird habitat. We created spatial datasets outlining the past 30 years of cattail management on the Refuge and delineated expansion of invasive cattails. We also gathered bathymetric data for nearly 10,000 wetland acres and developed digital elevation models.

By developing a better understanding of cattail management efforts and how elevation is changing, managers can more effectively identify areas and methods for targeted cattail management efforts.

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