The Ridges Sanctuary expands research on rare dwarf lake iris

The Ridges Sanctuary in Baileys Harbor, Wisconsin, is using federal grant funding and volunteer support to study what helps the threatened dwarf lake iris thrive. The work could guide future transplants, monitoring and conservation for a plant with only 165 known populations worldwide.

Why it matters: - The dwarf lake iris is federally and state threatened, yet it grows in abundance at The Ridges Sanctuary in Door County, Wisconsin. - Research at the sanctuary could help determine the conditions the plant needs to survive and inform future translocation and long-term conservation. - The species is highly limited in the wild, with only 165 known populations worldwide.

What happened: - The Ridges Sanctuary in Baileys Harbor launched a multi-year study of dwarf lake iris after receiving a U.S. Fish and Wildlife Service Coastal grant. - The grant supports a range light corridor tree maintenance project and research on how tree canopy manipulation affects iris survivorship, flowering and reproduction. - The U.S. Fish and Wildlife Service first approached The Ridges in January 2023 with a grant opportunity that aligned with the sanctuary’s mission.

The details: - The dwarf lake iris is found only along the northern edges of Lakes Michigan and Huron, with a few inland populations near Green Bay, Wisconsin. - The known populations include 89 in Michigan, 23 in Wisconsin and 40 in Ontario. - The plant has been federally listed since 1988. - The project includes nine research plots with monitors for sunlight, soil moisture and soil temperature. - Staff and volunteers are measuring tree canopy density and tracking plot conditions over time. - Baseline work included a plant inventory, transplant protocols and preliminary population data collection. - Corridor tree clearing was scheduled for winter to avoid disturbing bat and dragonfly habitat. - Educational presentations and signs were added to explain the research to visitors. - The sanctuary plans to select translocation sites after the monitoring period and then transplant populations for long-term study. - Long-range monitoring is also planned.

Between the lines: - The sanctuary’s large, healthy population gives researchers a rare chance to study the species in place before moving plants elsewhere. - The research also reflects a broader conservation problem: limited data on how sensitive species respond to changing environmental pressures. - Bob Wise, professor emeritus of botany at the University of Wisconsin-Oshkosh, is supporting work on the plant’s anatomical and physiological responses. - Beckham Sonnabend, a donor-funded resident research fellow and Lake Forest College graduate, is focusing on the research at The Ridges. - Additional grant funding this year expanded the work to Plum Island with the Friends of Plum and Pilot Island and the U.S. Fish and Wildlife Service. - Forest School children helped scout Plum Island populations before the land and research team established plots and trained volunteers. - Researchers plan to monitor Plum Island populations alongside The Ridges for comparison and to assess refugia potential. - Future genetic analysis of different populations is also under consideration.

What’s next: - Monitoring at The Ridges will continue until researchers can identify the environmental conditions that best support dwarf lake iris. - The sanctuary will use that information to choose translocation areas and begin transplantation. - Plum Island monitoring will continue in parallel with the sanctuary plots. - Further research may expand into genetic analysis and deeper study of the plant’s biology.

The bottom line: - The dwarf lake iris may be common in one protected corner of Wisconsin, but its broader survival depends on filling major research gaps before the plant faces more environmental pressure.