Earlier this week, a group of researchers from the U.S. Geological Survey, Army Corps of Engineers, and other groups published its third status and trends assessment of the Upper Mississippi River System. The group, called the Upper Mississippi River Restoration (UMRR) program, synthesized 25 years of long-term science to explore what is driving changes to the overall watershed.
Audubon has served as a partner of the UMRR program for over a decade, working primarily with the U.S. Army Corps of Engineers to monitor floodplain forest breeding birds and partnering with U.S. Fish and Wildlife Service and others to restore large tracts of forest, which provide habitat while also storing water and carbon.
The biggest takeaway from this report is the critical need to focus on both adapting to and reducing the severity of climate change. We are seeing long-term increases in water moving through the river system, which has significant implications for both habitat loss and threats to local communities living near waterways.
Increasingly severe rain and snow events, combined with less natural areas on the landscape to absorb waters are perhaps the biggest challenge to a healthy and resilient Upper Mississippi River System. Climate models for the upper Midwest region referenced in this report suggest up to 30 percent more precipitation through wetter spring and winter seasons.
The status and trends report also documents a broad decline in floodplain forest cover. Tree mortality rates are increasing in areas with increased flood duration. Invasive plants, like reed canary grass and common reed, are replacing old growth trees, threatening the future of this critical flyway for birds. Species like Prothonotary Warbler, Red-shouldered Hawk and Cerulean Warbler are suffering as the natural succession of these critical floodplain forests are altered. In the past half century populations of Cerulean Warblers, who depend on floodplain forest, have declined by more than 70 percent. Birds are telling us that it is critical to restore these forests.
While water quality indicators described in the report point to the river system still being highly eutrophic, or rich with nutrients, we have seen an important decline in total phosphorus and suspended solids (but not Nitrogen). This positive trend proves that we can make a difference in improving the health of this massive river system. By restoring and managing riverine marshes and forests, we can continue to improve water quality and store more carbon, all while providing a critical flyway of habitat for birds.
The release of the status and trends report illustrates the fundamental role of long-term monitoring in managing large river systems. As birds face warming temperatures over the coming decades healthy floodplains forests will be critical for the many species that migrate up and down the Mississippi flyway. Tracking bird populations and their response to restoration will help ensure our efforts are delivering for threatened wildlife.
Nat Miller is the senior conservation director for Audubon Great Lakes and the Upper Missippi Flyway.
Lindsay Brice is the policy director for Audubon Minnesota.