Spatial Patterns of Aquatic Habitat Richness in the Upper Mississippi River Floodplain

The restoration of aquatic habitats has been a central focus of the Upper Mississippi River Restoration-Environmental Management Program since its beginning in the late 1980's. In an effort to help regional decision makers identify areas that could benefit from habitat restoration, we developed a series of maps that depict habitat richness (# of habitat patch types) within neighborhoods surrounding each of the roughly 19 million 5-m aquatic pixels of the Upper Mississippi River for multiple neighborhood sizes (1-100 ha). Using these maps, we estimated the rate of increase in habitat richness with neighborhood size (z) for 87 management-relevant focal areas.

Variation in z reflected historical changes to spatial patterns of aquatic habitat richness in the UMR.  Across all focal areas z averaged 0.18, signifying an 18% chance of encountering a new habitat type with each incremental increase in neighborhood size (1 ha) for the typical focal area. However, in focal areas where the surface area of side channels or contiguous floodplain lakes was > 5% of the total floodplain,  or contiguous shallow-water areas was > 10%, z nearly always exceeded 0.18 indicating above average habitat diversity  In contrast, z was always less than 0.18 for focal areas where impounded water exceeded 40% of floodplain area. Our results suggest that rehabilitation efforts that target areas with <5% of the floodplain in side channels or floodplain lakes,  <10% in shallow-water areas, and/or >40% in impounded areas could improve habitat diversity across multiple scales in the UMR.