What Are Saline Wetlands?
Wetlands are among some of the most productive ecosystems in the world, providing several key functions, or ecological services, that both directly and indirectly affect wildlife, the environment, and the human sector. The Nebraska Game and Parks Commission had defined four regional wetland complexes that occur naturally in the state of Nebraska. These complexes include: Playa, Riverine, Sandhill, and Saline/Alkaline. Combined, Nebraska’s total wetlands cover over 1,500,000 acres statewide, and demonstrate different physical, chemical, biological, geological, and hydrological properties.
Of the four wetland complexes found in Nebraska, the Eastern Saline Wetlands of Lancaster and Saunders counties are among the most unique and threatened wetland communities in the state. Limited to the floodplain swales and depressions within the Salt Creek, Little Salt Creek, and Rock Creek drainages, it’s estimated that the Eastern saline wetlands once covered an area in excess of 20, 000 acres. Today, due to extensive degradation, draining and filling, through commercial, residential, and agricultural development, less than 4,000 acres remain and many of these remnants are highly degraded.
Nebraska’s saline wetlands are characterized by saline soils and halophytic (salt tolerant) plant species such as spearscale, inland salt grass, sea blite, prairie bulrush and the state endangered saltwort. Soils are saline belonging to the Salmo Series of deep, poorly drained bottomland soils of low permeability. This soil type commonly occurs near creeks, intermittent lakes, and marshes, and is usually only briefly flooded. The source of salinity for these wetlands is not fully understood, but it’s postulated that the salinity is from groundwater inflow that passes through a rock formation containing salts deposited by an ancient inland sea that once covered much of the Great Plains (USDA 1996). The remaining saline wetlands may be sustained by saline groundwaters that flow up through Dakota sandstone, the underlying bedrock of soils along the Salt and Little Salt Creeks. Dakota sandstone is very porous allowing saline groundwater from deeper shale rock formations containing salt depositions to seep up into overlaying soil horizons. The seepage of groundwater over thousands of years from deeply buried saline aquifers has accumulated in salts in the floodplain soils, allowing for the unique wetland type to form.
The abundant mud flats of the saline wetlands are rich in invertebrate life and frequented by a variety of migratory shore birds, other bird species, and wildlife. During the last century, more than 230 species of birds have been reported from the salt basins of Lancaster and Saunders counties. This includes a large number of water birds and migratory species including black and king rails, white-face ibis, herring gulls, western and eared grebes, the threatened least tern, two species of plovers, and most species of ducks and geese. In May of 2008, the Nebraska Game and Parks Annual District Birding Day recorded over 60 species of birds sited at Frank Shoemaker Marsh, a 160 acre saline wetland complex north of Lincoln. The Eastern saline wetlands are also home to many saline plants that are found nowhere else in Nebraska. Three plant species found growing in the salt marshes are considered rare in Nebraska including the saltmarsh aster (Aster subulatus var. ligulatus), Texas dropseed (Sporobolus texanus) and the state endangered saltwort (Salicornia rubra). In addition to the many unique invertebrate, bird, and plant species, the Eastern saline wetlands are also home to hundreds of more familiar mammal, fish, and reptile species.
Aside from providing habitat for wildlife and plant species, the saline wetlands offer several other ecosystem services. A watershed has many components and wetlands play an important role in this management by providing functions which improve water quality, reduce flooding and soil erosion, and supplying water. Saline wetlands are critical in protecting stream quality by filtering and collecting runoff water and aid flood control by storing water after heavy precipitation events and reducing peak flows. The unique landscape also provides for recreational opportunities such as hunting, trapping, wildlife watching, photography, and enjoyment of the serenity a wetland can offer. These wetlands offer an exceptional opportunity to study and observe flora and fauna not found on other more abundant landscapes.