Effigy Mounds National Monument - Environmental Factors (U.S. National Park Service)

Park visitors climb bluffside trails

The environment of Effigy Mounds National Monument is in a constantly shifting, dynamic state. Weather, climatic change, geologic processes, fire, past agricultural practices, and pollution are only a few of the agents that affect today's environment. The landscape provides managers an opportunity to better understand how these environmental factors have shaped park ecosystems. The agriculture of the early 1900s consisted of low intensity farming practices that eliminated some but not all of the native species that were endemic to the area. In the mid 1900s farming intensity increased with the use of tractors and row crop agriculture practices. Much of the native grasses and many of the native forbs were lost. Prairie remnants are the remains of the rarest of original habitat types. The majority of the remnants that exist today are the result of agricultural land that has been allowed to lie fallow. Eastern Iowa along the Mississippi River, is part of the eastern hardwood forest. This area, if left undisturbed, will eventually grow back to this condition through succession. The plant communities will go through a number of successional stages resulting in a climax, maple-basswood forest. The combination of topography, longitude, latitude, and climate has produced unique microhabitats that support island populations of flora and fauna. These microenvironments include north facing algific talus slopes and "goat prairies". Algific talus slopes are usually found on north facing slopes. They are cold air seeps connected to crevices in the limestone bedrock which are connected to underground caverns. The movement of cold air exiting the slope through the crevices creates a colder, moister environment down slope of the vent. This seepage of cold air down slope creates microhabitat for groups of relic ice age plant communities. These plant communities are remnants of populations that are associated with more northern climates. As the glaciers advanced during the last ice age, plant communities that were adapted to northern climates moved south. With the warming of the climate and the retreat of the glaciers, the cold climate environmentally adapted plants moved north also. The modifying effect of the cold air seeps maintained an artificially induced microclimate that maintains remnants of the prehistoric ice age plant communities. Goat prairies are small prairie remnants found on bluff faces. These prairies are associated with shallow soils, south facing slopes and rock outcrops. The south aspect, shallow soils, and drier conditions select the drought tolerant native grasses over woody vegetation giving the prairie species a competitive advantage. Locating, identifying and monitoring of all special microhabitats is important for maintaining and protecting the presettlement ecological remnants. The greatest potential for the existence of federally threatened and endangered species occurs in these areas.