Algific Talus Slopes
The upper corner of northeastern Iowa is like a window to the past. The earth’s underlying strata has literally been turned inside out by the glacial activity of prehistoric times. Bedrock, normally buried beneath glacial deposits hundreds of feet thick, dates back 600 to 400 million years. Cliffs and escarpments formed of this ancient limestone, dolomite and sandstone are scattered with sinkholes, subterranean caverns and perennial groundwater springs. This makes for a variety of microclimates that support diverse communities and species that were long thought extinct.
Small ice caves, where the core ice is believed to be more than 10,000 years old, are tucked away behind steep slopes of limestone scattered with loose (talus) rock, creating a unique feature called an Algific (cold-producing) Talus Slope. During the spring and summer the air in the ice caves is colder than the outside air. Warm air drawn down into the sinkholes is cooled as it flows over ice, and then escapes through vents in the slopes keeping them at a temperature between 37 and 45 degrees Fahrenheit. In the winter, air in the ice caves is warmer than the outside air, reversing the airflow. As the warm air rises and exits through the sinkholes, the cold air is drawn through vents, freezing the ground water.
Black Soil Prairie
Typically mesic-wet prairie growing on deep, well-developed soils. This would have been the dominant type of prairie in Iowa at the time of settlement, but is currently the rarest since these same soils are the ones best suited for crops.
Bur Oak Woodland
Unlike most other oaks, the bur oak or Mossycup oak seldom occurs as part of a forest stand. More frequently it grows singly in open stands within prairies and fields. It prefers moist but well-drained soils. The bur oak’s massive form, peculiarly lobed leaves, fringed acorns, and corky twigs make it stand out from all other oaks.
A peat filled wet land found in ancient river channels. Also see expanded definition of Fen on following page.
Prairie communities growing under dry moisture conditions. They may still have some tallgrass species, but are typically dominated by intermediate grasses such as little bluestem, sideoats grama, and prairie dropseed, and are beginning to show an increase in shortgrass species such as hairy and blue grama.
Fens are unique wetlands characterized by saturated organic soils (peat) fed by neutral to somewhat alkaline groundwater. They are similar to bogs except that fens consist of well-decomposed peat, are permeated by non-acidic water, and are vegetated predominantly with herbaceous plants. Bogs, in contrast, are composed of well preserved peat, distinctly acidic water, and shrub- or tree-dominated vegetation. Fens are typically associated with springs and seeps on hillsides or in valleys.
At some fens the upward seeping of hard groundwater flows into a series of shallow pools. The bottoms of these pools are layered with deposits of "tufa", a porous calcium deposit resulting from oxidation of the calcium-rich groundwater. These tufa deposits combined with sulfate bacteria found in the pools, create a most unusual environment for even more unusual vascular plants, algae, and zooplankton.
Fens are special both as a distinctive natural community and as habitat for rare plant and animal species. In Iowa over 200 species of plants are associated with fens, and a single fen could contain as many as 75 plant species. Rare Iowa plants found only in fens include bog bedstraw, narrow-leafed fringed gentian, alpine rush, beaked rush, sage willow, whorled nutrush, hooded ladies’-tresses, and slender bog arrow grass.
Forest land found near rivers that experiences frequent flooding.
Depressions formed durning the last ice-age when parts of glaciers were left behind and covered in soil. The ice would then melt, leaving a deep depression in the land.
Hill or Goat Prairie
Occurs on steep, thin soils with a south-southwest exposure. The best examples occur in northeast Iowa’s Paleozoic Plateau, but similar prairie can be found in other parts of the state.
Generally associated with thin soils over limestone bedrock. Many of northeast Iowa’s hill prairies might also classify as limestone Prairie.
Loess Hills Landform
The Loess Hills landform is both rare and intriguing. ‘Loess’ consists of tiny windblown silt particles. Iowa’s Loess Hills were literally blown into existence as the glaciers from the last Ice Age retreated. Most of the Midwest is covered in Loess – it’s what helps make our land so rich for farming. However, the extent and depth of the loess deposits along Iowa’s western border are matched only in China.
Loess Hills Prairie
The prairie ranges from dry prairie on the ridgetops and bluff faces to mesic prairie on the lower slopes and valleys. Species composition is similar to other prairies, but with the addition of species typically found further west in the Great Plains.
Maderate (cold water) cliffs are essentially algific talus slopes in which the talus layer has eroded away, leaving a cliff face. Little ice accumulates in these features since there is no insulating layer of talus. The cliff faces can be wet at times of the year (usually spring), but are frequently dry. Therefore, unlike algific talus slopes, which provide cold, wet conditions, maderate cliffs provide cold, dry conditions. Several rare plants and landsnails depend on these special habitats for their survival. Rare plants include Leedy’s roseroot, cliff goldenrod, and a species of whitlow grass.
Usually includes some open water, and is dominated by species such as cattails and rushes.
Prairie communities growing under intermediate moisture conditions. They are typically dominated by tallgrass species such as big bluestem, Indian grass and switchgrass, but are beginning to show an increase in intermediate grasses such as little bluestem, sideoats grama, and prairie dropseed.
Typically dry prairie growing on deep sandy soils.
Occurs in soils saturated by surface water, and is typically dominated by sedge species.
Swamp White Oak Woodland
Open savanna dominated by swamp white oak trees. Swamp White Oaks closely resemble other oaks but are distinguished by their leaves. They have shallow rounded lobes on each side and are green with a slight shine on the top while having soft whitish hair on the underside. Pin oaks, river birch and sycamores are also often found on terraces near rivers.
Lush native grasslands found in the eastern great plains and midwest in areas with high rainfall and rich soils. They are dominated by big blue stem and indian grass.
Forestland found on hills and plains away from rivers and marshes.
Areas of wet saturated soils or shallow open ponds of water. Containing plants that tolerate wet soil and standing water.
Prairie communities growing under relatively wet conditions. They are typically dominated by tallgrass species such as slough grass, bluejoint grass and big bluestem, and may also show an increase in sedge species.