Iowa Biodiversity

1. Iowa Biodiversity Biology/Env S 204 Spring 2009

2. Paleozoic Plateau • High relief landscape resulting from erosion • Karst topography: sinkholes, caves, springs • Extremely vulnerable to groundwater contamination • Cold-air (algific) talus slopes • Biologically rich

3. Iowan Surface • Low relief, gently rolling • Thin loess deposits, some local karst conditions, drainage mostly good • Fens, a special type of wetland (water-saturated peat deposits) are found in this region • A number of rare plant communities occur in fens

4. Southern Iowa Drift Plain • Steeply rolling topography derived from thick glacial drift (older than the most recent glaciations) • Well drained, few wetlands • Contains historically important coal deposits, surface mining once common • Primarily what you see on Interstate 80

5. Des Moines Lobe • Last part of the state covered by the most recent glaciers in N. America, ca. 12,000-14,000 years ago • Fresh glacial drift, no loess cover, poor surface drainage • Natural lakes district, with bogs, marshes, potholes, fens, kettleholes • Relatively low relief landscape

6. Northwest Iowa Plains • Gently rolling, low relief, good drainage • Moderate to thick loess • Fairly similar to the Iowan Surface but less woodland cover • Precambrian bedrock outcrops can be seen in Gitchie Manitou State Preserve

7. Alluvial Plains • Sedimentary deposits forming floodplains along major waterways (here, the Mississippi and Missouri Rivers) • Important corridors for wildlife (especially migrating waterfowl) • Rivers active, shifting

8. Loess Hills • Loess = wind-deposited silt composed of closely packed grains of quartz (in Iowa from Pleistocene glacial activity 31,000 to 12,500 years ago) • Loess deposits are fairly common, but the depth in Iowa is unusual; mostly over 60 feet, but locally can reach 150-200 feet

9. Loess Hills • Narrow band along full length of the Missouri Valley in W Iowa • Porous, unstable and easily eroded when wet, very cohesive when dry • Sharply ridged, gullies • Mosaic of specialized niches: prairie, woodlands, supports unusual native plants and animals

10. Iowa Landforms—Summary • Original landscape was a vast tallgrass prairie with interspersed savannas and wetlands with woodlands primarily along waterways • Best estimates: 79.5% prairie; 11.7% woodlands; 6.7% savanna; 1.4% wetlands • Highest species diversity in the Loess Hills and the Paleozoic Plateau

11. Major Iowa Vegetation Types • Forests and woodlands (discussed by Dr. Mabry McMullen) • Tallgrass prairie (discussed later today by Carl Kurtz) • Savanna • Wetlands

12. Tallgrass Prairie • Occurs in areas of relatively high rainfall (30-40 inches annually) and strong seasonality • Fire and grazing are the major factors in maintaining tallgrass prairie • Incredibly rich soil of Iowa due to prairie root system over 10,000-12,000 years

13. Tallgrass Prairie • Conversion of Iowa’s 28.6 million acres of tallgrass prairie began on 1 June 1833 • By 1902, “…the prairies are plowed almost to the last acre…” • Less than 0.1% of the original prairie cover remains • Loess Hills is the only area in Iowa with significant remaining remnants

14. Wetlands • Vast majority of Iowa wetlands found in the Des Moines Lobe as ponds, marshes, potholes, fens and bogs • About 99% of these have been drained • Wetlands along the Mississippi and Missouri Rivers also greatly affected • Wetlands extremely important as “sponges,” water filtering and wildlife