Great Horned Owl
Native grasses and trees
Wetland
Canada Goose, 1999
Wildlife on Restored Wetlands
Duck Habitat
Indiangrass Seedhead
Little Bluestem Seedheads
Native Plants
The Bering Land Bridge
Glaciers in Iowa
Lumber Milling in IowaIowa’s Habitats
Habitats
are communities. Each community is made of the land, climate and the plants
and animals these support. Each time Iowa’s land or climate has changed,
its habitats have changed as well. The plants and animals best suited to the
new conditions take over. The others die or are pushed into small areas. Most
of these changes have taken thousands or millions of years to occur.
Iowa’s habitats have changed drastically in the past 200 years. However,
these changes are not because of a change in the land or climate.
A Change of Habitats
Fossil records show that for long
periods of time, a shallow sea covered Iowa. Coral reef, sharks and ancient
animals all called the area home. Coal deposits in parts of Iowa are evidence
of an ancient subtropical swamp environment. Coniferous forests covered Iowa
between the times the land was covered by glaciers.
After the most recent glaciers retreated, the climate warmed. Plants and animals
more suited to the warmer, drier climate thrived. First, broadleaf trees replaced
most of the conifers. Then prairie grasses replaced most of the broadleaf
trees. The animal communities changed as the plants did.
Native Habitats
The Mississippi and other Iowa rivers
have long been used as transportation routes. In 1673 Father Jacques Marquette
and Louis Joliet traveled along the Mississippi River exploring the east "coast"
of Iowa. Rivers and riverbanks are also habitat for fish, insects, water plants,
amphibians, beaver, otter and many other animals. Iowa has 71,665 miles of
rivers and streams, making it an important habitat.
Growing along the rivers are woodlands. In order to survive trees need the
cooler temperatures, the water, and the lower wind speeds that these areas
provide. Silver maple, cottonwood and willow forests are found along the rivers'
edges and in floodplains. Oak and hickory forests are more common on the higher
banks. Iowa forests were the first area explorers and settlers were interested
in. They were familiar with forest animals and plants. Trees provided fuel
and lumber. Deer and beaver provided food and furs. And forests felt safer,
more like home. In the early 1800s, almost 19 percent of Iowa was covered
in forest.
Past the protected river valleys the climate was hotter, drier and windier.
Here, the dominant habitat was prairie. Prairie grasses and flowers stretched
as far as the eye could see. Around 70 percent of Iowa was prairie. Over 100
types of prairie grasses and wildflowers rippled across the hills and valleys.
Prairie plants grow deep roots. Deep roots are effective at obtaining water,
holding the soil in place, and discouraging trees from taking root. These
grasses also easily sprout again after a wildfire roars over them. The plants
provide food and shelter for many animals. Bison, elk and wolves once roamed
freely across the grasslands. Prairie chickens, passenger pigeons and bobolinks
were common birds. Butterflies and other insects were thick. This habitat
was strange and scary.
Tucked in places where water could collect, there are wetlands. Glaciers created
the numerous shallow prairie marshes in north central Iowa. These soggy depressions
usually hold water for only part of the year. Flooding and channel cutting
created backwater wetlands along the rivers and streams. Lakes, marshes, bogs
and fens dot small areas of the landscape. Many of these wetlands hold water
year round. They provide flood and pollution control. They are important stopover
and breeding places for ducks, geese and shorebirds. Muskrat, otter, herons,
cranes and many other animals are also wetland residents. Mosquitoes also
love these areas. For the most part, explorers did not. In 1800 wetlands covered
almost 11 percent of Iowa.
If early explorers returned to Iowa today, they would not recognize it. Less
than ten percent of the land looks the same. The rest has been changed.
Lost
Native Americans had long used the
bounty of Iowa’s habitats for their survival. However, they did not
make major changes to the natural communities. When European settlers migrated
into the state in the 1800s, they started modifying the habitats to meet their
needs.
Many people chose to settle near rivers and streams. To make farming and development
easier, people dug trenches to make streams run straight. They put levees
on top of riverbanks to control flooding. They dammed rivers to create larger
sources of drinking water and to provide recreation. Locks and dams were put
on major rivers to aid in navigation. These and other changes have had a negative
effect on waterway habitats.
Channelized streams usually do not have trees and shrubs to shade them. They
become warmer and shallower. Soil and chemicals from eroding land move into
the water faster and travel farther.
Forests were initially cut by settlers to provide wood for houses, fences
and fuel. In the 1850s, timber was needed for railroad ties. It took about
six acres of oak woods to provide ties for one mile of railroad. Forests were
cleared for roads and towns. As farms became larger in the 1950s, trees along fence rows were cut down. These trees that were cut were hedge rows planted in the 1870s for fences. Osage orange trees were planted for fences before barbed wire was available. If kept trimmed, the "hedge trees" grew very thick. Later, these trees were cut and used for fence posts.
Large animals were the first piece of the prairie community to be affected
by settlers. A bounty was placed on wolves nationwide in 1817. Bison and elk were heavily
hunted for food and skins. Bison were gone from the state by the 1850s and
elk by the 1860s. Around this time the prairie itself was being radically
changed. John Deere’s moldboard plow became available to Iowa settlers
in the 1850s. With this tool, the settlers had a way to cut through the dense
mat of prairie roots. They turned the soil and planted crops. In less than
100 years, over 99 percent of Iowa’s native prairie was gone.
Wetlands were Iowa’s last habitat to be changed. Most people avoided
wetland areas because of all the insects. But the federal government gave
the land to the counties under the Federal Swamplands Acts of 1850 and 1860.
County commissioners were told to drain the land and make it productive. Work
to improve navigation on Iowa’s major rivers began in the 1830s. These
efforts eventually led to the decline of backwater wetlands. Increased erosion
has silted in marshes along lakes. Less than ten percent of Iowa’s wetlands
remain.
Found
Iowa’s greatest wealth has been in the products of its habitats. Wood, soil and wildlife are all products that are valuable for business and recreation. For nearly 200 years people have harvested these products. Now, over 90 percent of the land has been changed.
Many people have come to realize
that native habitats are also valuable for business and recreation. Conservationists
are working to identify and protect remaining pieces of natural habitat. Other
groups are trying to recreate native habitat. The Iowa Department of Transportation
sponsors the Living Roadway Trust. This program helps highway departments
grow and maintain prairie plants along roadways. The U.S. Fish and Wildlife
Service operates DeSoto Bend, a backwater of the Missouri River, and the Neal
Smith Prairie Wildlife Refuge. The Neal Smith Refuge is a long-term project to recreate
prairie on over 8,000 acres of land. County Conservation Boards manage wetlands,
forests and prairie communities across the state.
What will Iowa look like after another 200 years? Only time will tell.
Sources:
- Dinsmore, James J. A Country So Full of Game: The Story of Wildlife in Iowa. University of Iowa Press, Iowa City 1994.
- Iowa Association of Naturalists. Iowa's Biological Communities: Iowa's Biological Community Series. Ames, Iowa: ISU Extension Service, 2001
