Thursday, December 12, 2013

Determining Your Bioregion (With the Nemaha Area as Example)

So what is your bioregion?

DETERMINING ONE'S BIOREGION

I refer the reader to United States, Canada and Mexico Bioregions/Ecoregions (http://en.wikipedia.org/wiki/List_of_ecoregions). (If you live outside the U.S., you
can start here instead: http://www.terrestrial-biozones.net)

Most of North America is located in the Nearctic.

Nearctic: The Nearctic is one of the eight terrestrial ecozones dividing the Earth's land surface. The Nearctic ecozone covers most of North America, including Greenland and the highlands of Mexico. Southern Mexico, southern Florida, Central America, and the Caribbean islands are part of the Neotropic ecozone, together with South America. (http://en.wikipedia.org/wiki/Nearctic)

The other site that is of immense help in breaking the maps into more detailed maps for many (but not all) Nearctic bioregions is at http://www.cas.vanderbilt.edu/bioimages/ecoframe-map.htm.

I will go through these steps, using the locale of the Iowa Reservation, defined in large part by the Big Nemaha River's outlet into the Missouri River.

Within the Nearctic Ecozone are several bioregions.

The Iowa Reservation (Nemaha) is located in the Eastern North America bioregion: "The Eastern North America bioregion includes the Temperate broadleaf and mixed forests of the eastern United States and southeastern Canada, the Great Plains temperate grasslands of the central United States and south-central Canada, the Temperate coniferous forests of the southeastern United States, the subtropical savannas of Florida, and the mangrove and hammock forests of the the Neotropic ecozone in south Florida. In terms of floristic provinces, it is represented by the North American Atlantic Region and part of the Canadian Province of the Circumboreal Region."

Specifically, Nemaha is in a transition zone between temperate broadleaf and mixed forests of the eastern United States and the Great Plains temperate grasslands of the central United States (the Tallgrass Prairie).  Really we are in the middle of the tall grass prairie, but the Missouri River bottoms, the loess hills and bluffs (called glacial hills here by some folks), and the heavily dissected terrain has created microclimates populated by hardwood forest species native to areas further east and south. Before settlement by white people, frequent prairie fires kept the advance of forests in check along the bluff tops.

We are between the Central Forest-Grasslands Transition .".. a prairie ecoregion of the central United States, part of the North American Great Plains" (http://en.wikipedia.org/wiki/Central_forest-grasslands_transition) and the Central Tall Grasslands (http://en.wikipedia.org/wiki/Central_tall_grasslands).

This area has been almost entirely destroyed and converted into mono cropped agricultural production because of its rich soils, except where the terrain is too steep.

Central Forest-Grasslands Transition
"This is a large area covering 407,000 square kilometres (157,000 sq mi) from northern Illinois through most of Missouri, eastern Kansas, Oklahoma and into Texas. This area was traditionally a mixture of woodland and tall grass prairie, which as the soil consists of highly fertile mollisols, most of the area has been converted to farmland. Rainfall varies from 600–1040 mm per year and the area is vulnerable to drought and fire. Along with the Upper Midwest forest-savanna transition this ecoregion separates the Central U.S. hardwood forests to the east from the largely treeless Central and Southern mixed grasslands and Central tall grasslands to the west…. The area has almost entirely been converted to agriculture, particularly planting corn and soybeans. Remaining blocks of intact habitat are small and ...are all highly fragmented…" (http://en.wikipedia.org/wiki/Central_forest-grasslands_transition).

Central Tall Grasslands
"This ecoeregion covers a large area of southern Minnesota, most of Iowa, a small part of eastern South Dakota and a narrow strip through eastern Nebraska and northeastern Kansas. Rainfall here is 1000mm per year, higher than most of the Great Plains. ...No substantial areas of original grassland remain in this ecoregion, only fragmented remnants but prairie restoration is happening, for example, at Neal Smith National Wildlife Refuge in Jasper County, Iowa" (http://en.wikipedia.org/wiki/Central_tall_grasslands).

Flora and Fauna
The Central Forest-Grasslands Transition "... is rich in reptiles, birds and insects. Birds of the area include the greater prairie chicken. Reptiles include the Osage copperhead snake." (ibid.) The Central Tall Grasslands: The high rainfall and long summer allows a rich plant cover and this area was once the largest area of tallgrass prairie in the world, with grasses reaching up to 2m in height and interspersed with many wildflowers. For example 265 species of plants were recorded in Iowa, 237 in a square mile near Lincoln, Nebraska, and 225 in the Missouri River Valley. However the soil is rich here and the original grasslands have now largely been converted to farmland, much more so than in the neighboring Flint Hills tall grasslands for example. The central tall grasslands are now a large part of the Corn Belt of the Midwest and covered with fields of corn and soybeans. Grasses of the area include big bluestem (Andropogon gerardii), switchgrass (Panicum virgatum) and Indian grass (Sorghastrum nutans)….This prairie was probably once grazing land for American bison (Bison bison) and elk (Cervus elapses)" (ibid.).

From the World Wildlife Fund:
"Biological Distinctiveness 
The Central Tall Grasslands must have been one of the most visually appealing ecoregions of North America in its original state. Before being settled and converted, it was the largest tallgrass prairie on Earth. The large number of brightly flowering herbaceous plants added greatly to the plant diversity as well as to its physical beauty. The dominant grass species in this ecoregion are big bluestem (Andropogon gerardii), switchgrass (Panicum virgatum), and Indian grass (Sorghastrum nutans) (K├╝chler 1975). The richness of the herbaceous cover is obvious across this ecoregion: about 265 species constitute the bulk of the Tall-Grass Prairie in Iowa; 237 species were recorded in a square mile near Lincoln, Nebraska, and 225 species were recorded from the Missouri Valley (Weaver 1934?). Many of the plant species found here originated from several different regions; having been exposed to a wide range of climates over the long term, they exhibit relatively wide ecological ranges and thus are widespread throughout the Great Plains…. Like other ecoregions of this section of North America, bison and elk once roamed these tallgrass prairies, where they were hunted by the prairie wolf (Canis lupus). These species are now gone" (http://worldwildlife.org/ecoregions/na0805). Actually there is confusion on the term "prairie wolf" in historical sources, some authors meaning a variety of wolf also known as the buffalo wolf, and others meaning the coyote, which is not a true wolf. Around here, some people call the coyote a "wolf" though it is not one biologically.

(continued from the WWF site:) "The Central Tall Grasslands is now the corn belt of the United States. Nearly all of this ecoregion has been converted to tilled crop land and the rest is used for haying and pasture.

Remaining Blocks of Intact Habitat: Essentially no sizeable blocks of intact habitat exist in this ecoregion. Remnants of the Central Tall Grasslands in southern Iowa and adjacent Missouri are restricted to 20 patches, all less than 0.08 km2 (20 acres) in size (USDA 1994). The Loess Hills in western Iowa (16 km2) and the Prairie Coteau in eastern South Dakota contain important remnants, although the former is rather linear in shape and grazed by livestock.

Degree of Fragmentation: Fragmentation is high among the few, widely scattered parcels of tallgrass prairie.

Degree of Protection: None of the remaining fragments have any formal protection, although restoration is underway at Walnut Creek National Wildlife Refuge in central Iowa" (http://worldwildlife.org/ecoregions/na0805).

I am aware of only really one surviving patch of prairie on the reservation, a few acres in size, across from the three elders' houses, and it is often cut for hay. I do not know if it is native, but it is rich in various grasses like Andropogon and Panicum and other herbs and forbs, so it is a pretty nice patch. I am trying to convince the tribe to preserve it. The main focus of preservation here is done by the Nature Conservancy, which owns and manages a chunk of our alienated lands within the reservation boundaries as the Rulo Bluffs Preserve. Most of that land is forested though. I hope to meet with Nature Conservancy personnel and have invited them to talk.

(To be continued)

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