ECOLOGY

NORTHWESTERN GREAT PLAINS

LINK TO INTERACTIVE MAP OF SD ECOREGIONS

43c – River Breaks – Elevation 1300 – 2700 ft.
The River Breaks form broken terraces and uplands that descend to the Missouri River and its major tributaries. They have formed particularly in soft, easily erodible strata, such as Pierre shale. The dissected topography, wooded draws, and uncultivated areas provide a haven for wildlife. Riparian gallery forests of cottonwood and green ash persist along major tributaries such as the Moreau and Cheyenne rivers, but they have largely been eliminated along the Missouri River by impoundments.

43f – Subhumid Pierre Shale Plains – Elevation 1700 – 2800 ft.
A continuous vegetation cover is essential to keep the Subhumid Pierre Shale Plains intact. Tilling the rolling hillsides risks wind and water erosion. Stream channels are deeply incised in its soft, black shale soils and slumping is common along exposed banks.

South Dakota Ecoregions

South Dakota Ecoregions

River Breaks

Physiography
Elevation/Local Relief (feet): 1300-2700/200-500
Unglaciated. Highly dissected hills and uplands bordering major rivers and associated alluvial plains.
Geology- Surficial Material and Bedrock
In South Dakota, Cretaceous Pierre Shale, on the west side of the Missouri River
Temperature/Moisture Regimes
Mesic (south of Moreau River)/Ustic
Climate
Precipitation – Mean annual (inches)
16-18
Frost Free – Mean annual (days)
100-130
Mean Temp. – Jan. min/max; July min/max, (°F)
3/27;60/91
Potential Natural Vegetation
Blue grama, western wheatgrass, buffalograss, and some bluestem. Juniper and deciduous trees on northfacing slopes. Cottonwood gallery forests on the floodplain.
Land Use and Land Cover
Steep slopes restrict landuse to cattle grazing. Land cover is mostly rangeland and native grasses. Remnant woodlands in draws and on existing (unimpounded) alluvial flats.
-

Sub-humid Pierre Shale Plains

Physiography
Elevation/Local Relief (feet): 1700-2800/50-500
Unglaciated. Undulating plain. Steep-sided, incised stream channels.
Geology- Surficial Material and Bedrock
Cretaceous Pierre shale.
Soil
Temperature/Moisture Regimes
Mesic/Ustic
Climate
Precipitation – Mean annual (inches)
15-17
Frost Free – Mean annual (days)
110-135
Mean Temp. – Jan. min/max; July min/max, (°F)
4/29;60/91
Potential Natural Vegetation
Wheatgrass, grama grass, needlegrass, porcupine grass, needleandthread.
Land Use and Land Cover
Cattle grazing, dryland farming. Winter wheat, alfalfa and sorghum.

VEGETATION

LINK TO INTERACTIVE MAP
Vegetation by class (dominant general growth forms)
SOIL28

Vegetation by NVC formation (macroclimatic conditions as modified by altitude, precipitation, substrates, and hydrology)
soil29

Vegetation by NVC macrogroup (sub-continental to regional differences in mesoclimate, geology, substrates, hydrology, and disturbance regimes)
soil30

Vegetation by Ecological system (co-occurring plant communities influenced by similar ecological processes)
soil31

Soil Root Zone Available Water Capacity – (RZAWC)
The Root Zone Available Water Capacity (RZAWC) is the sum of available water capacity (AWC) times thickness for all layers in the root zone. This approximates the volume of water that is held in the root zone and can be used by crop plants. RZAWC effects crop production and is an important physical soil property. The RZAWC soil is calculated from the surface to the beginning of the first root restrictive soil layer, such as bedrock or a very dense layer, or to a depth of 150 cm. The quantity of water held in the rooting media that is available for plant use directly influences soil productivity. The importance of RZAWC varies somewhat geographically because the capacity to hold water during key parts of the growing season is more critical in some climates than in others. Water in the surface layer is critical to establish plants, but the amount of available water stored throughout the root zone usually determines the most productive soils.
Tatanka Wakpala Root Zone Available Water Capacity: 1-8 inches
LINK TO RZAWC MAP OF SOUTH DAKOTA

RZAWC of Dewey County

RZAWC of Dewey County

GRASSLAND

Tatanka Wakpala: Mixed-grass prairie
Prairies are dominated by grasses and other herbaceous plants called forbs.Legumes, nitrogen-fixing plants in the Fabaceae (bean) family, for example, are a common component of prairie vegetation as are members of the Asteraceae (sunflower) family . Prairie plants exhibit a number of adaptations to drought and fire.

Trees are absent or scarce on the prairie. When they do occur, they are limited to areas of broken topography (hillsides and bluffs) and the margins of streams and rivers that traverse them. Timber also occurs in groves; isolated and sometimes extensive ‘islands’ of trees surrounded by prairie. Scattered oak openings or savannas are also a common occurrence within or bordering the prairies of the Midwest.

Within the North American Grasslands, rainfall decreases from the east to west, and the prairie vegetation consequently changes. The most visually obvious response to reduced precipitation is that the grasses and forbs become shorter, which leads to a somewhat oversimplified classification scheme of tallgrass, mid- or mixed-grass, and short-grass prairie.

Tallgrass prairie occurs in the eastern part, reaching its ultimate development in the Prairie Peninsula. Short-grass prairie occurs on the high plains east of the Rocky Mountains, and mid-grass prairie occurs in between. The height of the vegetation not only becomes shorter westward, but the species composition also changes. For example, big bluestem (Andropogon gerardii) and Indian grass (Sorghastrum nutans) are dominant in the tallgrass prairie, whereas buffalo grass (Buchloë dactyloides) and blue grama (Bouteloua gracilis) are prevalent in the short-grass prairie.
LINK TO PRAIRIES IN THE PRAIRIE STATE (Illinois)
grasslandmap

Dewey County: 30,001 to 50,000 acres of Grassland/Wetlands/Shrub lands were converted to all crops between 2008 and 2011
soil33

NATIVE GRASSES

LINK TO PRAIRIE XERISCAPING
LINK TO SOUTH DAKOTA XERISCAPING

Native Grasses for Ground Covers
Screen shot 2014-04-15 at 10.48.55 PM

Native Grasses for Landscape Accents
Screen shot 2014-04-15 at 10.50.34 PM

South Dakota Native Grass Map
Tatanka Wakpala prairie: blue grama, western wheatgrass, buffalograss, needle-and-thread, dryland sedges
Tatanka Wakpala floodplain: western wheatgrass, blue grama, sideoats grama, little blue stem, sand dropseed
LINK TO SD VEGETATION MAPS
SOIL34

FAUNA

LINK TO GRASSLANDS OF CENTRAL NORTH AMERICA
LINK TO INTERACTIVE NORTHERN GREAT PLAINS CONSERVATION

Bison
At the time of early exploration of the American grassland, bison (Bison bison) were the dominant large herbivore in the Great Plains, although pronghorn antelope were also abundant. [It is] estimated that as many as 40-60 million head of bison were present in the North American grassland before settlement. Numbers of pronghorn were probably comparable to those for bison.

Small Mammals
Grasslands also provided habitat for a wide variety of small mammals, including prairie dogs (Cynomys spp.), jackrabbits (Lepus spp.), ground squirrels (Spermophilus spp.), gophers (Geomys spp. and Thomomys spp.) and voles (Microtus spp.). Originally, several species of prairie dogs occupied over 800 000 ha of grasslands in central USA, but by the early 1990s their distribution had been reduced by 98 percent.

Insects
A wide number of invertebrates such as grasshoppers, beetles, ants, sap feeders and members of other orders are important components of grassland ecosystems. Some, such as grasshoppers, have been studied because of their economic importance while others, such as nematodes, have only recently been properly assessed as to abundance and importance.

Birds
Central plains grasslands also support diverse populations of birds. However, within the grassland geographical region, habitats other than grasslands have higher numbers of avian species. Only 11 percent of the bird species within the grassland geographic area were actually inhabitants of grassland per se: 51 percent were associated with woodland and forest habitats and 22 percent with wetland habitats. Nevertheless, birds are abundant in grasslands. Glover (1969) listed over 150 species found on the Central Plains Experimental Range in short-grass habitat in north-central Colorado. These included both primary consumers and secondary consumers. Common grassland birds include western meadowlark (Sturnella neglecta), grasshopper sparrow (Ammodramus savannarum), horned lark (Eremophila aplestris) and chestnut-collared longspur (Calcarius ornatus).

Cattle
Cattle have largely replaced bison as the dominant large herbivore on the Great Plains. …50 percent of all USA beef cattle are found in the northern and southern Great Plains. …although vegetation changes resulting from the shift from bison to cattle have been minimal, there are differences in grazing patterns and behaviour: bison select a diet higher in grasses than cattle; bison select a diet higher in digestibility than cattle; bison spend less time grazing than cattle; and cattle are restricted in grazing by fences while bison were free to move over the landscape.

Screen shot 2014-04-08 at 1.40.59 AM

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>