KUCHLER TYPE DESCRIPTION
Kuchler Type: Bluestem Prairie


PHYSIOGRAPHY : 
Varies greatly, although most of the topography is flat to gently
rolling, with plateaus, glacial moraines, ravines, and potholes [24,25].


CLIMATE : 
The climate in this type is extremely varied from its northern to its
southern limits.  Data for North America show that three major air
masses affect the prairie climate:  the humid Gulf air mass, the drier
Pacific air mass, and the cool polar air mass.  All help dictate prairie
structure by influencing periods of drought and wet conditions [1].

The growing season in eastern North Dakota is about 131 days.  Average
temperature for July is 69 degrees Fahrenheit (20.7 deg C) and for
January is 5 degrees Fahrenheit (-15.4 deg C).  Mean annual
precipitation is 19.7 inches (500 mm) and falls mostly between April and
September [25].

Climate data near Lincoln, Nebraska, show an average annual
precipitation of 28 inches (700 mm), almost 80 percent of which falls
during the growing season.  Periods of drought typically occur after
midsummer [24].


SOILS : 
Soils vary widely on the bluestem prairie.  Prairie topsoil near
Lincoln, Nebraska, is about 18 inches (46 cm) thick with a granular
structure.  The subsoil is about 2.5 feet (0.35 m) deep with a higher
clay content.  Below the subsoil, the C horizon is a fine-textured silty
loam with a high water-holding capacity [24].  Soils in North Dakota are
mostly silts and clays with areas of saline seeps due to fluctuating
water tables [25].  General soil information for the Konza Prairie,
Kansas, can be found in Reichman [27].


VEGETATION : 
Dominant vegetation is listed as big bluestem (Andropogon gerardii),
little bluestem (Schizachyrium scoparium), switchgrass (Panicum
virgatum), and Indiangrass (Sorghastrum nutans).  Other important
associated species include leadplant (Amorpha canescens), field
pussytoes (Antennaria neglecta), asters (Aster spp.), indigo (Baptisia
spp.), sideoats grama (Bouteloua curtipendula), daisy fleabane
(Erigeron strigosus), small bedstraw (Galium trifidum), sawtooth
sunflower (Helianthus grosseserratus), junegrass (Koeleria cristata),
gayfeather (Liatris spp.), panicgrass (Panicum spp.), prairie phlox
(Phlox pilosa), scurfpea (Psoralea spp.), prairie coneflower (Ratibida
spp.), Arkansas rose (Rosa arkansana), compassplant (Silphium
laciniatum), goldenrod (Solidago spp.), prairie dropseed (Sporobolus
heterolepis), and porcupinegrass (Stipa spartea) [16].

Upland areas (those with low soil water content) are dominated by little
bluestem, which once made up about 50 percent of the cover.  Some big
bluestem and Indiangrass are intermixed, along with junegrass.  Other
grasses that have been listed as more abundant on the upland prairie
include sideoats grama, junegrass, needlegrass (Stipa spartea), and
prairie dropseed.  The lowland prairie (with relatively high soil
moisture) is dominated more by big bluestem, which comprised about 80
percent of the cover before the prairies were ploughed under for
agriculture.  Indiangrass and switchgrass are intermixed.  Grasses
listed as more abundant on lowland prairies are Indiangrass, prairie
cordgrass (Spartina pectinata), switchgrass, and Canada wildrye (Elymus
canadensis) [24].


WILDLIFE : 
Some wildlife species of the bluestem prairie include pronghorn,
white-tailed deer, ground squirrels, prairie dogs, pocket gophers, mice,
voles, badger, waterfowl (found in the potholes), grouse, and northern
bobwhite [26,27].


ECOLOGICAL RELATIONSHIPS : 
Big bluestem is more deeply rooted and "coarse rooted" than little
bluestem and grows mostly in lowland draws where soils are moist and
well aerated.  Indiangrass is the chief associate of big bluestem and
has nearly identical habitat requirements.  It can comprise as much as
90 percent of the cover locally in ravines.  It more typically comprises
1 to 5 percent of the cover, but can increase dramatically over big
bluestem with burning or flooding [24].

In saturated soils big bluestem is replaced by prairie cordgrass, and on
soils with intermediate to high moisture content, switchgrass is the
dominant species.  Switchgrass has the longest root system of the
dominant grasses [24].  It is most abundant on low, moist sites, but can
also occur on drier areas not aerated enough for big bluestem.  It
rarely grows in extensive pure stands.  Switchgrass can occur as a
transitional species between saturated and better-drained sites in
ravines [24].

Little bluestem has finer roots than big bluestem and dominates drier
areas, although Indiangrass may also occur on upland sites.  Little
bluestem readily invades disturbed areas.  On deep, dry soils it can
comprise 90 percent of the cover, declining to 50 to 75 percent on the
driest soils.  It can be replaced by needlegrass [24].

Among the forbs common in bluestem prairie, leadplant, indigo, asters,
and gayfeather all have deep root systems [24].

Grassland succession was studied in Oklahoma from 1949 to 1982.  On
protected plots the mature grasses (bluestems, Indiangrass, and
switchgrass) remained dominant for 9 years before rapid increases in
shrubs.  On plots that were plowed once, dominant grasses decreased over
9 years with gradual increases in woody vegetation.  On plots plowed
annually for 5 years, forbs dominated over grasses for a few years then
decreased.  Shrub cover stayed low for 5 years after plowing stopped. Of
the dominant grasses mentioned above, only big bluestem "recovered" from
the plowing treatment by year 10 [5].

Detritus accumulates rapidly on prairies and readily reduces overall
production of grasses.  It intercepts precipitation and can alter the
chemical makeup of the moisture that does wet the soil surface [15].

For more information on prairie ecology and history, or for specific
information on individual plant species refer to Reichman [27] and
Weaver [24].

Related categories for Kuchler Type: Bluestem Prairie