KUCHLER TYPE DESCRIPTION
KUCHLER TYPE: Nebraska sandhills prairie


PHYSIOGRAPHY : 
The Nebraska sandhills are characterized by dune topography.  The hills
are mostly round-topped or conical and smooth.  They were formed by
wind, and continue to be modified by wind [46].  Some areas are very
choppy, with no distinct long ridges; other areas have distinct ridges
with relatively broad valleys [39].  In between the hills, sandy basins
and valleys contain groundwater lakes and marshes.  There is very little
surface runoff.  Many streams and rivers flow out of the sandhills, but
these are largely fed by groundwater underflow [13,39,47].  The Nebraska
sandhills range in elevation from 2,000 feet (609 m) at the eastern edge
to 4,200 feet (1,280 m) in the northwest [49].

Burzlaff [13] described the Nebraska sandhills using a 'range site'
concept, and named three types:  dry valley range sites, choppy sands
range sites, and rolling sands range sites.  Dry valley sites are the
flat valleys between choppy sandhills or rolling sands, as small as 3 to
4 acres (1.2-1.6 ha) or as large as 320 acres (a half-section [1.3 sq
km]).  Choppy sands are composed mainly of stabilized dune sands and are
characteristically steep (20-40% slope) with variations in relief of 80
to 100 feet (24-30 m).  Rolling sands sites are gently undulating hills
and valleys, with 80 to 100 feet (24-30 m) in relief but without the
steep slopes of the choppy sandhills.


CLIMATE : 
In Nebraska, mean annual precipitation ranges from 36 inches (914 mm) in
the southeastern corner to 15 or 16 inches (381-406 mm) in the western
end of the state.  The sandhills are mostly between the 25 and 16 inch
isohyets [39].  In this area of Nebraska, 80 percent of the annual
precipitation falls between April and September [40], with peak amounts
falling from April to June [4].  Rainfall is often distributed in a
patchy fashion, creating frequent, local drought [40].  Wind has been a
major factor in shaping the sandhills.  There are frequent episodes of
high velocity winds that blow for days at a time [39].


SOILS : 
The soils of Nebraska sandhills prairie are mainly fine-grained sands
and sandy loams of the Balentine-Dunday association [24].  Coarser sands
are found on the dune tops.  Very little soil formation has occurred
since the dunes were formed, so the soils contain little or no organic
matter [24,47].  In the eastern portion of the Nebraska sandhills
prairie, nondune soils are derived from glacial drift and loess; the
drift consists of boulders, gravel, sand, and clay.  The loess consists
of silt, clay, and fine sand [39].  Soil profiles are poorly defined
[13].  The sandy soils are low in nutrient value [39,49].  The soil pH
ranges from 6.55 on choppy sands sites to 6.8 on dry valley sites [13].

Most dry valley sites have excellent drainage, but where there are
underlying clays the drainage is poor.  Choppy sands are usually
excessively well drained and rolling sands sites are adequately to
excessively well drained [13].  The surface sands dry out rapidly after
rainfall, but just below the surface abundant water is held in capillary
spaces [39,40].  The Nebraska sandhills have been described as an
enormous sponge soaking up and storing immense quantities of water.  It
was estimated that the 20,000 square miles (5 million ha) of Nebraska
sandhills can store 600 million acre-feet of water [13].


VEGETATION : 
The Nebraska sandhills prairie is a perennial grassland containing a
mixture of tallgrass and shortgrass prairie species and includes both
warm-season (mostly C-4 species) and cool-season (mostly C-3 species)
taxa [24,40,47].  Patches of open sand are characteristic of the
Nebraska sandhills prairie [24,39,47].  Lists of dominant species differ
by locale and range condition.  The most frequently listed dominants
include prairie sandreed (Calamovilfa longifolia, C-4), sand bluestem
(Andropogon gerardii var. paucipilus, C-4), needle-and-thread grass
(Stipa comata, C-3), little bluestem (Schizychyrium scoparium, C-4), big
bluestem (A. gerardii, C-4), blue grama (Bouteloua gracilis, C-4), hairy
grama (B. hirsutus, C-4), and sand dropseed (Sporobolus cryptandrus,
C-4) [7,33,37].  Differences in dominants have been ascribed to
topography, aspect, time of year, stage of succession, and grazing and
fire history [7].

Sims [42] described the Nebraska sandhills vegetation as an
Andropogon-Calamovilfa-Stipa community which also includes grama
(Bouteloua spp.) and cool-season invaders such as Kentucky bluegrass
(Poa pratensis) and smooth brome (Bromus inermis) [42].

Other major components include sand lovegrass (Eragrostis trichodes,
C-4), sand sagebrush (Artemisia filifolia), sand milkweed (Asclepias
arenaria), sedge (Carex heliophila), erigeron (Erigeron spp.),
flaxflowered gilia (Gilia longifolia), Indian ricegrass (Oryzopsis
hymenoides, C-3), switchgrass (Panicum virgatum, C-4), and silky
prairie-clover (Petalostemum vilosum) [24,33].

According to Weaver and Albertson [47] the most important grasses in the
bunchgrass community (their term for the major grass community in the
Nebraska sandhills) include little bluestem, sand bluestem, prairie
sandreed, and needle-and-thread grass.  Soapweed yucca (Yucca glauca) is
also characteristic.  Little bluestem was the most frequent and abundant
grass until the drought of the 1930's.  Sand bluestem has increased
since the decline in little bluestem.  In many areas needle-and-thread
grass has been grazed out.  Sand dropseed was not previously abundant in
the sandhills, but has increased in abundance with grazing, along with
prairie sandreed.  In the southwestern and western portion of the
Nebraska sandhills prairie, sand sagebrush is an abundant shrub,
associated with prairie sandreed and sand bluestem [47].  Ponderosa pine
(Pinus ponderosa) occurs on the western and north-central margins of
Nebraska sandhills prairie, reaching its eastern limit in the Niobrara
River Valley [43].

Pool [39] recognized a number of different communities on the Nebraska
sandhills.  The primary community, covering 60 percent of the total
area, is the upland prairie grass community dominated by bunchgrasses.
His list is similar to that of others [7,33,37,40,47], except that big
bluestem is not listed as a codominant [39].

Potvin and Harrison [40] recognized three main vegetation types on the
Arapaho Prairie, a preserve in the Nebraska sandhills prairie owned by
the Nature Conservancy:

        Ridge--dominated by hairy grama, prairie sandreed, and little
            bluestem
        Valley--dominated by prairie sandreed, needle-and-thread grass,
            and blue grama
        Slope--the most common type, dominated by blue grama, prairie
            sandreed, and hairy grama.  

This division resembles the three range site types of Burzlaff [13].  He
named four structural vegetation units (unions) based on the
characteristics of the dominant species: 1) Festuca octoflora union,
characterized by species that make their appearance early in the spring,
2) Stipa comata union, composed of species that start growth in
mid-spring and become dormant during summer heat, resuming growth in the
fall with adequate moisture, 3) Sporobolus cryptandrus union, consisting
of species that start growth in late spring and reach anthesis by
mid-summer, and 4) Calamolvilfa longifolia union, made up of the tall,
warm-season grasses that provide the true prairie aspect of the Nebraska
sandhill prairie.  Each of the four unions can be found on the three
types of range sites.  However, the relative abundance and dominance of
characteristic species changes with the range site and with
environmental conditions.  The latter two unions are the most abundant
and characteristic of most of the Nebraska sandhills prairie [13].



WILDLIFE : 
The Nebraska sandhills prairie supports a variety of wildlife species,
including many big game species:  pronghorn (Antilocapra americana),
white-tailed deer (Odocoileus virginianus), mule deer (Odocoileus
hemionus), and bighorn sheep (Ovis canadensis).  Small game animals
include eastern cottontail rabbit (Silvilagus floridanus), fox squirrel
([Sciurus niger], found along river bottoms), white-tailed jackrabbit
(Lepus townsendii), and black-tailed jackrabbit (Lepus californicus).
Other mammals include prairie dogs (Cynomys spp.), house mouse (Mus
musculus), deer mouse (Peromyscus maniculatus), western harvest mouse
(Reithrodontomys megalotis), northern grasshopper mouse (Onychomys
leucogaster), Ord's kangaroo rat (Dipodomys ordii), plains pocket mouse
(Perognathus flavescens), least shrew (Cryptotis parva), eastern mole
(Scalopus aquaticus), ground squirrels (Spermophilus spp.), coyote
(Canis latrans), kit fox (Vulpes macrotis), red fox (V. vulpes), swift
fox (V. velox), gray fox (Urocyon cinereoargenteus), badger (Taxidea
taxus), long-tailed weasel (Mustela frenata), and bobcat (Lynx rufus)
[11,19].

Numerous species of birds occur on the Nebraska sandhills prairie,
including greater prairie chicken (Tympanuchus cupido), sharp-tailed
grouse (T. phasianellus), mourning dove (Zenaida macroura), killdeer
(Charadrius vociferus), western kingbird (Tyrannus verticalis), swallows
(Hirundo spp.), sparrows, (Spizella spp.), western meadowlark (Sturnella
neglecta), red-tailed hawk (Buteo jamaicensis), Swainson's hawk (B.
swainsoni), rough-legged hawk (B. lagopus), sharp-shinned hawk
(Accipiter striatus), and American kestrel (Falco sparverius).  Other
raptors include short-eared owl (Asio flammeus) and burrowing owl
(Athene cunicularia) [11,19,24,55].  Waterfowl present as migrants (M)
or as summer residents (S) include Canada goose (Branta canadensis) (M,
possibly S), mallard (Anas platyrhynchos) (S), green-winged teal (A.
crecca) (M,S), blue-winged teal (A. discors) (M,S), ring-necked duck
(Aythya collaris) (M), ruddy duck (Oxyura jamaicensis) (M, possibly S),
and common merganser (Mergus merganser) (M, possibly S) [24,55].

Numerous species of reptiles occur on the Nebraska sandhills prairie
including western box turtle (Terrapene ornata), snapping turtle
(Chelydra serpentina), racerunner (Cnemidophorus sexlineatus), great
plains skink (Eumeces obsoletus), lesser earless lizard (Holbrookia
maculata), eastern fence lizard (Sceloporus nudulatus), garter snakes
(Thamnophis spp.), western hognose snake (Heterodon nasicus), milk snake
(Lampropeltis triangulum), and racer (Coluber constrictor) [11].

The former ranges of American bison (Bos bison), elk (Cervus elaphus),
and black-footed ferret (Mustela nigripes) included the Nebraska
sandhills region [12,19].


ECOLOGICAL RELATIONSHIPS : 
Soil moisture is the principal factor in Nebraska sandhills prairie
vegetation distribution.  The sand allows rapid and deep penetration of
precipitation [24].  The expected distribution of prairie species along
a moisture gradient from dry to wet is sideoats grama (dry sites),
little bluestem, indiangrass (Sorghastrum nutans), big bluestem,
switchgrass, and prairie cordgrass (Spartina pectinata) (wet sites).
The more mesic species, such as the bluestems, switchgrass, and
indiangrass, can be supported in the valleys of Nebraska sandhills
prairie.  Within community diversity is usually low; there is a tendency
for individual stands to be dominated by one or two species [5].  Big
bluestem, needle-and-thread grass and other shallow-rooted species,
including Canada wildrye (Elymus canadensis), blue grama, prairie
cordgrass, and western wheatgrass (Pascopyrum smithii), are more
abundant in valleys where the water table is near the surface [4,24].
North-facing slopes are dominated by needle-and-thread grass (average
37% cover); south-facing slopes are dominated by prairie sandreed (27%
cover).  Hilltops are dominated by both species, with 20 and 22 percent
cover respectively [9].  Sand bluestem occupies dry upland sand dunes;
big bluestem is restricted to adjacent, subirrigated meadows [4].

A characteristic feature of the Nebraska sandhills prairie is the
blowout, an area denuded of vegetation due to rapid wind erosion.
Blowouts occur where the vegetation is depleted due to fire or
overgrazing.  The sparse vegetation leaves the soil vulnerable to wind
erosion, which in turn creates conditions in which plants cannot
establish [47].  A blowout can be active for many years, and can reach a
depth of 100 feet and a circumference of more than 600 feet.  Blowouts
can become large and deep enough to become ponds [39].  Once a blowout
becomes at least partially stabilized, it is usually colonized by
blowout grass (Redfieldia flexuosa) and/or lance-leaved psoralea
(Psoralea lanceolata).  The vegetation remains sparse even after several
years.  Sandhill muhly (Muhlenbergia pungens) may invade the upper
slopes of a blowout, but little bluestem and other bunchgrasses are
usually absent from early succession [47].  Invaders of blowouts after
blowout grass has stabilized the area include spiderwort (Tradescantia
virginiana), annual umbrella plant (Eriogonum annuum), plains
yellow-primrose (Calyophus serrulatus=Oenothera serrulata), showy
peavine (Lathyrus ornatus var. flavescens), painted milkvetch
(Astragalus ceramicus=Phaca longifolia), prairie spurge (Euphorbia
missurica=Euphorbia petaloidea) and fineleaf hymenopappus (Hymenopappus
filifolius) [47].

Sand draws, which are steep, dry streambeds in which occasional
torrents of water cause rapid erosion, are colonized by clammy-weed
(Polanisia dodecandra ssp. trachysperma) and cristatella (P. jamesii) [39].

Related categories for Kuchler Type: Nebraska sandhills prairie