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The Sandy Plains ecological site is characterized by four states:Reference,Warm-Season Shortgrass,Increased Bare Ground,and Tilled
<br /> State.The Reference State is characterized by a dominance of warm-season tallgrasses(prairie sandreed,sand bluestem,and switchgrass).
<br /> Warm-season shortgrass(blue grama)is the primary understory species.The Warm-Season Shortgrass State is dominated by a warm-
<br /> season short bunchgrass(blue grama).The Increased Bare Ground State is characterized by early successional warm-season(Fendler
<br /> threeawn)and cool-season short bunchgrasses(squirreltail)and annual grasses and(orbs.The Tilled State has been mechanically disturbed
<br /> by equipment and includes either a variety of reseeded warm and cool-season grasses(Seeded Community)or early successional plants as
<br /> well as annual grasses and(orbs(Go-Back Community).
<br /> The degree of grazing has a significant impact on the ecological dynamics of the site.This region was historically occupied by large grazing
<br /> animals such as bison and elk,along with pronghorn and mule deer.Grazing by these large herbivores,along with climatic fluctuations,and
<br /> seasonal weather fluctuations,had a major influence on the dynamics of the ecology of this site.Deer and pronghorn are widely distributed
<br /> throughout the MLRA.Secondary influences of herbivory by species such as prairie dogs and other small rodents,insects and root feeding
<br /> organisms have impacted the vegetation and continues today.
<br /> Historically,it is believed,grazing patterns by herds of large ungulates was driven by water distribution,precipitation events,drought events,
<br /> and fire.It is believed that grazing periods would have been shorter,followed by longer recovery periods.These large migrating herds
<br /> impacted the ecological processes of nutrient and hydrologic cycles,by urination,trampling(incorporation of litter into the soil surface),and
<br /> breaking of surface crust,to increase water infiltration.
<br /> This is an important site for livestock grazing,especially beef cattle.Today the management of livestock grazing by humans has been a major
<br /> influence on the ecological dynamics of the site.This management,coupled with the effects of annual climatic variations,largely dictates the
<br /> plant communities for the site.Prescribed grazing that mimics the historic grazing of herds of migratory herbivores,as described earlier,has
<br /> been shown to result in desired improvements based on management goals for this ecological site.
<br /> Recurrent drought has historically impacted the vegetation of this region.Changes in species composition will vary depending upon the
<br /> duration and severity of the drought cycle,and prior grazing management.Recent drought events(since 2002)have increased mortality of
<br /> blue grama and other bunchgrasses significantly in some locales.
<br /> This site developed with occasional fires being part of the ecological processes.Historic fire frequency(pre-industrial),is estimated at 10-14
<br /> years(Guyette 2012),randomly distributed,and started by lightning at various times throughout the growing season.Early human inhabitants
<br /> were also likely to start fires for various reasons(deliberate or accidental).It is believed that fires were set as a management tool for attracting
<br /> herds of large migratory herbivores(Stewart,2002).The impact of fire over the past 100 years has be relatively insignificant due to the human
<br /> control of wildfires and the lack of acceptance of prescribed fire as a management tool.
<br /> Grazing by large herbivores,without adequate recovery periods following each grazing occurrence,will cause blue grama to increase.Blue
<br /> grama may eventually form a sod-like appearance.Prairie sandreed,sand bluestem,and switchgrass will decrease.Prairie sandreed may
<br /> persist in remnant amounts protected by remaining shrubs.Cool season grasses such as needleandthread and western wheatgrass will
<br /> decrease in frequency and production.Key shrubs such as western sand cherry and fourwing saltbush will decrease in frequency and
<br /> production.American vetch and other highly palatable(orbs will also decrease.Fendler threeawn,annuals and bare ground increases under
<br /> heavy continuous grazing,excessive defoliation,or long-term non-use.Much of this ecological site has been tilled and used for crop
<br /> production.Other areas of this ecological site have been converted to suburban residence and small acreages,especially near the larger
<br /> communities.
<br /> The following is a diagram illustrates the common plant communities that can occur on the Sandy Plains site and the community pathways
<br /> (CP)among plant communities.Plant Communities are identified by 1.1,1.2 etc.and are described in the narrative.Bold lines surrounding
<br /> each state represent ecological thresholds.Transitions(T)indicate the transition across an ecological threshold to another state.Once a
<br /> threshold has been crossed into another state,it may not be feasible to return to the original state,even with significant management inputs
<br /> and practices.The ecological processes plant communities,community pathways,transition and/or restoration pathways will be discussed in
<br /> more detail in the plant community descriptions following the diagram.
<br /> Warm-Season Shortgrass Plant Community
<br /> This plant community evolves with moderate to heavy continuous grazing caused by lack of adequate recovery periods between grazing
<br /> events.Blue grama dominates this plant community and has taken on a sodbound appearance.Large amounts of sand dropseed and Fendler
<br /> threeawn are common.White sage(aka Louisiana sage),lupine,stickleaf,croton,hairy goldaster,loco,wormwood,fringed sage and
<br /> soapweed have increased.Sand sagebrush may increase on sandy loam or coarser subsoils.Sand bluestem,switchgrass,western
<br /> sandcherry and fourwing saltbush have been removed.Prairie sandreed and needle and thread may persist in remnant amounts protected by
<br /> remaining shrubs.Western wheatgrass may be found in small depressions.
<br /> A significant amount of production and diversity has been lost when compared to the Reference Plant Community.The soil is stable at this
<br /> stage however,the nutrient cycle,water cycle,community dynamics and energy flow are all impaired do to the substantial increase of blue
<br /> grama and loss of warm-season tallgrasses,nitrogen fixing legumes and shrubs.Desertification is advancing.
<br /> Production varies from 200 to 900 pounds of air-dry vegetation per acre per year depending on weather and averages 700 pounds.
<br /> Plant Growth Curve
<br /> Growth curve number c06710
<br /> Growth Curve name: Warm-Season Dominant,MLRA-6713;upland coarse-textured soils.
<br /> Growth curve description:
<br /> Percent Production by Month
<br /> Jan Feb Mar Air May Jun Jul Aug Sep Oct Nov Dec
<br /> 0 0 0 5 20 40 20 10 5 0 0 0
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