Ecological dynamics
Historically, large areas of blowing sand resulted in the active movement of the sand dunes. Evaporation from the soil surface was extremely high due to the large areas of bare ground, lack of litter and sparse plant populations. The transpiration rate of these sparse plant populations was also high due to the harsh soil environment. Occasional wild fires, severe grazing by transient bison herds and drought contributed to the lack of stability of the sand dunes. This lack of stability caused the dunes to go back and forth through multiple stages of plant succession over the course of time. Early perennial plants such as sandhill muhly, blowout grass and blowout penstemon were common due to their ability to tolerate the movement of the sand and droughty conditions. As these plants began to colonize and stabilize the sand movement, other perennials such as prairie sandreed, sand bluestem, hairy grama, lemon scurfpea and rose slowly became evident on the site. Annual native plants such as sandbur, woolly Indianwheat, annual eriogonum and annual sunflower eventually colonized the areas between the perennials.
As this site deteriorates, prairie sandreed, sand dropseed, and blue grama will increase. Species such as sand bluestem and switchgrass will decrease in frequency and production. The site is extremely resilient and well adapted to the Northern Great Plains climatic conditions. The diversity in plant species allows for high drought resistance.
Interpretations are primarily based on the Bluestem/Prairie Sandreed Plant Community. It has been determined by study of rangeland relic areas, areas protected from excessive disturbance, and areas under long-term rotational grazing regimes. Trends in plant community dynamics ranging from heavily grazed to lightly grazed areas, seasonal use pastures, and historical accounts also have been used. Sub-climax plant communities, states, transitional pathways, and thresholds have been determined through similar studies and experience.
The following is a diagram that illustrates the common plant communities that can occur on the site and the transition pathways between communities. The ecological processes will be discussed in more detail in the plant community descriptions following the diagram.
Plant Community and Vegetation State Narratives
Following the diagram are the narratives for each of the described plant communities. These plant communities may not represent every possibility, but they are the most prevalent and repeatable plant communities. The plant composition tables shown below have been developed from the best available knowledge at the time of this revision. As more data are collected, some of these plant communities may be revised or removed, and new ones may be added. The main purpose for including any description of a plant community here is to capture the current knowledge and experience at the time of this revision.
State 1
Reference State
This state contains four community phases historically maintained by frequent fire and herbivory (grazing) with adequate recovery periods. High perrennial grass cover and production facilitates increased soil moisture retention, high infiltrates rates, plant vigor, and overall soil quality.
Community 1.1
Bluestem/ Prairie Sandreed
Interpretations are primarily based on the Bluestem/Prairie Sandreed Plant Community. This site evolved with grazing by large herbivores and is well suited for grazing by domestic livestock. This plant community can be found on areas that are properly managed with grazing and/or prescribed burning, and sometimes on areas receiving occasional periods of rest.
This plant community consists chiefly of tall and mid warm season grasses. Principle dominants are sand bluestem, prairie sandreed, and little bluestem. Grasses of secondary importance are Indiangrass, needlegrasses, switchgrass, sand lovegrass, and hairy or blue grama. Sedges occur in the understory. Forbs and shrubs such as dotted blazing star, leadplant, rose and sandcherry are significant. This plant community is about 85 percent grasses, 10 percent forbs, and 5 percent shrubs by weight.
This plant community is extremely resilient and well adapted to the Northern Great Plains climatic conditions. This is a sustainable plant community in terms of site/soil stability, watershed function, and biologic integrity. Plant litter is properly distributed with some movement off-site and natural plant mortality is low. The diversity in plant species allows for high drought tolerance. Moderate or high available water capacity provides a favorable soil-water-plant relationship.
Table 5. Annual production by plant type
| Plant type |
Low
(kg/hectare) |
Representative value
(kg/hectare) |
High
(kg/hectare) |
| Grass/Grasslike |
2292 |
2709 |
3094 |
| Forb |
146 |
228 |
336 |
| Shrub/Vine |
28 |
91 |
157 |
| Total |
2466 |
3028 |
3587 |
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
Community 1.2
Bluestem/ Prairie Sandreed/ Switchgrass
Plants resistant to grazing are maintaining themselves in this plant community which developed under grazing by domestic livestock. Most of the palatable plants from the Bluestem/Prairie Sandreed Plant Community are present but occur in lesser amounts. Warm season grasses still comprise a significant component of this plant community.
Dominant grasses include sand bluestem, little bluestem, switchgrass and prairie sandreed. Grasses of secondary importance include blue or hairy grama, and Scribner’s panicum. Forbs commonly found in this plant community include blazingstar, white heath aster and goldenrod. Indiangrass, sand bluestem, and perennial forbs are present in lesser amounts. This plant community has higher overall production of shrubs as compared to the Bluestem/Prairie Sandreed Plant Community. Excessive removal of forage will cause shrubs to increase further.
Strong healthy root systems allow production on this plant community to increase with favorable precipitation. This plant community contributes to optimum soil health. This plant community is drought resistant due to its tall and mid grass diversity. These warm-season grasses cure well for winter forage stockpiling. This plant community has slightly less litter than the Bluestem/Prairie Sandreed Plant Community. This plant community is somewhat resistant to change; however, either improved management or increased disturbance can move the plant community. The resiliency of this plant community is dependent on the type of management system implemented, and the intensity and duration of the disturbance.
The following growth curve shows the estimated monthly percentages of total annual growth of the dominant species expected during a normal year:
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
Community 1.3
Prairie Sandreed/ Ragweed
This plant community occurs under historic heavy grazing with continued seasonal grazing starting early in the growing season. The plant community is a mix of warm season and short cool season grasses, with an increase of forbs and shrubs. The percent ground cover and plant density increases from the Bluestem/Prairie Sandreed/Switchgrass Plant Community due to considerable encroachment by the sod-forming bluegrasses.
The potential vegetation is about 60 percent grasses or grass-like plants, 25 percent forbs, and 15 percent shrubs. The dominant grasses include prairie sandreed, bluegrass, blue grama and sand dropseed. Other grasses present include little bluestem, switchgrass and Scribner’s panicum. Major forbs include Cuman ragweed, with lesser amounts of green sagewort and blazingstar. The dominant shrub is rose. There can be an increase in shrubs, especially snowberry and plum. There is a significant increase in cool-season plants such as ragweed and bluegrass. With the exception of an increase in prairie sandreed, a decrease can occur in the mid and tall warm-season grasses such as sand bluestem, switchgrass, little bluestem.
The soil surface has remained intact. Compared to the Bluestem/Prairie Sandreed Plant Community, the total annual production is reduced by 25-35 percent, and plant diversity and amount of litter is lower. This plant community is considered stable, but is at risk if a major shift in climatic conditions or overgrazing occurs. The resiliency of this plant community is moderate depending on the intensity and duration of disturbance. Infiltration and runoff are not greatly affected because of the sandy nature of the soil.
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
Community 1.4
Excessive Litter
This plant community occurs after an extended period (10-30 years) of non-use by domestic livestock (periodic fire may extend the amount of time it will take to reach this plant community). Livestock grazing and fire has been eliminated. Litter amount has clearly increased and few or no sedges or understory plants (shortgrass) are present. There is reduced plant basal cover which is replaced by litter. Bunch grass plants tend to colonize by individual species and are very mature. These mature plants tend to have dead centers, and pedestalling is usually evident. These plants have very few tillers for vegetative reproduction.
The potential vegetation is about 90 percent grasses or grass-like plants, 5 percent forbs, and 5 percent shrubs. The dominant grasses include sand bluestem, prairie sandreed, little bluestem and needlegrasses. Other grasses present include sand dropseed, switchgrass and prairie junegrass. The dominant forbs include Cuman ragweed and green sagewort, with less dominant forbs including blazingstar and spiny phlox. The shrubs present on this plant community include rose, leadplant and western sandcherry. Plant diversity has decreased and native plants tend to occur in individual colonies. This plant community has a high amount of litter covering the soil between widely dispersed mature plants.
This plant community will change rapidly if plant manipulation is allowed to occur (grazing by domestic livestock or periodic fire). Soil erosion is low, and infiltration and runoff are not significantly different than the Bluestem/Prairie Sandreed Plant Community.
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
Pathway 1.1A
Community 1.1 to 1.2
Heavy grazing (usually including improper rest periods) will convert this plant community to the Bluestem/Prairie Sandreed/Switchgrass Plant Community. Continuous heavy grazing tends to accelerate this movement.
Pathway 1.1B
Community 1.1 to 1.4
No use and no fire causes Bluestem/ Prairie Sandreed to shift to the Excessive Litter community phase.
Pathway 1.2A
Community 1.2 to 1.1
Prescribed grazing can convert the plant community to the Bluestem/Prairie Sandreed Plant Community.
Pathway 1.2B
Community 1.2 to 1.3
Heavy grazing (usually including improper rest periods) or excessive disturbance (e.g., defoliation by rodents) can convert this plant community to the Prairie Sandreed/Ragweed Plant Community. Continuous heavy grazing tends to accelerate this movement to the Prairie Sandreed/Ragweed Plant Community.
Pathway 1.2C
Community 1.2 to 1.4
Non-use and no fire can convert this plant community to the Excessive Litter Plant Community.
Pathway 1.3A
Community 1.3 to 1.2
Prescribed grazing can convert the plant community to the Bluestem/Prairie Sandreed Switchgrass Plant Community.
Pathway 1.4A
Community 1.4 to 1.1
Prescribed grazing and/or prescribed fire will convert the plant community to the Bluestem/Prairie Sandreed Plant Community.
(Depending on the length of time non-use occurred and the composition of the plant species prior to removal of use and/or fire, these practices will move this plant community to the Bluestem/Prairie Sandreed Plant Community or the Bluestem/Prairie Sandreed/Switchgrass Plant Community).
Pathway 1.4B
Community 1.4 to 1.2
Prescribed grazing and/or prescribed fire will convert the plant community to the Bluestem/Prairie Sandreed/Switchgrass Plant Community.
(Depending on the length of time non-use occurred and the composition of the plant species prior to removal of use and/or fire, these practices will move this plant community to the Bluestem/Prairie Sandreed Plant Community or the Bluestem/Prairie Sandreed/Switchgrass Plant Community).
Prescribed grazing and/or fire will eventually shift Excessive Litter back to the Bluestem/ Prairie Sandreed/ Switchgrass community phase.
Pathway 1.4C
Community 1.4 to 1.3
Heavy grazing (usually including improper rest periods) can convert this plant community to the Prairie Sandreed/Ragweed Plant Community. This change will be accelerated if coupled with several years of below average precipitation.
State 2
Native/Invaded Grass State
This state consists of one community phase that has deteriorated from the reference state and consists of warm season short grasses and cool season grasses. It may be invaded by introduced species such as smooth bromegrass and Kentucky bluegrass. The loss of native warm season grasses/functional groups and increased bare soil will reduce forage productivity, soil moisture retention, organic matter, and plant vigor.
Community 2.1
Grama/ Sedge Sod
This plant community occurs under heavy grazing and inadequate recovery periods. This may occur where too little time is allowed before areas are re-grazed, or in large pastures where animals graze individual plants repeatedly. It is made up of warm-season short grasses, and cool-season grasses and grass-likes. The dominant grass is blue grama. Other grasses or grass-likes include hairy grama, sedges, sand dropseed, prairie sandreed and needleandthread. The dominant forbs include Cuman ragweed and annual sunflower. The dominant shrubs include rose and cactus. Compared to the Bluestem/Prairie Sandreed Plant Community, blue grama, hairy grama, sedges, ragweed and rose have increased, while prairie sandreed, sand bluestem and switchgrass have decreased or are absent. The plant diversity has decreased from that of the Bluestem/Prairie Sandreed Plant Community.
This plant community is resistant to change due to a lower percentage of bare ground. Under disturbance, this plant community is also highly resilient. The soil erosion is low. The water cycle is impaired because of the high density of short-rooted grasses which decreases infiltration.
| Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| J |
F |
M |
A |
M |
J |
J |
A |
S |
O |
N |
D |
State 3
Erosion State
This state includes two community phases that have very little plant cover, few native warm or cool season grasses and few perennial forbs. The vegetation that is present consists of pioneer species. The majority of the plants are annual forbs with a lesser amount of short-lived perennial species. Erosion has occurred and may still be occurring. There is very little plant cover, little forage production and poor soil quality.
Community 3.1
Annual/ Pioneer Perennials
As succession progresses, sandhill muhly, blowout grass and sand bluestem begin to colonize. Sandbur, lemon scurfpea and annual sunflower begin to come in with prairie sandreed, hairy grama, and rose slowly becoming evident on this plant community.
Community 3.2
Active Blowout
This plant community can be reached from any other plant community with significant disturbances such as heavy grazing. Large areas of blowing sand result in movement and possible enlargement of the blowout. Evaporation and transpiration of existing plants are extremely high due to bare ground, lack of litter,and few plants. This plant community is in a low successional stage from poor soil development, fire occurrence and sporadic herbivore use. Sandhill muhly and blowout grass are present due to their drought tolerance.
Pathway 3.1A
Community 3.1 to 3.2
Heavy grazing or overgrazing will eventually shift Annual/Pioneer Perennials to the Active Blowout community phase.
Pathway 3.2A
Community 3.2 to 3.1
With prescribed grazing, this plant community may move to the Annual/Pioneer Perennial Plant Community. Establishment of vegetation may be accelerated with concentrated short-term animal impact (such as feeding hay on the blowout), followed by broadcast seeding of a temporary cover crop prior to removal of animal impact.
State 4
Invaded Woody State
This state includes one plant community that has been invaded by Eastern red cedar. The woody species are present due to lack of prescribed fire and/or brush management measures. The sites typically have a loss of native warm season grasses, reduced forage production and reduced soil quality.
Community 4.1
Eastern Redcedar
This plant community can develop whenever eastern redcedar is adjacent to the originating plant community, and encroachment occurs. This can occur in areas adjacent to a seed source, such as near windbreaks or adjacent to ponderosa pine woodlands. With prescribed burning, encroachment can be controlled. This plant community has a canopy cover of 15% or more mature trees. Total tree canopy cover can exceed 40%. The herbaceous component decreases proportionately in relation to the increase in canopy cover.
This plant community is resistant to change. In higher canopy cover situations, the soil erosion will increase. The water cycle is also significantly altered under higher canopy cover. Infiltration is reduced because of interception of rainfall by the canopy. Runoff is not greatly increased, as the soil is still capable of absorbing the rainfall that reaches the soil surface.
State 5
Sod Disturbance
State influenced by some sort of sod disturbance, mainly tillage.
Community 5.1
Go Back Land
This plant community can be reached whenever severe mechanical disturbance occurs (e.g., abandoned farmland). The vegetation on this plant community varies greatly, sometimes being dominated by little bluestem, threeawn, sand dropseed, prairie sandreed, marestail, annual sunflower, green sagewort, and/or ragweed. Other plants that occur on this plant community include rose, yucca, sand bluestem, switchgrass, and needleandthread. Compared to the Bluestem/Prairie Sandreed Plant Community, warm-season natives have decreased. Annual forbs and grasses have become established in the plant community.
This plant community may not return to a higher successional plant community because of the long-term effects of the soil disturbance by tillage equipment. This plant community is variable in its resistance to change depending on past management practices. Soil erosion is typically evident in low successional stages. The water cycle is not greatly affected.
Transition T1A
State 1 to 2
Heavy grazing and improper rest periods can convert this plant state to the Native/Invaded Grass State. Continuous heavy grazing tends to accelerate this movement.
Transition T1B
State 1 to 3
Heavy grazing, prolonged drought, and soil disturbance can all cause the transition from the reference state to erosion state.
Transition T1C
State 1 to 4
Encroachment from lack of chemical or mechanical removal, of Eastern redcedar, as well as abscense of prescribed burning causes a transition from the reference state to the invaded woody state.
Transition T1D
State 1 to 5
Tillage followed by abandonment of soil causes a transition from the reference state to sod disturbance state.
Restoration pathway R2A
State 2 to 1
With long-term prescribed grazing, including adequate recovery periods, this plant community will move through the successional stages leading to the Bluestem/Prairie Sandreed Plant Community. This change will require a long period of time, and may be difficult to attain if the grama sod is extensive.
Transition T2A
State 2 to 3
Heavy grazing, wildfires, and other disturbance causes transition from Native/Invaded Grass State to Erosion State.
Transition T2B
State 2 to 4
Encroachment of Eastern redcedar due to lack of chemical or mechanical removal as well as abscence of prescribed burning causes transition from Native/Invaded Grass State to Invaded Woody State.
Transition T2C
State 2 to 5
Tillage and abandonment of farmland causes transition from Native/Invaded Grass State to Sod Disturbance State
Restoration pathway R3A
State 3 to 1
Under long-term prescribed grazing (10+ years), including adequate rest periods, succession will progress leading to the Bluestem/Prairie Sandreed Plant Community. The slope, aspect, size and relative abundance of perennial plants will influence the rate that change will occur.
Transition T3A
State 3 to 4
Encroachment of Eastern redcedar due to lack of chemical or mechanical removal or the abscence of prescribed burning causes transition from Erosion State to Invaded Woody State.
Restoration pathway R4A
State 4 to 1
With brush management, or prescribed burning, followed by prescribed grazing, succession will progress leading to the Bluestem/Prairie Sandreed/Needlegrass Plant Community.
Transition T4A
State 4 to 5
Tillage followed by abandonment of farmland causes a transition from Invaded Woody State to the Sod Disturbance State
