State 1
Savannah

This is the Reference state for this ecological site. It represents the historical variability of communities on this site under the natural disturbance regime.

Characteristics and indicators. The plant communities within this state are dominated primarily by herbaceous species. The woody species average 30% canopy or less across the landscape. This canopy may vary substantially as areas adjacent to creeks and streams are more protected from fire. This often leads to a feathered effect of low canopy further from the the water course and higher canopy adjacent to it.

Resilience management. Most of the variation can come from time since last fire. Without fire or alternative brush management, the site may transition to the woodland state.

Community 1.1
Bottomland Hardwood Savannah

Figure 10. Pulaski Soils with Pecan overstory, site has been hayed earlier in season. Payne County, Oklahoma

This biotic community is dominated by native warm season grasses that thrive under periodic grazing and fire. While this site is well suited for woody plant growth, periodic fires restrict the growth and reproduction of most of the woody species.

The reference community for the Loamy Bottomland ecological site is the Bottomland Hardwood Savannah community (1.1). This plant community is predominately tallgrass prairie species with a savannah overstory of Pecan (Carya illenoensis), Sycamore (Platanus occidentalis), and Cottonwood (Populus deltoides). Warm season tallgrass species include Big Bluestem (Andropogon gerardii), Switchgrass (Panicum Virgatum), Indiangrass (Sorghastrum nutans), Florida Paspalum (Paspalum floridanum) and Eastern Gamagrass (Tripsacum dactyloides). There are also a variety of native forbs and legumes including numerous sunflowers (Helianthus spp.), Baldwin’s Ironweed (Vernonia baldwinii), Pitcher’s Sage (Salvia azurea), Goldenrods (Solidago spp.), Illinois Bundleflower (Desmanthus illinoensis), Wild Indigo (Baptisia australis), and Tick-clovers (Desmodiium spp.). Some important cool season grasses include Canada Wildrye (Elymus canadensis), Texas Bluegrass (Poa arachnifera), and a variety of grasslike sedges (Carex spp.)

This biotic community provides adequate ground cover to prevent soil loss, limit runoff, and enhance water infiltration into the soil profile. It provides good habitat for many wildlife species and adequate forage plants for domestic grazing animals.

Although these sites are subjected to periodic flooding, the community phase is quite resilient. There may be some scouring after flood events, yet the majority of the plant communities will recover.

The following species cover, structure, and production tables have been developed using collected data and professional knowledge. As with anything in nature, there is a large amount of variability from year to year even within a relatively stable plant community. This is true for both vegetative production as well as foliar cover produced by a plant species. The following figures are to be viewed only as a representation of the estimated potential for a given species. As more data is collected and measurement methods are refined some values may be updated through future revisions.

Community 1.2
Midgrass Savannah

Figure 13. 1.2 Pulaski soils. Payne County, OK.

The dominant herbaceous plants within this community are Little Bluestem (Schizachyrium scoparium), Tall Dropseed (Sporobolus compositus), Silver Bluestem (Bothriochloa laguroides), and Western Ragweed (Ambrosia psilostachya). The dominant tallgrasses from the reference community (1.1) have declined due to excessive grazing pressure and have been replaced by less palatable species. These midgrass species have received less pressure from grazing animals and have been able to thrive. The more palatable legumes and forbs have also decreased. This community phase will most often still contain the fine fuel loads required to implement prescribed burning, however, proper planning and evaluation will be necessary to implement this practice.

Community 1.3
Savannah Transition

Figure 14. Pulaski soils, savannah transition

This community is usually the end result of excessive defoliation of palatable grasses and lack of fire. The desirable herbaceous species have been heavily grazed for long periods of time without being allowed to recover. The remaining undesirable grasses and forbs will not produce the fuel loads necessary to implement prescribed fire to control woody species encroachment. These woody species will begin to encroach into open areas and grow unrestricted. This community is considered “at risk” of transitioning to a woody dominated ecological state (2). The woody canopy coverage is 30-40%.

Pathway 1.1A
Community 1.1 to 1.2

Bottomland Hardwood Savannah

Midgrass Savannah

If the reference plant community (1.1) is subjected to abusive grazing for long periods of time, it may begin to shift to a Midgrass Savannah plant community (1.2). With heavy grazing pressure, preferred tallgrass species, will decrease in vigor and eventually be replaced by less palatable midgrasses. This shift can be avoided by following proper stocking rates and allowing periodic rests between grazing events. This shift may also be the result of a long term drought as the tallgrass species tend to be less drought tolerant than some midgrasses. While the soils of this site are not considered excessively droughty, long dry periods can begin to have an impact on the plant community. These impacts are compounded with improper grazing management (inadequate rest). The removal of fire from the ecosystem can also negatively affect the reference plant community (1.1).

Pathway 1.2A
Community 1.2 to 1.1

Midgrass Savannah

Bottomland Hardwood Savannah

With the implementation of a prescribed grazing system that involves periodic growing season rest (deferment), this plant community may shift back to the reference plant community (1.1). It is important to remember that adequate precipitation during these rest periods is required in order to allow the plants to recover and regain vigor.

Pathway 1.2B
Community 1.2 to 1.3

Midgrass Savannah

Savannah Transition

If this site is continually subjected to abusive grazing without adequate rest, the more desirable plants will continue to decline. These plants will be replaced by less palatable midgrasses and annuals. As this plant community is shifted to the transitional community (1.3), the fine fuel loads are decreased and it becomes very difficult to implement prescribed fire. Woody species will be able to grow unrestricted and compete for resources.

Pathway 1.3A
Community 1.3 to 1.2

Savannah Transition

Midgrass Savannah

With the implementation of a prescribed grazing system that involves periodic growing season rest (deferment), and the reintroduction of fire, this plant community may shift back to the reference plant community (1.2). It is important to remember that adequate precipitation during these rest periods is required in order to allow the plants to recover, regain vigor and produce fuel loads necessary to control the encroaching woody species. At this stage, the community is at risk of crossing a threshold because canopy is approaching 40 percent. Once this happens, changes in grazing management will have little effect on the return of warm season grasses as there is not enough sunlight to sustain them.

State 2
Woodland

This ecological state is the result of long term exclusion of fire from the ecosystem.

Characteristics and indicators. Woody species that were historically reduced by periodic fire the savannah ecosystem of the reference state (1) may now increase in abundance. The ecological function (energy flow, hydrology, nutrient cycling) of the site has been altered and is now dominated by woody species.

Resilience management. While sites in this state may be grazed by cattle, the production of palatable herbaceous species is diminished. Thus, the production value of grazing is greatly reduced. Some species of wildlife will find use of site in this state; however, other species will not persist as the site becomes dominated by woody plants.

Community 2.1
Woodland/Midgrass

Figure 15. Pulaski soils.Transitional community from 2.1 to 2.2. Cleveland County, OK

The woodland/midgrass plant community is dominated by woody species including American Elm, Hackberry, Pecan, Persimmon, Green Ash, and Sumac. Invasives such as Eastern Redcedar and Honeylocust are common and may take over some sites. The woody canopy may average around 50 – 60%. Some herbaceous species still occupy canopy interspaces. The herbaceous community may include remnants of Little Bluestem, Purpletop, Dropseeds, Broomsedge Bluestem, and a variety of Sedge species depending on current and prior grazing management. Shrub species including Poison Ivy, Greenbriar, and Buckbrush are also common. Overall herbaceous vegetative productivity is significantly lower than the reference community. While there is still some value for wildlife in this community, the value for grazing livestock is diminished. (With the exception of browsing goats.)

Community 2.2
Closed Canopy Woodland

Figure 16. Pulaski soils invaded by Eastern Redcedar

This plant community is the result of fire exclusion from the ecosystem. In the absence of fire, woody species have encroached and now completely dominate the site. The fertile, coarse bottomland soils and close proximity to groundwater are favorable for woody plant growth. Major woody increasers include American Elm (Ulmus Americana), Hackberry (Celtis laevigata), Green Ash (Fraxinus pennsylvanica), and Eastern Redcedar (Juniperus virginiana). Some understory woody species include Saw Greenbriar (Smilax bona-nox), Eastern Poison Ivy (Toxicodendron radicans), and Virginia Creeper (Parthenocissus quinquefolia). Some of these woody species occur in small amounts within the reference state (1), however, most have been limited by periodic fires. Once the species are fully mature they are very difficult to control with fire alone (except for wildfires). The closed canopy created by these woody species creates a mesophytic microclimate in the understory that favors woody species and a few shade tolerant herbaceous species. This plant community may provide some benefits to wildlife species that use it for browse and cover, but the value of the site for cattle grazing has severely deteriorated. There is potential for use of this plant community by goats due to the amount of understory woody species.

Pathway 2.1A
Community 2.1 to 2.2

Woodland/Midgrass

Closed Canopy Woodland

Without periodic fire, the woodland/midgrass plant community will be susceptible to woody encroachment and may shift to a closed canopy woodland plant community.

Pathway 2.2A
Community 2.2 to 2.1

Closed Canopy Woodland

Woodland/Midgrass

Through some selective thinning of woody species and re-introduction of fire through prescribed burning, the closed canopy plant community may be shifted to a woodland/midgrass community.

State 3
Cultivated

Many loamy bottomland sites have been cultivated over the past century in order to produce crops.

Characteristics and indicators. Due to the level, deep, sandy loam soils, these sites are well suited for Ag production. Within this state, most woody species have been cleared in order to facilitate the access of farm machinery.

Resilience management. Upon cultivation, the physical and chemical properties of the soil have been altered. The degree of this change is very site specific depending on cultivation type and duration.

Community 3.1
Cropland

Figure 17. Pulaski soils in current cultivation

This plant community is the result of farming practices for the production of commodity crops. Common crops include Wheat, Sorghum, Soybeans, and sometimes Corn. Refer to Ag extension publication, web soil survey, or soil survey manuscripts for site specific crop yield data.

State 4
Re-Seeded

This ecological state is the result of reseeding herbaceous plant species or abandonment following a period of cultivation.

Characteristics and indicators. The plant communities within this state are highly variable in both species composition and production. Under carefully planned management strategies, this state may be restored to a plant community that appears similar to the reference state (1).

Resilience management. However, the species composition, ecological function, and soil health may never be restored to reference conditions. Therefore, careful consideration should be taken when evaluating a loamy bottomland site that may have been broken out for cultivation in the past.

Community 4.1
Go Back/Range Seeding

Figure 18. Pulaski Soils, formerly cultivated, go back community with johnsongrass. Payne County, OK

This plant community is the result of abandonment or range seeding after cultivation. The pioneer species of a “go back” plant community might include Purpletop (Tridens flavus), Broomsedge Bluestem (Andropogon virginicus), Giant Ragweed (Ambrosia trifida), and often times Johnsongrass (Sorghum halepense). There is often a large amount of variability within both species composition and production within this community. Most often, early successional trees, grasses, and forbs will begin to encroach on the site. Without fire or brush management, this state may develop into something that resembles state 2 (Woodland). However, since the site has been cultivated, the soil health, organic matter, and potential plant communities may be different. Site specific ecological evaluations will be necessary in order to develop management strategies.

Some sites may be seeded to a diverse mixture of native grasses, forbs, and legumes, while other sites were seeded with very few species or simply abandoned. It is important to remember that without periodic fire or other brush management, the site may be invaded by woody species, regardless of the establishment methods of herbaceous plants.

Community 4.2
Tame Pasture

Figure 19. Pulaski Soils w/Tall Fescue and Pecan Trees

When this site is taken out of crop production, it is often planted to an introduced perennial grass. The most common species are Bermudagrass (Cynodon dactylon) and Tall Fescue (Schedonorus arundinaceus). Many of these sites are used for grazing, cut for hay, or both. The productivity of these perennial grasses is greatly dependent upon nutrient inputs (fertilizer). Nutrient management is key to the establishment and management of these introduced species. Additionally, the addition of nutrients may help to expedite the buildup of soil microorganisms and potentially soil organic matter. For more information about suitable pasture species, planting specifications, and yield data, refer to ag extension publications, web soil survey, and forage suitability group descriptions (if available).

Transition T1B
State 1 to 2

In the absence of fire, many woody species increase across the landscape. Once these woodies are abundant enough, they begin to drive the ecological functions of the site.

Constraints to recovery.Shading negatively affects the herbaceous plants, as well as, hydrologic changes limiting available water. As the woody species begin to dominate the site, it will transition to a woodland ecological state (2).

Transition T1A
State 1 to 3

A majority of these sites have been plowed for farming purposes over the last century. Once the site is cultivated, it transitions to an alternative state (3).

Constraints to recovery.The soils structure, organic matter, and biota have been altered and will no longer function the same as the soils in the reference state.

Restoration pathway R2A
State 2 to 1

Through an integrated program of Brush Management (selective thinning), Grazing Management (deferment), and Prescribed Fire, the Woodland State may be restored to the Reference Savannah State (1).

Context dependence.Selective thinning will be required to remove undesirable woody species while leaving the large bottomland trees that occur in the Reference State. Prescribed grazing will be required in order to allow the tallgrasses, forbs, and legumes recover and re-establish once the canopy is thinned. This will also be required in order to establish proper fuel loads in order to successfully implement a prescribed fire program. Prescribed fire will be necessary in order to clean up remaining understory species and can be used as a management tool to prevent future woody encroachment.

Transition T3A
State 3 to 4

Once cultivation of this site is stopped, the Cultivated State will transition to the Reseeded State.