State 1
Native tallgrass

This state comprises the communities within the range of natural variability under historic conditions and disturbance regimes. Patterns created by wildlife use and fire would have created a mosaic of communities across the landscape; however, tall and/or mid warm-season grasses would remain dominant, with a subdominant contribution from native cool-season grasses, forbs, and shrubs. The cool-season contribution increases with latitude, with species such as needleandthread and green needlegrass becoming more prevalent northward. Fire and bison herbivory were the dominant disturbance regimes that historically maintained the tallgrass dominance with a diverse forb component. Furthermore, bison grazing was closely linked to fire patterns as the animals preferred grazing burned areas offering lush regrowth devoid of decadence and of higher nutritive quality. Thus, historic plant communities were subjected to occasional burning and grazing, with substantial rest/recovery periods as the fuel load rebuilt to eventually start the process again. Fire return intervals of 3-4 years served to suppress woody species, particularly non-sprouting eastern redcedar. The degree to which observed conditions represent this state largely depends on how closely the management has mimicked these past disturbance effects.

Community 1.1
Little bluestem-Big bluestem (Schizachyrium scoparium-Andropogon gerardii)

Figure 8. Loess Breaks 1.1

This is the reference plant community and can be found on areas that are managed to allow for adequate recovery periods following defoliation or drought stress. In addition to tallgrass vigor, suppression of woody species either through natural (e.g. fire) or artificial (e.g. chainsaw) methods is necessary to maintain herbaceous dominance. The plant community consists of 75-90% grasses and grass-likes, 5-10% forbs and 1-5% shrubs. Dominant grasses include little bluestem, big bluestem, sideoats grama, and plains muhly. Other grasses and grass-likes are indiangrass, blue grama, prairie junegrass, and switchgrass. Forb species are diverse and include prairieclovers, and goldenrods, and black samson. Common shrubs include leadplant and New Jersey tea (Kaul 2006, Steinauer 2010, USDA/NRCS 2012). This plant community is diverse, stable, and productive with nutrient and water cycles, and energy flow functioning near full potential considering the slope limitations. Plant litter is properly distributed with negligible movement off-site, and natural plant mortality is very low. This community is resistant to many disturbances except continuous season-long heavy grazing, tillage, or non-use. Broadcast herbicide application will dramatically reduce non-target forb diversity and abundance. Total annual production, during an average year, ranges from 2400 to 4300 pounds per acre air-dry weight and will average 3500 pounds.

Community 1.2
Little bluestem-Sideoats grama (Schizachyrium scoparium-Bouteloua curtipendula)

Figure 11. Loess Breaks 1.2

This community largely resembles central Great Plains mixed-grass prairies where rainfall is more limiting and overall conditions are relatively drier. Tallgrasses are a minor component with midgrasses - typically sideoats grama and little bluestem - dominating site structure and function. While still within the range of natural variability, energy capture, nutrient cycling, and hydrology are not functioning at their full potential relative to the reference condition. Reduced photosynthetic biomass does not capture as much light energy, less lignified plant material produces lower quality litter (e.g. less persistent, more easily transported), and reduced soil protection impairs the site''s ability to capture and retain moisture.

Pathway 1.1A
Community 1.1 to 1.2

Little bluestem-Big bluestem (Schizachyrium scoparium-Andropogon gerardii)

Little bluestem-Sideoats grama (Schizachyrium scoparium-Bouteloua curtipendula)

Events which remove tallgrass growing points and photosynthetic tissues without adequate recovery periods will shift community composition towards shorter statured species, particularly little bluestem and sideoats grama. Likewise, shortgrasses such as hairy and/or blue grama may also proliferate. As cattle grazing pressure increases/persists, rhizomatous grasses may assume a more sodbound growth habit which can further reduce overall diversity and adversely affect both infiltration and litter. Periods of extended drought can have similar impacts on species composition and bring about a shift towards mixed/shortgrass prairie species more tolerant of drier conditions.

Pathway 1.2A
Community 1.2 to 1.1

Little bluestem-Sideoats grama (Schizachyrium scoparium-Bouteloua curtipendula)

Little bluestem-Big bluestem (Schizachyrium scoparium-Andropogon gerardii)

Management that provides adequate recovery periods and does not annually prevent tallgrass seedset or otherwise impair vigor will facilitate a return to community phase 1.1. In the case of drought, the return to more typical precipitation patterns will promote shift towards tallgrass species.

State 2
Native/invaded mix

This state can manifest three ways: 1) the appearance of introduced cool-season grasses, 2) the expansion of deciduous shrubs and/or trees, or 3) some combination of these. Kentucky bluegrass and smooth brome are the primary cool-season grass invaders in this region, commonly found in roadsides, disturbed areas, and pastures intentionally seeded for cool-season forage. Management practices and/or environmental conditions that are not favorable to native grass vigor may allow introduced grasses to invade the site thereby decreasing native diversity and abundance, particularly of forbs. In the absence of the historic fire regime, woody deciduous species may also expand to become an influential component of the community. The invasive component tends to have very high reslience, is extremely difficult to eradicate, and what might be considered a new "contemporary" range of natural variability is seen as competition between the native grasses and introduced/woody species for space and resources.

Community 2.1
Subdominant Smooth brome-Kentucky bluegrass (Bromus inermis-Poa pratensis)

While native grasses still dominate the site, introduced cool-season species have established a foothold in the system and can be found interspersed throughout the stand. The stand may still have a native tall and midgrass appearance overall, but bluegrass and/or brome can be easily found. Deciduous shrub/tree species may also have begun to expand into areas where they did not persist historically, but the overall appearance can vary depending on the propagation method of a particular species. Seed propagated species, such as Siberian elm, tend to colonize further from the parent plant and affect larger areas, but in lower densities. In contrast, rhizomatous species such as smooth sumac tend to progress as a higher-density encroachment spreading directly from the parent plants.

State 3
Woody dominant

Woody species have established a significantly closed canopy that influences the herbaceous understory through processes such as stemflow, litterfall, and variable understory insolation, creating more heterogenous resource distribution relative to historic grassland conditions. Also, the precipitation gradient produces changes in both overstory and understory species composition seen as increased eastern deciduous forest influence mixing with bur oak southeasterly in MLRA.

Community 3.1
Bur oak-Eastern redcedar (Quercus macrocarpa-Juniperus virginiana)

Figure 14. Loess Breaks - Bur oak

Figure 15. Loess Breaks - Deciduous/cedar mix

Bur oak is the most common tree species, although mulberry, ash, and black walnut can often be found in lesser numbers. A profound shift in herbaceous plants is seen as a near total loss of warm-season tallgrasses towards native and/or introduced cool-season species such as Carex spp., and wildryes, as well as smooth brome and Kentucky bluegrass if present. Eastern redcedar can also be prominent, either as a subdominant component of a deciduous woodland or as the dominant with few to no interspersed deciduous.

Transition T1A
State 1 to 2

In the presence of introduced cool-season grasses, environmental conditions and/or management that reduces native vigor and stand resilience, and frees up resources (space, sunlight, nutrients, water) will allow for colonization of Kentucky bluegrass and smooth brome. Likewise, similar processes may also allow for deciduous woody shrubs and trees such as smooth sumac, roughleaf dogwood, and Siberian elm to expand.

Constraints to recovery. Reduced native competitiveness allows for introduced grass colonization and expansion

Transition T1B
State 1 to 3

The presence of an invasion source coupled with fire exclusion allows woody species to expand and establish within the herbaceous stand. This typically begins near woody draws and accelerates outward as propagules increase. Lack of intervening action allows woody expansion to continue, and tree sizes to increase. Trees will eventually modify site function in ways that promote further encroachment such as rainfall interception and stemflow, heavy leaf litter, and shading of the herbaceous understory.

Restoration pathway R2A
State 2 to 1

Eradication of introduced cool-season grasses from this site will require long-term, targeted management efforts to create an adverse environment during the spring and late fall when bluegrass and brome are most actively growing, with favorable conditions during the summer to promote native warm-season species. Targeted practices such as prescribed burning, flash grazing, and herbicide are often employed at strategic times of the year to set back undesirable species. The combination of practices should strive to mimic the historic disturbance regimes to which the desirable native species are best adapted.

Transition T2A
State 2 to 3

The presence of an invasion source coupled with fire exclusion allows woody species to expand and establish within the herbaceous stand. This typically begins near woody draws and accelerates outward as propagules increase. Lack of intervening action allows woody expansion to continue, and tree sizes to increase. Trees will eventually modify site function in ways that promote further encroachment such as rainfall interception and stemflow, heavy leaf litter, and shading of the herbaceous understory.

Restoration pathway R3A
State 3 to 1

With deciduous dominance, taller trees, thicker bark, and reduced understory ladder fuels have created a woodland community virtually invulnerable to fire. Overstory thinning/removal will require labor-intensive mechanical and/or chemical methods on difficult terrain. Solid cedar stands may be able to carry an effective fire, but this will steep slopes largely denuded and exposed thereby requiring additional mitigative actions to preserve site stability. The outcomes of restoration activities can vary, depending heavily on both the present understory and the seedbank, and may instead result in a rapid increase of sprouting species such as roughleaf dogwood and/or smooth sumac which will require further efforts.