State 1
Reference State

Community 1.1
Historic Climax Plant Community (HCPC) Tall, cool- and warm-season grasses, medium-height cool-season grasses and sedges, less than 10 percent native forbs, less than 5 percent native shrubs, zero percent bare ground

Tall, cool- and warm-season grasses, medium-height cool-season grasses and sedges, less than 10 percent native forbs, less than 5 percent native shrubs, zero percent bare ground, annual production 4000 lbs/ac The interpretive plant community for this site is the Historic Climax Plant Community (HCPC). Cool season tall and mid-grasses (such as prairie cordgrass, western wheatgrass, slender wheatgrass, bearded wheatgrass, mat muhly, tall reedgrasses, and tufted hairgrass) dominate the HCPC. These grasses represent about 80% of the total annual plant production in the community. Short grasses, sedges and rushes make up another 5% of the total annual production. Dotted blazing-star, meadow hawksbeard, lance-leaf goldenweed, goldenrods, maximilian sunflower, cinquefoil, and blue-eyed grass are important forbs. Total forb production normally represents less than 10% of the total annual production. Buffaloberry, willows, chokecherry, snowberry, shrubby cinquefoil, and rose are important shrubs. Overall, shrubs account for about 10% of the annual plant production. Historic NRCS data indicate that total annual production on this site varies from 5000 lbs/ac in favorable years to 3500 lbs/ac in unfavorable years. Annual production averages 4000 lbs/ac. Average annual production is expected to be slightly higher or lower, respectively on more mesic and xeric portions of the northern Glaciated Plains. This plant community is well adapted to the climatic conditions of the glaciated plains and to the presence of a permanent water table. The diversity of plant species helps make the site resistant to environmental changes. The functional and structural diversity of plant species (perennials, cool and warm season grasses, sedges, forbs and shrubs) optimize the capture of solar energy and maximize subsequent plant growth through the efficient use of available soil water and nutrient cycling. Continued adverse disturbances reduce the competitiveness of perennial plants, and precipitate the replacement of high successional species with lower successional grasses, forbs, shrubs, and annual species. With proper grazing management and a “natural” fire regime, more species found at HCPC will replace these lower successional species within a few years. Litter is in contact with 55% of the soil surface. Plant litter remains in place and is not moved by erosional forces. Less than 1% of the soil surface should be bare, or unprotected by litter, rock, moss, and plant canopy. Rills should not be present and water flow patterns should be barely observable. The major plant species composition and production by dry weight are shown for the HCPC in the following table. Total annual production has been derived from several sources, and has been adjusted to represent a typical annual moisture cycle.

Community 1.2
Plant Community A Medium-height cool-season grasses and sedges, tall cool- and warm-season grsses, less than 15 percent native forbs, less than 5 percent native shrubs, 5 to 10 percent bare ground

Medium-height cool-season grasses and sedges, tall cool- and warm-season grsses, less than 15 percent native forbs, less than 5 percent native shrubs, 5 to 10 percent bare ground, annual production averages 3200 lbs/ac Total plant production averages about 3200 lbs/ac in this Plant Community. Annual production of the tall, more palatable grasses (tufted hairgrass, prairie cordgrass and narrow-spiked reedgrass) declines by about 20%. In response, western wheatgrass, mat muhly, and lower successional sedges have increased. Exact response by these lower successional species varies with the kind and intensity of disturbance (drought, grazing, etc.) and with precipitation (amount and timing). Production of native forbs increases relative to the HCPC and now accounts for more than 10% of the total production. Dotted blazing-star and Maximilian sunflower decrease in abundance while meadow hawksbeard, prairie thermopsis, and cinquefoil increase. Shrubs account for about 5% of the total annual production. Species such as snowberry, rose and shrubby cinquefoil increase at the expense of chokecherry and willows. Litter cover decreases to 50% and bare ground increases to about 5%. In contrast to the HCPC, range conservationists have slight to moderate concerns regarding lower infiltration rates and potentially higher runoff rates, plant functional/structural group shifts, and decreasing amount of litter. There shouldn’t be any, or only a trace of invasive plants present. The tall cool season grasses have poor vigor, with reduced seed production. Most of the seedlings and young plants appear to represent short grasses and warm season forbs.

Community 1.3
Plant Community B Native medium and short grasses and sedges, 15 percent native forbs, 10 percent native shrubs, some invasive forbs

Native medium and short grasses and sedges, 15 percent native forbs, 10 percent native shrubs, some invasive forbs, annual production averages 2000 lbs/ac. Mid and short grasses and grasslike plants dominate this Community. A few western wheatgrass, tufted hairgrass plants persist with reduced vigor in the community. Mat muhly, sedges and Baltic rush are common species. Grasses and grass-like plants contribute 75% of total annual production. Arrowgrass, white-prairie aster, cudweed sagewort, cinquefoil, prairie thermopsis, and other native low successional forbs make up about 15% of the total annual production. Dandelions, salsify, Canada thistle, and other invasive forbs may be present in this community. Total vegetative production declines to about 2000 lbs/ac in a normal year. Litter provides cover for about 40% of the ground, while bare ground increases to about 10%. Rills, water flow patterns and litter movement are evident on the site.

Pathway 1.1A
Community 1.1 to 1.2

Non-prescribed grazing, no fire, drought Successional pathways from the HCPC are influenced by frequency, timing and intensity of grazing, precipitation patterns, fire, insect infestations, noxious weed invasions, etc. As communities regress from HCPC, medium and short grasses increase at the expense of mid and tall, cool season grasses. Total annual production decreases.

Pathway 1.2A
Community 1.2 to 1.1

Prescribed grazing, fire (natural interval 5 to 7 years) Plant Community A is highly resistant to disturbance. It is also resilient. With prescribed grazing, the high successional species are able to replace the lower-successional species and also expand into the bare areas.

Pathway 1.2B
Community 1.2 to 1.3

Non-prescribed grazing, prolonged drought (5 to 7 years), no fire Non-prescribed grazing, prolonged or extended drought, and the prolonged elimination of the natural fire regime from the system results in regression to Plant Community B. The effects of poor grazing management are readily apparent with careful observation. However, the influence of fire is more difficult to verify. It is believed that these sites burned naturally at 5 – 7 year intervals (Frost 1998). Without fire and/or grazing, litter accumulation becomes excessive and adversely impacts plant vigor, seedling establishment, and nutrient cycling.

Pathway 1.3A
Community 1.3 to 1.2

Prescribed grazing, fire (natural interval 5 to 7 years), normal precipitation Plant Community B should be recognized as the pre-threshold community. It is generally resilient but it is not highly resistant to stress. Under prescribed grazing this Community can return to Community A through succession. However, it will regress under the influence of NPG to lower successional Plant Community C (State 2). Regression also occurs to Community D (State 3). However, it is theorized that the pathways for this transition originate from within the Reference State, and not necessarily from Community B.

State 2
Degraded State

Community 2.1
Plant Community C Rushes, short grasses and sedges, low successional forbs, invasive forbs conspicuous

Rushes, short grasses and sedges, low successional forbs, invasive forbs conspicuous, 1500 lbs/ac annual production Baltic rush, western wheatgrass, clustered field sedge, ticklegrass, mat muhly, Kentucky bluegrass, meadow barley and other short grasses and grass-like plants dominate this Community. HCPC dominant species such as prairie cordgrass and tufted hairgrass may persist as individual plants. Normally there is minimal regeneration of these species. Wooly plantain, cudweed sagewort, arrowgrass, cinquefoil, dandelion, and western yarrow are common forbs. These low successional forbs contribute about 20% of the annual production. In comparison to the HCPC, fringed sagewort, snowberry and rose tend to increase and may contribute about 10% of the total annual production. Soil erosion is not a serious problem because of the cover provided by the short native grasses and the rhizomatous grasses. However, the loss of the tall cool season bunchgrasses, results in a simplification of the compositional and structural plant communities. The hydrologic cycle (capture, storage and redistribution of precipitation), energy flow, and nutrient cycles are believed to be adversely impacted. Total vegetative production averages about 1500 lbs/ac. In contrast to the HCPC, range conservationists express moderate concerns about plant community composition, functional/structural groups, litter, annual production, and invasive plants. Each of the primary processes: 1) hydrology (the capture, storage and redistribution of precipitation), 2) energy capture (conversion of sunlight to plant and animal matter), and 3) nutrient cycling (the cycle of nutrients through the physical and biotic components of the environment) has been degraded beyond the point of self-repair within a reasonable length of time. For example, when tall, high producing, cool season grasses are replaced by short grasses (Kentucky bluegrass, mat muhly and Baltic rush), the abilities of the plant community to maximize the conversion of solar energy to plant biomass and efficiently utilize available precipitation are impaired. Less solar energy is captured and converted to carbohydrates for plant growth. Plant growth declines, and there are less plant canopy and less litter to protect the soil. As bare ground increases, infiltration decreases and/or surface runoff and soil evaporation increases. Because ecological processes of the site are no longer balanced and sustained, shallow rooted, warm season species continue to gain a competitive advantage over the deep rooted, cool season species. The biotic integrity of the site is degraded. Thus, the transitions from Plant Community B in State 1 to either Communities C (State 2) or D (State 3) represent thresholds. Thresholds are defined as a point in space and time at which one or more of the primary ecological processes responsible for maintaining the sustained equilibrium of the state degrades beyond the point of self-repair.

State 3
Invaded State

Community 3.1
Plant Community D Invasive forbs and grasses, noxious weeds, and native short grasses and sedges

Invasive forbs and grasses, noxious weeds, and native short grasses and sedges This plant community is dominated by invasive forbs, Kentucky and Canada bluegrasses, and noxious weeds. Some native short grasses and sedges remain in the Community.

Transition T1A
State 1 to 2

Non-prescribed grazing, no fire, extended drought (greater than 7 years) Plant Community B should be recognized as the pre-threshold community. It is generally resilient but it is not highly resistant to stress. Under prescribed grazing this Community can return to Community A through succession. However, it will regress under the influence of NPG to lower successional Plant Community C (State 2).

Transition T1B
State 1 to 3

Non-prescribed grazing, no fire, drought (3 to 5 years), other disturbance Regression also occurs to Community D (State 3). However, it is theorized that the pathways for this transition originate from within the Reference State, and not necessarily from Community B.

Transition T2A
State 2 to 3

Non-prescribed grazing, no fire, drought (3 to 5 years) Plant community C is not a precise assemblage of species that remain constant from place to place or from year to year. Variability is apparent in productivity and occurrence of individual species. Changes in climate, fire patterns and frequency, and grazing all play a role in determining which plant species express dominance. Plant community C can regress into Community D with non-prescribed grazing and/or the absence of a natural fire regime.

Restoration pathway R2A
State 3 to 2

The noxious weeds and introduced rhizomatous grasses are competitive. Succession to Plant Community C is not likely to occur without a pro-active management of a significant input of energy into the natural system. Practical experience indicates that Garrison Creeping Foxtail (GCF) can be introduced into this community by feeding livestock GCF on the site, or by scattering seed and allowing livestock to trample it into the soil. Within a few years, the GCF often dominates the community. The seasonal water table and extensive below ground biomass that characterizes this restricts the use of conventional tillage. Research suggests that desirable species can be seeded into the site with a no-till drill following the application of Roundup R to control undesirable plants. In most situations, these agronomic approaches are usually economically and ecologically prohibitive.