State 1
Reference State

Community 1.1
Historic Climax Plant Community (HCPC) Tall- and medium-height cool-season perennial grasses, less than 15 percent native forbs, and 5 percent native shrubs.

Tall- and medium-height cool-season perennial grasses, less than 15 percent native forbs, and 5 percent native shrubs, production@1300 lbs/ac. The interpretive plant community for this site is the Historic Climax Plant Community (HCPC). Cool season, tall and mid-grasses (such as bluebunch wheatgrass, green needlegrass, western wheatgrass, and thickspike wheatgrass) dominate the HCPC. Prairie junegrass is the most common short grass. Other short grasses and sedges include plains reedgrass, threadleaf sedge and needleleaf sedge. Bluebunch wheatgrass is a dominant species on the Clayey 10-14” p.z. site in the northern Glaciated Plains. Blue grama is the only common warm season grass. The range inventories on Fort Peck and Fort Belknap Reservations (2001-2004) did not report any sideoats grama or little bluestem on this site. Grasses represent about 80% of the total annual production in the community. Dotted gayfeather, American vetch, white prairie clover and purple prairie clover are warm season forbs that commonly occur on these Clayey 10-14” p.z. sites. American vetch and the prairie clovers are nitrogen-fixing species, and are also valuable forage producing plants. Groundplum milkvetch, scurfpea and prairie thermopsis are lower-successional forbs that have the ability to fix nitrogen. White milkwort, biscuitroot, wild onion and western yarrow may be present as minor components of the plant community. Forbs represent about 15% of the total annual production. Winterfat and Nuttall’s saltbush are common warm and cool season shrubs, respectively. They are valuable forage for wildlife and livestock. Silver sagebrush and fringed sagewort, two additional warm season shrub species, may represent a minor component of the HCPC. One would not expect to find more than a trace of broom snakeweed and pricklypear cactus in the HCPC. Very few cool season shrubs grow on the site. Overall, shrubs account for about 5% of the annual plant production. Range inventory data collected (in 2001 and 2004) on the Fort Peck and Fort Belknap Indian Reservations, and previous clipping studies by the NRCS indicate total annual production averages 1300 lbs/ac during normal years. Production varies from 900 to 1800 lbs/ac in unfavorable and favorable years, respectively. Average annual production is expected to increase and decrease, respectively on more mesic and xeric portions of the Glaciated plains. Although similarity indices (SI) >75% are expected to be associated with the HCPC, none were recorded during the recent range inventories on the two Reservations. This plant community is well adapted to the semi-arid, temperate climate that characterizes the glaciated plains. The predominance of cool season species has evolved to take advantage of the precipitation regime that peaks in late spring-early summer (June). Seventy-five percent of the annual precipitation usually falls as steady, soaking, frontal system rains. Summer rains usually come with thunderstorms. Precipitation is the most important factor influencing production. Severe drought occurs on average in two out of every ten years (Cooper, et al., 2001). Annual bromes and other annual species may invade the HCPC following a drought or period of non-prescriptive grazing. Continual adverse impacts over a period of several years will cause a shift in species composition from the mid and tall cool season grasses to warm season grasses and forbs/half-shrubs such as prairie junegrass, plains reedgrass, white milkwort, fringed sagewort, etc. With proper grazing management and/or normal precipitation, the desirable perennial plants regain vigor and competitiveness. The annual opportunistic species normally do not persist for more than a few years. Litter is in contact with 50-60% of the soil surface. Less than 5-10% 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. Soil erosion by wind and water should be minimal.

Community 1.2
Plant Community A Reduced plant height, lower production, more than 5 percent bare ground, medium- and tall-height cool-season perennial grasses with more than 5 percent native shrubs.

Reduced plant height, lower production, more than 5 percent bare ground, medium- and tall-height cool-season perennial grasses with more than 5 percent native shrubs. A plant height shift to lower stature plants distinguishes Community A from the HCPC. Although cool season perennial grasses (bluebunch wheatgrass, western/thickspike wheatgrass and green needlegrass) still dominate the vegetative community, the percentage of short stature cool and warm season perennial plants such as prairie junegrass and blue grama has increased. Fringed sagewort and silver sagebrush often increase in abundance and contribute more than 5% of the total production. Total vegetative production decreases to about 1050 lbs/ac, or 80% of HCPC. Basal cover provided by plants decreases to 25%, while litter cover decreases to 40%. Careful examination will yield slight evidence of rills and surface water runoff.

Community 1.3
Plant Community B - Pre-threshold Short, warm-season perennial grasses, few medium-height warm- and cool-season perennial grasses, more than 15% native forbs and more than 5% native shrubs, few invasive species present, more bare ground.

Short, warm-season perennial grasses, few medium-height warm- and cool-season perennial grasses, more than 15% native forbs and more than 5% native shrubs, few invasive species present, more bare ground, total annual production about 50% of HCPC. Vegetative production averages about 800 lbs/ac in this Community. The community is dominated by short, warm and cool season perennial grasses. Production of western and thickspike wheatgrass, green needlegrass, and bluebunch wheatgrass is greatly reduced. The production, composition and diversity of cool season mid and tall grasses in the plant community have been significantly reduced. Production of hairy goldenaster, western yarrow, hoods phlox, scurfpea, and other lower-successional native forbs increased. Fringed sagewort and silver sagebrush make up more than 5% of the total vegetative production. Plant replacement (seedlings and young plants) will be weighted in favor of opportunistic warm season species. Recruitment of mid and tall height cool season grasses is limited to only be a few seedlings and young plants. Japanese brome and other annual grasses occur on the site. Japanese brome density will be highest in microsites, where there is excess moisture or an abundance of litter, or in disturbed areas (rodent mounds, roads, trails, etc.). This community is characterized by a functional shift from a cool season dominant to a mix of warm and cool season species. The warm season plants are less well-adapted to exploit the precipitation and temperature conditions during May and June. Consequently, less solar energy is captured and converted to carbohydrates. The transfer of energy through the site has been adversely impacted. The site also tends to be more xeric as evaporation and runoff increases. Plant community B is called the “pre-threshold community.” It is critical that this community be recognized and management strategies implemented to prevent further regression. Although this community can improve to either Community A or HCPC through successional processes, further disturbances will result in regression to a lower state. Succession from a lower state (State 2) to State 1 is unlikely without significant inputs into the system.

Pathway 1.1A
Community 1.1 to 1.2

No fire, non-prescribed grazing, drought (3 to 5 years) Non-prescribed grazing, drought, insect infestations (grasshopper, etc) and/or a cessation of fire will cause regression from HCPC to Community A.

Pathway 1.2A
Community 1.2 to 1.1

Fire (natural interval 5 to 7 years), prescribed grazing, normal precipitation Favorable growing conditions, the implementation of prescribed grazing, or the reintroduction of periodic fire into the system will move Plant Community A to the HCPC. This succession can occur within a couple of years.

Pathway 1.2B
Community 1.2 to 1.3

No fire, non-prescribed grazing, prolonged drought (5 to 7 years) Community A will regress to Community B under non-prescribed grazing, prolonged drought (5 to 7 years), or an extended period of no fire (greater than 7 years). The rate of regression varies with the intensity and frequency of disturbances

Pathway 1.3A
Community 1.3 to 1.2

Prescribed grazing, fire (natural interfal 5 to 7 years), favorable precipitation The Clayey 10-14” p.z. site is resistant within the reference state. It is also resilient. Prescribed grazing, the re-implementation of the natural fire regime and/or a period of favorable precipitation will induce successional changes toward the HCPC. Succession will normally occur within a few years.

State 2
Degraded State

Community 2.1
Plant Community C Short, warm-season perennial grasses, many low-successional forbs (greater than 15 percent), low successional shrubs greater than 5 percent, invasive species more conspicuous, more bare ground and less litter.

Short, warm-season perennial grasses, many low-successional forbs (greater than 15 percent), low successional shrubs greater than 5 percent, invasive species more conspicuous, more bare ground and less litter. State 2 Plant Community C is dominated by warm season species (blue grama, prairie junegrass, sandberg bluegrass and other short grasses). Both the percentage of total forbs on the site and the percentage of warm season forbs, with respect to percent of cool season forbs have increased. Curlycup gumweed, a warm season biennial plant will often establish in disturbed areas. Silver sagebrush may either increase or decrease in this State; however fringed sagewort normally increases. Prickly pear and brittle cacti usually increase in abundance. Broom snakeweed may encroach onto the site. Annual grasses such as Japanese brome and cheatgrass often increase in abundance until they actually dominate portions of the community. Dense clubmoss, a low growing, vascular cryptogam forms a carpet-like mat that provides up to 30% ground cover in some of these communities. Total vegetative production in a normal year is usually less than 500 lbs/ac. Many resource concerns exist in this State. There is little or no regeneration of cool season perennial grasses and cool season forbs/shrubs. Litter is inadequate to protect the soil from erosion by wind and water. Surface erosion is moderate to severe, and there is more bare ground than expected. Rills, water flow patterns, and pedestals are evident.

State 3
Converted State

Community 3.1
Seeded Community Land formerly used for crop production, and these acres seeded to introduced species (with some native mixes) under Bankhead Jones, Soil Bank, and CRP Programs.

Land formerly used for crop production, and these acres seeded to introduced species (with some native mixes) under Bankhead Jones, Soil Bank, and CRP Programs. More than one million acres of former cropland in the Glaciated Plains have been seeded to introduced and native species. These seedings resulted from society’s concerns regarding land stewardship and erosion, and have been largely funded by the Federal Government. The government programs have spanned from the 1940s (Bankhead Jones Act) to the present (Conservation Reserve Program - CRP). Crested wheatgrass was the primary species seeded under the direction of the Bankhead Jones Act. Crested wheatgrass, intermediate wheatgrass, smooth brome and some native grasses were seeded during several Soil Bank Programs of the 1960-1970 era. Both introduced species and native species were seeded during the CRP (1985-present). There are over 220,000 acres of CRP in Valley County alone. The future of these Communities is not predicted in the S&T model. Depending on government programs and agricultural prices, these lands could stay in permanent vegetation with limited haying and grazing, be used as pasture for grazing livestock, or be converted to cropland.

Transition T1A
State 1 to 2

Extended drought (greater than 7 years), non-prescribed grazing, no fire Community B is not highly resistant to regression. In comparison to higher seral stages there is less vegetative production, less litter, and increased bare ground. Extended drought (longer than 7 consecutive years) and non-prescribed grazing can quickly cause regression to a lower state (State 2).

Transition T1B
State 1 to 3

Cultivated and farmed, seeding

Restoration pathway R2A
State 2 to 1

Prescribed grazing, favorable precipitation, fire (natural interval 5 to 7 years), possible mechanical treatment (NRCS job sheet 548) This plant community is resistant to change, it is a steady state. The short grasses tend to form a sod that prevents seedling establishment of higher successional species. Less than 10% of the seed bank in State 2 is comprised of seed from cool season perennial plants (Romo and Bai 2004). Thus, potential for succession is limited without significant inputs. Prescribed grazing minimizes the risk of further regression and enhances the potential for succession to State 1. The combination of prescribed grazing, a natural fire regime, and a prolonged period of favorable precipitation may allow significant succession in communities that have less than 20% clubmoss cover. This potential is depicted with the dashed line in the state and transition model. . Mechanical treatments may be feasible in areas where potential erosion is not a concern. However, mechanical treatments are not normally recommended on soils with a clay content > 60%. Grazing management practices following a mechanical treatment must be prescribed to address deferment, stocking rates, season of grazing, and other considerations (NRCS Conservation Practice 548). Failure to do so will adversely affect economic returns and is likely to result in retrogression rather than plant succession.