State 1
Reference State

Community 1.1
Historic Climax Plant Community (HCPC) Tall- and medium-height cool-season perennial grasses, less than 10 percent native perennial forbs, less than 5 percent native shrubs.

Tall- and medium-height cool-season perennial grasses, less than 10 percent native perennial forbs, less than 5 percent native shrubs, total annual production averages 1200 lbs/ac. The interpretive plant community for this site is the Historic Climax Plant Community (HCPC). This community is highly resistant and resilient to change. Cool season, tall and mid-grasses (such as green needlegrass, bluebunch wheatgrass, western wheatgrass, and thickspike wheatgrass) dominate the HCPC. Bluebunch wheatgrass is dominant on this site in the northern Glaciated Plains. Plains muhly and blue grama are the only common warm season grasses. Prairie junegrass, plains reedgrass, and threadleaf sedge are common, cool season short grasses and grasslike plants. Grasses represent about 85% of the total annual production in the community. Dotted gayfeather, white prairie clover, and purple prairie clover are warm season forbs that commonly occur on Clayey-Steep 10-14” p.z. sites. American vetch is a highly palatable, common cool season forb. American vetch and the prairie clovers are nitrogen-fixing plants. Although these have a much lower value as forage, ground plum milkvetch, milkvetch, prairie thermopsis and scurfpea are also nitrogen-fixing legumes. White milkwort, biscuitroot, wild onion and western yarrow may be present as a minor component of the plant community. Forbs represent about 5% of the total annual production. Winterfat, silver sagebrush and rose are common shrubs. Winterfat is valuable forage for wildlife and livestock. Silver sagebrush and fringed sagewort, two 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 prickly pear cactus in the HCPC. Very few cool-season shrubs grow on the site. Overall, shrubs account for about 10% of the annual plant production. Historic NRCS data indicate that total annual production averages 1200 lbs/ac during normal years on Clayey-Steep 10-14” p.z. ecological sites. Average annual production is expected to increase and decrease, respectively on more mesic and xeric portions of the northern Glaciated plains. Although similarity indices (SI) >75% are expected to be associated with the HCPC, none were recorded during recent range inventories. Annual bromes and other annual species may colonize the HCPC following a drought or periods 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 prairie junegrass, plains reedgrass, white milkwort, fringed sagewort, etc. With proper grazing management and non-drought conditions, the higher successional cool season perennial plants regain vigor and will replace the lower successional species within a few years. Litter is in contact with 50-60% of the soil surface. Less than 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. Runoff and soil erosion increase as the HCPC regresses to earlier seral states. 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 precipitation cycle.

Community 1.2
Plant Community A Plant composition shift to shorter grasses and lower annual production, medium- and tall-height cool-season perennial grasses, about 5 percent perennial forbs and 10 percent shrubs.

Plant composition shift to shorter grasses and lower annual production, medium- and tall-height cool-season perennial grasses, about 5 percent perennial forbs and 10 percent shrubs. Total plant production averages about 1,000 lbs/ac in this Plant Community, or 200 lbs/ac less than the HCPC. The decrease in production results from a shift in species composition. Western/thickspike wheatgrasses, threadleaf sedge, blue grama and plains reedgrass increase at the expense of the tall, cool season grasses (bluebunch wheatgrass and green needlegrass). In comparison to the HCPC, production of blue grama, prairie junegrass, plains reedgrass, threadleaf sedge and other short grasses now accounts for about 20% of the total annual production. Exact responses of these species vary with the kind, intensity, frequency and duration of disturbance (drought, grazing, etc.) and precipitation (amount and timing). Total production of native forbs remains at about 5% of annual production of the community. However, the palatable species (prairie clovers, American vetch and dotted gayfeather) decrease in abundance (relative to the HCPC). The open niches allow hairy goldenaster, bastard toadflax, prairie thermopsis, etc. to become more abundant. Shrubs continue to account for about 10% of the total production. However, species such as fringed sagewort and silver sagebrush increased (relative to the HCPC). SI indices from 55-75% are associated with this community. In contrast to the HCPC, range conservationists have serious concerns regarding lower infiltration rates and potentially higher runoff rates, plant functional/structural group shifts, and decreasing amount of litter.

Community 1.3
Plant Community B - Pre-threshold Medium- and short-height cool- and warm-season perennial grasses, increase of forb species, more than 15 percent shrubs.

Medium- and short-height cool- and warm-season perennial grasses, increase of forb species, more than 15 percent shrubs. Plant Community B is dominated by needle and thread grass, blue grama, plains reedgrass, prairie junegrass and upland sedges. Individual plants and remnants of bluebunch wheatgrass, green needlegrass, and western/thickspike wheatgrasses remain in the Community. They have low vigor and there is little successful regeneration. There is an increased presence of lower successional plants. The short grasses and grasslike plants make up about 30% of the total production. Japanese brome, cheatgrass, and lower successional forbs colonize disturbed areas. Total vegetative production declines to about 800 lbs/ac in a normal year. Hairy goldenaster, scarlet globemallow, scurfpeas, cudweed sagewort and other warm season forbs increase at the expense of the prairie clovers and American vetch. Forbs increase and account for about 10% total annual production. Fringed sagewort, a half-shrub, increases at the expense of winterfat. Silver sagebrush, rose and prickly pear cactus also increase in some locations on this site. Shrubs account for about 15% of the total plant production. SI indices for this community vary from 35-55%. Litter provides cover for about 25-30% of the ground, while bare ground increases to about 25%. Rills, water flow patterns and litter movement are evident on the site. The tall cool season grasses have poor vigor, with little seed production. Most of the seedlings and young plants appear to represent short grasses and warm season forbs. Regeneration of desired species is inadequate. Plant Community B is fairly resilient, but it is not highly resistant to disturbance. It is the “pre-threshold” community. Therefore, it is critical that this community be recognized and management strategies implemented to prevent further regression (USDI and USDA 2000). Community B can readily regress to a lower state (State 2), from which succession back to any community within State 1 is restricted without significant energy inputs.

Pathway 1.1A
Community 1.1 to 1.2

No fire, non-prescribed grazing, drought (3 to 5 years) Successional pathways from the HCPC are influenced by frequency, timing and intensity of grazing, precipitation patterns, fire, insect infestations, noxious weed colonization and recruitment, etc. As communities regress from HCPC, medium and short grasses increase at the expense of mid and tall cool season grasses. The medium and short grasses are comprised of cool and warm season species.

Pathway 1.2A
Community 1.2 to 1.1

Prescribed grazing, fire (natural interval 5 to 7 years), normal precipitation Plant Community A is resilient. Successional processes can readily return Plant Community A to the HCPC. The process can be facilitated by prescribed grazing, the incorporation of the natural fire regime into the system, etc. Prior to the arrival of European man, fire occurred at natural intervals of 5-7 years. This succession can occur during normal precipitation regimes.

Pathway 1.2B
Community 1.2 to 1.3

No fire, non-prescribed grazing, drought (3 to 5 years) Prolonged drought, non-prescribed grazing, and the failure to re-introduce fire into the system will result in retrogression to Community B. The causative factors of regression at a specific site should be apparent with careful observation.

Pathway 1.3A
Community 1.3 to 1.2

Prescribed grazing, fire (natural interval 5 to 7 years), favorable precipitation Favorable precipitation, re-introduction of the natural fire regime, and prescribed grazing are normally required for succession to higher communities (HCPC and/or Community A). Management strategies should focus on grazing deferment to increase vigor and seed production of desirable plants, and to increase litter cover. Increasing litter is extremely critical to protect soils from erosion due to the steepness of the slopes.

State 2
Degraded State

Community 2.1
Plant Community C Short, warm-season perennial grasses, cool-season upland sedges, few medium height cool-season grasses, clubmoss may be present, about 10 percent forbs and 20 percent shrubs, invasive species present, more bare ground

Short, warm-season perennial grasses, cool-season upland sedges, few medium height cool-season grasses, clubmoss may be present, about 10 percent forbs and 20 percent shrubs, invasive species present, more bare ground Community C is dominated by blue grama, prairie junegrass, sandberg bluegrass, plains reedgrass, other short grasses, and clubmoss. There are usually some individual western wheatgrass, bluebunch wheatgrass, etc. plants scattered throughout the Community. The ability of these individuals to persist in this state may be due to the relative inaccessibility of the site to grazing. Red threeawn, Japanese brome and cheatgrass are the most common opportunistic plants that colonize this Community. Wooly plantain, hoods phlox, hairy goldenaster, cudweed sagewort and bastard toadflax are common forbs. Fringed sagewort usually increases. Silver sagebrush and rose may also increase. Pricklypear cactus is common in most locations. The most palatable shrubs are nearly absent. SI indices of less than 25% are probably associated with State 2, but none were recorded during the range inventories on Fort Peck and Fort Belknap Reservations in 2001 and 2004. Because of slope and texture, surface runoff and soil erosion should always be concerns on this site. However, wind and water erosion are critical concerns in State 2. As plant cover and litter decrease, rills, water flow patterns and litter movement become more apparent and the potential for erosion escalates. In comparison to the State 1 plant communities, Plant Community C (State 2) is less efficient in capturing solar energy and converting it to carbohydrates for plant growth. Total aboveground vegetation production averages about 400 lbs/ac. The scarcity of tall and mid cool season perennial grasses, plus the shift from cool season plants to warm season plants, indicates that the structural and functional processes of the site have been disrupted.

Transition T1A
State 1 to 2

Non-prescribed grazing, extended drought (greater than 7 years), no fire Any combination of extended drought, non-prescribed grazing and unfavorable climatic patterns can cause regression from Plant Community B to State 2. 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 (USDI, USDA 2000). Thus, the transition from Community B to State 2 represents a threshold. 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 degrade beyond the point of self-repair.

Restoration pathway R2A
State 2 to 1

Prescribed grazing, fire (natural interval 5 to 7 years), time, favorable precipitation Succession from State 2 to State 1 is favored by the implementation of prescribed grazing, a favorable precipitation pattern, and the re-introduction of the natural fire regime. The rate of this succession is influenced by the genetic pool of HCPC plants (seed plants, rhizomes, and seed bank) remaining on the site (Dyksterhuis 1949). In rare instances of prolonged favorable climatic conditions combined with proper management, the significant input of energy that is normally required to move this site from across the threshold from State 2 to State 1 may not be needed. More research is needed on this assertion. Because of the steep slopes, mechanical treatments and range seeding are not recommended. Ranchers should be aware of the limitations of this site. Rather than trying to change nature, managers must learn to live within the environmental boundaries of this site.