State 1
Reference State

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

Tall and medium-height warm- and cool-season perennial grasses, less than 5 percent native perennial forbs, and less than 5 percent native shrubs The HCPC is comprised of a mixture of cool and warm season grasses, forbs and shrubs. About 90% of the annual production is from grasses and sedges, most of which is produced during the cool season. Forbs and shrubs each contribute about 5% to total annual production. Total vegetative production at HCPC averages 2500 lbs/ac in normal years, 3000 lbs/ac in favorable years, and 1750 lbs/ac in “unfavorable” years. The Saline Overflow 10-14” p.z. ecological site is not characterized by a precise assemblage of species that remains constant from place to place or from year to year. Variability is apparent in productivity and occurrence of individual species. Western/thickspike wheatgrasses, alkali sacaton, alkali cordgrass, Nuttall alkaligrass, inland saltgrass and sedges are the most common grasses and grasslike plants in this community. They account for about 90% percent of the total production. Prairie aster and slimleaf goosefoot are common forbs. Forbs usually make up about 5% of the total annual production. Greasewood and Nuttall saltbush are the most common shrubs. They should be present in the HCPC. However, all shrubs only account for about 5% of the total annual production. Plant basal cover is normally around 35%, while litter provides 65% cover. Therefore, plant cover and litter are adequate to efficiently utilize infiltration, minimize runoff and erosion, and provide good hydrologic conditions. Runoff and soil erosion normally increase as the HCPC regresses to earlier seral states. The HCPC is believed to have evolved with periodic fires occurring at intervals of 5-7 years. Fires temporarily reduce litter, thus allowing more runoff. However, fire favors the succession of grasses and forbs at the expense of half-shrubs and shrubs. The HCPC regresses to lower seral stages when subjected to grazing management strategies that do not allow adequate recovery periods between grazing events, drought, the disruption of the normal fire sequence, and or a change in the availability of run-in water. The above disturbances favor the replacement of alkali sacaton, alkali cordgrass, and western/thickspike wheatgrasses with blue grama, sandberg bluegrass, curlycup gumweed, western yarrow, and foxtail barley. 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 Salt-tolerant, short-height warm-season perennial grasses, less than 5 percent salt-tolerant shrubs

Salt-tolerant, short-height warm-season perennial grasses, less than 5 percent salt-tolerant shrubs In contrast to the HCPC, total vegetation production may be 1000 lbs/ac lower in Community A. Selective grazing and increasing salinity adversely affect the competitiveness of alkali sacaton, alkali cordgrass, wheatgrasses and Nuttall’s alkaligrass. Thus, these taller warm and cool season grasses are replaced by inland saltgrass and other low-growing grasses and grasslike plants. The lower-stature plants tend to produce less forage than the mid- grasses that they replaced, use less ground water for total vegetative production, and produce less litter to protect the surface of the soil. As the groundwater rises to the surface during the summer and evaporates, salt crystals form on the surface. Thus the amount of bare ground increases, in comparison to the HCPC. Greasewood tends to increase and the total shrub production in Community A is >5%. Shrub composition also shifts, favoring chenopod species. Plant Community A is considered the pre-threshold community. It can be recognized because annual production is reduced by about 40% from the HCPC. The percentage of short, warm season perennial grasses and forbs has increased at the expense of the taller warm and cool season perennial grasses. Litter amount is moderately reduced from site potential and amount of bare ground is moderately to much higher than expected. This community remains resilient and succession can move the plant community toward the HCPC. However, Plant Community A is only moderately resistant to disturbance. Without proper management it can readily regress to a lower state.

Pathway 1.1A
Community 1.1 to 1.2

Non-prescribed grazing, no fire, reduced run-in moisture from adjacent upland sites. Non-prescribed grazing and reduced run-in moisture from adjacent upland sites will cause regression from HCPC to Community A.

Pathway 1.2A
Community 1.2 to 1.1

Prescribed grazing, fire, normal precipitation The implementation of prescribed grazing, or periodic fire will move Plant Community A to the HCPC. Under non-drought conditions, this succession can occur within a few years.

State 2
Short Grass Dominated

Community 2.1
Plant Community B Warm-season short perennial grasses with patches of bare ground and surface salts, increase of low-successional salt-tolerant forbs

Warm-season short perennial grasses with patches of bare ground and surface salts, increase of low-successional salt-tolerant forbs Inland saltgrass, sand dropseed, sandberg bluegrass, bottlebrush squirreltail, foxtail barley, and sedges dominate this community. In contrast to the HCPC, the mid and tall warm season perennial grasses (alkali sacaton, western/thickspike wheatgrasses, alkali cordgrass, etc.) are either significantly reduced or absent. Poverty weed, knotweed, seepweed, curlycup gumweed and other forbs account for about 10% of the annual production. Amount of bare ground is moderately higher than expected. Surface salts are quite extensive. Most of the study sites examined on the Saline Overflow 10-14” p.z site during the range inventory of the Fort Peck and Fort Belknap Reservations (2001-2004) had similarity indices of 0-25%. A lack of species diversity also characterizes the data. In most plots, fewer than 8-9 species were recorded. Shrubs were recorded at 3 of the 15 sampling locations. In these inventories, which took place during a prolonged drought, the annual production varied from 53 to 1043 lbs/ac, and averaged 600 lbs/ac. The amount of bare ground was much higher than expected for the site. This plant community is resistant to change. The short warm season perennial grasses are well-adapted to the salinity. It is believed that the seeds of native HCPC species are scarce or absent in the seedbank. Succession is not expected to occur within a reasonable length of time.

State 3
Shrub dominated

Community 3.1
Plant Community C Salt-tolerant native shrub-dominated with minimal herbaceous component, bare ground conspicuous.

Salt-tolerant native shrub-dominated with minimal herbaceous component, bare ground conspicuous. Greasewood is the dominant plant is this community, which is less than fully understood at this time (dash lines mark its boundary in the S&T diagram). Other shrubs include Nuttall saltbush, rabbitbrush, fringed sagewort and silver sagebrush. Inland saltgrass, foxtail barley, Nuttall alkali grass, and other herbaceous species usually produce less than 50% of the total annual production. Poverty weed, curlycup gumweed, arrowgrass, knotweed and other weedy forbs are usually present in small amounts. Total annual production is usually less than 500 lbs/ac. The amount of bare ground is much higher than expected for the site. In addition, litter cover averages about 30%, a significant reduction relative to site potential. This plant community is resistant to change. Greasewood is well adapted to the salinity. This community may not be resilient. Succession is not expected to occur within a reasonable length of time.

Transition T1A
State 1 to 2

Non-prescribed grazing, extended drought (greater than 7 years), no fire, reduced run-in moisture from adjacent upland sites The reference state (State 1) will regress to State 2 under non-prescribed grazing, prolonged drought, and an extended period of no fire. The rate of regression varies with the kind, intensity, frequency and duration of the disturbances. The transition may end up as a warm season short grass dominated community (State 2).

Transition T1B
State 1 to 3

Non-prescribed grazing, extended drought (greater than 7 years), no fire, increase in subsurface water The reference state (State 1) will regress to State 3 under non-prescribed grazing, prolonged drought, and an extended period of no fire. The rate of regression varies with the kind, intensity, frequency and duration of the disturbances. The transition may end up as a salt-tolerant shrub-dominated community (State 3). The shrub dominated community is depicted within the dashed lines (in the state and transition diagram) because its ecological characteristics are not presently fully understood.

Restoration pathway R2A
State 2 to 1

Prescribed grazing, fire, favorable precipitation The implementation of prescribed grazing is not expected to move these plant communities toward a higher successional state. In comparison to the HCPC, annual production is about 25% of the site potential. It is theorized that the salinity of the site increased during the regression from the “Reference State” to early seral states. Thus, the lower-successional plants occurring on the site may be better-adapted than some of the original climax species. Because of the soil limitations, mechanical treatments and range seeding are not normally recommended.