State 1
Needleandthread, Little Bluestem/Bluebunch Wheatgrass, Rhizomatous Plant Community

Community 1.1
Needleandthread, Little Bluestem/Bluebunch Wheatgrass, Rhizomatous Plant Community

This is the interpretive plant community and is considered to be the Historic Climax Plant Community (HCPC). This plant community evolved with grazing by large herbivores and is well suited for grazing by domestic livestock and can be found on areas that are grazed and where the grazed plants receive adequate periods of rest during the growing season in order to recover. Historically, fires likely occurred infrequently. The potential vegetation is about 80-95% grasses or grass-like plants, 5-15% forbs, and 0-5% woody plants. Combinations of warm and cool-season mid-grasses dominate the plant community. The major grasses and grass-likes include needleandthread, little bluestem, rhizomatous wheatgrasses, threadleaf sedge, and blue grama. Other grasses include prairie sandreed, sideoats grama, and bluebunch wheatgrass. Bluebunch wheatgrass is found in Wyoming, primarily in the western portion of the 15-17” Precipitation Zone at higher elevations. Dominant forbs are prairie clovers, dotted gayfeather, hairy goldaster, fringed sagewort, buckwheats, and lemon scurfpea. Commonly found shrubs include yucca, winterfat, and pricklypear cactus. Skunkbush sumac and true mountainmahogany can also be found primarily on rock outcrops. In the 12 to 14 inch precipitation zone, the total annual production (air-dry weight) is about 900 pounds per acre during an average year, but it can range from about 600 pounds per acre in unfavorable years to about 1200 pounds per acre in above average years. In the 15 to 17 inch precipitation zone, the total annual production (air-dry weight) is about 1100 pounds per acre during an average year, but it can range from about 750 pounds per acre in unfavorable years to about 1500 pounds per acre in above average years. This plant community is well adapted to the Northern Great Plains climate. This is a sustainable plant community (soil stability, watershed function, and biologic integrity). Infiltration rates are moderate due to the rapid intake rate of the soils and the relatively steep topography. Soil erosion is low. Transitions or pathways leading to other plant communities are as follows: • Frequent and severe defoliation will move this plant community towards the Threadleaf Sedge, Blue Grama with Remnant Mid-grasses Plant Community. Over a period of years, plant species less tolerant to frequent or severe defoliation will begin to decrease, and those more tolerant will begin to increase. • No use and no fire will move this plant community towards the Low Plant Density, Excess Litter Plant Community. Initially, excess litter begins to build-up. Eventually native plant density begins to decrease and weeds and introduced species may begin to invade.

State 2
Threadleaf Sedge, Blue Grama with Remnant Mid-Grasses Plant Community

Community 2.1
Threadleaf Sedge, Blue Grama with Remnant Mid-Grasses Plant Community

This plant community typically develops over a period of several years, under frequent and severe defoliation during the growing season of the mid-grasses. It typically is made up of sod-forming grasses with only remnants of mid-grasses remaining. Palatable forbs have been reduced. Compared to the HCPC, threadleaf sedge and blue grama have increased noticeably. Many of the mid-grasses have been reduced. If the plant community received adequate rest periods only during the early part of the growing season, the little bluestem, prairie sandreed, and sideoats grama will have been reduced. If the plant community received adequate rest periods only during the later part of the growing season, the rhizomatous wheatgrasses, bluebunch wheatgrass, and needleandthread will have been reduced. Significant forbs include cudweed sagewort, hairy goldaster, western ragweed, and slimflower scurfpea. Common shrubs include broom snakeweed, yucca, and pricklypear cactus. Plant diversity is moderate. In the 12 to 14 inch precipitation zone, the total annual production (air-dry weight) is about 700 pounds per acre during an average year, but it can range from about 450 pounds per acre in unfavorable years to about 950 pounds per acre in above average years. In the 15 to 17 inch precipitation zone, the total annual production (air-dry weight) is about 850 pounds per acre during an average year, but it can range from about 550 pounds per acre in unfavorable years to about 1,150 pounds per acre in above average years. Nearly all the plant species typically found in the HCPC are present and will respond to changes in grazing management. This plant community can become somewhat resistant to change, depending on how sod-bound the plant community has become. While soil erosion is low, infiltration has been reduced, and overland flow has been increased. This can result in off-site gully erosion. Transitions or pathways leading to other plant communities are as follows: • Frequent and severe defoliation will over time move this plant community toward the Threadleaf Sedge/Blue Grama Sod without Mid-grasses Plant Community. Plants less tolerant to grazing will decrease and those more tolerant to grazing will increase or invade. • Prescribed grazing will move this plant community towards the Needleandthread, Little Bluestem/Bluebunch, Rhizomatous Wheatgrass Plant Community (HCPC). If the community has become sod-bound, grazing land mechanical treatment (such as chiseling on the contour) could accelerate this transition by increasing infiltration and breaking up the sod. However, this may not be economically feasible due to shallow soils and low production potential.

State 3
Low Plant Density, Excess Litter Plant Community

Community 3.1
Low Plant Density, Excess Litter Plant Community

This plant community developed under the absence of grazing and fire. At first, excessive litter builds up shading out plants such as blue grama. Plants become decadent with low vigor. Bunch grasses, such as little bluestem and bluebunch wheatgrass, often develop dead centers. Eventually, the interspaces between the plants increase in size leaving more soil surface exposed. The dominant plants are similar to those found in the HCPC, but with less vigor. Annual weeds, cool-season grasses, and cactus typically have increased. Blue grama is reduced and western wheatgrass is increased. Noxious weeds such as Canada thistle, leafy spurge, and Dalmatian toadflax will invade, if a seed source is readily available. Kentucky bluegrass also tends to invade under these conditions. In the 12 to 14 inch precipitation zone, the total annual production (air-dry weight) is about 800 pounds per acre during an average year, but it can range from about 550 pounds per acre in unfavorable years to about 1,050 pounds per acre in above average years. In the 15 to 17 inch precipitation zone, the total annual production (air-dry weight) is about 1,000 pounds per acre during an average year, but it can range from about 650 pounds per acre in unfavorable years to about 1,350 pounds per acre in above average years. This plant community can be improved relatively quickly, if it has not been significantly eroded or invaded by noxious weeds. The introduction of grazing or fire will quickly move the plant community towards the HCPC. Soil erosion can become accelerated because of increased bare ground, if these conditions are allowed to continue over the long-term. Water flow patterns and pedestaling can become obvious. At that point, infiltration is reduced and runoff is increased. Transitions or pathways leading to other plant communities are as follows: • Prescribed grazing or fire will move this plant community towards the Needleandthread, Little Bluestem/Bluebunch, Rhizomatous Wheatgrass Plant Community (HCPC). This can occur relatively fast.

State 4
Threadleaf Sedge/Blue Grama Sod without Mid-Grasses Plant Community

Community 4.1
Threadleaf Sedge/Blue Grama Sod without Mid-Grasses Plant Community

This plant community develops under long-term frequent and severe defoliation. This typically occurs when the community has been continuously grazed with heavy stocking rates, throughout the growing season over a period of many years. It is a dense sod made up of sedges and warm season grasses. The mid-grasses and palatable forbs have been nearly eliminated. Compared to the HCPC, threadleaf sedge and blue grama have greatly increased and now dominate. Little bluestem, sideoats grama, bluebunch wheatgrass, and needleandthread have been removed. Only remnants of rhizomatous wheatgrasses typically remain. Plant diversity is very low. In the 12 to 14 inch precipitation zone, the total annual production (air-dry weight) is about 550 pounds per acre during an average year, but it can range from about 350 pounds per acre in unfavorable years to about 750 pounds per acre in above average years. In the 15 to 17 inch precipitation zone, the total annual production (air-dry weight) is about 650 pounds per acre during an average year, but it can range from about 450 pounds per acre in unfavorable years to about 850 pounds per acre in above average years. Even with the best range management, this plant community is extremely resistant to change. This is due to the fact that many of the plant species are missing and a seed source is not readily available. Also, the sod-forming grasses tend to maintain themselves due to their resistance to any further overgrazing. If disturbed, it will usually return to a plant community very similar to that found prior to the treatment. The soil erosion is very low due to the sod-bound condition. Greatly reduced infiltration and increased runoff typically cause off-site gully erosion. This significantly reduces the amount of precipitation available for plant growth. Transitions or pathways leading to other plant communities are as follows: • Frequent and severe defoliation can move this plant community to a Bare Ground, Threadleaf sedge, Invaders Plant Community. • Very long-term prescribed grazing may eventually result in the Threadleaf Sedge, Blue Grama with Remnant Mid-Grasses Plant Community. This change may take generations depending on the availability of an adequate seed/vegetative source. Range or pasture planting may be the only option to return this community to a productive condition in a realistic time frame; however, this may not be economically feasible due to the shallowness of the soils and low production potential.

State 5
Bare Ground, Threadleaf sedge, Invaders Plant Community

Community 5.1
Bare Ground, Threadleaf sedge, Invaders Plant Community

This plant community occurs where the rangeland is grazed year-round, at high stock densities. Physical impact such as trampling, soil compaction, and trailing typically contribute to this transition. The plant composition is made of annuals with a few species of perennial forbs and grasses that are very tolerant to frequent and severe defoliation. The dominant perennial grasses and grass-likes include threadleaf sedge, blue grama, and threeawns. Annual grasses such as cheatgrass and sixweeks fescue have increased. The dominant forbs include curlycup gumweed, phlox, sandwort, hairy goldaster, green sagewort, and annuals. Broom snakeweed, yucca, and pricklypear cactus are increasing. Compared to the Historic Climax Plant Community, all perennial plants have been greatly reduced with only remnants of the most grazing tolerant species present. Plant diversity is very low if annuals and weedy species are not considered. In the 12 to 14 inch precipitation zone, the total annual production (air-dry weight) is about 450 pounds per acre during an average year, but it can range from about 300 pounds per acre in unfavorable years to about 600 pounds per acre in above average years. In the 15 to 17 inch precipitation zone, the total annual production (air-dry weight) is about 550 pounds per acre during an average year, but it can range from about 350 pounds per acre in unfavorable years to about 750 pounds per acre in above average years. This plant community is very resistant to change. Even with the best range management, this plant community may never return to the HCPC. If disturbed, it will usually return to the plant community found prior to the treatment, sometimes only affecting production for a short time. Soil erosion can be highly variable depending on the amount of ground cover. Typically there is a large amount of bare ground unless covered by annuals. Typically, runoff is high and infiltration is low. Transitions or pathways leading to other plant communities are as follows: • Very long-term prescribed grazing will move this plant community toward the Threadleaf Sedge/Blue Grama Sod without Mid-Grasses Plant Community over many years. Range or pasture planting may be the only option to return this community to a productive condition in a realistic time frame; however, this may not be economically feasible due to shallow soils and low production potential.