Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
Figure 1. Mapped extent
Areas shown in blue indicate the maximum mapped extent of this ecological site. Other ecological sites likely occur within the highlighted areas. It is also possible for this ecological site to occur outside of highlighted areas if detailed soil survey has not been completed or recently updated.
Major Land Resource Area (MLRA): 058C–Northern Rolling High Plains, Northeastern Part
MLRA 58C covers 2,780 square miles and encompasses approximately 1.8 million acres. MLRA 58C spans two states with 96% of the area in North Dakota and 4% in Montana. The acreage inside MLRA 58C is 54% privately owned and 44% federal land. The federal land consists of the Fort Berthold Indian Reservation, Little Missouri National Grasslands, and Theodore Roosevelt National Park. MLRA 58C landscape is characterized by steeply sloping, dissected badlands along the Little Missouri River and its tributaries. Tertiary marine shale, siltstone, and sandstone sediments are the most common soil parent materials in this MLRA. Primary land uses are rangeland for grazing and wildlife habitat. Micro-climates inherent in badlands landscapes influence both variety and abundance of vegetation in MLRA 58C. South- and west-facing exposures are dry, hot, and sparsely vegetated. More humid and cooler north- and east-facing exposures are favorable for abundant forage and woody vegetation.
Major land resource area (MLRA): 058C-Northern Rolling High Plains, Northeastern Part
Ecological site concept
The Clayey ecological site in MLRA 58C occurs on stable backslopes, erosional foot slopes, and toe slopes of upland landforms. Slopes range from 0 to 35 percent. Soils on this site are moderately deep to deep, fine-textured soils with greater than 18 percent clay in the surface horizon and greater than 35 percent clay in the subsoil. Soils on the Clayey ecological site formed in calcareous residuum and in alluvium derived from residuum. Thickness of the soil surface horizon ranges from 3 to 15 inches.
The Claypan ecological site is adjacent to and in conjunction with the Clayey ecological site. The Claypan site has well or moderately well drained, moderately deep to very deep soils on the same upland landforms as the Clayey site, but lateral subsurface water movement and sodium in the soil have formed a dense claypan layer in these soils. The Claypan site has soils with a dense sodic subsoil below 6 inches with visible salts and gypsum crystals below 16 inches. Like the Clayey ecological site, Claypan sites are down slope from Shallow Loamy sites and up slope from Loamy Overflow ecological sites. The indicator species are western wheatgrass with blue grama, heath aster, and western yarrow along with a few shrubs of fringed sagewort and Nuttall’s Saltbush. This site has less western wheatgrass, significantly less green needlegrass, and lower production than the Clayey ecological site.
Soils on the Loamy Overflow ecological site developed in run-on positions such as swales and drainageways that accumulate sediments eroded from the surrounding landforms and receive additional moisture from runoff. When associated with Clayey ecological sites, soils on Loamy Overflow sites are typically fine-textured and will make a ribbon longer than 2 inches before breaking. Soils on the Loamy Overflow site are moderately well drained, very deep soils with a thick, dark A horizon that is usually at least 16 inches thick. Carbonates, if present, are deeper in the soil profile than on the Clayey site. The Loamy Overflow ecological site is down slope from Clayey, Loamy, Limy Residual, and Claypan sites, and is typically in drainageways below steeper landforms or in swales at the head of upland wooded draws. Principle species: Big bluestem, green needlegrass, and western wheatgrass.
Loamy ecological sites are often adjacent to Clayey ecological sites on upland landforms that do not receive additional moisture from runoff or flooding. Loamy sites are on similar upland landforms and landscape positions as the Clayey sites, but the soil parent materials are medium-textured, soft siltstone or mudstone sedimentary beds, rather than fine-textured shale beds. Loamy ecological sites have well-drained, moderately deep to very deep, medium-textured soils that will form a ribbon longer than 1 inch, but less than 2 inches before breaking. Like the Clayey ecological site, Loamy ecological sites are up slope from Loamy Overflow sites and down slope from Limy Residual and Shallow Loamy ecological sites. Indicator species are western wheatgrass, green needlegrass, and blue grama, with fringed sagewort and western snowberry being the dominant shrubs. This site has less green needlegrass and western wheatgrass, but has slightly higher production than the Clayey ecological site.
Due to limited acres in MLRA 58C, the Shallow Clayey ecological site was combined with the Shallow Loamy ecological site. When associated with the Clayey site in MLRA 58C, soils on Shallow Loamy sites may be fine-textured or medium-textured, depending on the sedimentary parent material from which they formed. If fine textured, the soils on Shallow Loamy sites will make a ribbon longer than 2 inches before breaking. If medium textured, the soils will make a ribbon longer than 1 inch, but less than 2 inches before breaking. Soils on the Shallow Loamy ecological site are well drained with soft, unweathered shale, siltstone, or mudstone beds between 10 inches and 20 inches below the soil surface. The unweathered shale, siltstone, and mudstone beds are a root restrictive layer. Shallow Loamy sites are up slope from Clayey, Claypan, and Loamy sites and down slope from Very Shallow sites. This site has less production than the Clayey site due to its position on droughty shoulder slopes of steep upland landforms and the presence of a restrictive layer above twenty inches. Indicator species: western wheatgrass, blue grama, little bluestem, plains muhly, and sideoats grama, with dotted gayfeather, fringed sagewort, western yarrow, and shrubs like broom snakeweed.
Table 1. Dominant plant species
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