Natural Resources
Conservation Service
Ecological site R010XC042OR
SR Juniper Tableland 12-16 PZ
Last updated: 12/13/2023
Accessed: 10/03/2024
General information
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.
MLRA notes
Major Land Resource Area (MLRA): 010X–Central Rocky and Blue Mountain Foothills
This MLRA is characterized by gently rolling to steep hills, plateaus, and low mountains at the foothills of the Blue Mountains in Oregon and the Central Rocky Mountains in Idaho. The geology of this area is highly varied and ranges from Holocene volcanics to Cretaceous sedimentary rocks. Mollisols are the dominant soil order and the soil climate is typified by mesic or frigid soil temperature regimes, and xeric or aridic soil moisture regimes. Elevation ranges from 1,300 to 6,600 feet (395 to 2,010 meters), increasing from west to east. The climate is characterized by dry summers and snow dominated winters with precipitation averaging 8 to 16 inches (205 to 405 millimeters) and increasing from west to east. These factors support plant communities with shrub-grass associations with considerable acreage of sagebrush grassland. Big sagebrush, bluebunch wheatgrass, and Idaho fescue are the dominant species. Stiff sagebrush, low sagebrush, and Sandberg bluegrass are often dominant on sites with shallow restrictive layers. Western juniper is one of the few common tree species and since European settlement has greatly expanded its extent in Oregon. Nearly half of the MLRA is federally owned and managed by the Bureau of Land Management. Most of the area is used for livestock grazing with areas accessible by irrigation often used for irrigated agriculture.
Classification relationships
Plant Associations of the Blue and Ochoco Mountains, Johnson and Clausnitzer, 1992:
CJS8 - Juniperus occidentalis/Artemisia rigida plant community
Bunchgrass Plant Communities of the Blue and Ochoco Mountains: A Guide for Managers, Johnson and Swanson, 2005:
CJS811- Juniperus occidentalis/Artemisia rigida plant community type
Landfire Biophysical Setting Model:
Note: This model was developed specifically for the Columbia Plateau but fits the characteristics of this site very well despite the absence of old growth juniper
0810650: Columbia Plateau Scabland Shrubland
Ecological site concept
This site occurs on upland tablelands with very shallow soils over hard igneous extrusive geologies (basalt, andesite, rhyolite, tuff, etc.). In the reference state, the site is characterized by old growth juniper (Juniperus occidentalis), scabland sagebrush (Artemisia rigida), Sandberg bluegrass (Poa secunda) and one-spike oatgrass (Danthonia unispicata). Highly fractured bedrock and low fuel loads would have historically facilitated the persistence of old growth juniper on this site. This is a low production site (potentially the lowest of the juniper community types at the foothills of the Blue and Ochoco mountains, Johnson and Swanson 2005) with production limited by the low water holding capacity of the soil. Precipitation comes in the form of snow and rain primarily in the winter and early spring. The soil profile is not able to store all the moisture that the site receives, and excess moves to adjacent sites. Historically, plant community dynamics were driven primarily by drought disturbance and very infrequent fire due to patchy fuel distribution.
Associated sites
R010XC047OR |
SR Mountain South 12-16 PZ SR Mountain South 12-16 PZ (moderate deep soil, south aspect, higher production, different composition – ARTRV-X,T/PSSPS association) |
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R010XC054OR |
SR Mountain Shallow South 12-16 PZ SR Mountain Shallow South 12-16 PZ (shallow soil, south aspect, higher production, different composition – ARTRV-X,T/PSSPS association) |
R010XC059OR |
SR Mahogany Rockland 12+ PZ SR Mahogany Rockland 12+ PZ (shallow soil over fractured bedrock with areas of exposed rock outcrop, higher production, different composition – JUOC/CELE3-PUTR2/PSSPS-FEID association) |
R010XC068OR |
SR Cool Mountain North 12-16 PZ SR Cool Mountain North 12-16 PZ (moderate deep to deep soil, north aspect, higher production, different composition ARTRV-X,T/FEID association) |
R010XC075OR |
SR Mountain Shallow North 12-16 PZ SR Mountain Shallow North 12-16 PZ (shallow soil, north aspect higher production, different composition – ARTRV/FEID-PSSPS-POSE association) |
R010XC041OR |
SR Very Shallow Rockland 12-16 PZ SR Very Shallow Rockland 12-16 PZ (very shallow soil depth with areas of exposed bedrock, lower production, different composition – ACTH7-POSE/ERIOG association) |
R010XC029OR |
SR Shallow Cool 12-16 PZ SR Shallow Cool 12-16 PZ (shallow soil, higher production, different composition – ARTRV-X,T/FEID-PSSPS association) |
R010XC033OR |
SR Cool 12-16 PZ SR Cool 12-16 PZ (moderate deep soil, higher production, different composition – ARTRV-X,T/FEID association) |
R010XC037OR |
SR Mountain Shallow 12-16 PZ SR Mountain Shallow 12-16 PZ (shallow soil, higher production, different composition – ARTRV/FEID association) |
R010XC039OR |
SR Very Shallow 12-16 PZ SR Very Shallow 12-16 PZ (very shallow soil with less substratum fracture, lower production, different composition – ARRI2/POSE-DAUN-FEID association) |
Similar sites
R010XC041OR |
SR Very Shallow Rockland 12-16 PZ SR Very Shallow Rockland 12-16 PZ (very shallow soil depth with areas of exposed bedrock, lower production, different composition – ACTH7-POSE/ERIOG association) |
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R010XC040OR |
SR Very Shallow 16-20 PZ SR Very Shallow 16-20 PZ (higher elevation, greater precipitation and production) |
R010XC038OR |
SR Very Shallow 9-12 PZ SR Very Shallow 9-12 PZ (lower elevation and precipitation, less production, different composition – DAUN absent) |
R010XC039OR |
SR Very Shallow 12-16 PZ SR Very Shallow 12-16 PZ (very shallow soil with less substratum fracture, lower production, different composition – ARRI2/POSE-DAUN-FEID association) |
Table 1. Dominant plant species
Tree |
(1) Juniperus occidentalis |
---|---|
Shrub |
(1) Artemisia rigida |
Herbaceous |
(1) Poa secunda |
Click on box and path labels to scroll to the respective text.
Ecosystem states
T1 | - | Introduction of non-native species. |
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T2A | - | Catastrophic fire and/or soil disturbing treatments. |
T2B | - | Prolonged time without fire during climate conditions conducive to juniper expansion. |
T3A | - | Continued inappropriate grazing management leading to excessive trampling, compaction and soil loss. |
R4A | - | Removal of young juniper infill and reduction of excessive shrub cover may be possible by mechanical means but will be limited by site characteristics. |
T4A | - | Catastrophic fire, multiple fires, or failed rehabilitation attempt allowing for the increased invasion of annual herbaceous species. |
T4B | - | Time and lack of fire allowing for further juniper expansion and loss of soil cover. |
State 1 submodel, plant communities
P1.1a | - | Low severity fire creates shrub/grass mosaic; high severity fire significantly reduces shrub and young juniper cover and leads to early/mid seral community, dominated by grasses and forbs. |
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P1.1b | - | Time and lack of disturbance. Excessive herbivory and long-term drought may also reduce perennial understory. |
P1.2a | - | Time and lack of disturbance allows for shrub regeneration. |
P1.3a | - | Low severity fire reduces some shrub and tree cover and creates shrub/grass mosaic. |
P1.3b | - | Moderate severity fire significantly reduces shrub and tree cover and leads to early/mid seral community, dominated by grasses and forbs. |