Natural Resources
Conservation Service
Ecological site R010XA024OR
Pumice North 8-10 PZ
Last updated: 12/13/2023
Accessed: 11/21/2024
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.
Ecological site concept
In reference condition, this site supports a plant community dominated by Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Pseudoroegneria spicata) with an overstory of mountain big sagebrush (Artimesia tridentata ssp. vaseyana) and sparse old growth western juniper (Juniperus occidentalis). Abiotically, this site is characterized by moderately deep, pumice and ash influenced soils occurring primarily on north aspects. The high ash content of these soils increases available water content and effective precipitation thereby facilitating the presence of species such as Idaho fescue and mountain big sagebrush. The soil climate is Mesic/Aridic. Historically, plant community dynamics were driven by disturbances such as fire, drought and insect/disease. Presently, reference conditions are less common and current dynamics are influenced by the spread of invasive species, infill of western juniper, livestock grazing pressures and fire suppression.
Associated sites
R010XA007OR |
Juniper Pumice South 9-12 PZ South aspects receiving higher precipitation |
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R010XA022OR |
Juniper Lava Blisters 8-10 PZ Occupying adjacent lava blisters |
R010XA027OR |
Juniper Pumice Flat 8-10 PZ Occupying adjacent low slope, non-aspect positions |
Similar sites
R010XA026OR |
Juniper Pumice North 10-12 PZ Higher precipitation |
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Table 1. Dominant plant species
Tree |
(1) Juniperus occidentalis |
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Shrub |
(1) Artemisia tridentata ssp. vaseyana |
Herbaceous |
(1) Festuca idahoensis |
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Ecosystem states
States 2 and 5 (additional transitions)
T1A | - | Introduction of non-native species |
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T2A | - | Less frequent fire and/or extended drought reduces perennial bunch grasses and allows for an increase in shrub/tree species. |
T2B | - | Catastrophic fire; often coupled with soil disturbing activities and/or extended drought. |
T2C | - | Time and lack of disturbance allows for maturation of the tree community. |
T3A | - | Catastrophic fire, multiple fires, and/or soil disturbing treatments/activities. |
T3B | - | Time and lack of disturbance allows for maturation of the tree community. |
R5A | - | Mechanical treatment of trees coupled with seeding of desired species. |