Ecological site group description

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.

Physiography

Hierarchical Classification
Major Land Resource Area (MLRA): 8 – Columbia Plateau

LRU – Common Resource Areas (CRA):
8.5 - Moist Yakima Folds


Site Concept Narrative:
Diagnostics:

Sand, south aspect, Columbia Hills is an upland grassland site occurring on the south side of the Columbia Hills in Klickitat county. Soils are moderately deep to deep, coarse textured and well drained. The most common textures are sand and loamy fine sand.

Note: due to historic farming and grazing the south side of the Columbia Hills has been heavily disturbed. No pristine remnant is known, so the reference state has been reconstructed based on experience in MLRA 8.

The south side of the Columbia Hills is a grassland steppe area and has not had sagebrush for more than 50 years and is not expected to have sagebrush. This area does not have sagebrush, nor bitterbrush, and no rabbitbrush except for one small area near the Columbia River.

Needle and thread and Indian ricegrass would be the dominate species in the reference state. Onespike oatgrass, Eriogonum species and balsamroot would also be common.


Principle Vegetative Drivers:

The coarse-textured soils and south aspect drive the vegetative expression of this site. The soil would favor sand-loving species such as needle and thread and Indian ricegrass.


Influencing Water Features:

A plant’s ability to grow on a site and overall plant production is determined by soil-water-plant relationships
1. Whether rain and melting snow runs off-site or infiltrates into the soil
2. Whether soil condition remain aerobic or become saturated and become anaerobic
3. Water drainage and how quickly the soil reaches wilting point

Sand, south aspect, Columbia Hills ecological sites are well drained and dry down quicker than adjacent Loamy ecological sites.


Physiographic Features:

The landscape is part of the Columbia basalt plateau. Sand, south aspect, Columbia Hills is commonly found on terraces, terrace escarpments, benches and plateaus of the Columbia Hills in Klickitat County.

Physiographic Division: Intermontane Plateau
Physiographic Province: Columbia Plateau
Physiographic Sections: Walla Walla Plateau Section

Landscapes: Hills and plateaus
Landform: Terraces, terraces escarpments, hillslopes, dunes

Elevation: Dominantly 150 to 1,700 feet
Central tendency: 300 to 1,500 feet
Slope: Total range: 0 to 65 percent
Central tendency: 10 to 50 percent
Aspect: Dominantly southern aspects, but can occur on all aspects


Geology:

This MLRA is almost entirely underlain by Miocene basalt flows. Columbia River basalt is covered in many areas with as much as 200 feet of loess and volcanic ash. Small areas of sandstones, siltstones, and conglomerates of the Upper Tertiary Ellensburg Formation are along the western edge of this area. Some Quaternary glacial drift covers the northern edge of the basalt flows, and some Miocene-Pliocene continental sedimentary deposits occur south of the Columbia River, in Oregon.

A wide expanse of scablands in the eastern portion of this MLRA, in Washington, was deeply dissected about 16,000 years ago, when an ice dam that formed ancient glacial Lake Missoula was breached several times, creating catastrophic floods. The geology of the northernmost part of this MLRA is distinctly different from that of the rest of the area. Alluvium, glacial outwash, and glacial drift fill the valley floor of the Okanogan River and the side valleys of tributary streams. The fault parallel with the valley separates pre-Tertiary metamorphic rocks on the west, in the Cascades, from older, pre-Cretaceous metamorphic rocks on the east, in the Northern Rocky Mountains. Mesozoic and Paleozoic sedimentary rocks cover the metamorphic rocks for most of the length of the valley on the west.

Climate

Grasslands do not have shrubs because they receive more spring precipitation especially in March (Daubenmire). The climate is characterized by moderately cold, wet winters, and hot, dry summers, with limited precipitation due to the rain shadow effect of the Cascades. Winter fog is variable and often quite localized, as the fog settles on some areas but not others. Compared to the rest of MLRA 8, the south side of the Columbia Hills is dry and hot. Taxonomic soil climate is xeric moisture regime with a mesic temperature regime.

Mean Annual Precipitation:
Range: 10 – 14 inches
Seventy to seventy-five percent of the precipitation comes late October through March as a mixture of rain and snow. June through early October is mostly dry.

Mean Annual Air Temperature:
Range: 46 to 54 F
Central Tendency: 48 – 52 F
Freezing temperatures generally occur from late-October through early-April. Temperature extremes are 0 degrees in winter and 110 degrees in summer.

Frost-free Period (days):
Total range: 110 to 180
Central tendency: 120 to 150
The growing season for Sands is March through mid-May.

Soil features

Edaphic:

The Sand, south aspect, Columbia Hills ecological site occurs with Loamy, Shallow Stony, and Very Shallow ecological sites.


Representative Soil Features:

This ecological site components are dominantly Typic and Xeric taxonomic subgroups of Haploxerolls and Xeropsamments great groups of the Mollisols and Entisols taxonomic orders. Soils are dominantly very deep. Average available water capacity of about 3.0 inches (7.6 cm) in the 0 to 40 inches (0-100 cm) depth range.

Soil parent material is dominantly mixed eolian deposits with colluvium and residuum.

The associated soils are Dallesport, Ewall, Haploxerolls and similar soils.

Dominate soil surface is sand to very cobbly fine sandy loam.

Dominant particle-size class is loamy to sandy-skeletal.

Fragments on surface horizon > 3 inches (% Volume):
Minimum: 0
Maximum: 2
Average: 0

Fragments within surface horizon > 3 inches (% Volume):
Minimum: 0
Maximum: 25
Average: 10

Fragments within surface horizon ≤ 3 inches (% Volume):
Minimum: 0
Maximum: 25
Average: 10

Subsurface fragments > 3 inches (% Volume):
Minimum: 0
Maximum: 25
Average: 10

Subsurface fragments ≤ 3 inches (% Volume):
Minimum: 0
Maximum: 50
Average: 20

Drainage Class: Well drained to excessively drained
Water table depth: Greater than 60 inches

Flooding:
Frequency: None

Ponding:
Frequency: None

Saturated Hydraulic Conductivity Class:
0 to 10 inches: Moderately high and high
10 to 40 inches: Moderately high and high

Depth to root-restricting feature (inches):
Minimum: Greater than 60
Maximum: Greater than 60

Electrical Conductivity (dS/m):
Minimum: 0
Maximum: 0

Sodium Absorption Ratio:
Minimum: 0
Maximum: 0

Calcium Carbonate Equivalent (percent):
Minimum: 0
Maximum: 10

Soil Reaction (pH) (1:1 Water):
0 - 10 inches: 6.1 to 8.4
10 - 40 inches: 6.6 to 8.4

Available Water Capacity (inches, 0 – 40 inches depth):
Minimum: 1.3
Maximum: 4.6
Average: 3.0

Vegetation dynamics

Ecological Dynamics:

Sand, south aspect, Columbia Hills produces about 450-750 pounds/acre of biomass annually.

The line between sagebrush steppe and true grasslands has been discussed and debated for many years. Daubenmire states that the line has nothing to do with pre-settlement as native ungulates played no significant role in the evolution of ecotypes. He also says that there is no evidence that the distribution of vegetative types is related to fire. And he also says there is no useful correlation between soil classification and the line between grasslands and sagebrush steppe.

The ecotones between Daubenmire’s vegetation types can be defined on the basis of consistent differences in climate and consistent differences in vegetation. Higher spring precipitation, especially in March, favors grasses over sagebrush. The grassland area of southeastern Adams and eastern Franklin counties have more precipitation in March. The same for the grasslands in Walla Walla, Asotin and Garfield counties. The Goldendale Prairie and the high elevation grassland above Coulee Dam in Douglas county also have higher spring precipitation. So, the grassland areas of MLRA 8 are consistent with Daubenmire’s findings.

Needle and thread and Indian ricegrass would be dominant in the reference state and warrants a degree of understanding. Needle and thread is a very drought tolerant perennial bunchgrass. It prefers excessively drained sandy and coarse textured gravelly loam soils. Needle and thread produces erect, unbranched stems about 3 feet in height. The seeds have a 4 to 5-inch long twisted awn. With wetting and drying the seed drills itself into the ground. Thus, needle and thread is one of the best seeders in the reference community. With grazing pressure needle and thread initially increases.

Indian ricegrass is a winter hardy, cool-season bunchgrass. It has tightly rolled, slender leaves. Indian ricegrass is known for its ability to reseed and stabilize shifting sand.

The stability and resiliency of the reference communities is directly linked to the health and vigor of needle and thread and Indian ricegrass Research has found that the community remains resistant to medusahead if the site maintains at least 0.8 mid-sized bunchgrass plant/sq. ft. (K. Davies, 2008). These two grasses help hold the system together. If we lose either grass the ecosystem begins to unravel.

The natural disturbance regime for grassland communities is periodic lightning-caused fires. The fire return intervals (FRI) listed in research for sagebrush steppe communities is quite variable. Ponderosa pine communities have the shortest FRI of about 10-20 years (Miller). The FRI increases as one moves to wetter forested sites or to dries shrub steppe
communities. Given the uncertainties and opinions or reviewers, a mean of 75 years was chosen for Wyoming sagebrush communities (Rapid Assessment Model). This would place the historic FRI for grassland steppe around 30-50 years.

The effect of fire on the community depends upon the severity of the burn. With a light to moderate fire there can be a mosaic of burned and unburned patches. Bunchgrasses thrive as the fire does not get into the crown. With adequate soil moisture the bunchgrasses can make tremendous growth the year after the fire. Largely, the community is not affected by lower intensity fire. Needle and thread and Indian ricegrass are native species that can increase via new seedlings following a fire.

A severe fire puts stress on the entire community. Spots and areas that were completely sterilized are especially vulnerable to exotic invasive species. Sterilized spots must be seeded to prevent invasive species (annual grasses, tumble mustard) from totally occupying the site. Needle and thread and Indian ricegrass may have weak vigor for a few years but generally survive.

Grazing is another common disturbance that occurs in this ecological site. Grazing pressure can be defined as heavy grazing intensity, or frequent grazing during reproductive growth, or season-long grazing (the same plants grazed more than once). As grazing pressure increases the plant community unravels in stages:
1. Indian ricegrass declines while needle and thread increase
2. Needle and thread declines as invasive species such as cheatgrass and knapweed colonize the site
3. With further decline the site can become a cheatgrass community

Managing grasslands to improve the vigor and health of needle and thread and Indian ricegrass begins with an understanding their needs. New growth each year begins from basal buds. Both grasses reproduce via seed and need to produce viable seed on a regular basis. During seed formation, the growing points of Indian ricegrass become elevated and are vulnerable to damage or removal??

Repeated critical period grazing (boot stage through seed formation) is especially damaging. Over several years each native bunchgrass pasture should be rested during the critical period two out of every three years (approximately April 15–July 15). And each pasture should be rested the entire growing-season every third year (approximately
March 1 – July 15).

In the spring each year it is important to monitor and maintain an adequate top growth: (1) so plants have enough energy to replace basal buds annually, (2) to optimize regrowth following spring grazing, and (3) to protect the elevated growing points of bluebunch wheatgrass.

Needle and thread and Indian ricegrass remains competitive if:
(1) Basal buds are replaced annually,
(2) Enough top-growth is maintained for growth and protection of growing points, and
(3) The timing of grazing and non-grazing is managed over a several-year period. Careful management of late spring grazing is especially critical

For more grazing management information refer to Range Technical Notes found in Section I Reference Lists of NRCS Field Office Technical Guide for Washington State.

In Washington, needle and thread-Indian ricegrass communities provide habitat for a variety of upland wildlife species.


Supporting Information:

Associated Sites:
Sand, south aspect s is associated with other ecological sites in the Columbia Hills grassland steppe areas of MLRA 8, including Shallow Stony and loamy. Very Shallow may also be nearby.

Similar Sites:
The MLRA 7 Columbia Basin Sands is a needle-and-thread – Indian ricegrass ecological site, but with sagebrush and rabbitbrush as well.

Inventory Data References (narrative):
Data to populate Reference Community came from several sources: (1) NRCS ecological sites from 2004, (2) Soil Conservation Service range sites from 1980s and 1990s, (3) Daubenmire’s habitat types, and (4) ecological systems from Natural Heritage Program

Major Land Resource Area

MLRA 008X
Columbia Plateau

Subclasses

• R008XY546WA–Sand South Aspect Columbia Hills

Stage

Provisional

Contributors

Provisional Site Author: Kevin Guinn
Technical Team: K. Moseley, G. Fults, R. Fleenor, W. Keller, C. Smith, K. Bomberger, C. Gaines, K. Paup-Lefferts