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Ecological site R006XA212OR

Forested Sandy Loam 8-11 PZ

Last updated: 9/11/2023
Accessed: 11/13/2024

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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): 006X–Cascade Mountains, Eastern Slope

Stretching from northern Washington to southern Oregon, MLRA6 encompasses the mountain slopes, foothills, elevated plateaus and valleys on the eastern slopes of the Cascade mountains. This MLRA is a transitional area between the Cascade Mountains to the west and the lower lying Columbia Basalt Plateau to the east. Situated in the rain shadow of the Cascade Crest, this MLRA receives less precipitation than portions of the cascades further west and greater precipitation than the basalt plateaus to the east. Geologically, the majority of the MLRA is dominated by Miocene volcanic rocks, while the northern portion is dominated by Pre-Cretaceous metamorphic rocks and the southern portion is blanketed with a thick mantle of ash and pumice from Mount Mazama. The soils in the MLRA dominantly have a mesic, frigid, or cryic soil temperature regime, a xeric soil moisture regime, and mixed or glassy mineralogy. They generally are moderately deep to very deep, well drained, and loamy or ashy. Biologically, the MLRA is dominated by coniferous forest, large expanses of which are dominated by ponderosa pine, Douglas-fir or lodgepole pine. Areas experiencing cooler and moister conditions include grand fir, white fir, and western larch while the highest elevations include pacific silver fir, subalpine fir and whitebark pine. Economically, timber harvest and recreation are important land uses in these forests. Historically, many of these forests would have experienced relatively frequent, low and mixed severity fire favoring the development of mature forests dominated by ponderosa pine or Douglas-fir. In the southern pumice plateau forests, less frequent, higher severity fire was common and promoted the growth of large expanses of lodgepole pine forests.

LRU notes

This unit is characterized by a landscape of basalt terraces, abandoned lakebeds and dunes where exceedingly dry ponderosa pine – western juniper forests occur. These forests are largely geographically confined to the Lost Forest Research Natural Area, and despite receiving less than 11 inches of annual precipitation, persist among a desert shrubland due to unique soil characteristics. Here, deep eolian deposits of ash and pumice increase water holding capacity relative to nearby soils. Geologically, these deposits are underlain by Pliocene basalt from the High Cascades volcanic province. Botanically, these forests share characteristics with other dry pine forests as well as the nearby shrub steppe. Common members include, antelope bitterbrush, big sagebrush, needle and thread, Indian ricegrass, creeping wildrye and granite prickly gilia. The climate of this unit is cool and very dry with a soil climate defined by a frigid temperature regime and an aridic moisture regime. The historical fire regime of this site is likely similar to other very dry ponderosa pine communities, with moderately frequent, low severity fire common.

Ecological site concept

This site represents a geographically unique, very dry ponderosa pine (Pinus ponderosa) and western juniper (Juniperus occidentalis) woodland occurring within the Lost Forest Research Natural Area at the northwestern edge of the Great Basin. Dislocated from other ponderosa pine sites at the Eastern foothills of the Cascades, the Lost Forest stands in stark contrast to the adjacent sagebrush steppe landscape. Heredeep eolian deposits of volcanic ash and pumice have created the conditions for ponderosa pine persistence despite receiving precipitation generally lower than is required for the species (Moir and Franklin 1974). The influence of ash in these soils increases water holding capacity and bolsters site resilience during drought, facilitating the survival of ponderosa pine. In contrast to similar ecological sites found on terrace landforms within this landscape, this site has deeper, loamy soils and therefore supports greater cover of ponderosa pine.

This is a provisional ecological site and is subject to extensive review and revision before final approval. All data herein should be considered provisional and contingent upon field validation prior to use in conservation planning.

Associated sites

R006XA213OR	Pumice Terrace 8-10 PZ adjacent shallow terraces
R006XA214OR	Forested Pumice Dunes 8-11 PZ adjacent forested dunes
R006XA216OR	Forested Shrubby Dunes 8-11 PZ adjacent forested dunes
R006XA217OR	Very Shallow Pumice Terrace 8-11 PZ adjacent very-shallow terraces

Similar sites

R006XA213OR	Pumice Terrace 8-10 PZ Shallower soils (moderately deep vs deep or very deep)
R006XA217OR	Very Shallow Pumice Terrace 8-11 PZ Shallower soils (shallow and very shallow vs deep and very deep)

R006XA213OR

Pumice Terrace 8-10 PZ

Shallower soils (moderately deep vs deep or very deep)

R006XA217OR

Very Shallow Pumice Terrace 8-11 PZ

Shallower soils (shallow and very shallow vs deep and very deep)

Table 1. Dominant plant species

Tree	(1) Juniperus occidentalis (2) Pinus ponderosa
Shrub	Not specified
Herbaceous	(1) Hesperostipa comata (2) Achnatherum hymenoides

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Physiographic features

These sites are found on old lake terraces, sand sheets and hills in Pleistocene lacustrine basins where eolian sands accumulate. Slopes are commonly nearly level to 3 percent and elevations range from 4,300 to 4,600 feet (1,300 to 1,400 meters). This site occurs on all aspects. This site is not subject to ponding or flooding and no water table is present within 100 inches of the soil surface.

Table 2. Representative physiographic features

Landforms	(1) Basin > Terrace (2) Basin > Sand sheet (3) Basin > Hill
Flooding frequency	None
Ponding frequency	None
Elevation	1,311 – 1,402 m
Slope	0 – 3%
Ponding depth	0 cm
Water table depth	254 cm
Aspect	W, NW, N, NE, E, SE, S, SW

Climatic features

This site is characterized by hot dry summers and cold wet winters. Precipitation, largely in the form of rain and snow, ranges from 8 to 11 inches, averaging 10 inches annually. Frost-free days range from 85 to 95 and the freeze-free period ranges from 120 to 135 days. The soil temperature regime is frigid and the soil moisture regime is aridic. The graphs below are populated from the closest available weather station to representative site locations and are provided to indicate general climate patterns.

Table 3. Representative climatic features

Frost-free period (characteristic range)	85-95 days
Freeze-free period (characteristic range)	120-135 days
Precipitation total (characteristic range)	203-279 mm
Frost-free period (average)	90 days
Freeze-free period (average)	125 days
Precipitation total (average)	254 mm

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) THE POPLARS [USC00358420], Silver Lake, OR

Soil features

Soils that typify this site concept are deep to very deep sands and loamy fine sands over sands and loamy cobbly sands. These soils were formed in eolian deposits of pumice and volcanic ash, allowing for increased water holding capacity and the ability to sustain ponderosa pine unlike adjacent desert shrub communities. These soils are somewhat excessively to excessively drained with rapid permeability. Soils on this site are classified into the Psamments great group, which are largely unconsolidated sand deposits with little soil development.

A representative soil component associated with this site:

Morehouse, 0 – 10% slopes.

Table 4. Representative soil features

Parent material	(1) Eolian sands – pumice (2) Volcanic ash
Surface texture	(1) Sand (2) Loamy fine sand (3) Cobbly loamy sand
Family particle size	(1) Ashy
Drainage class	Somewhat excessively drained to excessively drained
Permeability class	Rapid
Depth to restrictive layer	112 – 203 cm
Soil depth	112 – 203 cm
Surface fragment cover <=3"	0 – 45%
Surface fragment cover >3"	0 – 45%
Available water capacity (0-101.6cm)	6.35 – 12.7 cm
Soil reaction (1:1 water) (0-101.6cm)	7.4 – 9
Subsurface fragment volume <=3" (10.2-152.4cm)	0 – 30%
Subsurface fragment volume >3" (10.2-152.4cm)	0 – 20%

Ecological dynamics

Reference Plant community:

The reference vegetative community of this site has an overstory dominated by western juniper and ponderosa pine with an herbaceous layer largely dominated by needle and thread (Hesperostipa comata) and Indian ricegrass (Achnatherum hymenoides), these grass species are typically found in desert environments due to their superior drought tolerance. While the loamy well-drained soils allow for the presence of ponderosa pine, the low precipitation and rapid drainage requires that these species be adapted to dry site conditions. This site represents a scenario where ponderosa and juniper may persist in a codominant woodland composition for an extended period, in part due to an infrequent fire rotation and their ability to tap into deeper water during summer dry periods. These are generally open stands where moisture limitations may preclude dense, closed canopy conditions. A comprehensive forest health study of the Lost Forest was undertaken by the USFS in 2007. Researchers recorded an abundance of western juniper greater than 150 years old, with considerable numbers of younger trees that were less than 150 years old (40 and 60 percent of all trees recorded respectively) (Chadwick and Eglitis 2007). This suggests that this is a persistent juniper site, yet infill of younger trees may be greater than it was historically due to grazing practices and harvest of mature pine.

Disturbance:

A complex host of mortality agents and disturbance factors have been recorded for sites in the Lost Forest. Factors that have contributed to the mortality of juniper and pine in the past include the drought of the 1920s and 1930s, movement of dune landforms into forest stands, annosus root disease and windthrow (Chadwick and Eglitis 2007). Timber harvest in the 1940s and 1950s also removed mature ponderosa pine from primarily the most productive sites on the forest (Chadwick and Eglitis 2007). Other disturbances include livestock grazing which may have produced vegetation changes prior to its exclusion in 1968 and ongoing off road recreational activity (Moir et al. 1973). Grazing disturbance may alter the composition of the herbaceous layer and favor an increase in bottlebrush squirreltail (Elymus elymoides), creeping wildrye (Leymus triticoides) and Sandberg bluegrass (Poa secunda) at the expense of needle-and-thread and indian ricegrass. Despite a high frequency of lightning strikes, research suggests that fire was likely not a common disturbance agent in this forest due to low fuel loads and continuity (Chadwick and Eglitis 2007). According to the best available knowledge of similar systems, the fire regime is likely comparable to other very dry ponderosa pine sites and influenced by the surrounding Wyoming big sage (Artemesia tridentata ssp. wyomingensis) plant communities (Landfire fire regime group 3: 35-100+ year frequency, mixed severity) (Landfire 2007). The fire regime of this site is approximated by the landfire biophysical setting model 0710532 - Northern Rocky Mountain Ponderosa Pine Woodland and Savanna – Xeric. The resilience and resistance of this site to widespread invasions of exotic annual grasses is not known, however plant data collected to describe the reference state indicates a minimal cover of weed species present, indicating that this site may have the potential for widespread weed infestation.

Given that this site occupies a limited geographic area, little is known about the plant community dynamics over time, therefore the model below represents a generalized and simplified understanding of community response to disturbance. Emerging evidence is suggesting that climate change is leading to hotter and drier conditions in western forests that will increase fire frequency and extent and lengthen fire seasons (Halofsky et al. 2020). When combined with the interacting impacts of fire suppression, drought, and insect outbreaks, it is possible that this ecological system will experience unpredictable ecosystem shifts and additional alternative states. For warm and dry sites, these impacts may include the possibility of regeneration failure following wildfire disturbance (Halofsky et al. 2020). As our understanding of these systems evolves and this site is updated in future iterations, descriptions will include more thorough treatments of disturbance and ecological change.

State and transition model

Custom diagram

Standard diagram

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More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective text

Ecosystem states

1. Historical Reference State

2. Grazing Managed State

3. Invaded State

T1A	-	Prolonged improper grazing management
T1B	-	Catastrophic fire, prolonged improper grazing management
R2A	-	Extended rest from grazing, possible reseeding of native grasses
T2A	-	Continued improper grazing management, catastrophic fire

State 1 submodel, plant communities

1.1. Mature juniper pine savannah: JUOC - PIPO/HECOC8 - ACHY

1.2. Stand Initiation: HECOC8 - ACHY -ELEL5

1.1A	-	High severity fire, severe windthrow, extreme drought or disease
1.1B	-	Time without severe fire

State 2 submodel, plant communities

2.1. JUOC - PIPO/POSE - LETR5 - ELEL5

State 3 submodel, plant communities

3.1. JUOC - PIPO/BRTE

State 1
Historical Reference State

This is the reference plant community given an unaltered disturbance regime.

Dominant plant species

western juniper (Juniperus occidentalis), tree
ponderosa pine (Pinus ponderosa), tree
needle and thread (Hesperostipa comata ssp. comata), grass
Indian ricegrass (Achnatherum hymenoides), grass

Community 1.1
Mature juniper pine savannah: JUOC - PIPO/HECOC8 - ACHY

The reference vegetative community of this site has an overstory dominated by a mature, open stand of western juniper and ponderosa pine with an herbaceous layer largely dominated by needle-and-thread and Indian ricegrass. Exotic annuals may be present in low numbers. Severe fire is relatively infrequent in this state and the community will be maintained by periodic mortality of young juniper and ponderosa pine caused by mixed severity fire, drought, insects disease and windthrow (Chadwick and Eglitis 2007). Given the likelihood that this state, even in the best condition and highest potential, will almost always include at least some component of exotic species regardless of management inputs, this may also be referred to as the “current potential state”. In this document, the term “reference state” is used synonymously with “current potential state” for the sake of simplicity.

Dominant plant species

western juniper (Juniperus occidentalis), tree
ponderosa pine (Pinus ponderosa), tree
needle and thread (Hesperostipa), grass
Indian ricegrass (Achnatherum hymenoides), grass

Figure 7. Annual production by plant type (representative values) or group (midpoint values)

Table 5. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Grass/Grasslike	235	392	555
Shrub/Vine	45	73	101
Tree	39	67	90
Forb	17	28	39
Total	336	560	785

Community 1.2
Stand Initiation: HECOC8 - ACHY -ELEL5

Following severe fire, extreme drought, widespread disease outbreak or a severe incidence of windthrow, the overstory canopy may be lost. The community will be become dominated by perennial grasses with young western juniper and ponderosa pine returning overtime.

Dominant plant species

western juniper (Juniperus occidentalis), tree
ponderosa pine (Pinus ponderosa), tree
squirreltail (Elymus elymoides), grass
beardless wildrye (Leymus triticoides), grass

Pathway 1.1A
Community 1.1 to 1.2

High severity fire, severe windthrow, extreme drought or disease

Pathway 1.1B
Community 1.2 to 1.1

Time without severe fire

State 2
Grazing Managed State

In this state the site is being managed for livestock grazing. This may lead to altered plant community composition and production where plants adapted to grazing disturbance may increase while those sensitive to disturbance may decrease. Additionally, impacts to the abiotic conditions of the site may occur as soil is compacted due to hoof trampling or eroded due to an increase in bare ground cover.

Dominant plant species

western juniper (Juniperus occidentalis), tree
ponderosa pine (Pinus ponderosa), tree
Sandberg bluegrass (Poa secunda), grass
beardless wildrye (Leymus triticoides), grass
squirreltail (Elymus elymoides), grass

Community 2.1
JUOC - PIPO/POSE - LETR5 - ELEL5

Following prolonged improper grazing management grazing, native increaser species such as bottlebrush squirreltail, creeping wildrye and Sandberg bluegrass may increase at the expense of the Reference Community dominants needle and thread and Indian ricegrass.

State 3
Invaded State

In this state much of the native herbaceous vegetation has been replaced by exotic annual grasses which at high levels may create positive feedbacks that alter fire regimes and promote prolonged invasion.

Dominant plant species

western juniper (Juniperus occidentalis), tree
ponderosa pine (Pinus ponderosa), tree
cheatgrass (Bromus tectorum), grass

Community 3.1
JUOC - PIPO/BRTE

Following continued improper grazing management , or catastrophic fire, where invasive annual grasses are already present on site, these grasses may increase while perennial grasses decline. Juniper and ponderosa pine will temporarily decline with catastrophic fire yet will return overtime. An abundance of annual grass will increase fine fuels and may increase fire frequency, creating a positive feedback that will encourage the maintenance of the site in this state.

Transition T1A
State 1 to 2

Prolonged improper grazing management

Transition T1B
State 1 to 3

Catastrophic fire, prolonged improper grazing management

Context dependence. Invasive species must be present onsite or within a sufficiently close distance for dispersal from nearby invaded sites

Restoration pathway R2A
State 2 to 1

Extended rest from grazing, possible reseeding of native grasses

Context dependence. Excessive grazing leading to a loss of plant species diversity, plant reproductive output or altered abiotic conditions such as compacted or eroded soil, for example, will not recover by rest alone and will require additional inputs

Transition T2A
State 2 to 3

Continued improper grazing management, catastrophic fire

Constraints to recovery. Invasive species must be present onsite or within a sufficiently close distance for dispersal from nearby invaded sites

Additional community tables

Table 6. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (kg/hectare)	Foliar cover (%)
Grass/Grasslike
1	Grass and grasslike plants			280–432
	needle and thread	hecoc8	Hesperostipa comata ssp. comata	168–224	–
	Indian ricegrass	ACHY	Achnatherum hymenoides	56–84	–
	Idaho fescue	FEID	Festuca idahoensis	28–56	–
	beardless wildrye	LETR5	Leymus triticoides	11–28	–
	Alaska hollyfern	POSE5	Polystichum setigerum	11–28	–
	squirreltail	ELEL5	Elymus elymoides	6–11	–
2	Other perennial grasses			39–129
Forb
3	Forbs			6–11
	granite prickly phlox	LIPU11	Linanthus pungens	6–11	–
4	Other perennial forbs			17–39
Shrub/Vine
5	Shrubs			34–101
	antelope bitterbrush	PUTR2	Purshia tridentata	0–28	–
	basin big sagebrush	artrt	Artemisia tridentata ssp. tridentata	3–17	–
	mountain big sagebrush	ARTRV	Artemisia tridentata ssp. vaseyana	6–17	–
6	Other perennial shrubs			11–28
Tree
7	Trees			50–129
	western juniper	JUOC	Juniperus occidentalis	28–56	–
	ponderosa pine	PIPO	Pinus ponderosa	11–28	–

Interpretations

Animal community

This site is seasonally utilized by several grazing animals; mule deer, elk, and antelope are the large native herbivores using this site. Other animals that use this site are quail, coyotes, bobcats, and rabbits. Cattle are the primary livestock utilizing this site.

Wildlife: This site is beneficial as nesting and feeding cover to a variety of wildlife species. Use should be managed in such a manner as to maintain or improve conditions for wildlife populations.

Wood products

This site has little potential for wood products. Some fence posts and firewood have been harvested from this area in the past.

Other products

Grazing: This site is suited to use under a planned grazing system by cattle. Care should be taken to avoid use until soils are sufficiently dry to reduce the impacts of trampling and root reserves have been established.

Supporting information

Inventory data references

Information presented here has been derived from NRCS data. Field observations from range trained personnel were also used. Other sources used as references include USDA NRCS Water and Climate Center, USDA NRCS National Range and Pasture Handbook, and USDA NRCS Soil Surveys from various counties.

References

. Fire Effects Information System. http://www.fs.fed.us/database/feis/.
. 2021 (Date accessed). USDA PLANTS Database. http://plants.usda.gov.

Other references

Chadwick, Kristen L. and Andris Eglitis. 2007. Health Assessment of the Lost Forest Research Natural Area, Central Oregon Service Center for Insects and Diseases, United States Forest Service, United States Department of Agriculture, Bend, Oregon.

Halofsky, J.E., Peterson, D.L. & Harvey, B.J. Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA. fire ecol 16, 4 (2020). https://doi.org/10.1186/s42408-019-0062-8

LANDFIRE, 2007, Biophysical Settings Model Descriptions, LANDFIRE 1.1.0, U.S. Department of the Interior, USDA Forest service, Accessed 20 April 2020 at https://www.landfire.gov/bps-models.php

Moir, William H., Jerry F. Franklin, and Chris Maser. 1973. Lost Forest Research Natural Area, Pacific Northwest Forest and Range Experiment Station, United States Forest Service, Department of Agriculture, Portland, Oregon.

Steinberg, Peter D. 2002. Artemisia arbuscula. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/plants/shrub/artarb/all.html [2020, June 18].

Zouhar, Kris. 2003. Bromus tectorum. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/graminoid/brotec/all.html [2020, June 25].

Contributors

Andrew Neary - 2020/2021 PES update of draft site

Approval

Kirt Walstad, 9/11/2023

Acknowledgments

Development of this site as a range site was based on field data collection completed in 1998 by the Burns ESI team. It was revised and updated with information regarding ecological dynamics in 2020.

Rangeland health reference sheet

Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.

Author(s)/participant(s)
Contact for lead author
Date	11/13/2024
Approved by	Kirt Walstad
Approval date
Composition (Indicators 10 and 12) based on	Annual Production