Horse Ridge 

Research Natural Area

Guidebook Supplement 37

Reid Schuller and Ron Halvorson

United States 

Department of 

Agriculture

Forest Service

Pacific Northwest 

Research Station

General Technical Report

PNW-GTR-771

October 2008

DEPAR TMENT OF AGRICULT URE
The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of 

multiple use management of the Nation’s forest resources for sustained yields of wood, 

water, forage, wildlife, and recreation. Through forestry research, cooperation with the 

States and private forest owners, and management of the National Forests and National 

Grasslands, it strives—as directed by Congress—to provide increasingly greater service 

to a growing Nation.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and 

activities on the basis of race, color, national origin, age, disability, and where applicable, 

sex, marital status, familial status, parental status, religion, sexual orientation, genetic 

information, political beliefs, reprisal, or because all or part of an individual’s income 

is derived from any public assistance program. (Not all prohibited bases apply to all 

programs.) Persons with disabilities who require alternative means for communication of 

program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET 

Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write 

USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 

20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal 

opportunity provider and employer.

Authors

Reid Schuller is a plant ecologist, Western Stewardship Science Institute, P.O. 

Box 1173, Bend, Oregon 97709. Ron Halvorson is a botanist, U.S. Department of 

the Interior, Bureau of Land Management, Prineville District, 3050 NE 3rd Street, 

Prineville, Oregon 97754.

The Pacific Northwest Research Station is publishing this guidebook as part of a 

continuing series of guidebooks on federal research natural areas begun in 1972.

Cover:

Horse Ridge Research Natural Area—Southeast-facing view from midslope on 

Horse Ridge looking into Millican Valley. The lower slopes of Pine Mountain are 

visible in the distance. Foreground of western juniper woodland with western juniper saplings and juveniles mixed with older trees. An understory of big sagebrush, 

threadleaf sedge, Idaho fescue, and bluebunch wheatgrass is mixed with a relatively 

inconspicuous herbaceous layer. Bare soil surface alternates with patches of (barely 

visible) microbiotic crust in foreground. 
Abstract

Schuller, Reid; Halvorson, Ron. 2008. Horse Ridge Research Natural Area: 

guidebook supplement 37. Gen. Tech. Rep. PNW-GTR-771. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

25 p.

This guidebook describes Horse Ridge Research Natural Area, a 243-ha (600-ac) 

tract established to represent an example of the western juniper/big sagebrush/

threadleaf sedge (Juniperus occidentalis/Artemisia tridentata/Carex filifolia) plant 

association.

Keywords: Research natural area, Juniperus occidentalis, western juniper, 

Artemisia tridentata, big sagebrush, Carex filifolia, threadleaf sedge, relict 

vegetation, juniper invasion, juniper woodland, sagebrush steppe, Northern 

Great Basin, Oregon High Desert.
Preface

The research natural area (RNA) described in this supplement1 is administered by 

the Prineville District, Bureau of Land Management (BLM), U.S. Department of 

the Interior.

Scientists and educators wishing to visit or use the RNA for scientific or 

educational purposes should contact the Prineville BLM field office manager in 

advance and provide information about research or educational objectives, sampling 

procedures, and other prospective activities. Research projects, educational visits, 

and collection of specimens from the RNA all require prior approval. There may be 

limitations on research or educational activities.

Horse Ridge RNA is part of a federal system of such tracts established for 

research and educational purposes. Each RNA is a site where natural features are 

protected or managed for scientific purposes and natural processes are allowed to 

dominate. Their main purposes are to provide:

• Baseline areas against which effects of human activities can be measured 

or compared.

• Sites for study of natural processes in undisturbed ecosystems.

• Gene pool preserves for all types of organisms, especially rare and 

endangered types.

The federal system is outlined in A Directory of the Research Natural Areas 

on Federal Lands of the United States of America.

2 

Of the 183 federal RNAs established in Oregon and Washington, 45 are 

described in Federal Research Natural Areas in Oregon and Washington: 

A Guidebook for Scientists and Educators (see footnote 1). Supplements to 

the guidebook such as this publication constitute additions to the system or 

comprehensive revisions of previously published guidebooks.

The guiding principle in management of RNAs is to prevent unnatural 

encroachments or activities that directly or indirectly modify ecological processes 

or conditions. Logging and uncontrolled grazing are not allowed, for example, 

nor is public use that might impair scientific or educational values. Management 

practices necessary to maintain or restore ecosystems may be allowed.

1 Supplement No. 37 to Franklin, J.F.; Hall, F.C.; Dyrness, C.T.; Maser, C. 1972. Federal 

research natural areas in Oregon and Washington: a guidebook for scientists and educators. 

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest 

and Range Experiment Station. 498 p.

2 Federal Committee on Ecological Reserves. 1977. A directory of the research natural 

areas on federal lands of the United States of America. Washington, DC: U.S. Department 

of Agriculture, Forest Service. [Irregular pagination].
Federal RNAs provide a unique system of publicly owned and protected 

examples of undisturbed ecosystems where scientists can conduct research with 

minimal interference and reasonable assurance that investments in long-term 

studies will not be lost to logging, land development, or similar activities. In 

return, a scientist wishing to use an RNA is obligated to:

• Obtain permission from the appropriate administering agency before 

using the area.3

• Abide by the administering agency’s regulations governing use, including 

specific limitations on the type of research, sampling methods, and other 

procedures.

• Inform the administering agency on progress of the research, published 

results, and disposition of collected materials.

The purpose of these limitations is to:

• Ensure that the scientific and educational values of the tract are not impaired.

• Accumulate a documented body of knowledge and information about the tract.

• Avoid conflict between studies and activities.

Research must be essentially nondestructive; destructive analysis of vegetation 

is generally not allowed, nor are studies requiring extensive modification of the 

ground surface or extensive excavation of soil. Collection of plant and animal specimens should be restricted to the minimum necessary to provide voucher specimens 

and other research needs. Under no circumstances may collecting significantly 

reduce populations of species. Collecting also must be carried out in accordance 

with agency regulations. Within these broad guidelines, appropriate uses of RNAs 

are determined by the administering agency.

Prineville BLM management direction is to preserve, protect, or restore native 

species composition and ecological processes of biological communities including 

terrestrial and aquatic cells4 listed in the 2003 Oregon Natural Heritage Plan. These 

RNAs are available for short- or long-term scientific study, research, and education 

and will serve as a baseline against which human impacts on natural systems can 

be measured. 

3 Six federal agencies cooperate in this program in the Pacific Northwest: U.S. Department 

of the Interior, Bureau of Land Management, Fish and Wildlife Service, and National Park 

Service; U.S. Department of Agriculture, Forest Service; U.S. Department of Energy; and 

U.S. Department of Defense.

4 Cells are the basic units that must be represented in a natural area system. A cell can 

be an ecosystem, community, habitat, or organism. Taken from Dyrness, C.T.; Franklin, 

J.F.; Maser, C.; Cook, S.A.; Hall, J.D.; Faxon, G. 1975. Research natural area needs in 

the Pacific Northwest: a contribution to land-use planning. Gen. Tech. Rep. PNW-38. 

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest 

and Range Experiment Station. 231 p.
Contents

1 Introduction

1 Access and Accommodations

1 Environment

4 Climate

5 Vegetation

10 Fauna

10 Disturbance History

10 Research History

12 Site History

13 Maps

13 Acknowledgments

13 English Equivalents

13 References

18 Appendix 1: Vascular Plants and Ferns

21 Appendix 2: Lichens and Mosses 

22 Appendix 3: Amphibians, Reptiles, Birds, and Mammals
Horse Ridge Research Natural Area: Guidebook Supplement 37

Introduction

Horse Ridge Research Natural Area (RNA) is a 243-ha (600-ac)1 tract that occupies 

predominantly north- to northeast-facing slopes on Horse Ridge in southeast 

Deschutes County, Oregon. The site was originally established as an RNA in 1967. 

A guidebook was written for the area in 1972 (Hall 1972, Franklin et al. 1972).

The tract supports a late-seral example of the western juniper/big sagebrush/

threadleaf sedge (Juniperus occidentalis/Artemisia tridentata/Carex filifolia) plant 

association (Hall 1972), and limited examples of the western juniper/big sagebrush/

Idaho fescue (Juniperus occidentalis/Artemisia tridentata/Festuca idahoensis) plant 

association, and the western juniper/big sagebrush/bluebunch wheatgrass (Juniperus 

occidentalis/Artemisia tridentata/Pseudoroegneria spicata) plant association. The 

RNA is located in the extreme southwest portion of the Blue Mountains Ecological 

Province in central Oregon (Oregon Natural Heritage Program 2003, USDA FS 

2008). 

Access and Accommodations

From the intersection of U.S. Highway 97 and U.S. Highway 20 in Bend, Oregon, 

proceed east-southeast for 32.2 km (20 mi) to Millican Valley. Turn south (right) on 

County Road 2015 (all season, gravel) and proceed 0.9 km (0.6 mi) south to Bureau 

of Land Management (BLM) Road 6515-A. Turn northwest (right) onto BLM Road 

6515-A (dirt, seasonal) and proceed for 3.5 km (2.2 mi) paralleling the northwestsoutheast trending ridge of Horse Ridge and park your vehicle in the turnaround 

next to the fence just east of the southeast corner of Horse Ridge RNA (fig. 1). 

Permission for public access must be obtained prior to entering the site. Inquiries 

should be directed to the Prineville District Office, Bureau of Land Management in 

Prineville, Oregon. Lodging is available in Bend, Redmond, and Prineville, Oregon.

Environment

Elevations within the RNA range from 1210 m (3,970 ft) near the northeast corner of 

the perimeter fence to 1455 m (4,774 ft) along the west-central portion of the perimeter fence. About 85 percent of the RNA is enclosed by a barbed-wire fence. Terrain 

is generally oriented in an east to north direction on steep to moderately inclined mid 

to upper slopes. These canyons do not support seasonal streams and lack streambed 

development (fig. 2). The long axis of the RNA extends 2 km (1.25 mi) in a northsouth orientation. The shorter, east-west axis extends for 1.2 km (0.75 mi).

1 These data are on file at the Bureau of Land Management, Prineville District Office, and 

at the USDA Forest Service, Pacific Northwest Research Station, Corvallis, Oregon.
GENERAL TECHNICAL REPORT PNW-GTR-771

Figure 1—Horse Ridge Research Natural Area location and access.
Horse Ridge Research Natural Area: Guidebook Supplement 37

Figure 2—Horse Ridge Research Natural Area topography and boundary.
GENERAL TECHNICAL REPORT PNW-GTR-771

Bedrock consists of highly fractured Columbia River basalt. Soils within the 

RNA are primarily classified as Stookmoor-Westbutte complex, taxonomic class 

ashy, glassy, frigid Vitritorrandic Haploxerolls. The soil is moderately deep and 

somewhat excessively drained. It is formed in pumiceous ash and loamy mixed 

material (Miller et al., n.d.). Depth to lithic bedrock is 51 to 102 cm (20 to 40 in). 

Generalized soil profiles for the Stookmoor-Westbutte complex, 25 to 50 percent 

north slopes are (USDA NRCS 2008):

Soil depth Soil texture

 Centimeters Inches

Westbutte north 0 to 23 0 to 9 Stony loam

23 to 53 9 to 21 Very cobbly loam

53 to 76 21 to 30 Cobbly clay loam

76 to 102 30 to 40 Unweathered bedrock

Stookmoor north 0 to 20 0 to 6 Loamy sand

20 to 61 6 to 14 Sandy loam

61 to 74 14 to 24 Sandy loam

74 to 84 24 to 34 Unweathered bedrock

Climate

Climate within the RNA is continental and semiarid, modified by marine air currents from the Pacific Ocean that provide precipitation as rain and snow. Located 32 

km (20 mi) west of Horse Ridge, the Bend 7 NE, Oregon (350699) weather station 

for the 1991–2007 period provides the most comparable data (table 1). 

In winter, precipitation is a mixture of rain and snow (Driscoll 1964). Annual 

precipitation is low. Summers are dry with warm days and cool nights. Frost occurs 

rarely during the summer but may occur anytime between October and June. 

Twenty-five percent of annual precipitation occurs during the 3-month growing 

period from April through June. Snowfall occurs from October through March and 

occasionally into April. Snow depths accumulate to 25 mm (1 in) in December and 

January. January receives the highest average monthly snowfall of 114 mm (4.5 in) 

(Western Regional Climate Center 2008).

Table 1—Temperature and precipitation summary, 

5/01/1991 to 6/30/2007—Bend 7 NE, OR (350699)

Average minimum January temperature -3.9 °C (25.0 °F)

Average maximum January temperature 6.4 °C (43.6 °F)

Average minimum July temperature 9.1 °C (48.3 °F)

Average maximum July temperature 28.8 °C (83.8 °F)

Average annual precipitation 245 mm (9.63 in)

Average July–September precipitation 35 mm (1.39 in)


Horse Ridge Research Natural Area: Guidebook Supplement 37

Vegetation

The RNA is situated along the boundary of three major ecological provinces 

(Franklin and Dyrness 1988). Depending on the mapping scheme and criteria used 

to define major physiographic, geologic, and vegetation zones, Horse Ridge may 

be placed within the Blue Mountains, the Eastern Cascades, or the High Lava 

Plains province. Vegetation within the RNA is characteristic of portions of all 

three provinces. The distinctive feature at Horse Ridge RNA is the abundance of 

threadleaf sedge (Carex filifolia) as an understory dominant or co-dominant (Hall 

1972). The primary basis for designation of Horse Ridge as an RNA is based on 

the presence of the western juniper/big sagebrush/threadleaf sedge (Juniperus 

occidentalis/Artemisia tridentata/Carex filifolia plant association (Oregon Natural 

Heritage Program 2003, Dyrness et al. 1975). Driscoll (1964) did not find this plant 

association sufficiently widespread or common enough to warrant inclusion in his 

study of central Oregon plant communities. The relative abundance of threadleaf 

sedge throughout most of the site indicates the area has only been lightly grazed by 

livestock over the years. The relatively steep slopes at Horse Ridge, coupled with 

lack of a nearby water source for cattle has resulted in low grazing pressure from 

domestic livestock over the years. All but the extreme southeastern part of the RNA 

has been essentially ungrazed by domestic animals and consequently has great 

value as a reference area or baseline area to compare with other more intensively 

managed juniper woodlands in central Oregon (Hall 1972). 

Minor amounts of the western juniper/big sagebrush/Idaho fescue (Juniperus 

occidentalis/Artemisia tridentata/Festuca idahoensis), and the western juniper/big 

sagebrush/bluebunch wheatgrass (Juniperus occidentalis/Artemisia tridentata/

Pseudoroegneria spicata) plant associations also occur within the RNA (Miller 

et al., n.d.; Oregon Natural Heritage Program 2003).

In addition to the threadleaf sedge, the herb layer is dominated by native 

bunchgrasses, including Idaho fescue, bluebunch wheatgrass, Sandberg bluegrass 

(Poa secunda), prairie junegrass (Koeleria macrantha), and bottlebrush squirreltail 

(Elymus elymoides). Horse Ridge is the best example of hybridization between 

bluebunch wheatgrass, bottlebrush squirreltail, and possibly, thickspike wheatgrass 

(Elymus lanceolatus ssp. lanceolatus) in central Oregon (Hall 1972). 

In June 2005, four 0.1-ha circular plots were established to monitor structural 

and compositional change over time within the western juniper/big sagebrush/

threadleaf sedge, and the western juniper/big sagebrush/Idaho fescue plant associations. Table 2 provides a summary of the physical characteristics of the plots. 
GENERAL TECHNICAL REPORT PNW-GTR-771

2 Microbiotic crust is composed of ground-surface-dwelling mosses and lichens.

Table 2—Physical features of four permanent plots within Horse Ridge 

Research Natural Area

Plot

Feature 993 995 996 997

Elevation (m) 1357 1397 1405 1431

Aspect (°) 217 76 58 42

Slope grade (°) 7 10 18 16

Slope position Mid Upper 1/3 Upper 1/3 Upper 1/3

Table 3 shows soil, rock, litter, and microbiotic crust2 aerial cover and frequency 

within the four plots. Table 4 summarizes shrub and herb foliar cover and herb 

frequency. Big sagebrush averages 5 percent cover and the principal graminoids 

are Idaho fescue, threadleaf sedge, bluebunch wheatgrass, Sandberg bluegrass, 

and prairie junegrass. Other grasses, such as Cusick’s bluegrass (Poa cusickii), 

bottlebrush squirreltail, and the invasive cheatgrass (Bromus tectorum) are 

occasionally represented. Typical herbs include maiden blue-eyed Mary (Collinsia 

parviflora), obscure cryptantha (Cryptantha ambigua), broadleaf milkvetch 

(Astragalus lentiginosus), and woolly groundsel (Senecio canus) (fig. 3).

Table 3—Soil, rock, litter, and microbiotic crusta cover and frequency within four permanent plots, 

Horse Ridge Research Natural Area

Plot

993 995 996 997

Cover type Coverb Frequency Cover Frequency Cover Frequency Cover Frequency

Percent

Rock c 2 18 4 18 9 32 6 43

Gravel 1 21 + 11 0 0 2 21

Bare soil 59 86 46 75 54 75 55 86

Litter 20 100 27 89 8 57 26 89

Moss 8 54 7 32 16 64 10 43

Lichen 11 57 5 54 10 64 7 39

Note: + = <0.5 percent cover.

a The combined foliar cover of ground-surface-dwelling mosses and lichens.

b Cover is expressed as percentage of aerial cover; frequency is expressed as percentage of occurrence within 28 2- by 5-dm microplots. 

Zero values are not included.

c Rock = particles >8 cm, gravel = 2 mm to 8 cm, bare soil = <2 mm.
Horse Ridge Research Natural Area: Guidebook Supplement 37

Table 4—Plant association, understory coverage and frequency within four permanent plots in Horse Ridge 

Research Natural Area

Plant association

JUOC/ARTR/CAFI a JUOC/ARTR/CAFI JUOC/ARTR/CAFI JUOC/ARTR/FEID

Plot 993 Plot 995 Plot 996 Plot 997

Species Coverb	 Frequency Cover Frequency Cover Frequency Cover Frequency

Percent

Shrub cover:

Artemisia tridentatac 5 — 4 — 6 — 15 —

Chrysothamnus viscidiflorus 3 — — 1 — —

Tetradymia canescens 2 — — — 3

Grass and sedge cover and frequency:

Festuca idahoensis 9 61 15 57 13 71 9 43

Carex filifolia 3 + 9 25 3 21

Pseudoroegneria spicata 4 29 + 11 1 21 1 11

Poa secunda 1 29 1 36 1 25 1 7

Koeleria macrantha + 11 1 25 2 32 1 21

Elymus elymoides + 4

Poa cusickii 1 4 2 18

Bromus tectorum + 4 + 7

Achnatherum thurberianum 1 21

Hesperostipa comata 1 7

Herb cover and frequency:

Cryptantha ambigua + 7 2 18 1 4 + 4

Collinsia parviflora 1 32 + 7 1 39 + 14

Astragalus lentiginosus 1 11 + 4 + 7

Senecio canus + 11 + 7 1 11 + 4

Eriogonum strictum + 4 + 4 + 7

Descurainia pinnata + 4 + 4 + 7

Arabis puberula + 7 + 4

Lomatium triternatum + 7 + 7

Achillea millefolium + 4

Leucocrinum montanum + 4

Fritillaria atropurpurea + 4

Leptosiphon septentrionalis + 4

Phlox gracilis + 4

Antennaria dimorpha + 4

Calochortus macrocarpus + 4

Lupinus argenteus + 7 + 4

Arabis sp. + 4

Eriogonum umbellatum 1 4

Antennaria geyeri + 7

Eriogonum microthecum + 4

Gilia sinuata + 7

Note: JUOC = Juniperus occidentalis, ARTR = Artemisia tridentata, CAFI = Carex filifolia, FEID = Festuca idahoensis, 

+ = trace (<0.5 percent foliar cover), — = not recorded.

a Plant association names and acronyms follow Driscoll (1964) and Hall (1972), but have been modified to incorporate current 

nomenclature employed in the Flora of North America (1993+). b Cover is expressed as percentage of foliar cover; frequency is expressed as percentage of occurrence within 28 2- by 5-dm microplots. 

Zero values are not included.

c See appendix 1 for a listing of scientific and common names.
GENERAL TECHNICAL REPORT PNW-GTR-771

Figure 3—Example of typical expression of western juniper/big sagebrush/threadleaf sedge plant association taken in plot 993. 

Exposed surface soil is sandy loam with high stone content. Native bunchgrasses predominate in the understory. Grasses include 

Idaho fescue, bluebunch wheatgrass, and Sandberg bluegrass mixed with threadleaf sedge. 

3 “Saplings” refers to two groups of small trees (a) those > 10 cm and < 1.47 m (> 4 in 

and < 4.8 ft) in height but less than 5 cm (2 in) diameter at breast height and (b) those 

trees > 1.47 m in height but less than 5 cm (2 in) diameter at breast height.

Plot 997 (western juniper/big sagebrush/Idaho fescue plant association) was 

similar in overall appearance to the other plots, except for the presence of Thurber’s 

needlegrass (Achnatherum thurberianum) and needle-and-thread (Hesperostipa 

comata), and the absence of threadleaf sedge (table 4, fig. 4).

Western juniper sapling3 and live tree density data recorded in the four, 0.1-ha 

plots in 2005 are shown in table 5. Small sapling densities average 180 per ha (445 

per ac), with a range from 110 to 340 per ha (272 to 840 per ac). Large sapling 

densities average 117.5 per ha (290 per ac), with a range from 70 to 120 per ha (173 

to 297 per ac). Western juniper live tree density averages 202.5 per ha (500 per 

ac), with a range from 140 to 280 per ha (346 to 692 per ac). Western junipers that 
Horse Ridge Research Natural Area: Guidebook Supplement 37

Figure 4—An example of the western juniper/big sagebrush/Idaho fescue plant association (plot 997). Note concentration of Idaho 

fescue beneath western juniper canopy in foreground.

Table 5—Western juniper density per hectare by size class and other stand 

structure attributes, Horse Ridge Research Natural Area

Plot

993 995 996 997 Mean

Number per hectare

Small sapling 340 150 110 120 180

Large sapling 120 80 70 100 117.5

Live trees 280 140 190 200 202.5

Standing dead trees 0 0 0 0 0

Multibranched trees 60 80 20 30 47.5

branched below 1.47 m average 47.5 per ha (117 per ac), with a range from 20 to 80 

per ha (49 to 198 per ac). Based on field observations elsewhere in central Oregon, 

these densities appear to be average for these associations. No standing dead trees 

or large coarse woody debris were found in these plots. 
10

GENERAL TECHNICAL REPORT PNW-GTR-771

A list of soil crust moss and lichen scientific names appears at the end of the 

text in appendix 2.

Fauna

Reptiles, amphibians, birds, and mammals known or expected to occur within the 

RNA are listed in appendix 3. These lists have been compiled from a combination 

of field observations and knowledge of species’ geographic ranges and habitat 

affinities (Csuti et al 1997). Species on this list are likely within the RNA for at 

least some portions of their life cycles.

Disturbance History

Lightning-ignited fire has played a role at Horse Ridge as evidenced by scattered, 

large fire-scarred, burned-out western juniper. It is unclear whether recent fires 

were small, burning in patches around individual trees, or were more extensive. 

Lack of surface fuels has been offered as an explanation for lack of fire spread in 

this region (Hall 1972).

Long-lived individuals of big sagebrush can be periodically subjected to infestation by Aroga websteri, a leaf-defoliating moth. This was observed throughout 

eastern and parts of central Oregon from 1962 to 1966 (Gates 1964).

The dominance and vigor of the grazing-sensitive threadleaf sedge coupled 

with the minor presence of invasive grasses (i.e., cheatgrass) suggests that the role 

of disturbance from grazing by domestic livestock appears to have played only a 

minor role at Horse Ridge and that the RNA has been relatively undisturbed. One 

notable exception to this is in the extreme southeast portion of the RNA, which was 

grazed by cattle prior to construction of the fenced exclosure.

The impact of invasive species on sagebrush ecosystems and juniper woodlands 

throughout the Northern Great Basin and the Intermountain West has been well 

documented (Young et al. 1972) 

Research History

Research on vegetation classification, community ecology, and inventory:

• Biotic Soil Crusts of Oregon’s Shrub Steppe (Ponzetti 2000).

• Horse Ridge Western Juniper Permanent Plot (Miller et al., n.d.).

• Plant Associations of the Crooked River National Grassland (Hopkins and 

Kovalchik 1983).

• Vegetation-Soil Units in the Central Oregon Juniper Zone (Driscoll 1964).
11

Horse Ridge Research Natural Area: Guidebook Supplement 37

Research on Juniperus occidentalis (western juniper) growth and expansion:

• Occurrence of Sustained Droughts in the Interior Pacific Northwest (A.D. 

1733–1980) Inferred From Tree-Ring Data (Knapp et al. 2004).

• Comparative Rates of Western Juniper Afforestation in South-Central 

Oregon and the Role of Anthropogenic Disturbance (Soulé et al. 2003).

• Climatic Regionalization and the Spatio-Temporal Occurrence of Extreme 

Single-Year Drought Events (1500–1998) in the Interior Pacific Northwest, 

USA (Knapp et al. 2002).

• Detecting Potential Regional Effects of Increased Atmospheric CO2 on 

Growth Rates of Western Juniper (Knapp et al. 2001a).

• Post-Drought Growth Responses of Western Juniper (Juniperus 

occidentalis var. occidentalis) in Central Oregon (Knapp et al. 2001b).

• Juniperus occidentalis (Western Juniper) Establishment History on Two 

Minimally Disturbed Research Natural Areas in Central Oregon (Soulé 

and Knapp 2000).

• Geographical Distribution of an 18th Century Heart Rot Outbreak in 

Western Juniper (Juniperus occidentalis ssp. occidentalis Hook.) (Knapp 

and Soulé 1999).

• Recent Juniperus occidentalis (Western Juniper) Expansion on a Protected 

Site in Central Oregon (Knapp and Soulé 1998).

Research on primary production:

• Environmental Limits on Aboveground Net Primary Production, Leaf Area, 

and Biomass in Vegetation Zones of the Pacific Northwest (Gholz 1982, see 

also Greene et al. 1986).

• Structure and Productivity of Juniperus occidentalis in Central Oregon

(Gholz 1980, see also Greene et al. 1986).

• Limits on Aboveground Net Primary Production, Leaf Area, and Biomass 

In Vegetational Zones of the Pacific Northwest (Gholz 1979, see also 

Greene et al. 1986).

Other research 

• Pogonomyrmex owyheei Nest Site Density and Size on a Minimally 

Impacted Site in Central Oregon (Soulé and Knapp 1996)

• Remote Sensing of the Leaf Area Index of Temperate Coniferous Forests

(Spanner et al. 1984, see also Greene et al. 1986).

• Studies on the Incidence of Coniferous Needle Endophytes in the Pacific 

Northwest (Carroll and Carroll 1978, see also Greene et al. 1986).
12

GENERAL TECHNICAL REPORT PNW-GTR-771

• Bird Populations in Four Vegetational Types in Central Oregon (Gashwiler 

1977, see also Greene et al 1986).

In addition to the research and monitoring described above, four permanent 

vegetation plots were established in 2005 to characterize and monitor change in 

forest/shrub steppe composition and structure (this project summarized, in part, in 

tables 1 through 4.) Data are on file at the Prineville District Office, Bureau of Land 

Management, and the Pacific Northwest (PNW) Research Station, USDA Forest 

Service (USFS), Corvallis, Oregon.

Site History

Subsequent to designation as an RNA in 1967 (Hall 1972), Horse Ridge RNA 

was established as a research natural area and as an area of critical environmental concern (ACEC) in 1989 with publication of the Brothers/LaPine Resource 

Management Plan and Record of Decision (USDI BLM 1989). This management 

designation was subsequently revalidated in 2005 in the Upper Deschutes Resource 

Management Plan and Record of Decision (USDI BLM 2005).

The land that is now the RNA was withdrawn from all forms of appropriation under the public land laws, including the mining laws, and designated as the 

“Juniper Natural Area” in 1962 based on its representation of a “juniper savannah.” 

There is no information in the record as to the history of or motivation for this 

designation. In 1967, the area was formally designated as the Horse Ridge RNA as 

an “example of western juniper (Juniperus occidentalis)–big sagebrush (Artemisia 

tridentata) vegetation within the juniper zone of central Oregon” (Hall 1972, 

Franklin et al. 1972). Designation as a national natural landmark by the National 

Park Service followed in 1968 along with installation of a plaque in the southeast 

corner (USDI BLM 1996).

The designation of Horse Ridge ACEC/RNA in the Brothers/LaPine Resource 

Management Plan (1989) was to formalize Horse Ridge RNA as both an RNA and 

an ACEC.

The RNA was evaluated for potential wilderness designation as an “instant 

study area” in 1979 (ISA OR-5-5) but was determined to not have wilderness characteristics, mainly related to its small size and the noise intrusion from Highway 20 

to the north. This evaluation was sent to Congress as part of a national package in 

1985. Congress has yet to take action on this package. 

The extreme southeastern part of the RNA has been grazed by domestic 

livestock in the past. Prior to designation as an RNA, western juniper trees were 

cut for fenceposts and firewood in this same area in the southeastern part of the 

RNA. Traces of the access road into this area still exist (USDA USFS 2008).

Horse Ridge RNA was 

further designated 

as a national natural 

landmark in 1968.
13

Horse Ridge Research Natural Area: Guidebook Supplement 37

In the early 1970s, a barbed-wire perimeter fence was constructed, which 

further restricted livestock access into the RNA from adjacent lands. Recent use 

of the area includes trail riding within the RNA by mountain bikers, especially 

during the late winter and early spring. 

Maps 

Maps applicable to Horse Ridge RNA: topographic—Horse Ridge, Oregon 7.5 

minute, 1:24,000 scale, 1962; Brothers/LaPine Planning Area–west half, 1:100,000, 

1998.

Acknowledgments

We thank BLM specialists Rick Demmer and Bill Dean for assistance in creating appendix 2. We thank Sarah Greene, Todd Wilson, and Craig Obermiller for 

reviewing the manuscript. We also thank the Prineville District BLM for funding 

this project and the USFS PNW Research Station for publishing this guidebook 

supplement.

English Equivalents

1 hectare (ha) = 2.47 acres (ac)

1 kilometer (km) = 0.62 miles (mi)

1 meter (m) = 3.28 feet (ft)

1 decimeter (dm) = 3.94 inch (in)

1 centimeter (cm) = 0.394 inch 

1 millimeter (mm) = 0.0394 inch

References 

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New Haven and London: Yale University Press. 795 p.

Carroll, G.C.; Carroll, F.E. 1978. Studies on the incidence of coniferous 

needle endophytes in the Pacific Northwest. Canadian Journal of Botany. 

56(24): 3034–3043.

Csuti, B.; Kimerling, A.J.; O’Neil, T.A.; Shaughnessy, M.M.; Gaines, E.P.; 

Huso, M.M.P. 1997. Atlas of Oregon wildlife. Corvallis, OR: Oregon State 

University Press. 427 p. + map.
14

GENERAL TECHNICAL REPORT PNW-GTR-771

Driscoll, R.S. 1964. Vegetation-soil units in the central Oregon juniper zone. Res. 

Pap. PNW-19. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Forest and Range Experiment Station. 60 p.

Dyrness, C.T.; Franklin, J.F.; Maser, C.; Cook, S.A.; Hall, J.D.; Faxon, G. 

1975. Research natural area needs in the Pacific Northwest: a contribution to 

land-use planning. Gen. Tech. Rep. PNW-38. Portland, OR: U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment 

Station. 231 p.

Esslinger, T.L. 2006. A cumulative checklist for the lichen-forming, lichenicolous 

and allied fungi of the continental United States and Canada. North Dakota 

State University: http://www.ndsu.nodak.edu/instruct/esslinge/chcklst/chcklst7.

htm (First Posted 1 December 1997, Most Recent Update 10 April 2006), Fargo, 

North Dakota. (January 31, 2008).

Federal Committee on Ecological Reserves. 1977. A directory of the research 

natural areas on federal lands of the United States of America. Washington, DC: 

U.S. Department of Agriculture, Forest Service.

Flora of North America. 1993+. Partial nomenclature of vascular plants, ferns, 

and fern allies within Oregon. http://www.efloras.org/flora_page.aspx?flora_id=1. 

(November 3, 2006).

Franklin, J.F.; Dyrness, C.T. 1988. 2

nd ed. Natural vegetation of Oregon and 

Washington. Corvallis, OR: Oregon State University Press. 452 p.

Franklin, J.F.; Hall, F.C.; Dyrness, C.T.; Maser, C. 1972. Federal research 

natural areas in Oregon and Washington: a guidebook for scientists and 

educators. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Forest and Range Experiment Station. 498 p.

Gashwiler, J.S. 1977. Bird populations in four vegetational types in central 

Oregon. Special Scientific Report Wildlife 205. Washington, DC: U.S. 

Department of the Interior, Fish and Wildlife Service. 20 p.

Gates, D.H. 1964. Sagebrush infested by leaf defoliating moth. Journal of Range 

Management. 17(4): 209–210.

Gholz, H.L. 1979. Limits on aboveground net primary production, leaf area, and 

biomass in vegetational zones of the Pacific Northwest. Corvallis, OR: Oregon 

State University. Ph.D. dissertation. 61 p.
15

Horse Ridge Research Natural Area: Guidebook Supplement 37

Gholz, H.L. 1980. Structure and productivity of Juniperus occidentalis in central 

Oregon. American Midland Naturalist. 103(2): 251–261.

Gholz, H.L. 1982. Environmental limits on aboveground net primary production, 

leaf area, and biomass in vegetation zones of the Pacific Northwest. Ecology. 

62(2): 469–481.

Greene, S.E.; Blinn, T.; Franklin, J.F. 1986. Research natural areas in Oregon 

and Washington: past and current research and related literature. Gen. Tech. Rep. 

PNW-GTR-197. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 115 p.

Hall, F.C. 1972. Horse Ridge Research Natural Area. In: Franklin, J.F.; Hall, 

F.C.; Dyrness, C.T.; Maser, C. Federal research natural areas in Oregon and 

Washington. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Forest and Range Experiment Station. 7 p.

Hopkins, W.E.; Kovalchik, B.L. 1983. Plant associations of the Crooked River 

National Grassland. PNWR6Ecol. 133-1983. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 98 p.

Johnson, C.G., Jr.; Swanson, D.K. 2005. Bunchgrass plant communities of the 

Blue and Ochoco Mountains: a guide for managers. Gen. Tech. Rep. PNWGTR-641. Portland, OR: U.S. Department of Agriculture, Forest Service. Pacific 

Northwest Research Station. 119 p.

Knapp, P.A.; Soulé, P.T. 1998. Recent Juniperus occidentalis (western juniper) 

expansion on a protected site in central Oregon. Global Change Biology. 

4(3): 347–357.

Knapp, P.A.; Soulé, P.T. 1999. Geographical distribution of an 18th century heart 

rot outbreak in western juniper (Juniperus occidentalis ssp. occidentalis Hook.) 

Journal of Arid Environments. 41(3): 247-256.

Knapp, P.A.; Grissino-Mayer, H.D; Soulé P.T. 2002. Climatic regionalization 

and the spatio-temporal occurrence of extreme single-year drought events (1500–

1998) in the interior Pacific Northwest, USA. Quaternary Research. 58: 226–233. 

Knapp, P.A.; Soulé P.T.; Grissino-Mayer, H.D. 2001a. Detecting potential 

regional effects of increased atmospheric CO2 on growth rates of western 

juniper. Global Change Biology. 7: 902–917.

Knapp, P.A.; Soulé P.T.; Grissino-Mayer, H.D. 2001b. Post-drought growth 

responses of western juniper (Juniperus occidentalis var. occidentalis) in central 

Oregon. Geophysical Research Letters. 28(13): 2657–2660.
16

GENERAL TECHNICAL REPORT PNW-GTR-771

Knapp, P.A.; Soulé P.T.; Grissino-Mayer, H.D. 2004. Occurrence of sustained 

droughts in the interior Pacific Northwest (A.D. 1733–1980) inferred from tree 

ring data. Journal of Climate. 17(1): 140-150.

Miller, R.; Rose, J.; Van Pelt, B.; Acker, S. [N.d.]. Horse Ridge western juniper 

permanent plot. Unpublished report. On file at: Bureau of Land Management 

Prineville District Office. 3050 NE 3rd Street, Prineville, OR 97754. 

Missouri Botanical Garden. 2008. W3MOST database. Current moss 

nomenclature and authorities, MOSs TROPICOS. http://mobot.mobot.org/

W3T/Search/most.html. (January 31, 2008).

Oregon Flora Project. 2008. The Oregon plant atlas. http://www.oregonflora.org/ 

oregonplantatlas.html. (January 11, 2008).

Oregon Natural Heritage Program. 2003. Oregon natural heritage plan. Salem, 

OR: Department of State Lands. 167 p.

Ponzetti, J.M. 2000. Biotic soil crusts of Oregon’s shrub steppe. Corvallis, OR: 

Oregon State University. 112 p.

Soulé, P.T.; Knapp, P.A. 2000. Juniperus occidentalis (western juniper) 

establishment history on two minimally disturbed research natural areas in 

central Oregon. Western North American Naturalist. 60(1): 26–33.

Soulé, P.T.; Knapp, P.A. 1996. Pogonomyrmex owyheei nest site density and 

size on a minimally impacted site in central Oregon. Great Basin Naturalist. 

56(2): 162–166. 

Soulé, P.T.; Knapp, P.A.; Grissino-Mayer, H.D. 2003. Comparative rates 

of western juniper afforestation in south-central Oregon and the role of 

anthropogenic disturbance. The Professional Geographer. 55(1): 43-55.

Spanner, M.A.; Teuber, K.; Acevedo, W. [et al.]. 1984. Remote sensing of 

the leaf area index of temperate coniferous forests. In: Machine processing 

remotely sensed data. Proceedings of a symposium. West Lafayette, IN: Purdue 

University: 362–370.

U.S. Department of Agriculture, Natural Resources Conservation Service 

[USDA NRCS]. 2008. Soil maps from Deschutes County, Oregon. http://

websoilsurvey.nrcs.usda.gov/app/. (February 5, 2008).

U.S. Department of Agriculture, Forest Service [USDA FS]. 2008. Horse 

Ridge Research Natural Area. http://www.fsl.orst.edu/rna/sites/horseridge.htm. 

(February 7, 2008).
17

Horse Ridge Research Natural Area: Guidebook Supplement 37

U.S. Department of the Interior, Bureau of Land Management [USDI BLM]. 

1989. Brothers/LaPine resource management plan record of decision and 

rangeland program summary. On file with: Prineville District Office, 3050 NE 

3

rd Street, Prineville, OR 97754. 

U.S. Department of the Interior, Bureau of Land Management [USDI BLM]. 

1996. Horse Ridge ACEC/RNA management plan. Unpublished document. On 

file with: BLM, Prineville District Office, 3050 NE 3rd Street, Prineville, OR 

97754. 

U.S. Department of the Interior, Bureau of Land Management [USDI BLM]. 

2005. Upper Deschutes resource management plan record of decision and 

rangeland program summary. On file with: Prineville District Office, 3050 

NE 3rd Street, Prineville, OR 97754. 

Western Region Climate Center. 2008. Oregon climate data. http://www.wrcc.dri.

edu/cgi-bin/cliMAIN.pl?orfall (February 5, 2008).

Young, J.A.; Evans, R.A.; Major, J. 1972. Alien plants in the Great Basin. Journal 

of Range Management. 25(3): 195–201.
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GENERAL TECHNICAL REPORT PNW-GTR-771

Appendix 1: Vascular Plants and Fernsa b

Scientific name Common name

Coniferous trees:

Juniperus occidentalis Hook. Western juniper

Pinus ponderosa Dougl. ex Laws. & C. Laws. var. ponderosa Ponderosa pine

Medium shrubs 0.5 to 2 m (1.6 to 6.6 ft) tall:

Artemisia tridentata Nutt. Big sagebrush

Chrysothamnus viscidiflorus (Hook.) Nutt. Yellow rabbitbrush

Ericameria bloomeri (Gray) Macbr. Bloomer’s goldenbush

Ericameria humilis (Greene) L.C. Anderson Truckee rabbitbrush 

Ericameria nauseosa (Pallas ex Pursh) Nesom & Baird Gray rabbitbrush

Grayia spinosa (Hook.) Moq. Spiny hopsage

Linanthus pungens (Torr.) J.M. Porter & L.A. Johnson Granite prickly phlox

Purshia tridentata (Pursh) DC. Antelope bitterbrush

Ribes cereum Dougl. Wax currant

Tetradymia canescens DC. Spineless horsebrush

Tetradymia glabrata T. & G. Smooth horsebrush

Low shrubs <0.5 m (1.6 ft) tall:

Ericameria resinosa Nutt. Columbia goldenweed

Ferns:

Cheilanthes gracillima D.C. Eaton Lace lipfern 

Herbs:

Achillea millefolium L. Common yarrow

Agoseris glauca (Pursh) Raf. var. glauca Pale agoseris

Alyssum alyssoides (L.) L. Pale madwort

Amsinckia lycopsoides Lehm. Tarweed fiddleneck

Antennaria dimorpha (Nutt.) T. & G. Low pussytoes

Antennaria geyeri Gray Pinewoods pussytoes

Antennaria microphylla Rydb. Littleleaf pussytoes

Arabis holboellii Hornem. Holboell’s rockcress

Arabis puberula Nutt. Silver rockcress

Arabis sparsiflora Nutt. Engelm. Sicklepod rockcres

Arceuthobium campylopodum Western dwarf mistletoe

Astragalus curvicarpus (Heller) J.F. Macbr. Curve-pod milkvetch

Astragalus filipes Torr. ex Gray Basalt milkvetch

Astragalus lentiginosus Dougl. ex Hook. var. chartaceus M.E. Jones Broadleaf milkvetch

Astragalus purshii Dougl. ex Hook. Woollypod milkvetch

Calochortus macrocarpus Dougl. Sagebrush mariposa lily

Castilleja chlorotica Piper Greentinge Indian paintbrush

Castilleja miniata Dougl. ex Hook. Giant red Indian paintbrush

Chaenactis douglasii (Hook.) Hook. & Arn. Douglas’ dustymaiden

Chenopodium fremontii S. Wats. Fremont’s goosefoot

Chenopodium leptophyllum (Moq.) Nutt. ex S. Wats. Narrowleaf goosefoot

Collinsia parviflora Dougl. ex Lindl. Maiden blue-eyed Mary

Collomia grandiflora Dougl. ex Lindl. Grand collomia

Collomia linearis Nutt. Tiny trumpet

Crepis acuminata Nutt. Tapertip hawksbeard

Cryptantha ambigua (Gray) Greene Obscure cryptantha

Cryptantha circumscissa (Hook. & Arn.) I.M. Johnston Cushion cryptantha
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Horse Ridge Research Natural Area: Guidebook Supplement 37

Scientific name Common name

Cryptantha pterocarya (Torr.) Greene Wingnut cryptantha

Cryptantha torreyana (Gray) Greene Torrey’s cryptantha

Descurainia pinnata (Walt.) Britt. Western tansymustard

Dieteria canescens (Pursh) Nutt. Hoary tansyaster

Draba verna L. Spring draba

Eriastrum sparsiflorum (Eastw.) Mason ssp. sparsiflorum Great Basin woollystar

Erigeron chrysopsidis Gray Dwarf yellow fleabane

Erigeron filifolius (Hook.) Nutt. Threadleaf fleabane

Erigeron linearis (Hook.) Piper Desert yellow fleabane

Erigeron poliospermus Gray Cushion fleabane

Erigeron speciosus (Lindl.) DC. Aspen fleabane

Eriogonum microthecum Nutt. var. laxiflorum Hook. Slender buckwheat

Eriogonum ovalifolium Nutt. var. ovalifolium Cushion buckwheat

Eriogonum strictum Benth. ssp. proliferum (T. & G.) Stokes Blue Mountain buckwheat

 var. anserinum (Greene) R.J. Davis

Eriogonum strictum Benth. ssp. strictum Blue Mountain buckwheat

Eriogonum umbellatum Torr. Sulphur-flower buckwheat

Eriogonum vimineum Dougl. ex. Benth. Wickerstem buckwheat

Eriophyllum lanatum (Pursh) J. Forbes Common woolly sunflower

Erodium cicutarium (L.) L’Her. ex Ait. Redstem storksbill

Erysimum sp. Wallflower

Fritillaria atropurpurea Nutt. Spotted fritillary

Gayophytum racemosum T. & G. Blackfoot groundsmoke

Gayophytum ramosissimum T. & G. Pinyon groundsmoke

Gilia sinuata Dougl. ex Benth. Rosy gilia

Hesperolinon micranthum (Gray) Sm. Tidytips

Holosteum umbellatum L. Jagged chickweed

Layia glandulosa (Hook.) Hook. & Arn. Whitedaisy tidytips

Leptosiphon septentrionalis (Mason) J.M. Porter & L.A. Johnson Northern linanthus

Leucocrinum montanum Nutt. ex Gray Common starlily

Lithospermum ruderale Dougl. ex Lehm. Western stoneseed

Lomatium nevadense (S. Wats.) Coult. & Rose Nevada biscuitroot

Lomatium triternatum (Pursh) Coult. & Rose Nineleaf biscuitroot

Lupinus argenteus Pursh Silvery lupine

Melilotus albus Medik. White sweet clover

Mentzelia albicaulis (Dougl. ex Hook.) Dougl. ex Torr. & Gray Whitestem blazingstar

Mimulus cusickii (Greene) Rattan Cusick’s monkeyflower

Mimulus nanus Hook. & Arn. Dwarf purple monkeyflower 

Nothocalais troximoides (Gray) Greene False agoseris

Orobanche corymbosa (Rydb.) Ferris ssp. corymbosa Flat-top broomrape

Orobanche fasciculata Nutt. Clustered broomrape

Penstemon humilis Nutt. ex Gray Low beardtongue

Phacelia hastata Dougl. ex Lehm. Silverleaf phacelia

Phacelia linearis (Pursh) Holz. Threadleaf phacelia

Phlox gracilis (Hook.) Greene Slender phlox

Plectritis macrocera T. & G. Longhorn plectritis

Polemonium micranthum Benth. Annual polemonium

Ranunculus occidentalis Nutt. var. occidentalis Western buttercup

Ranunculus testiculatus Crantz Curveseed butterwort

Scutellaria nana Gray Dwarf skullcap

Senecio canus Hook. Woolly groundsel
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GENERAL TECHNICAL REPORT PNW-GTR-771

Scientific name Common name

Silene douglasii Hook. Seabluff catchfly

Sisymbrium altissimum L. Tall tumblemustard

Stephanomeria minor (Hook.) Nutt. var. minor Narrowleaf wirelettuce 

Taraxacum officinale G.H. Weber ex Wiggers Common dandelion

Townsendia florifer (Hook.) Gray Showy Townsend daisy

Tragopogon dubius Scop. Yellow salsify

Zigadenus venenosus S. Wats. Meadow deathcamas

Grasses and sedges:

Achnatherum hymenoides (Roem. & Schult.) Barkw. Indian ricegrass

Achnatherum occidentale (Thurb.) Barkw. Common western needlegrass

Achnatherum thurberianum (Piper) Barkw. Thurber’s needlegrass

Bromus tectorum L. Cheatgrass

Carex filifolia Nutt. Threadleaf sedge

Carex rossii Boott in Hook. Ross’ sedge

Elymus elymoides (Raf.) Swezey Bottlebrush squirreltail

Elymus lanceolatus (Scribn. & J.G. Sm.) Gould ssp. lanceolatus Thickspike wheatgrass

Festuca idahoensis Elmer Idaho fescue

Hesperostipa comata (Trin. & Rupr.) Barkw. ssp. comata Needle-and-thread

Koeleria macrantha (Ledeb.) Schult. Prairie junegrass

Leymus cinereus (Scribn. & Merr.) A. Love Basin wildrye

Pascopyrum smithii (Rydb.) Barkw. & Dewey Western wheatgrass

Poa cusickii Vasey ssp. cusickii Cusick’s bluegrass

Poa secunda J. Presl ssp. juncifolia Big bluegrass

Poa secunda J. Presl ssp. secunda Sandberg bluegrass

Pseudoroegneria spicata (Pursh) A. Love Bluebunch wheatgrass

a Scientific names taken from Flora of North America. 1993+.

b Common names take from Oregon Flora Project. 2008.
21

Horse Ridge Research Natural Area: Guidebook Supplement 37

Appendix 2: Lichens and Mossesa b c

Scientific name Authority

Lichens:

Amandinea punctata (Hoffm.) Coppins & Scheid.

Arthonia glebosa Tuck.

Aspicilia filiformis Rosent.

Aspicilia hispida Mereschk.

Aspicilia reptans (Looman) Wetmore

Caloplaca jungermanniae (Vahl) Th. Fr.

Caloplaca tominii Savicz

Candelariella terrigena Rasanen

Cladonia spp. P. Browne

Diploschistes muscorum (Scop.) R. Sant.

Lecanora spp. Ach.

Leprocaulon subalbicans (Lamb) Lamb & Ward

Leptochidium albociliatum (Desmaz.) M. Choisy

Leptogium spp. (Ach.) A. Gray

Megaspora verrucosa (Ach.) Hafellner & V. Wirth

Ochrolechia upsaliensis (L.) A. Massal.

Peltigera spp. Willd.

Psora montana Timdal

Pterygoneuron ovatum (Hedw.) Dix.

Mosses:

Bryum argenteum Hedw.

Bryum spp. Hedw.

Ceratodon purpureus (Hedw.) Brid.

Encalypta rhaptocarpa Schwagr.

Tortula ruralis (Hedw.) G.Gaertn. B. Mey. & Scherb.

Tortula caninervis (Mitt.) Broth.

a Taken from Ponzetti, J.M. 2000.

b Lichen nomenclature follows Brodo et al. (2001), Lichens of North America. c Moss nomenclature follows Missouri Botanical Garden W3

MOST database (2008) for 

mosses and Esslinger (2006) for lichens.
22

GENERAL TECHNICAL REPORT PNW-GTR-771

Appendix 3: Amphibians, Reptiles, Birds, and Mammalsa

Family Scientific name Common name

Amphibians:

Bufonidae Bufo boreas Western toad

Hylidae Pseudacris regilla Pacific chorus frog

Pelobatidae Scaphiopus intermontanus Great Basin spadefoot

Reptiles:

Anguidae Elgaria multicarinata Southern alligator lizard

Boidae Charina bottae Rubber boa

Colubridae Coluber constrictor Racer

 Hypsiglena torquata Night snake

 Masticophis taeniatus Striped whipsnake

 Pituophis melanoleucus Gopher snake

 Thamnophis elegans Western terrestrial garter snake

 Thamnophis sirtalis Common garter snake

Iguanidae Phrynosoma douglasii Short-horned lizard

 Sceloporus graciosus Sagebrush lizard

 Sceloporus occidentalis Western fence lizard

 Uta stansburiana Side-blotched lizard

Scincidae Eumeces skiltonianus Western skink

Teiidae Cnemidophorus velox Plateau striped whiptail

Viperidae Crotalus viridis Western rattlesnake

Birds:

Accipitridae Accipiter cooperii Cooper’s hawk

 Accipiter gentilis Northern goshawk

 Accipiter striatus Sharp-shinned hawk

 Aquila chrysaetos Golden eagle

 Buteo jamaicensis Red-tailed hawk

 Circus cyaneus Northern harrier

 Haliaeetus leucocephalus Bald eagle

 Pandion haliaetus Osprey

Cathartidae Cathartes aura Turkey vulture

Falconidae Falco mexicanus Prairie falcon

 Falco peregrinus Peregrine falcon

 Falco sparverius American kestrel

Phasianidae Alectoris chukar Chukar

 Callipepla californica California quail

 Oreortyx pictus Mountain quail

 Perdix perdix Gray partridge

Charadriidae Charadrius vociferus Killdeer

Columbidae Columbia livia Rock dove

 Zenaida macroura Mourning dove

Tytonidae Tyto alba Barn owl
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Horse Ridge Research Natural Area: Guidebook Supplement 37

Family Scientific name Common name

Strigidae Asio otus Long-eared owl

 Athene cunicularia Burrowing owl

 Bubo virginianus Great-horned owl

 Glaucidium gnoma Northern pygmy owl

 Otus kennicottii Western screech-owl

Caprimulgidae Chordeiles minor Common nighthawk

Apodidae Aeronautes saxatalis White-throated swift

 Chaetura vauxi Vaux’s swift

Trochilidae Archilochus alexandri Black-chinned hummingbird

 Stellula calliope Calliope hummingbird

 Selasphorus rufus Rufous hummingbird

Picidae Colaptes auratus Northern flicker

 Picoides pubescens Downy woodpecker

 Picoides villosus Hairy woodpecker

 Sphyrapicus nuchalis Red-naped sapsucker

Tyrannidae Contopus sordidulus Western wood peewee

 Empidonax oberholseri Dusky flycatcher

 Empidonax wrightii Gray flycatcher

 Sayornis saya Say’s phoebe

 Myiarchus cinerascens Ash-throated flycatcher

 Tyrannus verticalis Western kingbird

Alaudidae Eremophila alpestris Horned lark

Hirundinidae Hirundo pyrrhonota Cliff swallow

 Hirundo rustica Barn swallow

 Stelgidopteryx serripennis Northern rough-winged swallow

 Tachycineta bicolor Tree swallow

 Tachycineta thalassina Violet-green swallow

Corvidae Aphelocoma californica Western scrub-jay

 Corvus brachyrhynchos American crow

 Corvus corax Common raven

 Cyanocitta stelleri Steller’s jay

 Gymnorhinus cyanocephalus Pinyon jay

 Nucifraga columbiana Clark’s nutcracker

 Pica hudsonia Black-billed magpie

Paridae Parus atricapillus Black-capped chickadee

 Parus gambeli Mountain chickadee

Aegithalidae Psaltriparus minimus Bushtit

Sittidae Sitta canadensis Red-breasted nuthatch

Troglodytidae Catherpes mexicanus Canyon wren

 Salpinctes obsoletus Rock wren

 Troglodytes aedon House wren

Muscicapidae Myadestes townsendi Townsend’s solitaire

 Sialia mexicana Western bluebird

 Sialia currucoides Mountain bluebird

 Turdus migratorius American robin

Mimidae Oreoscoptes montanus Sage thrasher

Bombycillidae Bombycilla cedrorum Cedar waxwing
24

GENERAL TECHNICAL REPORT PNW-GTR-771

Family Scientific name Common name

Laniidae Lanius ludovicianus Loggerhead shrike

Sturnidae Sturnus vulgaris European starling

Vireonidae Vireo solitarius Blue-headed vireo

Emberizidae Agelaius phoeniceus Red-winged blackbird

 Chondestes grammacus Lark sparrow

 Dendroica coronata Yellow-rumped warbler

 Dendroica nigrescens Black-throated gray warbler

 Euphagus cyanocephalus Brewer’s blackbird

 Icterus bullockii Bullock’s oriole

 Junco hyemalis Dark-eyed junco

 Molothrus ater Brown-headed cowbird

 Passerculus sandwichensis Savannah sparrow

 Passerella iliaca Fox sparrow

 Pipilo chlorurus Green-tailed towhee

 Pipilo maculatus Spotted towhee

 Pooecetes gramineus Vesper sparrow

 Spizella breweri Brewer’s sparrow

 Spizella passerina Chipping sparrow

 Sturnella neglecta Western meadowlark

 Zonotrichia leucophrys White-crowned sparrow

Fringillidae Carduelis pinus Pine siskin

 Carduelis psaltria Lesser goldfinch

 Carduelis tristis American goldfinch

 Carpodacus cassinii Cassin’s finch

 Carpodacus mexicanus House finch

Mammals:

Soricidae Sorex merriami Merriam’s shrew

 Sorex preblei Preble’s shrew

 Sorex vagrans Vagrant shrew

Talpidae Scapanus orarius Coast mole

Vespertilionidae Antrozous pallidus Pallid bat

 Corynorhinus townsendii Townsend’s big-eared bat

 Eptesicus fuscus Big brown bat

 Lasionycteris noctivagans Silver-haired bat

 Myotis californicus California myotis

 Myotis ciliolabrum Western small-footed myotis

 Myotis evotis Long-eared myotis

 Myotis lucifugus Little brown myotis

 Myotis thysanodes Fringed myotis

 Myotis volans Long-legged myotis

 Myotis yumanensis Yuma myotis

Leporidae Lepus californicus Black-tailed jackrabbit

 Sylvilagus nuttallii Mountain cottontail

Sciuridae Spermophilus beecheyi California ground squirrel

 Spermophilus beldingi Belding’s ground squirrel

 Spermophilus townsendii Townsend’s ground squirrel

 Tamias townsendii Townsend’s chipmunk
25

Horse Ridge Research Natural Area: Guidebook Supplement 37

Family Scientific name Common name

Geomyidae Thomomys talpoides Northern pocket gopher

Heteromyidae Dipodomys ordii Ord’s kangaroo rat

 Perognathus parvus Great Basin pocket mouse

Muridae Lemmiscus curtatus Sagebrush vole

 Marmota flaviventris Yellow-bellied marmot

 Microtus longicaudus Long-tailed vole

 Neotoma cinerea Bushy-tailed woodrat

 Onychomys leucogaster Northern grasshopper mouse

 Peromyscus crinitus Canyon mouse

 Peromyscus maniculatus Deer mouse

 Peromyscus truei Pinyon mouse

Erethizontidae Erethizon dorsatum Common porcupine

Canidae Canis latrans Coyote

 Vulpes vulpes Red fox

Procyonidae Procyon lotor Common raccoon

Mustelidae Mephitis mephitis Striped skunk

 Mustela frenata Long-tailed weasel

 Spilogale gracilis Western spotted skunk

 Taxidea taxus American badger

Felidae Felis concolor Mountain lion

 Lynx rufus Bobcat

Cervidae Odocoileus hemionus ssp. hemionus Black-tailed deer

a Nomenclature, distribution and habitat characteristics taken from Csuti et al. 1997.

Pacific Northwest Research Station

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