Taxonomy and Ecology of Sagebrush in Oregon

Home , Artemisia arbuscula, Artemisia nova

C 4 Taxonomy and Ecology of Sagebrush in Oregon

Station Bulletin 642 May 1980

Agricultural Experiment Station Oregon State University, Corvallis Contents

Abstract 5

Introduction

Taxonomy 6

Ecology 6 Scabland sagebrush 6 Black sagebrush 6 Low sagebrush 7 Cleftleaf sagebrush 7 Early sagebrush 7

Three-tip sagebrush 7

Bolander silver sagebrush 7 Mountain silver sagebrush 7 Wyoming big sagebrush 12 Basin big sagebrush 12 Mountain big sagebrush 12 Subalpine sagebrush 13

Diagramatic Key 8

Key to Artemisia (Section Tridentatae) in Oregon 10

Management Alternatives 13

Literature Cited 15

AUTHOR: A. H. Winward, Associate Professor, Rangeland Resources Program, Oregon State University, Corvallis, Oregon 97331. 3 Taxonomy and Ecology of Sagebrush in Oregon

A. H. Winward

ABSTRACT ally arise as to where or how much sagebrush is Twelve important sagebrush taxa form an needed for food or cover for native animals and important component of the vegetation on at birds. Should it be controlled or reduced, thereby least 19 million acres in Oregon. Each kind of releasing associated grasses and forbs for live- sagebrushhasitsown morphology,genetic stock and wildlife feed? If so, how should it be make-up, and ecologicalrequirements. Those reducedwith chemicals, by fire,or mechani- acquainted with these 12 taxa find them useful in cally? What was the ecological status of sage- recognizing range sites and understanding site brush during the presettlement period and how potential. This bulletin provides an update on information used toidentify these 12 taxa. A has this changed? What factors are responsible general description of their geographic distribu- for this change? tionis included, along with important features While arguments continue, scientists are gath- about their ecology and value as cover or forage. ering facts about sagebrush that will help answer these questions. For several years, scientists have been refin- INTRODUCTION ing sagebrush taxonomy. What was once de- The genus Artemisia (sagebrush) is known on scribed as a few separate species have been found most continents of the world. In the United States to be complexes of many subtaxa, each with its it occupies at least 96 million acres (Tisdale et al., own morphology, genetic make-up, and ecological 1969) and is found primarily in the steppe areas of requirements. Those acquainted withthe new the 11 western states. classification system find it easier to understand In the Pacific Northwest and Intermountain re- the ecology of each taxon and can better predict gions there are 20-plus recognized species, sub- responses to particular land management prac- species, and forms of woody sagebrush, plus at tices. least 15 herbaceous species. This paper covers The objectives of this paper are to: only the woody taxa which have perfect flowers Provide an update of the kinds of sagebrush (Tribe Anthemideae). Twelve representatives from in Oregon. this tribe are common in Oregon (Table 1). These Provide information necessary to recognize 12 taxa form an important component of the vege- each important taxon in Oregon. tation on at least 19 million acres in Oregon. A considerable amount of controversy about Stress the importance of keeping up with the value of sagebrush exists. Questions continu- the new sagebrush classification system.

Table 1.Important woody Artemisia taxa in Oregon1 Standard Scientific name Common name abbreviation Artemisia rigida Scabland or stiff sagebrush Arri Artemisia nova Black sagebrush Arno2 Artemisia arbuscula ssp. arbuscula Low sagebrush Arara Artemisia arbuscula ssp. thermo p0/a Cleftleaf sagebrush Arart Artemisia Ion giloba Early sagebrush Arlo2 Art emisia tripartita ssp. tripartita Three-tip sagebrush Artrt2 Art emisia cana ssp. bolanderi Bolander silver sagebrush Arcab Artemisia cana ssp. viscidula Mountain silver sagebrush Arcav Artemisia tridentata ssp. wyomingensis Wyoming big sagebrush Artrw Artemisia tridentata ssp. trident ata Basin big sagebrush Artrt Artemisia tridentata ssp. vase yana Mountain big sagebrush Artrv Artemisia tridentata form spiciformis Subalpine big sagebrush Artrs 1 Common names and standard abbreviations from Garrison et al., 1976. 5 4. Discuss the status of land management ECOLOGY practices based on the new system. Ecological features which influence where the sagebrush taxa grow include: TAXONOMY Elevation (as it affects temperature and soil moisture); Major morphological characteristics used to Soil depth, structure, drainage, and chem- classify sagebrush include: leaf shape, size, and i stry; color; shrub height and general form; branching of the inflorescence and number of seeds per Total yearly moisture and seasonal distri- flower head (see key). bution; and Since we deal with species, subspecies, and Other less defined features such as number forms, some characteristics are somewhat subtle. of cloud-free days per year and competing For this reason, several features often are used to vegetation. substantiate some separations. A few individual The following information is a general descrip- plants in most stands of sagebrush have unusual tion of the geographic distribution and ecology of oruncommon features.Generally,theseare sagebrush in Oregon. Specific areas where some caused by crossing of two taxa, "unnatural" envi- taxa have isolated or scattered occurrences may ronmental influences, or some other phenomenon not be mentioned. that alters a plant's natural appearance. In field work, however, problems from unusual individuals are minimal since we are dealing with full popula- Artemisia rigida (scabland sagebrush) tions, i.e., we are generally attempting to identify Scabland sagebrush occurs primarily in the sagebrush in an area versus an individual plant. north and northeastern part of the state.Itis In addition to using morphological features for found as far west as Wasco County, as far south classification, the number of chromosomes and as northern Harney County, and north and east chemical make-up have been used toidentify into Washington and Idaho.It grows on rocky, genetic variations of sagebrush. A useful chemical shallow soil areas from about 3,000 to 7,000 feet method to separate some sagebrush taxa is to elevation. The grass species most commonly as- place a few grams of leaf material in a clear glass sociated with scabland sagebrush under good con- bottle, add enough methanol or ethanol to thor- ditions is Sandberg's bluegrass (Poa sandbergii). oughly saturate the leaves, and allow the material Biscuitroots (Lomatium species) also are common to react for one-half hour (Winward and Tisdale, associates. Cheatgrass (Bromus tectorum) and 1969). The color of the fluorescing liquid can be other annual grasses and forbs become major increasers on disturbed sites of scabland sagebrush. Table 2.Fluorescent color of the sagebrush-methanol solution under long-wave, ultraviolet light (by taxon) Artemisia nova (black sagebrush) Group I.Fluoresce shades of creamish-blue Black sagebrush has been found in only three Artemisia arbuscula ssp. arbuscula southeastern Oregon countiesLake, Harney, and Artemisia arbuscula ssp. thermopola Malbeur. It extends in small patches as far north- Artemisia Ion giloba west as Christmas Valley but is more common in Artemisia tripartita ssp. tripartita the southern part of these three counties. It ap- Artemisia cana ssp. bolanderi pears to have some affinity to calcareous soils Artemisia cana ssp. viscidula with a high amount of surface rock or pavement. Artemisia tridentata ssp. vase yana It generally occurs above 4,000 feet elevation and Artemesia tridentata form spiciformis in some states has been found as high as 8,000 Group ILFluoresce shades of brownish-red feet. Several older range surveys describing black Artemisia tridentata ssp. wyomingensis sagebrush in other areas of Oregon apparently Artomisia tridentata ssp. tridentata are in error. Artemisia nova Vegetation commonly associated with this spe- Artemisia rigida cies under good conditions includes bluebunch wheatgrass (Agropyron spicatum), Indian ricegrass (OryzopsIs hymenoides), and, occasionally, needle- observed by shining a long-wave, ultraviolet light andthread grass (Stipa comata). Squirreltail(Si- on the bottle in a darkened room. The solution will tanion hystrix) and Sandberg's bluegrass are com- be shades of either creamish-blue or brownish- mon increasers. Under severely depleted condi- red. Colors which the sagebrush taxa fluoresce are tions, a large amount of bare ground becomes listed in Table 2. exposed on black sagebrush sites. 6 Artemisiasagebrush) arbuscula subsp. arbuscula (low tipArtemisia sagebrush) tripartita subsp. tripartita (three- thattheernless CascadesOregon. border than 3,000 theIt exceptoccurs Columbia feet theinelevation nearly northern River. all to Low Itcounties abovehalf is sagebrushfound of 9,000counties east from feet.of is found in many parts of east- outcounties.onlyareas positive. in Baker of Several the Three-tip andstate, reports northern but sagebrush none, have Harney asrecorded yet,canIn and Oregon,have be it Malheur foundin checked other three-tip in sagebrush has been found shallow,areasWithdrought.longed few with unfractured exceptions,spring an impermeable flooding bedrock.low sagebrushand "B" extensiveIt withstandshorizon is found orsummer withpro- on allmanagementfuselysoilserate states aboveto after thatdeep, border3,800fire considerations. well-drained, or feet Idaho,clipping elevation. and loamyand it growsrequires Itand resprouts sandy on specialmod- loam pro- onana).ensis),bunch low Sandberg's wheatgrass, andsagebrush Thurber's bluegrass, sites,Idaho needlegrass fescue a commonCommonly (Festuca (Stipa increaserthurber!- idaho-associated species include blue- is followed by annual fieldsstandsber'sIdahothree-tip withfescue, of sagebrush three-tip only needleandthread a fewsagebrush include understory bluebunch become grass,Dominant species. densewheatgrass, and Thur-Sand- grassesbrush commonly associatedneedlegrass. with Under heavy disturbance, ceptceouscentralsevere.forbs it and soil.grows Oregon grasses It isto appearssimilar3 feet as disturbances into to heightother have low andsomeA sagebrushvariantbecome can tie occur to of pumi-more thisex-on taxon which occurs across Artemisiathispratensis)berg's subspecies. bluegrass arecana common subsp. and Kentuckyincreasers bolanderi bluegrass in (Bolander stands (Poa of sagebrushcharacteristicsdeeperresearch soils. in is general.Other neededare similar morphological on to this low variant sagebrush. and ecologicaland Moreon low silverfardesertnally northwest sagebrush) drained areas ofas basins the Prineville, state. scattered In but Oregon its throughout majorBolander it occurs acreage silverthe as sagebrush is found in inter- Artemisia(cleftleafatWheeler, moderately Grant,arbuscula sagebrush) high and elevations Baker subsp. counties. (5,000 thermoCleftleaf to It 9,000occurs p0/a sagebrush feet), only is most common in Crook, wherehavebeenis portionsin the anfound it southeasterntendsupper of in California westerntolimit grade of one-thirdabout Idaho intoand mountain Nevada.5,500 and of thein feet the state.silverIt elevation, appearsnorthern Itsage- has to logicalsagebrushests.torta)usually or requirementsin ponderosa openings and appears in pine exceptlodgepole to (Pinus have for verypineitsponderosa) restriction similar(Pinus eco-con- for- to It has the same associated species as low weeksextremelyandbrush generallyduring (described clayey, winter have are later).and alkaline standing spring. Soils rather in water theseCurrently, than for basins saline,several associated are vegetation is sparse. No higher,ArtemisiaCrook, coolerand Ionnorthern areas. giloba Lake (early and sagebrush)HarneyEarly counties. sagebrush It has been found in Deschutes, sins.foundsupportedmuhlyrecords Wire as (Muhienbergia a exist muchrushband to(Juncus) aroundherbaceous suggest richardsonis) the also that margin vegetation. generally these of theseareas can ba- everbe is generally Alkali environmentalsimilarassociatedtensivemay betosearch lowfound species sagebrush. continues. requirements in surrounding and ecological EarlyMost which sagebrushlikelycounties characteristics setit has as also uniquemore has in- it apart Somefoundfunctionsagebrush scatteredareas of soilremainplants, chemistryamong andessentially thisthe than appearssagebrush ofbarren past to abuse. betweenbe more a plants. betterAsidedatesfromtified. low fromwarrantdescribed Thesagebrush, its earlyearlier its as treatment growth a butphenoiogy, subspecies these initiationas have a it separate ofmay not A. and havearbuscula.been maturitytaxon. beeniden- Artemisiasilver sagebrushsagebrush) cana subsp. occurs viscidula in the upperAs (mountain implied elevation, in the common name, mountain of Montana,ItNevada, is found Utah, andin several Wyoming,and Colorado. other and states, the northern primarily portions Idaho, thevationmountainous east-central to above areas. 8,000 and It southeastern feetoccurs and from is most 5,500 corner common feet of ele- the in 7 A. rigida

(scabland sagebrush) DIagramatIc XcqShon'Ing A. nova A. nova

(black (black sagebrush) ponicle spike sagebrush) entire vs. cleft vs. nffren tIntIng CharacterIs tics A. arbuscula A. arbuscula ssp. arbuscula ssp. arbuscula

(low sagebrush) (low sagebrush) lobed lvs. cleft vs n4nchSeparateSagebrush A. arbuscula A. arbuscula ssp. thermopola ssp. thermapola

gray green, sticky (cleft leaf (clef tleaf racme spike skioit cleft lobed spike or panicle eagebrush) sagebrush) entire lvs cleft lvs.roceme layeringnon-layering )nxa In Oregon A. longiloba A. longiloba

green, stickyseed set seed set (early gray '7 (early wedged vs cleft lvs spike Or (July - (mid Aug - sagebrush) sagebrush) lobed vs cleft Ivs.raCerne panicle mid Aug) Oct)non-layering layenng

A. tripartite A. tripartita ssp. tripartite ssp. tripartita

(three-tip cleft lvsclef t.wedged (three-tip sagebrush) panicle spike or sagebrush' cleft lvs lobed lvs rocemecleft lvs belied vs

A. cana A. cana rg?t asp. bolanderi sap. bolanderi (C!fr chracrcrisncs co ta.in onft) (Bolancler silver (gh chara.ctrrjstics nito taz u uo (Bolander silver sagebrush) (Jcf.sLzcs arc not- drawn to scale) sagebrush) entire vs cleft Ivsentire vs lobed vsentire lvs lobed lvsentire lvs cleft vsentire lvs belied lvs cleft lvs. A. cans A. cana asp. viscidula ssp. viscidula siiver-gray"sen.grot (mountain silver (mountain silver mt mecfl catohrnent sagebrush) sagebrush) entire lvs cleft esentire lvs lobed vsentire vs lobed vsentire l,s cleft lvs entire vs cleft vs stream edges basins A. .J-C )'Vui vanI QanqcIauL ic'urcc5 A. tridentata A. tridentata Qrrgon ..$catr Zi'uvciszy sap. wyonhingensis asp. wyamingensis (Wyoming big (Wyoming big uneven top even topuneven top even topuneven top even topuneven topeven topbelIed lvs cleff lvs sagebrush) sagebrush) lobed vs cleft lvsmediumshb small shbmedium shb small shbmedium shb small shbmedium shb small shbuneven top tven toplobed lvs entire lvsl lobed lvs. entire lvs

A. tridentata A. triclentata ssp. tridentata asp. trjdentata

(basin big brxwedged skat,belledlong,wedged sinai l,cleftkcng,wedged thrt,bel led (basin big uneven top even toplong,wedge left's sagebrush) uneven topeven topuneven topeven top sagebrush) lobed vs cleft vs large shb small shblarge shbsmall shblarge shbsmall stibuneventop even topwedged vsentire vs wedged vs. entire lvs A. fridentata A. tridentata ssp. vaseyana asp. vaseyana

even top uneven top (mountain big (mountain big bcwedged sksxbeiledbng,wuiged stsxbekedkjro,wedged sml,cleft ung,wedged st-o-telled even top uneven top sagebrush) sagebrush) cleft slarge shb small shblarge shbsmall shblarge shbsmall shb large shbsmall shblong, wedge cleft tvs wedged lvs entire lvswedged lvs entiretvswedgedlvs belledlvs.lvs !kwidest

A. tridentata A. tridentata form spiciformis form spicifomis (subalpine big (subalpine big larç,wedged short,beflekao,wedged st-ica-f,belled long,wedged smallleftlong,wed sut,beUed even top uneven top even top uneven top>7 (flowersl 4-6 sagebrush) sagebrush) non-layeringlayeringnon-layerinc lobed vs cleftislarge stt small shblarge shb small sob large shbsmall shblarge shbsmall shblong, wedge cleft lvwedged vs entire wedged tvs entire Fvswedged lvs belIed lvs layering

8 9 KEY TO ARTEM/SIA (SECTION TRIDENTATAE) IN OREGON

laLeaves entire1

2a Leaves silver-gray, plants from internally drained basins with seasonal flooding A. ccna ssp. bo1ander

2bLeaves green-gray, plants along stream bottoms or meadow margins from mid to high elevations---A. cctna ssp.vt.sci4u.taz

lb Leaves divided or lobed

3a MatureUshrubs less than 20II. high

4a Leaves divided (lobe length > 3 times width)

5a Flower stalk leaves divided, inflorescence spicate, all leaves winter deciduous

5b Flower stalk leaves entire

6aInfiorescence paniculate, upper flower stalk leaves much longer than flower heads---A. rrvpartTttl5sp. trtpertuTw

6b Inflorescence spicate or racemose, flower stalk leaves equal or only slightly longer than flower head---- 4. c.rbu.scuthssp. thermepota./

4b Leaves lobed (lobed length < 3 times width)

7aInflorescence paniculate, seed stalks brownish and persist into following year ,--..A. nova-

1' Key based on persistent (overwintering) eaves unless otherwise noted.

Mature infers at least 20 years old (see xylem layers).

10 KEY TO ARTEMISIA (CONTINUED)

7b lnflorescence spicate or racemose, seed stalks grayish and weakly persistent

8a Seeds mature mid-July to mid-August --A.LongIZoba

Sb Seeds mature late August to October- - ..A.arbuscuLa ssp arbuscuLa

3b Mature shrubs taller than 20"

9a Uneven topped shrubs, flower stalks arise throughout crown

lOoMature plants > 40" in height, leaf margins straight - - tridentcztv sp.tridentua/

lObMature plants <40" in height, leaf margins belIed outward-----..'4-.rrIdentata/ssp. '4yomzngenszs

9b Even topped shrubs, flower stalks arise from upper crown and extend above foliage

1 Ia Leaf margins belied outward, inflorescence spicate or racemose-- ,&.crbuscuLiz ssp. cLrbuscuia.

11 b Leaf margins straight, inflorescence panicuaeI 4

12a Four to six flowers per head,& tr en-tata- .ssp. vtzscy2na

12b More than six flowers per head, plant often layering &.

11 state. As with Bolander silver sagebrush, moun- It is possible that cryptograms fill a major portion tain silver sagebrush grows in areas that have of these otherwise bare spaces with no disturb- high seasonal water tables. Sites supporting this ance, but the degree of this is unknown. Relatively subspecies are not internally drained, however, few perennial forbs occur with this subspecies, and include streamsides and meadow margins. It even under undisturbed conditions. has been found in all states west of the Continen- tal Divide. Artemisia tridentata subs p. trident a ta Communities of mountain silver sagebrush are rich floristically and may produce as many as (basin big sagebrush) 2,000 pounds per acre (dry weight) of herbaceous Basin big sagebrush is found in scattered, rel- vegetation. Numerous rushes and sedges (Carex atively small stands in every county of Oregon spp.) occur on these sitesalong withnative east of the Cascade Mountains. On an acreage grasses such as slender wheatgrass (Agropyron basis, however, it represents a minor portion of caninum), Nevada bluegrass (Poa nevadensis), and the sagebrush region in the state. Areas where several brome and fescue grasses. Many of the basin big sagebrush once was more extensive are seeded grasses such as timothy (Ph!eum pra- now under cultivation.It grows on deep, well- tense),orchardgrass (Dactylis glomerata), and drained soils and, depending on percent slope, is mountain brome (Bromus carinatus) are now pres- a good indicator of arable land. It is found from ent on these sites. In areas where these grass 100 feet elevation along the Columbia River to species have not become established, the under- above 7,000 feet in most mountain ranges. Above story is composed of a dense stand of Kentucky 6,000 feet elevation,itis generally restricted to bluegrass and rushes and sedges. Only under se- dry, shallow soil sites with southerly aspects or vere disturbances do these areas have low ground around the perimeter of tallus patches. cover. Grasses that occur with this subspecies are similar to the ones that grow with Wyoming big sagebrush. Additionally, basin wildrye (Elymus Artemisia tridenta ta su bsp. wyomingensis cinereus) may occur on bottomlands with slightly (Wyoming big sagebrush) saline soils or on soils with a source of ground- Wyoming big sagebrush is the most xeric mem- water within a few feet of the surface. Perennial ber of the big sagebrush group. It is the most com- forbs are more abundant than on Wyoming big mon sagebrush on the Oregon High Desert and is sagebrush sites and potential herbaceous produc- found on moderately deep, well-drained soils. In tion is from one-third to two times higher. Squirrel- many portions of the state, the soils are slightly tail and Sandberg's bluegrass are increasers on calcareous to the surface. In Oregon, its northern disturbed sites, with annual forbs and grasses be- limits are near Madras in central Oregon and coming more abundant as perennial vegetation is Baker in eastern Oregon. It is not common above reduced. 6,000 feet elevation. Where it does occur in the mountainous areas of the state, it is restricted to Artemisia tridentata subsp. vaseyana the more xeric environments. Associated grasses include bluebunch wheat- (mountain big sagebrush) grass, needleandthread grass, Thurber's needle- Mountain big sagebrush is found throughout grass, and, occasionally, Idaho fescue. Squirrel- the upper foothill and mountain areas of the state tail is a common increaser on many Wyoming big at elevations ranging from 3,500 to 9,000 feet. It sagebrushsites,exceptonsoilsespecially also is found in all counties east of the Cascade droughty or slightly saline where this grass is a Mountains.It grows on deep, well-drained soils natural dominant. Cheatgrass and Sandberg's blue- where moisture is available most of the summer grass are common increasers. Depending on the and is common in all Intermountain and Pacific stage of disturbance, Wyoming big sagebrush sites Northwest states. may support combinations of these grasses and Many species of forbs, grasses, and other annual forbs or a considerable amount of bare shrubs are often found growing with it.It is not ground. It must be noted, however, that even under uncommon to find 40 plant species in a standof natural condit'ions, Wyoming big sagebrush sites this sagebrush. Dominant perennial grass species may have about 25 percent bare ground under the undernatural conditionsincludebluebunch most restrictive environments. Other sites would be wheatg rass, Idaho fescue, needleandth read grass, expected to have less bare ground as limiting fac- Thurber's needlegrass, and junegrass (Koe!eria tors become less severe. The most mesic Wyo- cristata). Basin wildrye is a common associate in ming big sagebrush sites would have only about 5 areas where moisture in the rooting zone isavail- or 10 percent bare ground under natural conditions. able through summer. Increasers include Ken- 12 tuckybluegrass and Sandberg'sbluegrass, would not be beneficial. The most commonly as- squirreltail, and annual bromes and fescues. Gen- sociated grass species, Sandberg's bluegrass, is erally,disturbed areas support a few remnant not able to make use of additional soil moisture perennial species intermixed with annuals and that may result from removal of sagebrush. Reseed- dense sagebrush. ing of exotic grasses such as crested wheatgrass An unnamed variant of mountain big sagebrush would not be economical because of the nature of has been observed in central and northeastern the soils. Scabland sagebrush appears to be mod- Oregon. It occurs at the lower edge of the western erately palatable to livestock and wildlife, at least juniper (Juniperus occidentalis) zone and extends seasonally. It probably has low protein content in into the steppe areas. It appears to have devel- the winter season since it is deciduous. Programs oped on pumiceous soil, but this has not been ade- geared to managing most scabland sagebrush quately researched, It was originally believed to areas should be designed to maintain an open be the "X" big sagebrush found in west-central stand of sagebrush with a scattered understory of Idaho, but chromatographic patterns do not con- native perennial forbs and grasses, primarily Sand- firm this. More needs to be known about this var- berg's bluegrass. iant since areas in which it is found appear to be Black sagebrush sites also have low potential especially difficult to manage. Native and seeded for improvement through reseeding. Where Sand- grasses have been difficult to establish, and rab- berg's bluegrass has replaced the native bunch- bitbrush (Chrysothamnus spp.) has become ex- grasses, extremely long-termplant succession tremely dense in areas that have been opened up will be required to allow return of bunchgrasses. through disturbances. This may never be accomplished. Black sagebrush in Oregon was found to be extremely low in A rtemisia triden ta ta form spicitormis palatability to mule deer and only moderately palatable to domestic sheep (Sheehy and Winward, (subalpine big sagebrush) 1976), but observations suggest antelope use it Subalpine big sagebrush is restricted to areas extensively. The relatively few acres of black above 5,000 feet elevation and is more common sagebrush in Oregon should most likely be man- from 6,500 to 8,000 feet. It is found in most eastern aged to maintain a mixture of sagebrush, grasses, Oregon countiesincluding those on the east and forbs. slopes of the Cascade Mountains. It occurs as a Low sagebrush, cleftleaf sagebrush, and early discontinuous patch in the forest openings except sagebrush appear to have similar management on Steens Mountain, where it occupies the upper requirements. The sites on which they grow often one-third of the mountain (above 7,000 feet). On are unsuited for improvement through cultivation. more xeric sites at these elevations, mountain big Generally these areas have remnant forbs and sagebrush may occur as an inclusion within stands grasses and will improve through proper range of subalpine big sagebrush. management practices. Some areas have been Dominant native grasses include Idaho fescue successfullyreseededtocrestedwheatgrass and mountain brome, with occasional stands of through a no-till operation.If Sandberg's blue- elk sedge (Carex geyeri). Slender wheatgrass and grass is abundant on the site, this will not be pos- bluebunch wheatgrass often occur but are subor- sible. Only a few areas supporting these sagebrush dinate to the fescue and brome. Increaser species taxa have soil deep enough to allow seeding, include western need leg rass (St/pa occidentalis), however. In certain parts of the state, considera- oniongrasses(Mel/caspp.),bluegrasses(Poa tion should be given to wildlife since they use spp.), and several sedges. Cheatgrass and Sand- these areas extensively. Sheehy and Winward berg's bluegrass are seldom very competitive in (1976) found low sagebrush to be among the more these environments. Extremely dense stands of preferred taxa for forage in their study. subalpine big sagebrush often support high popu- Three-tip sagebrush is unique in that itis the lations of gophers (Thomomys spp.) in the winter. only sagebrush in Oregon which grows on deep, Their burrowing activities result in an increase in well-drained soil and resprouts. The combination annual forb species. of use by native and domestic animals and reduction by fire has allowed these areas to become more dense. Periodic chemical or mechanical MANAGEMENT ALTERNATIVES treatments may be the only way to keep densities Each sagebrush taxon mentioned has unique of this type of brush at a low enough level to allow ecological features that should be considered in healthy stands of herbaceous species. In the long its management. Since scabland sagebrush grows run, proper grazing or even non-use will not main- on extremely shallow, rocky soils, a control pro- tain stable densities of this subspecies. Periodic gram to reduce this type of sagebrush probably removalor thinningwillbe necessary. Good 13 stands of crested wheatgrass have been estab- been lost, introduced grasses such as crested lished on these sites in other states. wheatgrass or, on some sites, intermediate wheat- Bolander and mountain silver sagebrush are grass (Agropyron intermedium) can be estab- resprouting subspecies. Most sites on which Bo- lished. Basin big sagebrush was not a preferred lander silver sagebrush grows are not suited for taxon by deer and sheep (Sheehy and Winward, seeding grasses. The high water levelsin the 1976). spring and alkaline soils do not allow establish- Mountain big sagebrush has more potential for ment of crested wheatgrass. In a few locations, increasingits cover than any other sagebrush the perimeter of these basins probably would species. In some locations, dense stands are used grow tall wheatgrass (Agropyron elongatum), but by wildlife, especially during their reproductive acreage limitations make this impractical. Bolan- phase. Some of these areas should be maintained der silver sagebrush was found to be among the in a dense brush stage for this important purpose. group of sagebrush most preferred by deer and Mountain big sagebrush was in the high prefer- domestic sheep (Sheehy and Winward, 1976). ence group for mule deer and sheep in Oregon Stands of this subspecies are used each winter by (Sheehy and Winward, 1976). The majority of the mule deer in the Silver Lake area. Overall, Bo- many acres covered by this subspecies will need lander silver sagebrush sites should be left un- periodic sagebrush control efforts. Many areas are sprayed and untilled because the shrubs and the from two to six times more dense than they were few understory plants found growing in them are historically (Winward, 1970). Often there are ade- difficult to replace with other species. quate representatives of native understory spe- Mountain silver sagebrush sites also are better cies on mountain big sagebrush sites.If seeding left unaltered by mechanical treatments. Occa- isnecessary, crested wheatgrass, intermediate sionally some stands may have to be thinned with wheatgrass, and pubescent wheatg rass (Agropyron fire or chemicals since they can become rather trichophorum) have been the most successful in dense because of resprouting and layering, char- Oregon. acteristics of this taxon. Maintenance of a good Subalpine big sagebrush has a capacity to herbaceous cover will slow the densing process. form extremely dense stands also.Itslayering Relative palatability of mountain silver sagebrush characteristic allows it to spread and occupy all is unknown, but limited browsing has been ob- areas on a site. Spray-release programs have gen- served on the flower stalks in the early fall. erally been successful since native understory Many areas of Wyoming big sagebrush have species usually are still present. Where seeding is lost their natural understory vegetation. Livestock necessary,intermediatewheatgrass,mountain and wildlife have been partially responsible for brome, or smooth brome (Bromus inermis) have these changes, but increased density of sage- been most successful. Little reseeding of subal- brush and other shrubs due to fire protection also pine big sagebrush sites is needed in Oregon, but has had a significant impact. Where most of the periodic reduction of brush cover will be neces- remnant perennials have been lost, some type of sary in some areas. Important fawning sites such brush control will have to be implemented before as parts of the Steens Mountain may need to be either native or introduced herbaceous species left in the dense sagebrush stage. The relative can be established. The most common grass spe- palatability of this sagebrush has not been studied. cies seeded on Wyoming big sagebrush sites in Wyoming, basin, mountain, and subalpine big Oregon is crested wheatgrass. Bitterbrush (Pur- sagebrush make up the major sagebrush acreage shia tridentata)isnot a natural component of in the state. They have evolved to fit different habi- these sites, and attempts to seed this browse spe- tats within the sagebrush region and their recogni- cies into these areas probably will not be suc- tion as distinct taxa is basic for the management cessful. Wyoming big sagebrush was intermediate of the sagebrush-grass ranges. Differences in re- to low on the palatability scale in Oregon (Sheehy quirements for management among the four taxa and Winward, 1976). are related to the kind of sites each occupies, their Basin big sagebrush sites have a potential to reaction to depletion of understory vegetation, produce more herbaceous vegetation than Wyo- their use by wildlife and livestock, and their sea- ming big sagebrush sites. Most areas which once sonal growth development (Winward and Tisdale, supported this subspecies now are being farmed. 1977). The majority of the stands which remain have lost Big sagebrush sites have received the high- many of their native understory species. Basin big est amount of alterations through range improve- sagebrush shows only moderate increases in den- ment treatments. Since areas on which they grow sity with disturbance of associated vegetation, but have deep, well-drained soils, often they can be may increase greatly in foliage cover from crown improved by spray-release or reseeding programs. enlargement. Where the understory species have Spray programs essentially have stopped on public 14 rangelands. In 1978, only 43,000 acres of sagebrush LITERATURE CITED were sprayed in Oregon, and this was almost ex- clusively on private land. This represents one- Garrison, G. A., Jon Skovlin, C. E. Poulton, and fourth of one percent of the sagebrush acreage in A. H. Winward. 1976. Northwest Plant Names the state. Overall, less than two million acres of and Symbols for Ecosystem Inventory and An- sagebrush have been altered in Oregon through alysis, 4th ed. USDA Forest Service. range improvement practices, and some of this Sheehy, D. P., and A. H. Winward. 1976. Relative represents second- and third-time treatments on palatability of seven Artemisia taxa to mule the same acreage. deer and sheep. Abstracts of Papers, Society Cover of brush is often used as a measure of forRangeManagementAnnual Meeting. range condition. However, unless cover is related Omaha, Nebraska. to the particular subspecies in an area,it may have little value. For example, Wyoming big sage- Tisdale, E. W., M. Hironaka, and M. A. Fosberg. brush stands range from 8 percent sagebrush 169. The sagebrush region in Idaho, a prob- cover on good condition range to 23 percent on lem in resource management. Univ. of Idaho highly disturbed ranges (Winward, 1970). Moun- Agric. Expt. Sta. Bull. 512. tain big sagebrush, on the other extreme, ranges Winward, A. H. 1970. Taxonomic and ecological from 14 percent cover on good condition range to relationships of the big sagebrush complex in 41 percent on poor condition rangeland. Utah. Ph.D. dissertation, University of Idaho, There have been differences of opinion about Moscow. the geographic distribution of sagebrush in Ore- gon today compared to that of the presettlement Winward, A. H., and E. W. Tisdale. 1969. A sim- period. Tisdale et al. (1969) concluded that aside plified chemical method for sagebrush identifi- from some local movement of sagebrush into cation. Univ. of Idaho Forest, WildI. and f'ange meadows where the water table has been low- Expt. Sta. Note No. 11. ered, "the geographic area currently dominated Winward, A. H., and E. W. Tisdale. 1977. Tax- by woody species of sagebrush is essentially the onomy of the Artemisia tridentata complex in same today as in presettlement times." Idaho.For., Wildlf. and Range Expt. Sta. Bull. In north-central Oregon there is some evidence 19. that sagebrush has expanded from the intermound areas, where it is believed natural, onto the ad- Winward, A. H., and B. A. Youtie. 1976. Ecological jacent mounds which once supported grassland inventory of the Lawrence Memorial Grassland vegetation (Winward and Youtie, 1976). Absence Preserve. A report presented to the Pacific of fire appears to be the main factor responsible Northwest Chapter of the Nature Conservancy. for this change. Unpublished.