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A Comparative Study of the Vegetation of Grazed and Ungrazed of the Wasatch Range, Author(s): Walter P. Cottam and Frederick R. Evans Reviewed work(s): Source: Ecology, Vol. 26, No. 2 (Apr., 1945), pp. 171-181 Published by: Ecological Society of America Stable URL: http://www.jstor.org/stable/1930822 . Accessed: 06/07/2012 08:52

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http://www.jstor.org A COMPARATIVE STUDY OF THE VEGETATION OF GRAZED AND UNGRAZED CANYONS OF THE WASATCH RANGE, UTAH 1

WALTER P. COTTAM AND FREDERICK R. EVANS

Universityof Utah, Salt City, Utah

INTRODUCTION' CLIMATIC, PHYSIOGRAPHIC, AND GEOLOGIC FEATUREIS The past twodecades have been marked by intensifiedgovernmental efforts in The WVasatchMountains constitute rangerehabilitation. These effortshave the northeasternrim of the . been handicapped by lack of definitein- They rise abruptly as an escarpment formationabout the pristine nature of froma floorwith an elevation of grazed lands as well as about quantita- 4500 feet up to altitudes of 12,000 feet. tive and qualitative changes whichgraz- The range is deeply dissectedby numer- ing has doubtless induced in the plant ous canyons having a general east-west cover. The meagernessof the historical direction,of which Red Butte and Emi- recordconcerning the vegetation over the grationcaynons are typical. These two vast grazingareas of the West at the time canyons are parallel to each other with of settlement,together with the almost their mouths directlyeast of and adja- totalabsence of preserved primitive areas, cent to and discharge makes the problemof reconstructingthe their streams westward into Salt Lake originalplant cover difficultthough not . Red Butte , which lies impossibleto solve. In these problems one mile to the northof EmigrationCan- ecologyfinds both a duty and a privilege yon, drains an area of approximately25 to serve the land-use program. square miles. EmigrationCanyon drains The Wasatch east of Salt an area ofapproximately 40 square miles. Lake City,Utah, affordedan opportunity It is characteristicof the canyons of to ascertainsome ofthe effectsof nearlya the Wasatch Mountains that the south- centuryof intensive,unregulated grazing facing slopes are less precipitous than and otherhuman influences on the native their north-facingcounterparts. Since vegetationand soil of various elevations the drainage area of Red Butte Canyon and slope exposures. This study was is less and its lengthshorter than those confined to vegetational problems of of Emigration Canyon while both can- Emigration and Red Butte canyons, yons at theirmouths are approximately the same depth,both slopes of Red Butte while the resultsof parallel but indepen- Canyon are in generalsteeper than those dent soil investigationswere reportedby of EmigrationCanyon. Croft et al ('43) of the same and other In soil and geological features these areas of the Wasatch Mountains. Emi- two canyons show importantdifferences. gration and Red Butte canyons were EmigrationCanyon is composed princi- selected forstudy because of theircom- pally of Jurassic while Red parabilityin position,physiography, and Butte Canyon consistsin part of a com- historicaluse. plex mixtureof Triassic shale, , and limestone. Considering the great 1 Acknowledgmentsare due the Intermountain Forest and Range Experiment Station, Ogden, differencein grazing use, it was sug- Utah, for valuable suggestionsand financialaid gested by Croft,Woodward, and Ander- in the pursuit of this study. son ('43) that the soils of Red Butte 171 172 WALTER P. COTTAM AND FREDERICK R. EVANS Ecology, VTol,26, No. 2

Canyon erode much moreeasily than do title to most of the land in Emigration those of EmigrationCanyon. It is gen- Canyon. However, some of the canyon erallyrecognized also thatsandstone soils is includedin the Wasatch National For- are basically less favorable for plant est, and a fewsections still remainunder growththan are limestonesoils (Hilgard, private ownership. Because the perma- '06). These factswould seem to favora nent stream in Emigration Canyon is moreabundant vegetationin Emigration small and uncertain, the water is not Canyon and are importantin the analysis used by Salt Lake City fordomestic pur- of vegetationin this paper. poses, and littleattention has been given The , because of its to grazing or problems. City westernexposure and its abruptrise from propertyis still leased to private stock- the desert, is considerably more xeric men, and grazing in this canyon, there- than the canyons that dissect it. Pre- fore, has continued without regulation cipitation,which averages 16.13 inches since the time of settlement. annually at Salt Lake City, increases In addition to the grazing abuses al- with elevation to a maximumof about ready recounted,Emigration Canyon for 40 inches at 9000 feet. The growing a distance of six miles is used as a stock season shortens with higher altitude; trail to and from the higher summer has a frostlessperiod of rangesof the Wasatch and Uintah Moun- about 160 days while BrightonCanyon, tains. The number of sheep passing 10 miles south of Emigration Canyon, over this trail varies fromyear to year. with an elevation of 8700 feet, has an In the springof 1935,for example, 97,550 average growingseason of about 90 days. sheep and 200 cattle used thistrail; in the fall of the same year 123,000sheep were HISTORY OF RANGE USE ANDOWNERSHIP herded down the canyon. By compari- son, the spring drive of 1931 included Soon afterthe settlementof Salt Lake 145,510sheep, and the fall flockstotaled Valley in 1847,both Red Butte and Emi- 209,203 sheep. Trailing here is said to grationcanyons came underprivate own- have begun in the early "fifties." Each ershipand both were utilizedfor grazing flockhas the freedomof the canyonup to purposes. In 1888 the the six-milepoint where the trail passes governmentbegan the purchase of Red Butte Canyon for the purpose of estab- over Little into Parley's Can- lishingFort Douglas at its mouth,and by yon. It is not uncommonfor a single 1909 had acquired title to the entirewa- flockto remaina week withinthe lower tershed. Protectionfrom grazing prob- reaches of EmigrationCanyon. ably commencedwith the firstpurchase Many summerhomes with theirasso- of the land. Even then,however, gully ciated fenced enclosures are located in erosionwas manifestin the canyon. It Emigration Canyon along the stream is assumed that depletion of the plant course, and the canyon is much used for coverwas responsiblebecause, underpro- campingand generalsummer recreation. tection,gullies have become revegetated On the other hand, civilians have been and severeerosion at presentis only half rigidlyexcluded from Red Butte Canyon that foundin EmigrationCanyon. Ring since the turnof this century. counts fromtrees growingon these old Fires at the mouths of both canyons erosionscars place theirage at approxi- are not uncommon. Especially is this mately 40 years, a date which coincides trueof Red Butte Canyon wherevegeta- with the purchaseof Red Butte Canyon tion is purposelyburned to clear the land by the War Department. for target ranges. Both canyons have As a result of a policy to protect its sufferedfrom inadvertent burns at vari- watershed,Salt Lake City has acquired ous places and timesat higherelevations. April, 1945 CANYON VEGETATION OF WASATCH RANGE, UTAH 173

EARLY DESCRIPTIONS OF VEGETATION was compelledto return." (Quoted from Linn, '02.) Clayton ('21), in describing No recordsare extant whichrefer par- the pioneer trek down EmigrationCan- ticularlyto the vegetationof Red Butte yon, said, "The grass on the creekgrows Canyon, and but fewrefer to the vegeta- fromsix to twelve feethigh and appears tion of Emigration Canyon in 1847. veryrank." (Doubtless Elymusconden- However, it is significantthat available satus.2) At theirlast encampment,a po- referencesdescribe Emigration Canyon sition six miles fromthe mouth of this as denselyvegetated. William Clayton canyon, he wrote, "The grass here ap- ('21), an early Mormon historian,stated pears even thickeron the ground than that it was necessary, because of the where we left this morning. The soil dense growthof vegetation,for the pio- looks indeed rich, black and a little neersto reconstructa throughEmi- sandy. The grass is about fourfeet high gration Canyon which had apparently and very thick on the ground and well been used by the only the mixedwith rushes." At the presenttime year previous. In July, 1847, Erastus the vegetationin EmigrationCanyon has and Orson Pratt traveled through no such appearance,but, in general,these Emigration Canyon in advance of the main pioneer party. Snow said that 2 Authorityfor plant names is Tidestrom,Flora "The thicketdown the narrows at the of Utah and , with the followingexcep- mouth of the canyon was so dense that tions: grasses, Hitchcock's Manual of the grasses we could not penetrate through it. I of the United States; Populus tremuloidesvar. aurea, Pseudotsuga taxifolia,Berberis repens, and crawled for some distance on my hands Sisymbrium altissimum, Kearney and Peebles, and knees through this thicket until I Flowering plants and fernsof .

l: I

FIG. 1. A typicalview midwayup Red Butte Canyon showingthe dense vegetationin the bottomof thecanyon. Note theabundance of cow parsnip(Heracleum lanatum), a palatableweed rarelyseen in EmigrationCanyon. 174 WALTER P. COTTAM AND FREDERICK R. EVANS Ecology, Vol. 26, No. 2

FIG. 2. Emigration Canyon contrastsunfavorably with correspondingareas in Red Butte Canyon. Note the hedgednature of the haw shrubs(Crataegus rivularis) and the low ruderalvegetation in the foreground. descriptionsapply to Red Butte Canyon the canyon,though its exact positionwas as it appears today (figs.1, 2). placed at random. From this point the Three moreor less distinctbelts ofveg- centerof each succeedingtransect was es- etationhave been recognizedon the Wa- tablishedin the bottomof the canyon at satch front. A grass-sagebrushclimax exactlythree-mile intervals by speedom- extendsfrom the valley floorto an aver- eterreading. Each transectconsisted of age elevation of 5000 feet. Above this 40 plots evenlyspaced along a compass to about 7500 feet scrub oak (Quercus line and so distributedthat 20 plots lay gambeli)dominates the landscape, while on each hillside. The firstplot of each stillhigher there is a belt of aspen (Popu- transectlay 100 feetfrom the streambed, lus tremuloidesvar. area) and conifers and the twentiethplot lay on or near the consistingof white fir (Abies concolor), canyonridge tops. Plots wereseparated (Pseudotsugataxifolia), and by a distance of 200 feet,making the en- blue spruce (Picea pungens). tire transectof 40 plots 8000 feet long. Each plot was circularin shape and 100 FIELD PROCEDURE square feetin area. Correspondingtransects and plotswere The lengthof EmigrationCanyon to established for Red Butte Canyon, but the main tributariesof its drainage was since this canyon is not as long as Emi- found by speedometermeasurements to grationCanyon, altitudes at the stream be approximately12 miles. In order to bed wererecorded by means ofan aneroid sample adequately the vegetationin this barometerfor each transectin Emigra- canyon,four transects drawn at rightan- tion Canyon and the same altitude was gles to the directionof drainage and equi- used to locate the correspondingtransect distantfrom one anotherwere established . in Red Butte Canyon. Altitudinalposi- Transect I was located at the mouth of tions forcorresponding transects in each April, 1945 CANYON VEGETATION OF WASATCH RANGE, UTAII 175 canyonat the streambed wereas follows: 1, 5000 feet; Il, 5350 feet; 111, 5600 feet; IV, 6800 feet. The point-observation- plot methodof vegetationalanalysis de- vised by Stewart and Hutchings ('36) was adopted forthis study. The surveywas made in the summerof 1935 (late June, July). Each summer since then the authors have made a cur- sory study of the two canyons. Condi- tions at presentare essentiallythe same as thoseat the timeof the original survey.

rA7NSECrS 1II ANALYSIS OF VEGETATION FIG. 4. Comparison of densities of all vegeta- Data gatheredin this study permita tion in each transect of Red Butte and Emigra- comparativeanalysis of the vegetationin tion canyons. Solid bars = Red Butte Canyon; Red Butte and Emigrationcanyons with cross-hatchedbars = Emigration Canyon. respectto the densityof the plant cover as a whole and of the individualspecies, Except at the mouth,Red Butte Canyon and grazingcapacity. shows plant densitiesfar in excess of the Comparativedensities: Graphic com- correspondingareas in EmigrationCan- parisonsof plant densitiesof Red Butte yon. (3) The vegetation midway up and Emigrationcanyons are shownin fig- Red Butte Canyon (transect II1) is less ures 3 and 4. The densityof the plant dense than on adjacent areas below and cover of Red Butte Canyon is approxi- above (transect II and IV) in the same matelytwice that of EmigrationCanyon. canyon. Field observationsclearly re- The distributionof plant densities by veal the reason forthis in the prevalence transectsin the two canyons (fig.4) pre- of rockoutcroppings and poor soil chiefly sents several interestingfacts. (1) The on the south slope of the canyon. (4) canyons are nearly equal in the total Except at the mouth, EmigrationCan- amountof vegetationon transectI. (2) yon varies but slightlyin the densityof vegetationof all transects. /5 ~~~~~~.04- Vegetationtypes: Red Butte and Emi- grationcanyons are both dominated by scrub oak (Quercus gambeli). Figure 5

0: .03n gives a graphic comparison of the two k~~~~~~~~ canyonswith respect to total amountsof

PO weeds,3shrubs, and grassesin each of the fourtransects. Some outstandingfacts are illustrated by these graphs. (1) 0" Shrub densities exceed the combined Al.- densitiesof weeds and grassesin all areas

.0/ above the mouth in both canyons. (2) The mouth of Red Butte Canyon has a grass-weedaspect, while the mouth of Emigration Canyon is dominated by

FIG. 3. Comparison of the density of plant 3 The Forest Service classificationof vegetation cover and forage acre factor of Red Butte and is used in this study. Weeds include all non- Emigration canyons. Solid bars = Red Butte grassyherbaceous plants while the term"ruderal" Canyon; cross-hatched bars = Emigration Can- is reserved for plants falling under the popular yon. concept of "weed." 176 WALTER P. COTTAM AND FREDERICK R. EVANS Ecology,Vol. 26, No. 2

/4 _

i0

TRANSECTS: I H T U II Zf KE RED surrT EMICRAA r/Ov

FIG. 5. Comparison of densities of shrubs, weeds, and grasses in each transect of Red Butte and Emigrationcanyons. Solid bars = shrubs; cross-hatchedbars = weeds; stippled bars = grasses. shrubs. The grassyslopes of Red Butte parison of the vegetation of these two Canyon are burned by firemuch more canyons. An analysis of the vegetation often than are the correspondingslopes from the standpoint of livestock influ- of Emigration Canyon. (3) The pro- ences involved a re-examinationof the portionsof shrubs,weeds, and grasseson vegetation in each canyon on the basis the various transectsof each canyon are, of the palatability for sheep and cattle. in general,similar. Accordingto strati- In this analysis the authorsfollowed the graphicmaps of the area, the portionof Forest Service practice of determining Red Butte Canyon in the vicinity of the forageacre factorfor the sectionsof transectIII possesses,in additionto lime- each canyon throughwhich the transects stone, some shale and sandstone, prob- passed. The forageacre factoris a frac- ably accounting in part for the fewer tional unit of measurementfrom which shrubs on that transect. Other differ- actual stock-carryingcapacity of a given ences in proportionsof the three plant range is estimated. The amount of for- types (for example, on transect II of age on any given acre of range is depen- EmigrationCanyon) may be accounted dent on two importantmeasurable fac- for chieflyby the influenceof grazing, tors: first,the density of each forage although the greater excess of shrubs species, and second, the utility (palata- (chieflyscrub oak) overweeds and grasses bility)4of each foragespecies to livestock. at the head of Red Butte Canyon is Many laymen and even stockmenare doubtless due to the fact that at this proneto accept quantityof vegetationas altitudeclimate and topography(steeper the sole criterionof grazing capacity. slopes) favor the maximum growth of The errorin not consideringquality of shrubs. vegetation as well as quantity is illus- GRAZING CAPACITIES I Palatability tables used in this study were Differencesof grazing use to which secured fromthe U. S. Forest Service. A pala- Red Butte and Emigrationcanyons have tability rating is given for each species of plant. Palatability is definedas the per cent of current been subjected constitute a variable growth of a given species of plant utilized by which should prove significantin a com- stock when the range is properlygrazed. April, 1945 CANYON VEGETATION OF WASATCH RANGE, UTAH 177

plants as big sagebrush (Artemnisiatri- dentata), rabbit brush (Chrysothamnus speciosus),and barberry(Berberis repens), all oflow palatabilityto livestock. None of these plants was encounteredin meas- urable quantities at the mouth of Red '.11 Butte Canyon. DISCUSSION In the absence of detailed historical data it was impossibleto ascertain with accuracy the floristicchanges which oc- rRANsrcrs 1 curred in the vegetation of Emigration FIG. 6. Comparison of forage acre factors of Canyon (lue to grazingand otherfactors. each transectof Red Butte and Emigration can- yons. Solid bars = Red Butte Canyon; cross- That the vegetationin Red Butte Can- hatched bars = Emigration Canyon. yonwas richboth in quantityand quality offorage was evidentto thewriters at the trated in figures3, 4, and 6. The total outset of this study, and the foregoing densityof vegetation of EmigrationCan- analysisgives some numericalidea of the yon is 55 per cent of that of Red Butte differencesbetween the two canyons. Canyon,but the actual amount of forage The followingmore detailed considera- is only42 per cent as much (fig.3). This tion of the data on grasses, weeds, and fact stands out even more in comparing shrubs points to the great probability specificareas of the two canyons. The that grazingis chieflyresponsible for the density of vegetation at the mouthof impoverishmentand the retrogressive EmigrationCanyon is 87 per cent of that succession of vegetation which has oc- at the mouthof Red Butte Canyon (fig. curredin EmigrationCanyon. 4). Owing to the quality of the plant Grasses: The density of palatable cover, however,the amount of forageat grasses, including Agropyronspicatum, the mouthof EmigrationCanyon is only A. pauciflorum,A. dasystachyum,Bro- 45 per cent of that at the mouth of Red mus brizaeformis,B. carinatus,Poa pra- Butte Canyon (fig.6). tensis, and P. secunda, is five times The differencebetween the forageacre greater in Red Butte Canyon than in factorand the densityof plant cover in Emigration Canyon. The density of Red Butte and Emigration canyons is Bromus tectorum,an introducedspecies, much greaterat the mouths than else- is one and one-halftimes greaterin Red where. This may be explained by the Butte Canyon than in EmigrationCan- fact that at the mouth of Emigration yon. This grass,though palatable fora Canyon therehas been a greaterchange short time early in the growingseason, of vegetational types. It is here that has a low palatabilityrating most of the the competitionbetween grass and shrub summer. The successfulinvasion of this types is in most delicate balance in the species in Red Butte Canyon ( I) is undisturbedrange. These facts would doubtlessdue to the frequentburning at seemto supportthe conclusion of Pickford its mouth. That Bromustectorum is pri- ('32) and the unpublishedobservations of marilya grassof the foothillenvironment othersthat the foothillvegetation of the ofthe intermountain west is generallyob- mountainson theeastern rim of the Great served and specificallyshown for both Basin at the timeof the firstwhite settle- Red Butte and Emigrationcanyons. mentwasthe grass type. Approximately Grasses (except B. tectorum)are most one-thirdof the vegetationat the mouth abundant at lower elevations in Red of EmngrationCanyon consists of such Butte Canyon, but in EmigrationCan- 178 WALTER P. COTTAM AND FREDERICK R. EVANS Ecology,Vol. 26, No. 2

TABLE I. A comparison of densities in per gration cent of Broiiius tectorum and combined native Canyon is seen in the following grasses in the various transectsof Red Butte and significantdata: (1) The densityof weed Emigrationcanyons vegetationwith low palatabilityis twice as great in EmigrationCanyon as in Red Red Butte Canyon Emigration Canyon Butte Canyon. The densityof more pal- atable species,on the otherhand, is only IralsectsBromus Brms Combined BromCsombined native Brms native one-fifthas great in EmigrationCanyon tectorum grasses tectorum grasses as in Red Butte Canyon. (2) Herbace- I 2.01 0.85 1.62 0.11 ous vegetationof low palatabilityis twice II 0.86 0.66 0.08 0.09 III 0.21 0.18 0.25 0.01 as dense as palatable weeds in Emigra- IV 0.06 0.08 0.11 0.14 tion Canyon; in Red Butte Canyon the density of palatable weeds is five times that of unpalatable weeds. (3) Highly yon the reverseis true (table I). Several palatable species of weed vegetation, factors are probably responsible. Red probably once abundant in Emigration Butte Canyon with its more precipitous Canyon, are on the verge of extinction slopes and its less open upper drainageis (table II). more favorableto shrubsand less favor- able to grasses. This phenomenon is TABLE II. Percentagepalatability of important specieswith comparative densities in per cent common to narrowcanyons of the Wa- in Red Butteand Emigrationcanyons satch Mountains. The near absence of native grasses midway up Emigration Density Canyon (table I, transectI I I) is explained Palata- bility by the fact that the sheep trail passes Red Emi- Butte gratin over Little Mountain near this point, Grasses: and, consequently,grazing is heaviest in Agropyron spicatum ...... 80 0.23 0.03 Bromus tectorum...... 15 0.78 0.50 this vicinity. Despite grazing, grasses Poa longiligula ...... 85 0.15 0.02 are moredense in the upperareas of Emi- Weeds: Achillea lanulosa ...... 40 0.12 0.04 gration Canyon (table I, transect IV) Balsamorhiza sagittata...... 40 0.90 0.18 than at the correspondingelevation of Geranium fremoniii...... 45 0.22 0.04 Lathyrus leucanthus ...... 20 0.25 0.14 Red Butte Canyon. This observation Leptotaenia multifida...... 50 0.25 0.07 15 gives credence to the probability that Wyethia amplexicaulis ...... 1.11 0.28 Shrubs: grass was abundant in EmigrationCan- Amelanchier alnifolia ...... 75 0.39 0.19 Artemisia tridentala...... 0 0.04 0.53 yon in pioneerdays. Berberis repens...... 0 0.13 0.14 Chrysothamnus speciosus...... 0 trace 0.55 Ten native grasseswere found in Red Quercus gambeli...... 20 4.51 2.56 Butte Canyon which were not observed Rosa spp ...... 50 0.64 0.16 Symphoricarpos vaccinioides. .. 50 0.80 0.21 in EmigrationCanyon (table III). Con- versely,all but one of the native grasses encounteredin the plots of Emigration Mule's ear ( Wyethiaamplexicaulis), an Canyon appeared in Red Butte Canyon. herb of low palatability (15 per cent), is These factswould seem to emphasizethe much moreabundant in Red Butte Can- dangerof completeextermination of rare yon than in Emigration Canyon (table and highlypalatable speciesin overgrazed II). A possibleexplanation is that stock areas. A comparisonof the palatability in EmigrationCanyon is forcedto sub- and density of three principal grasses sist on plantsof low palatabilityand that (table II) leaves little doubt as to the sheep are fond of the seed heads and damaging influenceof severe grazingon therebyinterfere with the natural repro- palatable grasses. ductive processesof the plant. Weeds:The-influence of heavy grazing Shrubs: Scrub oak is by far the most on the native herbaceous flora5 of Emi- common shrub in both canyons. De- i All species of weeds whichaveraged in density whichwere given palatability ratingsby the U. S. at least one-eighthof one per cent per plot and Forest Service are included in the data. April, 1945 CANYON VEGETATION OF WASATCH RANGE, UTAH 179

TABLE III. List of grasses occurringin plots of Red Butte and Emigrationcanyons. Presence of a species is indicatedby a plus sign and absence by a zero sign

Red Emi- Emi- SpeciesSpecies | Butte gration SeisRedSpecies Butte gration

Agropyrondasystachyum + + Festuca kingii. + + A gropyronpauciflorum + + Festuca subulata. + 0 Agropyronsmithii molle + 0 Glyceriaelata .+ 0 Agropyronspicatum ...... 4-I + Glyceriastriata. + 0 Agropyronsubsecundum +.. 0 Hordeumjubatum .+ + *Agrostisalba .+ + Koeleria cristata.+ 0 Agrostisexarata .+ 0 Melica bulbosa.+ + Agrostisidahoensis. 0 + *Munroa squarrosa.0 + *Agrostisverticillata. + 0 Oryzopsishymenoides. + 0 Aristida longisetarobusta . + ?+ Q *Phleum pratense. + + *Bromusbrizaeformis .+ + *Poa annua .0 + Bromus carinatus.+ + *Poa compressa.+ 0 *Bromustectorum .+ + Poa longiligula.+ + Catabrosaaquatica .+ 0 *Poa pratensis.+ + *Dactylis glomerata.0 + Poa secunda.+ + Deschampsia caespitosa ..+ ?+ + *Setaria viridis. 0 + Elymus condensatus.+ + Stipa columbiana.+ +

* Introducedspecies spite the fact that this shrub has a pala- their growth. In Emigration Canyon, tability rating of only 20 per cent, the however,a major highway,a long-used densityof scrub oak in EmigrationCan- sheep trail, heavy grazing,and summer yon is but half of that in Red Butte homes all contributeto conditionsfavor- Canyon. The densityof otherspecies of able to an abundant ruderalflora. The shrubswith highpalatability is less than densityof ruderalsin Red Butte Canyon one-thirdas muchin EmigrationCanyon is 12 per cent less than in Emigration as in the other. Sagebrush and rabbit- Canyon (fig.7). ExceptingBromus tec- brushwith little forage value have a den- torum,the densityof ruderalsin Emigra- sity 13 timesgreater in EmigrationCan- tion Canyon is seven timesas great as in yon than in Red Butte Canyon. Red Butte Canyon. These ruderalsare Ruderals: The ruderal flora of Red most abundant in burnedareas on tran- Butte and Emigrationcanyons includes sect I, along the denuded sheep trail,and the followingspecies: Ambrosia psilo- in fencedareas near summerhomes where stachya,Asclepias speciosa,Bromus tecto- rum, Caulanthushastatus, Camelina mi- Z.00 crocarpa,Chenopodium album, Helianthus annuus, Lactuca scariola, Lepidium ape- talum,Lepidium perfoliatum, Marrubium vulgare,Polygonum douglasii, Salsola pes- tifer,Sisymbrium altissimum, Sophia par- - 100 viflora,and Zygadenuspaniculatus. Most ruderalsare practicallyvalueless as forageand many are exotic annuals. k.50 They appear either as pioneers on de- nuded areas or as the last stage in re-

trogressivesuccession. In Red Butte rRA NS ECTs I Canyon, with the exception of Bromus tectorum,they are confinedto the lower FIG. 7. Comparisonof densities of ruderals in each transectof Red Butteand Emigrationcan- elevations of the canyon where fire or yons. Solid bars = Red Butte Canyon; cross- disturbedsoil about Fort Douglas permit hatchedbars = EmigrationCanyon. 180 WALTER P. COTTAM AND FREDERICK R. EVANS Ecology, \Tol. 26, No. 2

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FIG. 8. Barren areas along the sheep trail in Emigration Canyon constitute a flood hazard to Salt Lake City thenative vegetation has been destroyed. alarming impoverishmentof the plant Owing to the decrease of native vegeta- cover, and sheet erosion is generallyin tion on heavily grazed slopes, ruderals evidence. Advanced gullyerosion is es- occur in all areas of EmigrationCanyon peciallynoticeable on the slopes of Little in contrastto the very small amount of Mountain where the trail passes out of these plants in the miidand upper areas EmigrationCanyon. Here barrenareas of Red Butte Canyon. Only one ruderal (fig. 8) more than ten acres in extent species, Bromus tectorum,was found in furnishrunoff which reaches flood pro- plots on transects III and IV of -Red portions when melt and heavy Butte Canyon. rains fall. A cloudburstin this vicinity mightresult in a floodthat would destroy EROSION homes of Salt Lake City lying directly For more than half a century,from in its path. That this menace is a very 100,000 to 200,000 sheep have trailed real one is evidenced by the fact that throughEmigration Canyon to themoun- such a floodhas already occurredin Dry tain summerranges each springand have Canyon which lies about one and one- returnedthrough this canyon to the des- half miles to the north (Alter, '21). ert winterranges each fall. Each herd There the drainage area is not nearly as leisurelygrazes in the canyon forseveral large as that in EmigrationCanyon, and days in transit. Besides this abuse, pri- the plant cover is considerably more vate flocksgraze on the upper areas of dense. EmigrationCanyon duringthe summer. Cattle also graze in the canyon during SUMMARY the summermonths. 1. Two canyons,Red Butte and Emi- Such overuse of thesegrazing lands in gration,extending parallel to each other, Emigration Canyon has resulted in an adjacent and generallysimilar in geogra- April, 1945 CANYON VEGETATION OF WASATCHI RANGE, UTAII 181 phy,slope exposure,and elevation,were Emigration Canyon have 13 times the compared in respect to quantity and densityof the same shrubsin Red Butte quality of plant cover. Canyon. 2. In theirpristine condition, because 8. The densityof ruderalsin Emigra- of morefavorable soil types,Emigration tionCanyon is 12 per cent greaterthan in Canyon probablycontained a vegetation Red Butte Canyon. Excepting Bromus equal to or surpassingthat which now tectorum,the densityof ruderalsin Emi- exists in Red Butte Canyon. grationCanyon is morethan seven times 3. For a periodof at least 40 yearsRed greaterthan in Red Butte Canyon. Butte Canyon has been protectedagainst 9. Sheet erosionis general throughout grazing. Emigration Canyon has been EmigrationCanyon and advanced gully grazed heavilysince settlementin 1847. erosionis commonalong a sheep trail. 4. Palatable vegetation has probably decreased, and unpalatable vegetation LITERATURE CITED has probably increased in Emigration Alter,J. Cecil. 1921. Forests in relation to cli- Canyon. Only 42 per cent as much for- mate and water supply. Trans. Utah Acad. age is producedhere as in equal areas in Sci. 2: 195-198. Clayton, William. 1921. Journal of William Red Butte Canyon. Clayton. Deseret News, Salt Lake City, 5. Ten native grasses found in Red Utah. Butte Canyon were not encounteredin Croft, A. R., Lowell Woodward, and Dean A. EmigrationCanyon, suggestingthe dan- Anderson. 1943. Measurements of accel- erated erosion on range-watershed land. ger of complete exterminationof highly Jour. Forestry41: 112-116. palatable species throughgrazing abuse. Hilgard, E. W. 1906. Soils. 593 pp. The 6. Evidence points to the probability Macmillan Co., New York. of the completesubstitution of the orig- Linn, W. A. 1902. Story of the Mormons. inal grass type with unpalatable shrubs The Macmillan Co., New York. Pickford, G. D. 1932. The influence of con- plus Bromus tectorumat the mouth of tinued heavy grazing and promiscuous burn- EmigrationCanyon. ing on spring-fallranges in Utah. Ecology 7. Some highly palatable shrubs in 13: 159-171. EmigrationCanyon have a density less Stewart,George, and S. S. Hutchings. 1936. The point-observation-plot(square-foot-den- than one-thirdthat in Red Butte Can- sity) method of vegetation surveys. Jour. yon. Othershrubs of low palatabilityin Anmer.Soc. Agron. 28: 714-722.