Effects of livestock management onSouthwestern riparian ecosystems

David J. Krueperl

Abstract.-Riparian habitats historically constituted 1% of the land mass inwestern North America. Within the past 100 years, an estimated 95% of thishabitat has been altered, degraded or destroyed due to a wide variety of landuse practices such as river channelization, clearing for agriculture, livestockgrazing, water impoundments and urbanization. Many authors now concurthat the single most important land management practice impacting westernriparian ecosystems has been unmanaged domestic livestock grazing. Over70% of the western United States is currently being grazed by livestock inhabitats ranging from sea level to alpine meadows. Unwise grazing practiceshave been shown to negatively affect Southwestern riparian vegetative com-position, ecosystem function, and ecosystem structure. This has resulted innegative impacts on native wildlife populations including insects, fish, reptiles,amphibians, birds, and mammals. Negative impacts due largely from over acentury of heavy domestic livestock utilization in riparian ecosystems hasresulted in the decline of many wildlife populatrons. Studies have shown thatup to 70% of avian species in the desert Southwest depend upon ripananhabitats for survival at some stage of their life. Over torty percent of Arizona’sstate-listed bird species are considered to be riparian obligate species. Ninetypercent of Arizona’s native fish species are now extinct, extirpated, or Feder-ally or state listed. Many other vertebrate species have declined in recentyears due to alteration of riparian habitats, and may soon be considered forFederal listing. To prevent future listings and to reverse population declines ofsensitive wildlife species, land management agencies need to implementappropriate practices within riparian ecosystems.

INTRODUCTION

“...(t)hey tell a story of bare dirt, manure, eroded gulliesand endless fences slicing through what once wasopen, wild rangeland. This story is all too familiar tothose who know and love the American West. FromCanada to Mexico and beyond, few arid and semi-arid landscapes west of the 100th meridian have beenfree of the influence of livestock, whose ‘manage-ment’ has contributed to loss of native vegetation,invasions by alien plants, decline of native fishes due

’ Bureau of Land Management, San Pedro Riparian NationalConservation Area, 1763 Paseo San Luis, Sierra Vista, AZ,65635.

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to dewatering of streams for irrigation and degrada-tion of riparian zones, eradication of native carni-vores and prairie dogs, diseases in native herbivores,and major changes in fire frequency, hydrology, soilsand other ecosystem properties. Many conservation-ists claim that livestock has done more damage to thenative biodiversity of western North America than allthe chainsaws and bulldozers combined.... Overall,agriculture - especially livestock production - has hada much greater influence on the ecosystems ofwestern North America than development. Yet, theresponse of conservationists to the problem oflivestock has been sluggish, perhaps because thecumulative effects of livestock grazing are much lessvisible to most people than clearcuts, subdivisions, orshopping malls....” (Ness 1994)

This file was created by scanning the printed publication.Errors identified by the software have been corrected;

however, some errors may remain.

The American Southwest encompasses portionsof 12 states within the western United States andnorthern Mexico, including Baja California Norte,Baja California Sur, Chihuahua, Coahuila, Sonora,Arizona, California, Colorado, Texas, New Mexico,Nevada and Utah (Rinne and Minckley 1991). Theregion is primarily composed of the Chihuahuanand Sonoran Deserts, with smaller portions of theMohave and Great Basin Deserts at the westernand northern boundary. Isolated mountains,plateaus, rivers and streams are dispersedthroughout the region. Elevations range frombelow sea-level to higher than 3500 m. Yearlytemperatures may vary up to 70” C between winterand summer extremes. Precipitation averages lessthan 5.0 cm per year in the driest portions of theSouthwest, and may exceed 120 cm in the moun-tains. Typically evaporation exceeds precipitationby a factor of up to five times the total yearlyrainfall, and surface water in streams or rivers isoften present for only portions of the year(Krueper 1993). Most of the vegetative life-zones ofthe western United States are present, often withinrelatively few miles of one another along anelevational gradient of up to 2500 m. These habi-tats include alpine tundra, coniferous forests ofponderosa pine and Douglas fir, madrean-oakwoodlands, chaparral, Chihuahuan grasslands,and Upper and Lower Sonoran Deserts. The majorwatersheds within the Southwest support riverswhich dissect portions of this seemingly inhospi-table region. The rivers include the Colorado, Gila,Little Colorado, Rio Grande, and Pecos in theUnited States, and the Rio Conches, Rio Yaqui, RioSonora, and Rio Conception in northern Mexico.

Riparian habitats within this region historicallytied all other vegetative life zone together within amatrix of “interconnectedness.” High elevationriparian habitats of aspen, maple and alder standsgrade to mid-elevation sycamore, walnut and ash,which connect with cottonwood and willowdominated riparian habitats at the lower eleva-tions. Water from ice melt in the southern Rockiesof New Mexico eventually empties into the Gulf ofCalifornia through the Gila and Colorado Riverdrainages, a journey of over 1500 km. The lifeblood of the Southwest is water which is readilyavailable for use by vegetative and wildlife popu-lations. Historically, the major rivers were thelarge arteries of the Southwest, while the smaller

cienegas, streams and oases of lush riparian habi-tats were the circulatory sinews which connectedthe entire region. Throughout the region, periodicdry spells occur relatively frequently, impactinggrasslands and deserts and stressing native plantand wildlife populations in all ecosystems. In a dryyear, or after a series of drought years, riparianecosystems buffer the effects bv providing cover,food and water for native wildlife. In these leanyears of thermal and water stress, the need forwater is often greatest when it is least available(Wiens and Dyer 1975).

Most studies of livestock grazing influences inthe western United States have concentrated oneffects of grassland change and how these changeshave affected game animals such as mule deer(Odocoileus hemionus), pronghorn (Antilocapraamevicana), or elk (Cervus canlzdensis). Almosttotally lacking are complete, in-depth researchprojects which measure influences of livestockgrazing on native vegetation and the resultantchange on nongame vertebrate species. In addi-tion, if these studies have been initiated, they aretypically of a short-term nature, often being com-pleted within two years or less. Long-term studiesof greater than five years which measure vegeta-tive and animal population response in the ab-sence of livestock utilization in western riparianecosystems are virtually lacking.

Because of competing economic, social andconservation interests, the issue of public landgrazing in the West has emotionally chargedproponents and opponents alike (Bock et al., 1993).Public land managers often are the targets whenconservationists pit themselves against the live-stock industry and vice versa. The issue of publicland grazing is equally as volatile as the issueswhich embroil the Pacific Northwest and itsremaining old growth forests. The romantic imageof the cowboy on the range has been ingrainedinto the consciousness of generations of Ameri-cans. The tough, pioneer spirit of early Westernsettlers was, and still is, admired by millions ofpeople. The cowboy was, and still is, perceived asa rugged individualist, struggling to tame a wildcountry and bring civilization and order to anuntamed land. This mythos continues to factor intoour everyday lives, and has been promulgated byinfluences from Hollywood to Wall Street. It is atough image to change. And with the image of the

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cowboy comes his trusted horse and domesticlivestock running across the open rangelands ofthe West.

IMPORTANCE OF RIPARIAN HABITATS

Riparian can be simply defined as the vegetationor habitats that are associated with the presence ofwater, whether it is perennial, subsurface, inter-mittent or ephemeral in nature (Krueper 1993). TheBureau of Land Management (BLM) expands thedefinition to include wetlands:“Wetlands includeboth natural and intentionally created areas adja-cent to, and influenced by, streams (whetherwaters are surface, subsurface, or intermittent),springs, lake shores, marshes, potholes, swamps,muskegs, lake bogs, wet meadows, and estuarineareas. Riparian areas are a form of wetland transi-tional between permanently saturated wetlandsand upland areas.“(BLM Manual 1737).

The BLM currently administers over 270 millionacres of public land in 13 western states. This totalsurface acreage is greater than the U.S.ForestService (USFS), the National Park Service (NPS),and the U.S. Fish and Wildlife Service (USFWS)combined. Of the 270 million acres of surfacelands, 23 million acres (8.5%) are consideredriparian or wetland areas. Over ninety percent ofthis total is within the state of Alaska. In the aridstates of Arizona and New Mexico, the BLMmanages over 25 million acres, of which 70,530acres are considered riparian or wetland habitats,along 1660 miles of stream. This constitutes lessthan three-tenths of one percent of the total Bu-reau-administered lands in Arizona and NewMexico (BLM files).

The importance of western riparian areas cannotbe overstated or overemphasized. Western riparianecosystems are among the rarest habitat types inthe Western Hemisphere. Of the 106 forest typesidentified in North America, the western cotton-wood (PopuIus)-willow (Salix) forest associationhas been identified as the rarest (Dan Campbell,1988 pers. comm.). Western riparian ecosystemsare highly fragmented and discontinuous due tothe nature of the topography in which they arefound. Even with such a limited and discontinuousdistribution, up to 80% of vertebrates use riparianhabitats in the desert Southwest at some stage of

their life. Over fifty percent of the nesting birdspecies in the American Southwest use riparianhabitats as the primary habitat for breeding pur-poses (Johnson et al. 1977). Within the San PedroRiparian National Conservation Area (NCA) insoutheastern Arizona, 526 mammal, bird, reptile,amphibian and fish species have been recorded(Table 1). Of that total, 356 species (68%) have beenfound using the riparian zone within the NCA forfeeding, resting, water or breeding requirements(Krueper unpub. data). A minimum of 67 species(13%) are considered to be riparian obligates.Thomas et al. (1979) attributed the high wildlifespecies density and diversity totals of riparianhabitats to the presence of highly varied vegetativestructure and what they termed “ecotonal” or edgeassociations. The high species diversity valuesrecorded within the San Pedro NCA are believedto be due to the availability of water, prey items(insects), high vegetative density and diversity,and the fact that it is located at the juxtapositionbetween several major floral and fauna1 ecoregions.

Table 1. Vertebrate species totals recorded within the SanPedro Riparian National Conservation Area,Cochise Co., Arizona and associated riparianoccurrence, 1995. (BLM files)

Taxa Non-rip. ’ Facult.’ Obligate3 Totals

F ish 0 0 1 3 13Amphibians 0 5 3 8Repti les 1 6 1 4 7 3 7Birds 149 189 3 9 3 7 7Mammals 5 7 5 5 8 5

_--------------Totals 170 2 8 9 6 7 5 2 6

’ Non-riparian. Non-riparian associated. Although may befound using riparian habitats it is not required for survival.

* Facultative. Requires use of riparian habitat at some stageof its life cycle.

3 Obligate. Riparian obligate species.

There is no doubt about the value of healthyriparian ecosystems, and yet these systems havetraditionally been the most heavily impactedthrough human over-utilization, abuse or neglect(Fleischner 1994). Carothers and Johnson (1975)candidly noted the recognized value of riparianhabitats in the American Southwest, yet

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“it seems incredible that man travelled along, campedand trapped on, settled in and drew water fromriverine ecosystems since the beginning of historywithout having a better understanding of the greatimportance of these rivers. Historians andarchaelogists have consistently pointed out theimportance of rivers to civilization. We heartily agreeand then use them for garbage and sewage effluentdisposals, dry them up, denude them of nativevegetation, turn them into canals or simply damthem. For decades, just as nongame management hasbeen subservient to game management, other valueson watersheds have been disregarded while ‘watermanagement’ and salvage projects receive theprincipal focus. This is especially true when wereview the lack of concern for maintenance of naturalriparian ecosystems compared to the ever increasingconcerns for supplying large metropolitan areas inthe Southwest with additional water for domestic,agricultural, industrial and recreational uses.”While Carothers and Johnson are accurate in

their assessment of current riparian habitat man-agement, it must be stressed that the insidious andcumulative impacts of unmanaged livestock use inSouthwestern riparian ecosystems for severalhundred years has probably been the single mostimportant factor in riparian ecosystem degradation(Wagner 1978, Ohmart 1995).

Riparian habitats historically constituted 1% ofthe land mass in western North America. Withinthe past 100 years, an estimated 95% of this habitathas been altered, degraded or destroyed due to awide variety of land use practices such as riverchannelization, unmanaged livestock utilization,clearing for agriculture, water impoundments andurbanization (Krueper 1993, Fleischner 1994,Ohmart 1994). Many authors now concur that thesingle most important land management practiceimpacting western riparian ecosystems has beenunmanaged domestic livestock grazing (Noss 1994).

HISTORIC RANGE MANAGEMENT IN THESOUTHWEST

Historically, the largest ungulates found in thelower elevations of the Southwest were pronghorn,mule deer and white-tail deer (Odocoileusvirginianus). Elk were common in the higherelevations of the southern Rocky Mountains,extending south to northern Arizona and NewMexico. Desert bighorn sheep (Ovis canadensis)

were restricted to isolated desert mountain rangesand rarely wandered to lower elevations. Large,heavy ungulates such as bison (Bison bison) werenot present in the grasslands of the arid South-west. The ecosystems of the Southwest hadevolved in the absence of large ungulate herds(Bock et al., 1993).

Over four hundred and fifty years ago, FrayMarco de Niza became the first Spanish explorer tocross what is now the United States/MexicoInternational Boundary near the headwaters of theSan Pedro River in Cochise Co., Arizona. Follow-ing de Niza’s glowing reports of the existence ofthe legendary seven golden cities of Cibola and ElDorado somewhere to the north, FranciscoVasquez de Coronado set forth with a large expe-dition in 1542 to locate the fictional cities. Accom-panying the expedition were several hundredhorses for transportation, and 5,000 sheep and 150head of cattle to be used as food during the journey(Allen 1989a). Although the expedition was a failureand all livestock were either eaten or died from therigors of the journey, the initial exploration andecological exploitation of the Southwest had begun.

One hundred and fifty years passed after theunsuccessful Coronado Expedition before the firstserious attempt at colonization of the interiorSouthwest was initiated under the leadership ofPadre Eusebio Francisco Kino. In the late seven-teenth century, Padre Kino initiated successfulanimal husbandry practices within mission settle-ments along the Santa Cruz River in an attempt toencourage native inhabitants to raise stock, farmagriculture and settle around the missions. In 1697,Padre Kino distributed livestock to missions alongthe San Pedro River, Tucson, and Nogales, andshortly thereafter cattle ranching had spread to allmissions and native villages in what is now south-eastern Arizona.

Within several generations, cattle ranching hadbecome the primary economic force in the region.Livestock were primarily concentrated in the lushriparian areas of the Santa Cruz and San Pedrowatersheds. Allen (1989a) stated that “the signifi-cance of the mission era to modern range manage-ment lies in the introduction of livestock to thearea and the beginnings of the pastoral culture, notto any widespread impacts on the surroundingrange. ” The precedent of livestock utilizationwithin riparian habitats had been initiated.

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Allen (1989a) estimated that 100,000 cattle weregrazing the headwaters of the San Pedro River andBavispe Rivers in southern Arizona and northeast-ern Sonora by 1694. Within another generation, theentire portion of inhabited southern Arizonadeserts had cattle and Mexican haciendas had beenestablished throughout the region (Hastings andTurner 1965). In the mid-eighteenth century, nativepeoples revolted and many of the missions andranches were abandoned. Livestock roamed freelythroughout the area until Spanish forts wereestablished to control fierce Apache raiding partiesin the early nineteenth century. Although theMexican military presence in the region deterredApache raiding on the re-established haciendas,periodic attacks resulted in a considerable numberof feral livestock. Allen (1989a) estimated thatwhen the San Bernardino Ranch was abandoned inthe 183Os, over 100,000 head of cattle were allowedto run wild. By 1846, all of the haciendas hadbowed to the pressures of Apache raiding partiesand had been abandoned again.

After the conclusion of the United States/Mexico War in 1848, settlers began to stream intothe region, bringing with them livestock for eco-nomic gain as they pioneered the region. After theCivil War, huge numbers of cattle were movedfrom rangelands in Texas to provide food for thearmy during the Apache Wars. The end of theApache Wars in the 1870s signalled the beginningof an unprecedented buildup of domestic livestockin Territorial Arizona. Hastings and Turner (1965)estimated that over one and a half million cattlewere present in Arizona by 1891, most of whichwere south of the Gila River. Ohmart (1995) cor-roborated these numbers and also estimated thatneighboring New Mexico supported two millionhead of cattle at the same time.

As with all regions in the West, the vagaries ofweather combine to create periods of time underwhich conditions of great environmental stressoccur. Drought and catastrophic rainfall patternsare of regular occurrence in the Southwest, andduring the later part of the late nineteenth centurya natural disaster occurred that was exacerbated bydecades of unmanaged livestock management:“Livestock, introduced to the region by ranchers, had

become abundant. As the uplands desiccated, cattleconcentrated near streams and rivers. But even thattactic soon failed, and 75% of all livestock in Arizona

were thought to have died from thirst or starvationby 1875. Ranges were severely damaged, so erosionprevailed when a wet cycle began....deep arroyoswere cut from downstream to upstream, incisingvalley fills so deeply that water tables were drained.Marshes and riparian plants were left high and dry,and disappeared. The erosive power was concen-trated downward by high channel walls.” (Rinne andMinckley 1991).The period of drought followed by damaging

rains occurred throughout the western UnitedStates. Even after this ecological disaster, cattleranching continued to hasten the demise of theregion as numbers again increased. Increasednumbers of cattle and sheep placed more ecologi-cal stress on riparian ecosystems which werealready severely compromised. Severe erosiveflooding occurred in 1887, 1890, 1891,1905, 1906,and 1916 (Dobyns 1981), and with each floodevent, stream and river channels became moreincised and riparian habitat destruction increased.

Historians and ecologists unequivocally agreethat the cattle numbers present in the arid grass-lands of southern Arizona at this time far exceededthe carrying capacity of the rangelands, and theinevitable result of such practices was severedegradation of the uplands and riparian habitats ofthe entire region. Overstocking of the range duringthe late nineteenth century throughout the westernUnited States initiated accelerated erosion anddowncutting of streams and rivers, thereby lower-ing the water table and permanently altering thehydrologic functioning of riparian ecosystems.Most Southwestern riparian ecosystems have notrecovered, and many authorities believe that theywill never be able to return to a condition thatresembles historic condition and function. Allen(198913) observed that even in 1936, over fortyyears after the disastrous drought and erosiveflooding events of the late nineteenth century,Secretary of Agriculture H.A. Wallace testified tothe United State’s Senate that:“There is perhaps no darker chapter nor greater tragedy

in the history of land occupancy and use in theUnited States than the story of the westernrange.... (R)ange depletion (is) so nearly universalunder all conditions of climate, topography, andownership that the exceptions serve only to prove therule.“In short, “(t)he impact of countless hooves and

mouths over the years has done more to alter the

type of vegetation and landforms of the West thanall the water projects, strip mines, power plants,freeways and subdivision developments combined(Fradkin 1979).

CURRENT CONDITION OFSOUTHWESTERN RIPARIAN HABITATS

Over 70% of the western United States is cur-rently being grazed by livestock in habitats rang-ing from sea level to alpine meadows. Livestockgrazing is the most widespread economic use ofpublic land in the American West (Bock et al.1993). The vast majority of the 270 million acres ofpublic land under domestic livestock use in theinterior West are managed by the BLM and theUSFS. According to Fleischner (1994), 7 millionhead of livestock graze the 16 western states, andof the entire BLM holdings in the West, 94% iscurrently being grazed. The loss of biologicaldiversity on these lands has recently sparkedrenewed interest by the concerned public, whoquestions the validity of multiple use managementon a sustained basis as required by law. Horning(1994) stated that livestock grazing in the westernUnited States has contributed directly and indirectlyto the decline of over 340 species of plants andanimals which are currently listed or are candidatespecies under the Endangered Species Act.

Riparian habitats are the most modified landtype in the American West (Bock et al. 1993).Nearly all public land in the western United Statesis currently or has been historically grazed. Ripar-ian systems are found throughout the region, andbecause of the paucity of water, palatable forageand lack of shade in adjacent habitats, riparianareas are heavily impacted by domestic livestock.Due to habitat alteration, natural riparian commu-nities persist only as isolated remnants of whatwas once a vast, interconnected web of rivers,streams, marshes and vegetated washes. Horning(1994) stated that grazing is the single most impor-tant factor in the destabilization of riparian andaquatic eosystems because cattle remove theprotective riparian vegetation, and break downstreambanks, thus increasing silt loading, widen-ing streams, and destabilizing the water bufferingqualities during temperature extremes in winterand summer.

Over 410 million acres of public and privaterangelands, constituting 21 percent of the UnitedStates outside of Alaska, are considered to be inunsatisfactory condition (Wuerthner 1993).Wuerthner (1993) also stated that according to a1990 Environmental Protection Agency report onthe rangelands of the western United States,riparian areas are in the worst condition in history,and that the principle agent for this degradation isgrazing. According to a 1991 BLM document, only0.8% of riparian habitats in Arizona and 6.0% inNew Mexico are considered to be meet&g riparianhabitat objectives (USDI BLM document 1991). Theremaining lands are either not meeting riparianhabitat objectives or are considered to be in “un-known status.”

The BLM initiated its Riparian-Wetland Initia-tive of the 1990’s which set goals and nationalstrategies to upgrade or improve the ecologicalcondition of wetland and riparian habitats onlands the agency manages. The principle objectiveof the initiative is to restore to “proper functioningcondition” 75% of its riparian and wetland habitatsby 1997. Proper functioning condition is deter-mined when a riparian habitat:

1. Purifies water by removing sediments andother contaminants;

2. Reduces risk of flooding and associateddamage;

3. Reduces stream channel and streambankerosion;

4. Increases available water and stream flowduration by holding water in stream banksand aquifers;

5. Supports a diversity of plant and wildlifespecies;

6. Maintains habitat for healthy fish populations;

7. Provides water, forage, and shade for wildlifeand livestock;

8. Creates recreational opportunities such as fish-ing, camping. picnicking and other activities.

To achieve proper functioning condition by1997, the BLM set four major goals:

1. To restore and maintain riparian and wetlandareas so that at least 75 percent are in properfunctioning condition by 1997;

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2. To protect riparian and wetland areas andassociated uplands through proper landmanagement and by avoiding or mitigatingnegative impacts;

3. To carry out a riparian and wetland informa-tion and outreach program that includestraining and research to raise awareness andunderstanding of the importance of healthyriparian habitats; and

4. To maintain existing and form new public-private partnerships to supplement andaccelerate the agency’s work by drawing onthe talents of volunteers and using non-Federal funding (USDI BLM document 1991).

While the goals and objectives established bythe Riparian-Wetland Initiative are laudable, theyare also very general and non-specific. The verydefinition of “proper functioning condition” isopen to interpretation by a wide variety of special-ists or special interest groups which often lobby forsupport of continued traditional and consumptiveuses in the interest of short-term gain rather thanfor the long-term benefit of riparian-related re-sources. Many of the remnant riparian ecosystemsin the arid Southwest, although classified as beingin fair to good condition within the context of theRiparian-Wetland Initiative, are actually consid-ered “functioning, but at risk” of total collapseunder current management practices (R. Ohmart,pers. comm.)

IMPACTS OF LIVESTOCK INSOUTHWESTERN RIPARIAN HABITATS

Wuerthner (1994) recently summed up thecumulative impacts of livestock grazing in theWestern United States by claiming that“(ajgriculture - both livestock production andfarming - rather than being compatible withenvironmental protection has had a far greaterimpact on the western landscape than all thesubdivisions, malls, highways, and urban centerscombined.” Noss (1994) stated that livestockmanagement practices have “contributed to loss ofnative vegetation, invasions by alien plants, de-cline of native fishes due to... degradation ofriparian zones, ..and major changes in hydrology,soils and other ecosystem properties. Many conser-

vationists claim that livestock has done moredamage to the native biodiversity of western NorthAmerica than all the chainsaws and bulldozerscombined. Livestock grazing on public lands israpidly becoming one of the hottest and mostpolarized environmental issues in the UnitedStates.”

Domestic livestock are disproportinately at-tracted to riparian areas. High moisture and nutri-tive content of riparian vegetation are critical tolivestock especially during dry summer monthswhen upland vegetation is relatively desiccatedand unpalatable. Add to that the availability ofopen water and shade during the hottest months,and it is no wonder why domestic livestock remainin riparian habitats for much of the season. Inmany areas of the West, the concentration oflivestock in riparian habitats is exacerbated due tosteep canyons, narrow riparian corridors andlimited accessibility (Dahlem 1979). The result inmany western riparian areas are beaten out ripar-ian systems which are devoid of understory veg-etation which most wildlife species depend uponfor survival and productivity.

Livestock grazing can alter vegetative structureand composition of riparian habitat. Ryder (1980)stated that grazing, especially by livestock and biggame, frequently changes plant species composi-tion and growth form, density of stands, vigor andseed production of plants. Grazing and browsingcan alter the growth form of individual plants,making shrubs and young trees grow “bushier” byremoving terminal buds and stimulating morelateral branching. While the resulting growth formmay benefit some species of wildlife temporarily,continued grazing on already stressed vegetationor on vegetation which has not evolved undergrazing pressure can injure or even kill shrub ortree species. Unlike grasses, many species of forbs,shrubs and trees are not adapted to continual orpersistent grazing and browsing pressure duringthe growing season (Ryder 1980). This loss ofvegetation alters the vegetative density and diver-sity of the community, most often shifting thecommunity from a climax condition to an earliersuccessional stage. Under these conditions, wild-life species which are adapted to an older, moremature vegetative ecological state will be selectedagainst while those species which have moregeneral habitat requirements will be selected for.

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Differences between riparian habitats in goodcondition and degraded condition should beextremely evident to even the untrained eye. Butwith over 300 years of grazing pressure withinriparian areas of the lowland Southwest, healthyriparian stands are virtually non-existent. Com-parisons of healthy versus degraded riparianhabitats are by default a moot point. A commonlyheard complaint from ranchers is that the riparianareas which they are utilizing “have always lookedlike this.” Ecological decline from overgrazing is aslow, insidious process which causes a decline inthe abundance and diversity of native riparianvegetation over several generations, and is usuallynot evident to even skilled observers unless excep-tional care is exercised. As the native plants die off,riparian areas are typically invaded by exoticplants such as Russian Olive (Elaeugnus angust$dia)and saltcedar (Tumarix chinensis) which are signifi-cantly less productive for wildlife habitat, water-shed protection and wildlife forage needs.

Western riparian habitats are extremely vulner-able to overgrazing (Rucks 1978, Platts and Nelson1985, Platts 1991, Ryder 1980, Ohmart 1994).Unmanaged grazing practices have been shown tonegatively affect Southwestern riparian vegetativecomposition, ecosystem function, and ecosystemstructure (Platts 1991, Ohmart 1994, Horning 1994,Ohmart 1995). Effects of grazing most often de-pends upon the intensity, duration and location ofthe activity. Domestic livestock typically concen-trate in riparian areas where forage, water andshade are readily available. Heavy use in sensitiveriparian habitats during the growing season or inyears of drought accelerates degradation of ripar-ian systems. Cattle, like all animals, must eat tosurvive, and in lean years they can strip a formallyproductive and functioning allotment into a waste-land if stocking rates are not immediately reduced.High intensity grazing also profoundly altersbreeding avifaunas from the “natural” state,generally in the direction of decreased speciesnumbers and complexity (Wiens and Dyer 1975).

Trampling of vegetation by large ungulates oreven humans can impact vegetation by removingprotective cover and affecting sensitive soil com-ponents, resulting in increased exposure of soil toeroding wind and water (Stoddart et al. 1975,Chaney et al 1990). Rauzi and Smith (1973) docu-mented decreased water infiltration rates in

heavily grazed habitats versus lightly grazedhabitats. Lusby (1979) reported increased runoffand sediment discharge from desert rangelands ofwestern Colorado under conditions of livestockgrazing, which eventually impacts riparian ecosys-tem function and condition. Kuss and Hall (1991)found that trampling of vegetation and the surfacelayers of sensitive soils causes significant damageto floral and soil structural components even withone passage of a human through undisturbedlandscapes. The weight of a two-hundred poundhuman being, and its resultant impact to the floraland soil components, pales in comparison to theeffect of repeated use by domestic livestock whichmay weigh 5 to 7 times as much as a human. Earlystudies which measured the recovery rates ofhuman-induced trampled habitats estimated that“50 to several hundred years may be required forthe impacted communities to recover originalfloristic composition and density” (Kuss and Hall1991). Their data suggested that even limitedtrampling delivered at one time can be as damag-ing as increasing levels of use delivered over amuch longer time.

IMPACTS OF LIVESTOCK ONWILDLIFE POPULATIONS

Negative impacts due largely from over a cen-tury of heavy domestic livestock utilization in aridSouthwestern riparian ecosystems have resulted inthe decline of insect, fish, reptile, amphibian, bird,and mammal populations. Excessive historicgrazing practices have significantly altered ripar-ian vegetative structure and density, which in turnhave impacted wildlife populations (Fleischner1994). Grazed riparian areas typically have lessground cover, a poorly developed understory andmidstory, and decreased vegetative biomass whencompared to similar ungrazed riparian areas.These conditions result in a paucity of availableniches which a great number of wildlife speciesdepend upon for feeding, resting and cover.

Horning (1994) estimated that livestock grazingplayed a significant role in the listing of 76 speciesof fish and wildlife, and that livestock grazing is afactor in the decline of another 270 candidate andlisted fish and wildlife species. Of this total, thetwo most arid western states (Arizona and Ne-

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vada) have the most number of species harmed bygrazing (86 and 75 respectively). Eighty percent ofthe 346 fish and wildlife species found to be seri-ously impacted are riparian dependent, andunmanaged grazing has severely compromised thequality of habitat upon which they depend forsurvival. Based on a critical literature review andadvice from wildlife experts, Horning (1994)added that “there is irrefutable evidence thatabusive grazing practices have severely compro-mised native biological diversity by damagingecologically vital riparian areas and fragile aridand semi-arid grassland ecosystems, in some casesirreparably.”

Determining the true impacts of unmanagedlivestock grazing on Southwestern riparian wild-life populations is difficult to assess because therewere virtually no extensive vertebrate studiesconducted before the Twentieth Century. Intensivegrazing has been present in the Southwest for over300 years. Scientists have no baseline informationfrom which to draw significant conclusions. How-ever, we can document historical changes withinthe past 100 years, and then based on the evidence,infer “what might have been” from studyingrecovering riparian habitats that have been ex-cluded from livestock grazing. Integral to thesestudies are measurements of the resultant changesin vegetation and wildlife communities throughtime in the absence of domestic livestock.

Carothers and Johnson (1975) mentioned thatalthough direct economic measures of riparianalteration are possible (economic cost and benefitratios measured in dollars earned or lost), the“intangible” values of riparian ecosystem healthare much harder to define and quantify. How canan economist measure the value of a spring morn-ing walk within the splendor of the riparianhabitat surrounding the Verde or the San PedroRivers? What is the value of seeing a Green King-fisher (Cevyle americana) amongst the root massesand overhanging streambanks of a healthy ripar-ian system, or the diagnostic ripples in a pond as abeaver forages near a remote mountain meadow?These are the intangible values of a healthy andfunctioning Southwestern riparian ecosystem, andalthough they are nearly impossible to measure,they must be taken into account in regard toriparian habitat management. To many public landusers, loss of wildlife and associated recreational

opportunities due to riparian habitat destruction oralteration is an increasingly unacceptable conse-quence of traditional land management practices.

Invertebrates

While very little research has been conducted onthe response of aquatic invertebrates to livestockgrazing, much of the available evidence shows thatmany invertebrate species decrease as habitat isdegraded (Horning 1994). Fleischner (1994) com-piled data from studies which show that domesticlivestock grazing has had negative impacts toterrestrial invertebrate populations in severalwestern states, including Arizona where grasshop-per densities were 3.7 times greater on protectedsites than on grazed sites. Ryder (1980) also statedthat insect production can be altered under heavygrazing practices. Most studies of grazing impactson invertebrate populations have been conductedin grasslands and not within riparian habitats, butit is obvious that with vegetative disturbance andremoval of plant biomass which sustains inverte-brate populations, certain taxa will be negativelyaffected.

Fish

Platts (1991) found that in 20 of 21 studies hereviewed, riparian habitats and fish populationswere negatively impacted by livestock grazing.Unmanaged livestock practices compact soils andlow-growing riparian vegetation, denude marshesand meadows, trample stream banks, and removeprotective riparian vegetation from the banks ofwatercourses. This results in increased siltationand sedimentation, increased water temperatures,and decreased habitat quality for native fishspecies. Behnke and Zarn (1976) concluded thatlivestock grazing within Western riparian ecosys-tems was the major threat to improving or stabiliz-ing degraded trout habitat.

Destruction of riparian vegetation and stream-bank stability results in unstable water tempera-tures which most fish species depend upon for eggdevelopment. Increased siltation can cover gravelspawning beds which cuts off oxygen required forproper development of eggs. In many streamswhere livestock grazing has been limited or elimi-nated, native fish species are able to more effec-

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tively compete with non-native fish species. Inriparian livestock exclosure studies, native fishspecies have been shown to increase populationsby nearly 600 percent (Crispin 1981, Platts andNelson 1983.

Fish, especially colder water species such astrout, have been shown to be good indicators ofecosystem health. However, species such as theLahontan cutthroat trout (Salmo clavki henshawi),the Bonneville cutthroat trout (Oncorhynchus clarkiufah), the Apache trout (Oncorhynchus apache) andthe Gila trout (Oncovhynchus gilae) are federallylisted or Candidate species. These and many otherspecies are at risk because of habitat loss anddegradation associated with livestock utilizationwithin sensitive riparian habitats. The destructionof spawning and natal rearing habitat due tologging and livestock production in sensitiveriparian areas of the upper Gila River in NewMexico and in the White Mountains of Arizonahave been responsible for the declines in the lattertwo trout species (Rinne and Minckley 1991).Fleischner (1994) stated that fish production andstanding crop biomass of salmonids increasedsignificantly when cattle were excluded fromriparian ecosystems in the Great Basin and inColorado. To determine whether these fish specieswould benefit from livestock exclusion fromriparian areas, measurements of biomass changeand overall population response need be imple-mented. Costs of fencing riparian areas fromlivestock may be less expensive than other expen-sive recovery efforts.

Economic costs to recover high elevation fishspecies to stable levels can be staggering. Forinstance, recovery of the Lahontan cutthroat troutis expected to top $14 million. To enhance riparianareas for the benefit of Apache trout in Arizonawill cost the USFWS up to $2 million over the next10 years. Even while these enhancement projectsare being conducted, adjacent riparian areascontinue to be grazed and degraded (Homing 1994).

Mid-elevation streams from 900 to 1900 m.elevation flow through low coniferous forests, oakwoodlands and portions of high elevation grass-lands. These habitats support most of the remain-ing native fish populations in the Southwest(Rinne and Minckley 1991). However, due to theextreme riparian degradation of the 1870s and

1880s as a direct result of overstocking the range inArizona, many native fish species were extirpatedfrom historic habitat and have not since been ableto return naturally (Rinne and Minckley 1991).These systems have not had the tremendousgrazing pressures that lower elevation ripariansystems have sustained, but continual degradationwhich accompanies livestock grazing has impactedthese fish populations as well.

Low elevation riparian systems below 900 m.elevation have been heavily impacted becausethese systems typically are-in areas with extremetemperatures and low rainfall. This creates condi-tions which concentrate cattle into small areas,which increases soil compaction, streambankerosion and decreases vegetative cover.

Of 41 species of freshwater fishes native to theSouthwest, 10 occur only in Mexico, 9 occur only inthe United States, and the remaining 22 species areshared by the two countries (Rinne and Minckley1991). By 1989,28 of the 41 species were officiallylisted as threatened, endangered or of specialconcern by the American Fisheries Society. Threeother species not considered in the above total arenow officially extinct. Ninety percent of Arizona’snative fish species are now extinct, extirpated; orFederally or state listed.

As a result of diversions, mineral activity,unmanaged domestic livestock practices, and otherimpacts ” . ..native fishes are being exterminated.Destruction of aquatic habitats, changes fromnatural to artificial conditions, and predation andcompetition by alien species enhanced by artificialconditions, all combine to destroy them. Many arenearing extinction, some are already gone, andneither legislation, nor determined attempts atconservation by agency, academic, or other manag-ers have succeeded in reversing the trend. Theonly chance seems to lie in an emergence of publicopinion that recognizes native fishes as valuableresources and demands their conservation.” (Rinneand Minckley 1991). Recovery of the hundreds ofspecies and subspecies of threatened or endan-gered western fish will depend upon restoration ofseverely degraded riparian ecosystems. One of themost effective methods is livestock exclusion ormore effective livestock management which willresult in the stabilization of sensitive riparian soilsand vegetation.

Amphibians and Reptiles

Amphibians have also been shown to decline inpopulation size and overall distribution as riparianhabitat has been degraded. In particular, specieswhich are candidates for listing such as the yellowand red-legged frogs, the Yavapai leopard frog, aswell as numerous toad species, are known to beharmed by grazing (Jennings 1988, Toone 1991,Jennings and Hayes 1993, Martin 1993). ManyWestern amphibian species which are dependenton functioning riparian habitats for breeding orshelter requirements are negatively impacted byunmanaged livestock grazing as riparianstreambanks break down, sedimentation increases,and erosion accelerates.

Certain reptile species, including various grass-land lizards and snakes, are less abundant due tolivestock caused alteration of riparian habitat(Fleischner 1994, Horning 1994). The wanderinggarter snake, an atypical riparian-associatedreptile, is much less abundant in grazed habitatsrelative to adjacent ungrazed habitats (Szaro et al.1985). Fleischner (1994) reported that in two stud-ies in California and Arizona, lizard abundancewas two times and biomass 3.7 times higher onungrazed sites relative to grazed sites, and thatabundance and diversity was higher on ungrazedsites rather than on grazed sites in 80% of thestudy sites measured. It is clear that, similar toimpacts imposed on fish populations, continueddegradation of riparian habitat will not onlyhinder the recovery of many listed species, but willalso accelerate the decline of dozens of candidateamphibian and reptile species.

Birds

Although consisting of less than 1% of the landmass of the western United States, western ripar-ian habitats are extremely important to neotropicalmigratory landbirds as well as resident species(Szaro 1980, Bock et al. 1993, Krueper 1993, Ohmart1994). In the Southwest, riparian areas support ahigher breeding diversity of birds than all otherwestern habitats combined (Anderson and Ohmart1977, Johnson et al. 1977, Johnson and Haight1985). Over 60% of all neotropical migratory birdsuse riparian habitat in the Southwest as stopoverareas during migration, and these habitats have

recorded up to 10 times the number of migrantsper hectare than adjacent non-riparian habitats(Stephens et al. 1977, Krueper unpub. data). Be-cause of high rates of metabolism, birds are ex-tremely dependent on the habitats in which theyfind themselves during the migratory period, andmust utilize seasonally abundant resources whenavailable (Sprunt 1975). Southwestern ripariansystems provide migratory bird species rich foodresources during the critical migratory periodbecause plant growth rates and resultant vegeta-tive biomass are very high, which allows forgreater insect production (Gori 1992).

The highest non-colonial avian breeding densi-ties in North America have been reported fromsouthwestern riparian habitats (Johnson 1970,Carothers and Johnson 1975, Anderson andOhmart 1984, Krueper 1993). Within the San PedroRiparian National Conservation Area in southeast-ern Arizona, migration and breeding densities of3000 individuals per 40 ha have been documented(Krueper, unpublished data). Johnson et al. (1977)reported that more than 75% (127 of 166) of south-western bird species nest primarily in riparianhabitats, and 60% (59 of 98) are neotropical migra-tory birds.

Bird species are differentially affected by cattlegrazing in riparian areas. Bird species have beenshown to respond to alterations in vegetativestructure and species richness within riparianhabitats (Bull and Slovlin 1982, Szaro and Jakle1985). Other avian studies have shown a higherdensity and diversity of birds in ungrazed riparianhabitats compared to adjacent grazed habitats(Crouch 1981, Mosconi and Hutto 1981, Taylor1986).

Neotropical migratory bird species have beenfound to be very sensitive to habitat change(Sedgwick and Knopf 1987, Knopf et al. 1988,Krueper 1993). Buttery and Shields (1975) statedthat if riparian conditions are not suitable due tochanges in key vegetative components, the stimu-lus to breed in one area may not be elicited. Onceriparian habitat has been compromised throughland use practices such as unmanaged livestockutilization, birds may simply vacate traditionallyused riparian breeding habitats in search of suit-able habitat elsewhere. Grazing pressure on veg-etation has been shown to alter growth form, plantvigor and plant species composition, resulting in

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increases or decreases in populations of birdspecies (Glinski 1977, Townsend and Smith 1977,Ryder 1980). Rucks (1978) stated that livestockgrazing causes the replacement of shrub-nestingbird species with species showing no preferencefor vertical vegetative structure. Vegetative struc-tural components such as foliage height diversity,total percent foliage cover, foliage volume, andplant species diversity are key factors determiningthe density and diversity of breeding birds (Balda1975, Anderson and Ohmart 1984). Birds werefound in lower numbers in habitats lacking highstructural diversity and suitable number of maturetrees. All of these key structural components of thevegetative community are directly impacted byunmanaged livestock practices to the detriment ofavian populations. Especially impacted are groundnesting riparian obligate species such as CommonYellowthroat (Geothlypis trichas), Yellow-breastedChat (Icferia sirens), Abert’s Towhee (Pipile aberfi),and Song Sparrow (Melospiza melodia), which havebeen shown to respond with significant if notspectacular population increases when livestockhave been removed from riparian ecosystems suchas within the San Pedro NCA (Krueper 1993).

Excessive livestock grazing can also affect typesand abundance of food items for birds (Ryder1980). Cattle and sheep have been shown to eatselected species of range and forest plants. Theseshelter mammal and insect populations whichspecies of birds utilize as food. Small mammalpopulations are affected by high levels of grazingwhich benefit open habitat specialists such as deermice, whereas various species of pocket mice andwestern harvest mice which prefer heavier coverare selected against. Raptors which utilize smallmammals as prey may not choose to frequent sub-marginal riparian habitats for feeding due to lackof preferred prey items. Additionally, insectbiomass may be decreased in riparian habitatswhich are heavily grazed due to lack of understoryvegetation (Krueper pers. obs., R.D. Ohmart pers.comm. 1995). Insectivorous birds using riparianhabitats for breeding and migratory habitat de-pend heavily on the annual insect biomass whichis found in undisturbed riparian zones for feedingof young and for replenishing energy resourcesbefore continuing migratory movements. Annualand perennial grasses in riparian habitats areheavily utilized during the summer breeding

season by many species of birds. During the latesummer and fall migration period within the SanPedro Riparian National Conservation Area(NCA), avian species such as Black-headed Gros-beak (Pheucficus ludovicianus), Lazuli Bunting(Passerim umoenu), Indigo Bunting (Passerimcyaned, Lincoln’s Sparrow (Melospizu lincolnii) andGreen-tailed towhee Pipilo ch2orurus) feed prima-rily on the seeds produced from grasses which areproduced within the riparian zone during thesummer growing season (Krueper pers. obs.).When cattle were present in the riparian habitatprior to a domestic livestock moratorium in 1988,little vegetation and seed production for granivo-rous bird species were noted. However, since themoratorium has taken effect, annual and perennialgrasses in and adjacent to the riparian zone havegreatly increased, and the resultant seed produc-tion currently attracts more granivorous birdspecies by a factor of ten over population densitiesbefore the livestock moratorium took effect (BLMfiles).

Bock et al. (1993) summarized results of previ-ous studies of the avifauna of riparian woodlandsof the West. Of the 43 avian species studied, 8responded positively to grazing while 17 werenegatively affected and the remaining 18 wereunresponsive or showed mixed response. Neotro-pica1 migratory bird species which were mostheavily impacted by livestock grazing were thosewhich require dense understory vegetation forfeeding or for nesting cover. Bock et al. (1993)noted that those species most critically impactedwere Common Yellowthroat and Lincoln’s Spar-row. Based upon known habitat requirements,they predicted that many of the other 18 specieswhich showed mixed results actually would benegatively impacted from riparian grazing prac-tices. In one of the largest studies in the Southwestmonitoring avian response to a grazing morato-rium, populations of Song Sparrow, CommonYellowthroat and Yellow-breasted Chat increasedfrom five to ten-fold within 5 years after cessationof livestock grazing pressure (Krueper 1993).

Although Schultz and Leininger (1991) foundthat while American Robin (Turdus migruforius)benefitted from heavy grazing and the resultantopen habitat, species such as Wilson’s Warbler(Wilsoniu pus&z) and Lincoln’s Sparrow whichrequire densely vegetated understory and

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midstory for feeding and breeding requirementswere much more common in ungrazed areas withabundant willows. Greater shrub cover inungrazed habitats allowed much higher breedingdensities of these avian species than in the grazedhabitats.

While riparian neotropical migratory birdspecies use fragmented habitats in high densities,due to the limited extent of western riparianecosystems, these species may actually havesmaller overall populations than the neotropicalmigratory bird species which breed in more expan-sive eastern forests (Bock et al. 1993). This is causefor concern because even species which currentlyhave high densities in southwestern riparianhabitats are at risk of extirpation if the remainingquality and quantity of riparian ecosystems arecompromised. DeSante and George (1994) docu-mented 58 species of migratory landbirds whichhave decreased in the western United Statesduring the past 26 years. Of this total, 16 specieshave declined as a direct result of riparian habitatdestruction, and one of the primary factors attrib-uted to these declines was overgrazing. Over fortypercent of Arizona’s state-listed bird species areconsidered to be riparian obligate species(Corman, Arizona Game and Fish Department,per. comm.). It becomes obvious why such a highpercentage of the state total has been designated assuch when one considers that historically less than5% of the total land mass of Arizona was classifiedas riparian habitat. Of that total, over 95% has beendestroyed or altered in a negative manner (Lofgren1990). While many avian species teeter on thebrink of becoming listed or extirpated, we mustrecognize that avian species declines are but theresult of a much larger problem. Hunter et al. (1987)succinctly summarized the dilemma in saying:“the greatest problem afflicting effective riparian

management throughout the Southwest, especially atlower elevations, is the attention given to singlespecies at the expense of an entire community ofspecies that is in trouble....Listing of any one specieswill not protect all other declining species...in theSouthwest. A radical change in orientation is needed,from the piecemeal approach of protecting singlespecies (which is still essential) to protecting habitats.Native riparian systems must be protected for whatthey are - endangered ecosystems. Only by riversystem management can we effectively stem thedecline of our riparian avifauna....”

Conservation of neotropical migratory bird popu-lations in the Southwest will continue to requireprotection and restoration efforts within riparianecosystems.

Mammals

One of the least understood and least studiedgroup of vertebrate animals using riparian habitatsare small mammals. Livestock grazing impacts onavian populations have been fairly well docu-mented. For the same reasons that understory birdspecies are affected by grazing in riparian habitats,small mammals have been shown to be similarlyimpacted. Shrews, voles and mice species whichrequire thick understory vegetation and availablewater resources have been shown to decline undera riparian grazing regime (Johnson 1982, Medinand Clary 1990, Schulz and Leininger 1991, Claryand Medin 1992). Mammal species richness anddiversity are significantly lower in many grazedriparian areas compared to ungrazed areas. Alter-nately, Johnson (1982) found that grazing increasesthe density of certain small mammal species whichprefer low levels of vegetative cover. In theseheavily utilized areas, small mammal specieswhich require high levels of vegetative coverdecreased significantly. Although this conclusionwould seem to be obvious to the trained biologist,few studies have been conducted for the durationneeded to generate hard data on impacts of live-stock on small mammal populations.

It appears that quality of vegetation and vegeta-tive composition within the community is moreimportant in determining suitable habitat for smallmammal communities than the availability ofwater (Cranford 1983, Schultz and Leininger 1990,1991). When unmanaged livestock grazing re-moves vegetative cover from riparian habitats,small mammals will vacate the area regardless ifavailable water is present. Thus, livestock grazingchanges vegetative habitat structure which resultsin a shift in small mammal species composition inriparian habitats.

CONCLUSION

Preservation, protection and restoration ofriparian habitats in the Southwest is of critical

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importance because of their limited geographicextent and their extraordinary abundance anddiversity of native wildlife. Domestic livestockgrazing is the most widespread economic land usein the western United States. Livestock utilizepublic lands in all western states, from sea level toalpine habitats. Because of this situation, domesticlivestock have now become the key element in theregulatory processes of nearly every Southwesternecosystem. This situation has existed in the low-land Southwest for nearly 300 years despite thefact that large ungulates such as domestic cattlewere not historically present in these habitats.Southwestern lowland riparian ecosystemsevolved in the absence of the tremendous grazingpressures which now exist. Due to historic stock-ing levels and unmanaged grazing systems, manySouthwestern riparian habitats have been perma-nently altered in their structural and functionalintegrity, resulting in loss of species diversity,richness and abundance.

Very little ecological management has occurredin Southwestern riparian habitats. Historic andcurrent management of these sensitive ecosystemshas traditionally centered around a concept ofsingle-purpose consumptive utilization such asmining, timber harvest, water management, live-stock production or hydroelectrical power. In theAmerican Southwest, the predominant land usebased upon total acreage under utilization, contin-ues to be domestic livestock management. Numer-ous studies have shown that unmanaged livestockgrazing results in serious deleterious impacts onnative flora and fauna.

Riparian habitats are critical for wildlife and fishspecies in arid ecosystems. The Public Land LawReview Commission (1970) wrote “(t)he FederalGovernment has a responsibility to make provi-sion for protecting, maintaining, and enhancingfish and wildlife values on its lands generallybecause of the importance of those values as partof the natural environment over and above theirvalue for hunting, fishing and other recreationalpurposes.” The health of these ecosystems is thebest indicator of whether livestock management isin accordance with the multiple use mandate of theFederal Land and Policy Management Act of 1976.Sadly, these requirements are not being met inmany riparian areas of the Southwest. Althoughthe BLM and the USFS have been directed by the

Public Rangelands Improvement Act of 1978 toimprove declining range conditions, the agencieshave been unable to meet the Congressionalmandates of the Act. The BLM and the USFS havenot been able to effectively administer an intensivelivestock management program because theseagencies do not have the capability in terms ofstaffing and funding. State land departments havean even worse track record for management of thelands they are entrusted with (Robert Ohmart1995, pers. comm.)

Many vertebrate species have declined in recentyears due to alteration of riparian habitats, andthese species may soon be considered for Federallisting. To prevent future listings and to reversepopulation declines of sensitive wildlife species,land management agencies need to implementappropriate practices within riparian ecosystems.Recent riparian ecosystem recovery efforts havebeen shown to benefit many wildlife species andcan be used as examples of balanced riparianecosystem management.

A major hurdle which continues to impederiparian area management is mixed ownershippatterns which fragment local communities andpolarize “consumptive” and “non-consumptive”users alike. Private landowners may see riparianecosystems as an opportunity for monetary gain,while others may choose to manage these systemsin a natural, “hands-off” approach. Land manage-ment agencies such as the USFS and the BLM aremandated to administer public lands in a multiple-use manner provided that the impacts do notjeopardize the continued sustainable use of thoselands. Herein lies the crux of the problem. Humanswill always agree to disagree on management of“their” public lands, and why shouldn’t they?Afterall, it is their public lands, to be enjoyed nowand for future generations. The challenge is tostrike a balance between consumptive needs andthe needs of the general public. The only way thiscan be accomplished is using a consensus problem-solving process where management techniquesand implementation are agreed upon by all af-fected parties. This has been shown to work, but itcan be a lengthy process. Communication, under-standing and acceptance of change for the integrityof the ecosystem and for the benefit of the greatestnumber of people are the answers. But how to getthere...?

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MANAGEMENT CONFLICT ANDRESOLUTION

Aldo Leopold, as early as 1924 said that “graz-ing is the prime factor in destroying watershedvalues” in Arizona. Over seventy years later,grazing management practices are still impactingthe rangeland and riparian ecosystems of the aridSouthwest. Why has this continued to occur whenso many dedicated public and private land ownershave recognized the problem for so long? As withmany new ideas, change is associated with unfa-miliarity and a reticence to accept even the mostbasic truth in light of past mismanagement. Wehave known for decades that unmanaged livestockuse in riparian habitats has caused great destruc-tion, yet political pressures and institutionalparadigms have made riparian habitat rehabilita-tion move at a snail’s pace. Land managers mustaccept this reality, and yet continue to move forwardin a progressive manner that addresses issues ofriparian degradation in both a humane and bio-logical context. We cannot simply force all cattleoff of the public lands with a sweep of the pen, andwe cannot expect ranchers to anonymously acceptthe inevitable changes which are on the horizon.Human acceptance of change will take time, butland managers must continue to work with theirallottees to determine the best management prac-tices possible for the health of riparian ecosystemsand sustainability of their fragile resources.

Management Recommendations

1. Recognize that a problem does exist. Riparianecosystems are uniquely sensitive habitats,and should not be managed as part of adja-cent upland sites. Most management activitiesdo not address riparian condition or recoveryas their main objective. Riparian habitatshould be managed as the most sensitive andmost productive North American habitat.

2. Manage riparian systems for biological integ-rity rather than for domestic livestock utiliza-tion until desired ecological condition isrestored.

l The grazing management system designedfor an area should be tailored to the condi-tions, problems, potential, objectives, and

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livestock management considerations on asite specific basis using the best informa-tion and science possible that will best meetthe needs of the resources (Kinch 1989).

Whenever possible, exclude all grazingfrom riparian habitats to protect vegetation,wildlife and watershed values. Livestockshould be permitted in riparian areas onlyif grazing contributes to the improvementof riparian health.

If riparian habitats are to be grazed, light tomoderate use during the late fall andwinter period are preferred.

Degraded riparian habitats may needcomplete rest for several years to initiaterecovery. In most cases, only completeexclusion from the riparian zone can re-cover these habitats. While a system of rest-rotation can increase forage production,there is no conclusive evidence that it cancompletely recover a badly degradedriparian ecosystem. Desired Future Condi-tion will never be achieved in anunmanaged livestock scenario.

Monitor results of vegetative and wildliferesponse regularly to determine if goals arebeing met. Change management as neededto achieve Desired Future Condition.

Allow extended non-use of grazing permitsto protect sensitive or recovering riparianecosystems and the wildlife these systemssupport.

Kinch (1989) correctly states that westernriparian systems can be resilient under contin-ued heavy livestock utilization and that thesesystems typically respond more quickly tomanagement change than drier upland habi-tats. He further states that there is currentlyno single grazing management system thathas conclusively proven to result in consistentimprovement of degraded riparian areas inthe western United States. It is widely ac-cepted that historically less than 1% of thearid Southwest was composed of riparianhabitat and that of that total an estimated 95%has been severely altered or destroyed. Iwould argue that because of the importance,

fragility and limited total riparian acreagethat remains, all riparian habitats should beexcluded from domestic livestock use untilthey recover their integrity and functionalitywithin an ecosystem-based context. It is atthis point that grazing be considered withinwestern riparian systems, but only afterwildlife, recreational and watershed valuesare adequately addressed.

resource activity should not be pursued tothe exclusion of other equally important(although possibly not as financially lucra-tive) activities. Riparian ecosystems cannotbe managed to achieve optimal productionfor all competing uses, and must be balancedamong a great variety of uses.

Grazing allotment decisions are made at thenational, resource area/forest, and allotmentlevel. The public is entitled and encouraged tocontribute input at all levels in the decisionmaking process. The public must get involvedin the formulation of land use plans. Byactively influencing land management agencydecisions, the public can bring a measure ofbalance and environmental concern to themanagement of the public lands. As respon-sible land managers, we need to insure thatfuture generations don’t inherit the sameproblems that the current generation hasinherited (Wald et al. 1991). Local consensusand support are critical to successful riparianarea management.

5. Hold managers and permittees “accountable”for the health of the ecosystem.

. Managers need to show riparian improve-ments in yearly appraisals. Protectingscenic, ecosystem, wildlife, recreation,cultural and hydrologic values are withinthe realm of mandated legal duties of theUSFS and the BLM.

Permittees should receive incentives to restpastures with riparian habitat. Grazing feesshould be restructured to reward therancher who is improving the health ofriparian areas, and to avoid rewarding therancher who continues to degrade thesesystems. Permittees who are achievingdesired riparian objectives may pay less peranimal unit month than permittees who arenot achieving riparian objectives.3. Monitor rates of recovery and potential

impacts of adjacent land management prac-tices. Domestic livestock grazing is but one ofmany management activities which impactriparian ecosystems. Other impacts whichneed to be monitored are recreation, mining,logging, mechanical manipulation of riparianhabitats and urbanization.

4. Address the issue of “burden of proof.” Donot assume that the Federal Land and PolicyManagement Act with it’s multiple-usemandate automatically reads “all uses in allhabitats unless you can prove it will have anadverse impact.”

l Consumptive users should bear the burdenof proof to show that their activities willnot impact sensitive riparian resources.

l Adopt the concept of “appropriate use inappropriate habitats under appropriatecircumstances.” Management effortsshould promote the biological integrity ofthe riparian ecosystem rather than politicalor economic gain. The use of one dominant

Land management agencies need to re-evaluate grazing systems within the contextof sound biological principles and recog-nize that all riparian systems are unique.One management prescription will notapply to all systems. Each system requiresthorough investigation, monitoring andmanagement techniques which are tailoredto that specific system. When change isrequired, land managers must have thebiological and professional integrity toadmit that change is needed, and thenimplement the change.

The preservation of functioning ecosystemsand native floral and fauna1 species shouldbe the primary goal of public land manage-ment.

The BLM and the USFS are mandated by thefollowing laws to administer lands in amanner which does not compromise theintegrity of the ecosystem health: the TaylorGrazing Act (1934); the National Environmen-

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tal Policy Act (1970); the Endangered SpeciesAct (1973); the Federal Land Policy andManagement Act (1976); the Public Range-lands Improvement Act (1978); the CleanWater Act (1977 and 1987 amended); and BLMand USFS riparian area policies and mandates(various dates). The Endangered Species Actof 1973 was clearly intended to protect andrecover all listed plant and wildlife species. TheAct states that recovery of these species willbe the highest priority for all land managementagencies, and that this mandate would super-sede the multiple-use mandates of the USFS andthe BLM. Even with this guidance, public landmanagement agencies have not been able tooperate their range programs without meet-ing their mandates as directed by the Act.

6. Encourage research and monitoring usingsound science to gather, synthesize anddispense information which will restoredegraded riparian ecosystems and associatedbiotic resources.

7. Manage riparian ecosystems and associatednongame wildlife resources with establishedprograms which utilize game species as afocal point for wildlife management. AsGottschalk (1975) stated: “(w)e have not yetreached the point in our public attitudestoward wildlife where we can assume sup-port for fish and wildlife resources that haveno obvious utility. Therefore the best ap-proach will be to attempt to tie programs fornongame species into an overall ecologicalorientation. To do so will require changes inpublic policy dealing with our renewablewildlife resources, and in the system oftraining land and wildlife managers. Mean-while such managers must do their best tobecome practical ecologists.”

Domestic livestock grazing is undoubtedlythe most ubiquitous land use within thewestern United States, and has been docu-mented to have greatly influenced all aspectsof the western landscape. Cooperrider (1990)stated that “since livestock grazing remainsone of the most common and widespread usesof western rangelands, and since impacts ofsuch grazing on biological diversity are so

poorly understood, livestock grazing must beconsidered as one of the primary threats tobiological diversity.” Conservation of biologi-cal diversity within Western ecosystems isessential because the accumulated loss ofpopulations and ecosystem fragments couldresult in the permanent disappearance ofmany plant and wildlife species as well asentire biological communities (Ehrlich 1987).Riparian habitats are an integral componentof western biological ecosystems, and theirloss could permanently impact the integrity ofthe land as well as all of the inhabitants whichdepend on the land, including plant, animaland human populations.

Aldo Leopold wrote that “to keep every cogand wheel is the first precaution of intelligenttinkering”. One of the most integral “cogs”that must be preserved are the endangeredriparian ecosystems of the Southwest. Ripar-ian ecosystems are fragile corridors of life inthe otherwise arid Southwest, and thesesystems link all other habitats together.Losing riparian habitats creates dysfunctionalecosystems. Unmanaged livestock utilizationhas resulted greatly in the dysfunctioning anddestruction of riparian ecosystems in theSouthwest.

I would warn land managers that if we do notaddress Southwestern riparian issues, and inparticular continued unmanaged livestockutilization, then plant and wildlife speciesthat are dependent on Southwestern riparianhabitats will create issues which could burythe issues facing wildlife managers in thePacific Northwest. While a Western Yellow-billed Cuckoo (Coccyzus amevica~usoccident&), Southwestern Willow Flycatcher(Empidonax traillii extimus) or Mexican GarterSnake (Thamnophis eques) may not have theeconomic impact or political sensitivity of aNorthern Spotted Owl (Strix occidentalis), theyare a few among the scores of wildlife specieswhich are now “teetering on the brink” inSouthwestern riparian ecosystems. This issuehas only recently been addressed, but it willeventually affect all future land use decisionsand management of Southwestern riparianecosystems.

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We have thus far been using a piecemealapproach to riparian management, but withlittle success. We must determine the carryingcapacity of a watershed before we compro-mise the quality of life and the ecosystemwhich sustains that quality of life. We have achoice as land managers. Continue to bereactive in our management techniques at theexpense of many species, or be proactive toprevent extinctions and future listings ofmany wildlife species. It is our choice, but weno longer have the luxury of time.

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