United States Department of Agriculture / Forest Service

Rocky Mountain Research Station

General Technical Report RMRS-GTR-303

August 2013

The Southern Nevada Agency Partnership 

Science and Research Synthesis:

Science to Support Land Management in Southern Nevada 
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Chambers, Jeanne C.; Brooks, Matthew L.; Pendleton, Burton K.; Raish, Carol B., eds. 2013. The 

Southern Nevada Agency Partnership Science and Research Synthesis: Science to support land management in Southern Nevada. Gen. Tech. Rep. RMRS-GTR-303. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 207 p.

Abstract

This synthesis provides information related to the Southern Nevada Agency Partnership (SNAP) 

Science and Research Strategy Goal 1 – to restore, sustain and enhance southern Nevada’s ecosystems – and Goal 2 – to provide for responsible use of southern Nevada’s lands in a manner that 

preserves heritage resources and promotes an understanding of human interaction with the landscape. The Science and Research Strategy has nine Sub-goals that address the topics of water and 

water use, fire, invasive species, biological diversity, restoration, cultural resources, historic content, 

recreation, and science-based management. This synthesis summarizes the state-of-knowledge 

related to each of these Sub-goals, addresses knowledge gaps, and provides management implications. It builds on previous efforts to develop the necessary scientific understanding for adaptive 

management of southern Nevada ecosystems.

Keywords: Mojave, Great Basin, anthropogenic disturbance, climate change, invasive species, 

altered fire regimes, water resources, species of conservation concern, restoration, 

heritage resources, recreation, ecosystem resilience, science-based management

Editors

Jeanne C. Chambers is a Research Ecologist with the U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station in Reno, Nevada, and an Adjunct Professor at the University of Nevada, Reno. Her research focuses 

on the restoration of disturbed or degraded upland and riparian ecosystems in the western United States. Since 1992, 

much of her work has been on understanding disturbance processes in the arid Great Basin and developing concepts 

and methods for maintaining or restoring ecosystem resilience.

Matthew L. Brooks is a Research Botanist with the Department of the Interior, U.S. Geological Survey, Western 

Ecological Research Center, Yosemite Field Station in Oakhurst, California. His primary research interest is the 

ecology and management of invasive species and wildfire in western North America. He has studied Mojave Desert 

ecosystems and evaluated effects of land use practices in that region since 1988.

Burton K. Pendleton is a Research Ecologist with the U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station in Albuquerque, New Mexico. His primary research interest is the ecology of desert shrub communities, with an emphasis on the blackbrush community. He is co-leader of the Comprehensive Inventory and Monitoring 

Project for the Spring Mountains National Recreation Area, Humboldt-Toiyabe National Forest from 2010-2013. 

Carol B. Raish is a Research Social Scientist with the U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station in Albuquerque, New Mexico. Her primary research interests include examining resource use 

on public land and exploring the role of traditional economic practices, such as small-scale ranching, in maintaining 

cultural heritage. Other projects have included working with communities to understand their preferences concerning 

fire and fuels management on public land.
Authors

Wayne R. Belcher

U.S. Geological Survey

Nevada Water Science Center

Henderson, NV 89074

wbelcher@usgs.gov

Matthew L. Brooks

U.S. Geological Survey

Western Ecological Research Center

Yosemite Field Station

Oakhurst, CA 93644

matt_brooks@usgs.gov

Jeanne C. Chambers

U.S. Department of Agriculture, Forest Service

Rocky Mountain Research Station

Reno, Nevada 89512

jchambers@fs.fed.us

Steven M. Ostoja

U.S. Geological Survey

Western Ecological Research Center

Yosemite Field Station

Oakhurst, CA 93644

sostoja@usgs.gov

Randy A. McKinley

U.S. Geological Survey

Earth Resources Observation and Science Center

Sioux Falls, SD 57198-0001

rmckinley@usgs.gov

Alice M. McSweeney

U.S. Department of Agriculture, Forest Service

Rocky Mountain Research Station

Albuquerque, NM 87102-3497

Current Address:

Box 24

Glorietta, NM 87535

amcsweeney@cybermesa.com

Acknowledgments

Financial and technical support for this project was provided by the Southern Nevada Agency Partnership. Additional support was provided by the U.S. Geological Survey, Terrestrial, Fresh Water, and Marine 

Ecosystems and Invasive Species Programs, and the U.S. Forest Service, Rocky Mountain Research 

Station, Grasslands Shrublands and Deserts Program. Review comments were provided by: Mark C. 

Slaughter (Bureau of Reclamation); Lauren Brown, Fred Edwards, Krystal Johnson, Sean McEldery, 

Marilyn Peterson and Boris Poff (Bureau of Land Management); Jill Craig and Ashley Fisher (Great Basin 

Institute); Steve Daron, Curt Deuser, Jim Holland, Eva Jensen, Gary Karst, Sky McCain, Alice Newton 

and Deborah Reardon (National Park Service); Derek Hall (National Security Technologies); Edith B. 

Allen (University of California, Riverside); Scott R. Abella (University of Nevada, Las Vegas); Kent Ostler 

(U.S. Department of Energy); Matt Flores, Darrell Freeman, Glenn Gibson, Johnny Jones, Mark (Tim) 

Rash, James M. Roberts, and Angelina Yost (U.S. Fish and Wildlife Service); Marisa Anderson, Richard 

Periman, Andrew Tanner, and Kelly Turner (U.S. Forest Service); Stan Kitchen (U.S. Forest Service, 

Rocky Mountain Research Station); Sue Jones, Phil Medica, A. Keith Miles, and Tom Suchanek (U.S. 

Geological Survey). Special thanks to the Southern Nevada Agency Partnership Science and Research 

Team for both guidance and manuscript review: Gordon Olsen (National Park Service), Brian Novosak 

and Laurie Simons (U.S. Fish and Wildlife Service); James Hurja (U.S. Forest Service); and especially 

Carolyn J. Ronning (Bureau of Land Management) and Kent Turner (National Park Service).

Michael J. Moran

U.S. Geological Survey

Nevada Water Science Center

Henderson, NV 89074

mjmoran@usgs.gov

Burton K. Pendleton

U.S. Department of Agriculture, Forest Service

Rocky Mountain Research Station

Albuquerque, NM 87102-3497

bpendleton01@fs.fed.us

Carol B. Raish

U.S. Department of Agriculture, Forest Service

Rocky Mountain Research Station

Albuquerque, NM 87102-3497

craish@fs.fed.us 

Megan E. Rogers 

U.S. Geological Survey

Nevada Water Science Center

Henderson, NV 89074

mrogers@usgs.gov

Donald W. Sada,

Desert Research Institute

Division of Hydrologic Sciences

Reno, NV 89509

don.sada@dri.edu

Kent Turner

National Park Service

Lake Mead National Recreation Area

Boulder City, NV 89005

kent_turner@nps.gov

Contents

1. An Overview of the Southern Nevada Agency Partnership Science and 

Research Synthesis .................................................................................................1

Jeanne C. Chambers, Matthew L. Brooks, Kent Turner, 

Carol B. Raish, and Steven M. Ostoja

Management Challenge...........................................................................................................1

Southern Nevada Agency Partnership.....................................................................................1

Science and Research Strategy ..............................................................................................2

Science and Research Synthesis Report ................................................................................9

Biophysical Setting of Southern Nevada..................................................................................9

Cultural Setting ...................................................................................................................... 11

Concepts for Management.....................................................................................................12

2. Southern Nevada Ecosystem Stressors .................................................................17

Burton K. Pendleton, Jeanne C. Chambers, Mathew L. Brooks, and Steven M. Ostoja

Introduction ............................................................................................................................17

Global Stressors ....................................................................................................................18

Local and Regional Stressors................................................................................................19

Knowledge Gaps and Management Implications...................................................................31

3. Water and Water Use in Southern Nevada.............................................................37

Wayne R. Belcher, Michael J. Moran, and Megan E. Rogers

Introduction ............................................................................................................................37

Study Area .............................................................................................................................37

Land Use................................................................................................................................38

Water Use ..............................................................................................................................38

Groundwater ..........................................................................................................................40

Surface Water........................................................................................................................45

Hydrologic and Water Quality Data Collection.......................................................................50

Knowledge Gaps and Management Information....................................................................51

4. Invasive Species in Southern Nevada.....................................................................59

Mathew L. Brooks, Steven M. Ostoja, and Jeanne C. Chambers

Introduction ............................................................................................................................59

Overview of Invasive Species Management..........................................................................60

Invasive Plants.......................................................................................................................62

Invasive Animals ....................................................................................................................65

Knowledge Gaps....................................................................................................................68

Management Implications......................................................................................................69
5. Fire History, Effects and Management in Southern Nevada..................................75

Mathew L. Brooks, Jeanne C. Chambers, and Randy A. McKinley

Introduction ............................................................................................................................75

Fire History.............................................................................................................................75

Temporal and Spatial Patterns of Burning .............................................................................80

Fire Effects.............................................................................................................................83

Management Actions .............................................................................................................89

Knowledge Gaps....................................................................................................................91

Management Implications......................................................................................................92

6. Species of Conservation Concern and Environmental Stressors: Local 

Regional and Global Effects..................................................................................97

Steven M. Ostoja, Mathew L. Brooks, Jeanne C. Chambers, and Burton K. Pendleton

Introduction ............................................................................................................................97

Alpine and Bristlecone Pine Ecosystems...............................................................................98

Mixed Conifer Ecosystem ....................................................................................................100

Piñon Pine and Juniper Ecosystem .....................................................................................102

Sagebrush Ecosystem.........................................................................................................104

Blackbrush and Shadscale Ecosystems..............................................................................106

Mojave Desert Scrub Ecosystem.........................................................................................108

Desert (Mojave Lowland) Riparian Ecosystem.....................................................................111

Spring Ecosystems .............................................................................................................. 113

Knowledge Gaps and Research Guidance.......................................................................... 115

Management Implications.................................................................................................... 118

7. Maintaining and Restoring Sustainable Ecosystems in Southern Nevada .......125

Jeanne C. Chambers, Burton K. Pendleton, Donald W. Sada, 

Steven M. Ostoja, and Matthew L. Brooks

Introduction ..........................................................................................................................125

Resistance and Resilience of Southern Nevada Ecosystems .............................................126

Restoration Considerations for Southern Nevada Ecosystems...........................................128

Knowledge Gaps..................................................................................................................145

Management Implications....................................................................................................145

8. Human Interactions with the Environment through Time in 

Southern Nevada ..................................................................................................155

Carol B. Raish

Introduction ..........................................................................................................................155

Focal Area............................................................................................................................157

Culture History and Chronology...........................................................................................157

Knowledge Gaps and Management Implications.................................................................170
9. Preserving Heritage Resources through Responsible Use of 

Southern Nevada’s Lands....................................................................................175

Carol B. Raish

Introduction ..........................................................................................................................175

Cultural Resources at Risk ..................................................................................................175

Cultural Resource Protection Measures and Organizations................................................177

Non-Destructive Techniques for Identifying, Recording, and Analyzing 

Archeological and Historic Remains...............................................................................180

Knowledge Gaps and Management Implications.................................................................182

10. Recreation Use on Federal Lands in Southern Nevada.....................................185

Alice M. McSweeney

Introduction ..........................................................................................................................185

Nevada’s Population............................................................................................................185

Outdoor Recreation Issues ..................................................................................................186

SNAP Interagency Recreation and Wilderness Planning ....................................................187

Regional Trail Planning and Outreach .................................................................................194

Knowledge Gaps and Management Implications.................................................................195

11. Science-based Management of Public Lands in Southern Nevada..................201

Matthew L. Brooks and Jeanne C. Chambers

Introduction ..........................................................................................................................201

Current Scientific Understanding and Information Needs....................................................202

The Role of Science in Land Management..........................................................................206

The Role of Science in Education........................................................................................207

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 1

Chapter 1

An Overview of the Southern Nevada Agency 

Partnership Science and Research Synthesis 

Jeanne C. Chambers, Matthew L. Brooks, Kent Turner, 

Carol B. Raish, and Steven M. Ostoja

Management Challenge

Southern Nevada is characterized by an arid to semi-arid environment with numerous 

cultural resources and a high level of biological diversity. Since 1980, the human population of the region has increased at unprecedented rates largely due to the expansion 

of suburban areas (Hughson 2009). The various human activities associated with this 

growth and the interactions of those activities with the generally dry and highly variable 

climate result in numerous stresses to ecosystems, species, and cultural resources. In 

addition, climate models predict that the rate of temperature increase and, thus, changes 

in ecological processes, will be highest for ecosystems with low topographic variability 

including deserts like the Mojave (Loarie and others 2009). These stresses vary in scale 

and can be characterized as global (e.g., large scale climatic processes and fluctuations), 

regional (e.g., atmospheric pollution sources from the southwest), and local (e.g., land 

use practices) (Fenstermaker and others 2009; Chapter 2). Although global and regional 

stresses have long-term and lasting effects, local stresses are often the most apparent. 

Human development in the region is increasing the number of roads and utility corridors, 

resulting in dust generation and desert trash, and causing an expansion of recreational 

activities. Past and present grazing by livestock, wild horses, and burros is having 

widespread effects on native vegetation. The spread of invasive non-native plants is 

altering fire regimes and causing the conversion of native ecosystems to invasive plant 

dominance. Groundwater pumping and water diversions coupled with invasive aquatic 

organisms are degrading many of the region’s spring, stream, and riparian ecosystems. 

The cumulative effects of these stresses are placing the region’s cultural and biological 

resources at risk, and causing the loss of habitat for the region’s native plant and animal 

species. There are multiple species of concern in the region, 17 of which are already 

listed as threatened. Maintaining and restoring the complex variety of ecosystems and 

resources that occur in southern Nevada in the face of such rapid socio-economic and 

ecological change presents numerous challenges to Federal land managers.

Southern Nevada Agency Partnership

In 1999, the Southern Nevada Agency Partnership (SNAP) was established to enhance 

cooperative management among the Bureau of Land Management, National Park Service, U.S. Fish and Wildlife Service, and USDA Forest Service. SNAP agencies work 

with each other, the local community, and other partners to address common issues 

pertaining to public lands in southern Nevada (http://www.SNAP.gov). The vision of 
2 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

SNAP is public lands and resources management in southern Nevada that provides for 

sustainable ecosystem goods and services for both present and future generations. SNAP 

agencies develop interagency programs and projects to enhance services to the public, 

improve stewardship of public lands, and increase the efficiency and effectiveness of 

their management activities. 

SNAP agencies manage more than seven million acres of public lands in southern 

Nevada (95 percent of the land in southern Nevada). Federal land includes two national 

recreation areas, two national conservation areas, four national wildlife refuges, 18 

congressionally designated wilderness areas, five wilderness study areas, and 22 areas 

of critical environmental concern. The partnership’s activities are mainly centered in 

southern Nevada’s Clark County (fig. 1.1). However, SNAP partner agencies also manage portions of the Lake Mead National Recreation Area in Mohave County, Arizona, 

U.S. Fish and Wildlife Service and USDA Forest Service-managed lands in Lincoln and 

Nye Counties, Nevada, and all lands and activities managed by the Southern Nevada 

District Office of the Bureau of Land Management. These lands encompass nine distinct 

ecosystem types (fig. 1.2; table 1.1), support multiple species of management concern 

and 17 listed species (table 1.2), and are rich in cultural and historic resources.

Science and Research Strategy

The SNAP managers share an interest in development of an interagency science program that is consistent across agency boundaries and that serves to inform management 

decisions regarding natural resources, cultural resources, and human use of public lands. 

To meet that objective, the SNAP managers established a science and research team 

that was charged with development of an interagency science program. The science and 

research team published the SNAP Science and Research Strategy (Strategy) in 2009 

(Turner and others 2009). The Strategy’s overall goal is to integrate and coordinate 

scientific research programs in southern Nevada and to improve the efficiency and 

effectiveness of these programs. The Strategy is intended to inform and guide SNAP 

agencies in identifying and articulating the highest priority science and research needs, 

sharing resources and funds to implement research addressing those needs, communicating research needs to potential research partners, and eliminating redundancy between 

agency research programs.

Key components of the Strategy are a periodic SNAP science needs assessment and 

a SNAP Science and Research Synthesis Report (Synthesis Report). The purpose of the 

needs assessment is to communicate SNAP’s immediate science and research needs to 

the broader scientific research community and to potential research partners. The needs 

assessment is prepared by the SNAP science and research team based on input from 

agency managers, resource staff, and scientists and documents high priority regional and 

management needs. The Synthesis Report summarizes the state of knowledge and key 

science findings related to the SNAP Science and Research Strategy Goals, identifies 

knowledge gaps, and provides management implications. It is prepared every 5 years and 

is used to guide the periodic SNAP science needs assessments. This General Technical 

Report (GTR) constitutes the first Synthesis Report.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 3

Figure 1.1—Map of the SNAP area illustrating land ownership within the region. 
4 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Figure 1.2—Map of the SNAP area illustrating the southern Nevada ecosystem types recognized in the Clark 

County MSHCP.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 5

Ecosystem Elevation Location Description Reference

Alpine 3,500 m 

(11, 483 ft)

Spring Mountains 

on Mt. Charleston

Alpine fell-fields on exposed rocky, dry soils and alpine meadows 

that occur in swales where moisture and fine-textured soils 

accumulate. The isolated nature of this system has facilitated 

development of a unique assemblage of plants, including several 

endemics.

Clokey 1951

Bristlecone 

pine 

2,600 m (8,530 

ft)

Spring and Sheep 

mountain ranges

Evergreen forest dominated by widely-spaced bristlecone pine 

(Pinus longaeva). Limber pine (Pinus flexilus) can be abundant at 

lower elevations within this zone. Associated shrub species include 

dwarf juniper (Juniperus communis), Clokey mountain sage (Salvia 

dorrii var. clokeyi), and sagebrush (Artemisia spp.)

Ackerman 

2003; Pase 

and Brown 

1982; RECON 

2000

Mixed 

conifer

Between 1,200 

m (3,937 ft) 

and 3,200 m 

(10,498 ft)

Spring and Sheep 

mountain ranges

Tree and shrub communities dominated by (1) white fir (Abies 

concolor) at higher elevations and (2) Ponderosa pine (Pinus 

ponderosa) or (3) Ponderosa pine/mountain shrub at mid-low 

elevations. Associated species at mid-low elevations are single-leaf 

piñon (P. monophylla), Utah juniper (Juniperus osteosperma) and 

mountain mahogany (Cercocarpus spp.). Understory shrubs include 

Gambel oak (Quercus gambelii), manzanita (Arctostaphylos spp.), 

and snowberry (Symphoricarpos albus).

Ackerman 

2003; RECON 

2000

Piñon 

-juniper

From 1,500 m 

(4,921 ft) to 

2,500 m 

(8,202 ft)

Spring, Sheep, and 

Virgin mountain 

ranges with island 

communities in 

the Delamar, 

McCullough, 

Papoose, and 

Parahnagat ranges 

(fig.1.2).

Tree and shrub communities dominated by singleleaf piñon, Gambel 

oak, mountain mahogany, and sagebrush (Artemisia spp.) at upper 

elevations, and Utah juniper, Rocky Mountain juniper (Juniperus 

scopulorum), western juniper (Juniperus occidentalis), rabbitbrush 

(Chrysothamnus spp.), and sagebrush at lower elevations. 

Associated perennial grass species include (Agropyron spp.), 

bluegrass (Poa spp.), and needlegrass (Achnatherum spp.).

RECON 2000

Sagebrush From 1,500 m 

(4,921 ft) to 

2,800 m 

(9,186 ft)

Spring, Sheep, and 

Virgin ranges in 

Clark County and in 

ranges farther north 

in Lincoln County 

(fig. 1.2). Cooccurs with several 

ecosystem types.

Several different community types that are dominated by three 

subspecies of big sagebrush (Artemisia tridentata ssp. tridentata, 

A. tridentata ssp. wyomingensis and A. tridentata ssp. vaseyana), 

low sagebrush (A. arbuscula), Bigelow sagebrush (A. bigelovii), 

and black sagebrush (A. nova). Other shrub species characteristic 

of these communities include rabbitbrush (Chrysothamnus and 

Ericamera spp.), snakeweed (Gutierrezia sarothrae), spiny hopsage 

(Grayia spinosa), and cliffrose (Purshia neomexicana). Associated 

perennial grass species include (Agropyron spp.), bluegrass (Poa 

spp.), and needlegrass (Achnatherum spp.). 

RECON 2000

Blackbrush/

shadscale

Between 

1,200 m 

(3,937 ft) and 

1,800 m 

(5,905 ft) 

Wide-spread 

below the piñon 

and juniper and 

sagebrush zones, 

and above the 

Mojave Desert 

scrub zone (fig. 1.2)

Blackbrush (Coleogyne ramosissima) tends to dominate areas 

with shallow limestone-derived soils, whereas shadscale (Atriplex 

confertifolia) tends to dominate on heavy, rocky soils. Other 

subdominant shrub species include cliffrose, budsage (Artemisia 

spinescens), Mormon tea (Ephedra spp.), snakeweed, wolfberry 

(Lycium spp.), and spiny hopsage. Additional species include 

Utah juniper, Joshua tree (Yucca brevifolia), banana yucca (Yucca 

baccata), Indian ricegrass (Achnatherum hymenoides), needlegrass, 

and galleta grass (Pleuraphis jamesii). 

Brooks and 

others 2007

(continued)

Table 1.1—Ecosystem types of southern Nevada defined based on climate, soils, water availability, and vegetation composition and relative abundance. The Clark County Multiple Species Habitat Conservation Plan (MSHCP) recognizes 11 ecosystem types in southern Nevada 

(RECON 2000). Here, we combine the upland shadscale (Atriplex confertifolia) component of the salt desert scrub type with blackbrush 

(Coleogyne ramosissima) and the saltbush (Atriplex spp.) component of the salt desert scrub type that occurs in alkaline soils of lowland 

basin areas with Mojave Desert Scrub.
6 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Ecosystem Elevation Location Description Reference

Mojave 

Desert 

scrub (most 

common 

ecosystem)

Below 1,200 m 

(3,937 ft)

Wide-spread in 

southern Nevada

Dominated by thermophile vegetation types characterized by 

creosotebush (Larrea tridentata) in upland areas and saltbush 

species (Atriplex spp.) in alkaline soils of lowland basin areas. 

Bajadas, the most common landform, are dominated by 

creosotebush and white bursage (Ambrosia dumosa); subdominants 

include desert thorn (Lycium andersonii), bladder sage (Salazaria 

mexicana), indigo bush (Psorothamnus fremontii), blackbrush, 

brittlebush (Encelia farinosa), and burro bush (Hymenoclea salsola).

Sand dunes, gypsum soils, cliff/rock outcrops, and steep slopes

occur as isolated patches that support unique plant and animal 

communities. Dominant vegetation in these patches include Joshua 

tree (Yucca brevifolia), prickly pear cactus (Opuntia spp.), yucca 

(Yucca spp.), cholla (Cylindropuntia spp.), and hedgehog cactus 

(Echinocereus spp.).

Areas with perennial groundwater not more than 10 m from the 

surface are characterized by the mesquite/catclaw community which 

occurs in patches (1 to over 1000 ha; 2.5 to over 2,500 acres) on 

diverse soils in scattered clumps on valley floors and near desert 

springs. Dominant tree species are screwbean mesquite (Prosopis 

pubescens), honey mesquite (P. glandulosa), catclaw acacia (Acacia 

greggii), and smoke tree (Psorothamnus spinosa); associated 

shrubs are fourwing saltbush (Atriplex canescens), quailbush (A. 

lentiformis), arrowweed (Pluchea sericea), creosotebush, burro bush 

(Hymenoclea salsola), bebbia (Bebbia juncea), and sandpaper plant 

(Petalonyx nitidus).

Clokey 1951; 

Schoenherr 

1992; 

Crampton and 

others 2006

Riparian/ 

aquatic

Below 1200 m 

(3,937 ft)

Lowland riparian/

aquatic systems 

occur in southern 

Nevada, along the 

Virgin and Muddy 

Rivers, Las Vegas 

Wash, and the 

Colorado River. 

Mountain riparian/

aquatic systems 

occur in high 

elevations of Spring 

Mountains.

Riparan/aquatic ecosystems are characterized by flows that 

are either persistent or intermittent, particularly during summer. 

Under natural, unregulated conditions, the aquatic component is 

relatively harsh because of seasonally high water temperatures, 

harsh water chemistry, high turbidity, scouring floods, and sandy 

substrates. In perennial reaches, the riparian community includes 

woody, deciduous, and emergent obligatory and facultative wetland 

vegetation. Principal native woody vegetation includes Fremont 

cottonwood (Populus fremontii), black cottonwood (Populus

trichocarpa), sandbar willow (Salix exigua), Gooding willow (S. 

gooddingii), velvet ash (Fraxinus velutina), desert willow (Chilopsis 

linearis), and honey mesquite. Mountain riparian/aquatic ecosystems 

are characterized by streams with highly variable base flows that 

have low to nonexistent discharges in dry years. 

RECON 2000; 

Chapter 3

Springs Throughout Clark 

County

Small-scale aquatic systems that occur where ground water 

reaches the soil surface. Several hundred springs are scattered 

throughout Clark County that are generally supported by mountain 

block, local, or regional aquifers. They range widely in size, water 

chemistry, morphology, landscape setting, and persistence. Springs 

support diverse aquatic communities and riparian zones. Spring 

environments are most influenced by the type of aquifer and amount 

of flow, landscape position, and disturbance regime (see Chapter 3).

Chapter 3

Table 1.1—(Continue)
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 7

Table 1.2—Southern Nevada Agency Partnership species of management concern. 

Common name Species name

Amphibian

Relict leopard frog Rana onca

Birds

Northern Goshawk Accipiter gentilis

Western Yellow-billed Cuckoo Coccyzus americanus occidentalis

Southwestern Willow Flycatcher Empidonax trailii extimus

American Peregrine Falcon Falco peregrinus anatum

Bald Eagle Haliaeetus leucocephalus

Blue Grosbeak Passerina caerulea

Phainopepla Phainopepla nitens

Summer Tanager Piranga rubra

Vermillion Flycatcher Pyrocephalus rubinus

Yuma Clapper Rail Rallus longirostrus yumanensis

Arizona Bell’s Vireo Vireo bellii arizonae

Fishes

Meadow Valley Wash desert sucker Catostomus clarki ssp. 2

Devils Hole pupfish Cyprinodon diabolis

Ash Meadows Amargosa pupfish Cyprinodon nevadensis mionectes

Warm Springs pupfish Cyprinodon nevadensis pectoralis

Pahrump poolfish Empetrichthys latos latos

Pahranagat roundtail chub Gila robusta jordani

Virgin River chub Gila seminuda

Virgin River chub (Muddy River pop.) Gila seminuda pop. 2

Virgin River spinedace Lepidomeda mollispinis mollispinis

Moapa dace Moapa coriacea

Woundfin Plagopterus argentissimus

Moapa speckled dace Rhinichthys osculus moapae

Ash Meadows speckled dace Rhinichthys osculus nevadensis

Pahranagat speckled dace Rhinichthys osculus velifer

Meadow Valley speckled dace Rhinichthys osculus ssp. 11

Razorback sucker Xyrauchen texanus

Reptiles

Western redtail skink Eumeces gilberti rubricaudatus

Agassiz’s Desert tortoise Gopherus agassizii

Banded Gila monster Heloderma suspectum cinctum

Invertebrates

Ash Meadows naucorid Ambrysus amargosus

Warm Springs naucorid Ambrysus relictus

Acastus Checkerspot Chlosyne acastus robusta

Spring Mountains dark blue Euphilotes ancilla purpura

Morand’s checkerspot Euphydryas chalcedona morandi

Spring Mountains Comma Skipper Hesperia colorado mojavensis

Charleston ant Lasius nevadensis

Nevada Admiral Limenitis weidemeyerii nevadae

Amargosa naucorid Pelocoris shoshone amargosus

Spring Mountains icarioides blue Plebejus icarioides austinorum

Mount Charleston Blue Plebejus shasta charlestonensis

Giuliani’s dune scarab beetle Pseudocotalpa giulianii

Moapa pebblesnail Pyrgulopsis avernalis

Blue Point pyrg Pyrgulopsis coloradensis

Spring Mountains pyrg Pyrgulopsis deaconi

Corn Creek pyrg Pyrgulopsis fausta

(continued)
8 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Invertebrates

Southeast Nevada pyrg Pyrgulopsis turbatrix

Carole’s fritillary Speyeria carolae

Moapa Warm Spring riffle beetle Stenelmis moapa

Mammals

Pale lump-nosed bat Corynorhinus townsendii pallescens

Spotted bat Euderma maculatum

Allen’s big-eared bat Idionycteris phyllotis

Silver-haired bat Lasionycteris noctivagans

Pahranagat Valley montane vole Microtus montanus fucosus

Fringed myotis Myotis thysanodes

Palmer’s chipmunk Neotamias palmeri

Hidden Forest Uinta chipmunk Neotamias umbrinus nevadensis

Big free-tailed bat Nyctinomops macrotis

Bighorn sheep Ovis canadensis nelsoni

Plants

Rough angelica Angelica scabrida

Charleston pussytoes Antennaria soliceps

Sticky ringstem Anulocaulis leiosolenus var. leiosolenus

Las Vegas bearpoppy Arctomecon californica

King’s rosy sandwort Arenaria kingii spp. rosea

Clokey milkvetch Astragalus aequalis

Threecorner milkvetch Astragalus geyeri var. triquetrus

Clokey eggvetch Astragalus oophorus var. clokeyanus

Spring Mountains milkvetch Astragalus remotus

Ash Meadows milkvetch Astragalus phoenix

Upswept moonwort Botrychium ascendens

Dainty moonwort Botrychium crenulatum

Slender moonwort Botrychium lineare

Spring-loving centaury Centaurim namophilum

Las Vegas cryptantha Cryptantha insolita

Jaeger whitlowgrass Draba jaegeri

Charleston draba Draba paucifructa

Ash Meadows sunray Enceliopsis nudicaulis var. corrugate

Nevada willowherb Epilobium nevadense

Pahrump Valley buckwheat Eriogonum bifucatum

Las Vegas buckwheat Eriogonum corymbosum var. nilesii

Sticky buckwheat Eriogonum viscidulum

Clokey greasebush Glossopetalon clokeyi

Ash Meadows gumplant Grindelia fraxinopratensis

Charleston ivesia Ivesia cryptocaulis

Jaeger ivesia Ivesia jaegeri

Ash Meadows ivesia Ivesia kingii var. eremica

Ash Meadows blazingstar Mentzelia leucophylla

Amargosa niterwort Nitrophila mohavensis

White-margined beardtongue Penstemon albomarginatus

Bicolored beardtongue Penstemon bicolor ssp. bicolor

Rosy two-colored beardtongue Penstemon bicolor ssp. roseus

Jaeger beardtongue Penstemon thompsoniae spp. jaegeri

Clokey’s catchfly Silene clokeyi

Charleston tansy Sphaeromeria compacta

Charleston kittentails Synthyris ranunculina

Charleston grounddaisy Townsendia jonesii var. tumulosa

Charleston violet Viola charlestonensis

Table 1.2 (Continued).

Common name Species name
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 9

The SNAP Science and Research Strategy established several goals for interagency 

science and research that is conducted in support of resource management in southern 

Nevada. The goals were developed based on individual agency goals, the SNAP Board 

vision, the interagency science and research team’s charter goals, the input of individual 

agency specialists, and input from interdisciplinary scientists that was obtained during 

several planning workshops. Each major goal has a set of Sub-goals and questions that 

address specific science needs. The three main Goals are:

Goal 1. Restore, sustain, and enhance southern Nevada’s ecosystems.

Goal 2. Provide for responsible use of southern Nevada’s lands in a manner that 

preserves heritage resources and promotes an understanding of human interaction 

with the landscape.

Goal 3. Promote scientifically informed and integrated approaches to effective, 

efficient, and adaptive management.

Science and Research Synthesis Report

The Goals and Sub-goals of the SNAP Science and Research Strategy provide key 

focal areas for both the periodic science needs assessments and the Synthesis Report. 

The Synthesis Report addresses information related to Goals 1 and 2 and their associated Sub-goals (table 1.3). The Sub-goals address the topics of fire, invasive species, 

landscapes and watersheds, biological diversity, cultural resources, historic content, 

recreation, land uses, and education. The Synthesis Report provides a summary of the 

state of knowledge related to each of the nine Sub-goals, addresses knowledge gaps, and 

provides management implications. It builds on previous efforts to develop the necessary scientific understanding for adaptive management of southern Nevada ecosystems, 

such as the Multi Species Habitat Conservation Plan (MSHCP) (RECON 2000) and a 

2007 workshop on the characteristics of southern Nevada ecosystems and the threats to 

ecosystem health (Desert Research Institute 2008). The Synthesis Report is organized 

around the topics addressed in the Sub-goals, and table 1.3 provides a crosswalk between 

the chapters in this document and the Goals and Sub-goals in the SNAP Strategy. An 

overview of the biophysical setting and cultural resources as well as the management 

concepts discussed in the report follow.

Biophysical Setting of Southern Nevada

Southern Nevada straddles a broad ecotone between the Central Basin and Range of 

the Cold Desert ecoregion to the north and the Mojave Basin and Range of the Warm 

Desert ecoregion to the south (U.S. Environmental Protection Agency 2002, 2010; 

fig. 1.2). The topography is characterized by broad basins separated by isolated mountain 

ranges that are punctuated by steep environmental gradients. These local environmental 

gradients mirror large-scale latitudinal gradients and result in Cold Desert and mesic 

forest conditions occurring at higher elevations on mountains within the Warm Desert 

ecoregion.

Climate within the region is spatially and temporally variable, and slope, aspect, 

and especially elevation—which ranges from 170 m (557 ft) at Laughlin, Nevada, to 

3,632 m (11,913 ft) at Charleston Peak in the Spring Mountains—strongly influence 

both precipitation and temperature. Recorded precipitation ranges from a long-term 

yearly mean of 10.5 cm (4.1 in), with a minimum of 1.4 cm (0.6 in) and maximum 

of 27.1 cm (10.7 in) at 662 m (2,170 ft) elevation in Las Vegas, to a mean of 60.1 cm 

(23.6 in), with a minimum of 30.8 cm (12.1 in) and maximum of 90.0 cm (35.4 in) at 

2,289 m (7,510 ft) at Mt. Charleston Lodge in the Spring Mountains (Western Regional 
10 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Table 1.3—A crosswalk relating the chapters in this document to the Goals and Sub-goals in the SNAP Science 

and Research Strategy.

Goal/Chapter Sub-goal

Goal 1. Restore, sustain, and 

enhance southern Nevada’s ecosystems

Chapter 1. An Overview of the southern 

Nevada Agency Partnership Science and 

Research Synthesis 

Chapter 2. Southern Nevada Ecosystem Stressors 

Chapter 3. Water and Water Use in Sub-Goal 1.3. Restore and sustain proper

Southern Nevada function of southern Nevada’s watersheds

and landscapes

Chapter 4. Invasive Species in Southern Nevada Sub-Goal 1.2. Protect southern Nevada’s

ecosystems from the adverse impacts of 

invasive species

Chapter 5. Fire History, Effects, and Sub-Goal 1.1. Manage wildland fire to

Management in Southern Nevada sustain southern Nevada’s ecosystems

Chapter 6. Species of Conservation Concern Sub-Goal 1.4. Sustain and enhance southern

and Environmental Stressors: Nevada’s biotic communities to preserve

Local, Regional, and Global Effects biodiversity and maintain viable populations

Chapter 7. Maintaining and Restoring, Sub-Goal 1.3. Restore and sustain proper

Sustainable Ecosystems in Southern Nevada function of southern Nevada’s watersheds

 and landscapes

Goal 2. Provide for responsible use of southern 

Nevada’s lands in a manner that preserves

heritage resources and promotes an understanding 

of human interaction with the landscape

Chapter 8. Human Interactions with the Sub-Goal 2.1. Develop an understanding of 

Environment through Time in Southern human interactions with the environment

Nevada through time

Chapter 9. Preserving Heritage Resources Sub-Goal 2.2. Preserve heritage resources

through Responsible Use of through responsible use of southern 

Southern Nevada’s Lands Nevada’s lands

Chapter 10. Recreation Use on Federal Lands Sub-Goal 2.4. Provide for appropriate 

in Southern Nevada (type and location), quality, and diverse

 recreational experiences, resulting in 

responsible visitor use on federal lands in

 southern Nevada

Chapter 11. Science-based Management of Sub-Goal 2.3. Manage current and future

Public Lands in Southern Nevada authorized southern Nevada land uses in a

manner that balances public need and 

ecosystem sustainability

Sub-Goal 2.5. Promote an effective 

conservation education and interpretation 

program to improve the quality of resources

and enhance public use and enjoyment of

southern Nevada public lands
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 11

Climate Center 2011). Most of the yearly precipitation falls during the winter months, 

but the southeastern part of the region receives relatively more summer precipitation 

than the northern or western areas. Temperatures in the region range from a long-term 

yearly mean of 19.5 °C (67.1 °F), with a minimum of 12.3 °C (54.1 °F) and a maximum 

of 27.0 °C (80.6 °F) at Las Vegas, to a mean of 7.8 °C (46.0 °F) with a minimum of 

0.2 °C (32.3 °F) and maximum of 15.8 °C (60.4 °F) at Mt. Charleston Lodge (Western 

Regional Climate Center 2011). 

The elevation/climate gradients in combination with the local topography of the region strongly affect soil characteristics, plant species composition, and productivity of 

vegetation communities and, consequently, animal species distributions. Lower elevation 

soils are typically classified as Entisols, Aridisols, or Inceptisols while higher elevation 

soils are Mollisols and, when derived from carbonate substrates, Alfisols (U.S. Environmental Protection Agency 2010). Wetland soils are Inceptisols or Mollisols (U.S. 

Environmental Protection Agency 2010). The diverse Warm and Cold Desert ecosystem 

types have been present in southern Nevada at least since the end of the last ice age and 

the beginning of the Holocene 10,000 years ago (Van Devender 1977; Van Devender 

and Spaulding 1979), although the ecotones between the major ecosystem types are 

presently higher in elevation than they were at the beginning of the Holocene (Spaulding 

1990). Low elevation basins and the toeslopes of mountain ranges have warmer and 

more arid climates typical of warm deserts and are dominated by Warm Desert Mojave 

Desert Scrub ecosystems (table 1.1). Less common cold desert shrublands (blackbrush 

and sagebrush), woodlands (pinyon and juniper), forest stands (mixed conifer), and 

even bristlecone pine and alpine ecosystem types have cooler and more mesic climates 

and occur with increasing elevation within these mountain ranges. Spring and riparian 

ecosystems occur across the elevation/climate gradient, but spring ecosystems occur 

where local geology and hydrology result in water flowing to the surface, and riparian/

aquatic ecosystems are associated with streams and rivers that flow during the majority 

of the year. These ecosystems differ in soil characteristics, water chemistry, and species 

composition depending on topographic location and setting. 

The strong topographic differences and diverse ecosystem types result in a high 

number of species in southern Nevada (Kolter and Brown 1988). Also, the degree of 

habitat diversity and geographic isolation of similar habitat types like mountain ranges 

has produced a high degree of endemism. For example, there are many species of 

endemic butterflies (Fleishman and others 2001; Forister and others 2004). Finally, 

the climatic history of the region also has contributed to high levels of endemism. The 

region is much drier today than it was even 10,000 years ago, and this has resulted in 

highly isolated aquatic remnant habitats that support a large number of endemic pupfish 

(Cyprinodon spp.) and other species (Brown 1971; Miller 1950).

Cultural Setting

Southern Nevada is rich in irreplaceable cultural and historical resources that include 

archaeological remains, historic sites, cultural landscapes, and other areas of significance 

to Native American and other cultural groups. There is evidence of human occupation 

of southern Nevada from about 12,000 years ago. These early residents were nomadic 

hunters of large Pleistocene fauna who also used both small game and plant resources 

(Harper and others 2006). Climate change during the early Holocene resulted in broad 

adaptation to a range of resources, and small, mobile groups of hunter-gatherers moved 

between ecological zones utilizing plant resources and small game (Ezzo and Majewski 

1996). Agriculture began prior to 2350 years ago and increased in intensity until 

ca. 750/650 years ago (AD 1200/1300). Exploitation of wild resources and seasonal 
12 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

movement continued during this time period. Southwestern Puebloan peoples that were 

characterized by agriculture and the use of pit structures, the bow and arrow, ceramics, 

above-ground rooms, and pueblos occupied the region during this period (Lyneis 1995). 

After about 650 years ago, archeological remains reflect a return to a more nomadic 

foraging way of life, supplemented by smaller-scale agriculture (Altschul and Fairley 

1989; Ezzo and Majewski 1996). This adaptation is associated with the Southern Paiute who were residents of the region during European contact and who continue to 

live in southern Nevada today. European contact began in the 1700s with the Spanish 

and continued with the well-documented establishment of Mormon settlements in the 

mid-1800s (Sterner and Ezzo 1996). The now seemingly inhospitable desert has a long 

history of change and has provided diverse ecosystems from which native people and 

later historic immigrants have been able to sustain themselves.

Concepts for Management

Management aimed at maintaining sustainable ecosystems is essential if public lands 

in southern Nevada are to continue to support both public needs and habitat for the region’s diverse assemblage of plants and animals. Sustainable or “healthy” ecosystems 

supply important ecological services and goods. Over the normal cycle of disturbance 

events, sustainable ecosystems retain characteristic processes including hydrologic flux 

and storage, geomorphic processes, biogeochemical cycling and storage, biological 

activity and productivity, and biotic population regeneration and reproduction (modified from Chapin and others 1996 and Christensen and others 1996). Thus, managing 

for sustainable ecosystems in southern Nevada requires maintaining or restoring the 

ecological processes that structure the region’s ecosystems.

A large number of studies have revealed a tight connection between ecosystem 

sustainability and ecological resilience to stress and disturbance and resistance to invasive species (see Folke and others 2002). Resilience is defined as the capacity of an 

ecosystem to regain its fundamental structure, processes, and functioning (or recover) 

when subjected to stressors or disturbances like drought, livestock grazing, or wildfire 

(e.g. Allen and others 2005; Hollings 1973; Walker and others 1999). A reduction in 

resilience can increase the vulnerability of an ecosystem and reduce its ability to recover 

following stress or disturbance. The inherent resilience of southern Nevada ecosystems to 

stress and disturbance differs due to the strong elevation/climate gradients in the region 

and the large differences in abiotic and biotic characteristics along these gradients. In 

general, the resilience of intact desert ecosystems tends to increase along gradients of 

increasing available resources (water and nutrients) and annual net primary productivity (Brooks and Chambers 2011; Chambers and others 2007; Wisdom and Chambers 

2009). Thus, higher precipitation and more moderate temperatures at moderately high 

elevations result in greater productivity and can increase the capacity of native communities to recover following stress or disturbance. 

Non-native invaders are having major effects on the sustainability of southern Nevada’s terrestrial and aquatic ecosystems and are a major management concern. Resistance is the capacity of an ecosystem to retain its fundamental structure, processes, and 

functioning (or remain largely unchanged) despite stresses, disturbances or invasive 

species. Resistance to invasion is a function of the biotic and abiotic factors and ecological processes in an ecosystem that limit the establishment and population growth of an 

invading species (D’Antonio and Thomsen 2004). Resistance of ecosystems to widely 

distributed invasive species like cheatgrass (Bromus tectorum) and red brome (Bromus 

madritensis) often reflects the climate suitablility of the species or its ability to establish 

and persist under a given set of environmental conditions. In general, resistance to annual 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 13

invaders tends to be higher in the most stressful environments (true desert and alpine 

ecosystems) because only a limited suite of species is adapted to establish and persist 

due to the harsh conditions. For example, establishment of the invasive annual grass, 

cheatgrass, in the Great Basin is limited in salt desert shrub types at the low end of the 

precipitation gradient due to insufficient water availability (Meyer and others 2001), 

while growth and reproduction is limited in mountain brush types at high elevations 

due to insufficient degree days (Chambers and others 2007).

Several factors interact to influence resilience to stress and disturbance and resistance 

to invasive species in desert ecosystems. Climate, topography, and soils determine the 

abiotic and biotic attributes of an ecosystem and thus the potential to support a given 

ecosystem type or community. The abiotic attributes that characterize ecosystems are 

hydrologic flux and storage, biogeochemical cycling and storage, and geomorphic 

processes, while biotic attributes are biological productivity, composition and structure, 

and population regulation and regeneration. Climate change, disturbance and stress act 

on these attributes and influence the relative resilience and resistance of the ecosystem 

over time. Changes in resilience and resistance are indicated by factors like soil stability 

and past or present erosion, the composition and abundance of native plants and animals, 

seed banks and seed sources, and the composition and abundance of invasive species. 

The severity and frequency of disturbance can alter resilience to stress and disturbance 

and resistance to invasive species and, consequently, the capacity of a site to support 

desirable alternative states (Briske and others 2008). In the deserts of North America, 

inappropriate grazing by wild horses, burros, and livestock has significantly influenced 

resilience and resistance by reducing a major structural and functional component, 

specifically native perennial herbaceous species, and by serving as a dispersal agent 

for non-native invaders (Milchunas and others 1988; Van de Koppel and others 2002). 

Loss of perennial herbaceous species decreases the resistance of desert ecosystems to 

invasion (Chambers and others 2007) and resilience to disturbances like drought and 

wildfires (D’Antonio and others 2009). Once established, invasive species promote 

shorter fire return intervals and larger fire sizes than southern Nevada deserts experienced historically. These changes can result in positive feedbacks for the invader and 

negative effects on native species, especially woody perennials and succulents (Brooks 

and others 2004).

Adaptive management that is aimed at maintaining or increasing resistance and resilience can reduce the uncertainty associated with management decisions and increase 

the region’s capacity to deal with stresses without losing options for the future (Folke 

and others 2002). Key aspects of adaptive management are a scientific understanding 

of the underlying processes structuring southern Nevada ecosystems, the effects of the 

numerous stresses on these ecosystems and their associated species, and the factors that 

influence their resilience to stress and disturbance and resistance to invasion. Routine 

monitoring of the effects of stresses, disturbances, and management actions on the 

ecological conditions of the Region’s diverse ecosystems can provide the necessary 

feedback for adaptive management. Periodic science syntheses, such as those in this 

GTR, give information on the current state of knowledge, the ecological trajectories of 

the region’s ecosystems and species, and needed information for effective management.

References

Ackerman, T.L. 2003. A flora of the desert national wildlife range, Nevada. In: Bair, J.; Tiehm, A. (eds). 

Mentzelia. No. 7. 90 p.

Allen, C.R.; Gunderson, L.; Johnson, A.R. 2005. The use of discontinuities and functional groups to 

assess relative resilience in complex systems. Ecosystems. 8:958-966.
14 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Altschul, J.H.; Fairley, H.C. 1989. Man, models, and management: an overview of the archaeology of the 

Arizona Strip and its cultural resources. Washington, DC: U.S. Department of the Interior, Bureau of 

Land Management.

Briske, D.D., Bestelmeyer, B.T.; Stringham, T.K.; Shaver, P.L. 2008. Recommendations for development 

of resilience based state and transition models. Rangeland Ecology and Management. 61:359–367.

Brooks, M.L.; Chambers, J.C. 2011. Invasive plants and altered fire regimes in the deserts of North America. Rangeland Ecology and Management. 64:431–438. doi: 10.2111/REM-D-09-00165.1.

Brooks, M.L.; D’Antonio, C.M.; Richardson, D.M.; Grace, J.B.; Keeley, J.E.; DiTomaso, J.M.; Hobbs, R.J.; 

Pellant, M.; Pyke, D. 2004. Effects of invasive alien plants on fire regimes. Bioscience. 54:677-688.

Brooks, M.L.; Esque, T.C.; Duck, T. 2007. Creosotebush, blackbrush, and interior chaparral shrublands. 

In: Hood, S.M.; Miller, M. (eds.). Fire ecology and management of the major ecosystems of Southern 

Utah. Gen. Tech. Rep. RMRS-GTR-202. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station: 57-71.

Brown, J. H., 1971. The desert pupfish. Scientific American. 225:104-110.

Chambers, J.C.; Roundy, B.A.; Blank, R.R.; Meyer, S.E; Whittaker, A. 2007. What makes Great Basin 

sagebrush ecosystems invasible by Bromus tectorum? Ecological Monographs. 77:117-145.

Chapin, F.S., III.; Torn, S.E.; Tateno, M. 1996. Principles of ecosystem sustainability. The American Naturalist. 148:1016-1037.

Clokey, I.W. 1951. Flora of the Charleston Mountains, Clark County, Nevada. Berkeley, CA: University 

of California Press. 274 p.

Christensen, N.L.; Bartuska, A.M.; Brown, J.H.; [and others]. 1996. The report of the Ecological Society 

of America Committee on the scientific basis for ecosystem management. Ecological Applications. 

6:665-691.

Crampton, L.; Krueger J.; Murphy, D. 2006. Conservation management strategy for mesquite and acacia 

woodlands in Clark County, Nevada. [Place of publication unknown]: U.S. Bureau of Land Management, Las Vegas Field Office.

D’Antonio, C.M.; Chambers, J.C.; Loh, R.; Tunison, J.T. 2009. Applying ecological concepts to the management of widespread grass invasions. In: Inderjit, R.L. (ed.). Ecological invasions and restoration. 

Netherlands: Springer: 123-149.

D’Antonio, C.M.; Thomsen, M. 2004. Ecological resistance in theory and practice. Weed Technology. 

18:1572-1577.

Desert Research Institute. 2008. Task 7: First iteration conceptual models for 11 MSHCP ecosystems. Annual Report. Project 2005-DRI-574A-P. Reno, NV: Desert Research Institute.

Ezzo, J.A.; Majewski, T. 1996. The cultural resources of the project area: prehistory, protohistory, and 

ethnography. In: Ezzo, J.A. (ed.). A Class I cultural resources survey of the Moapa and Virgin Valleys, 

Clark County, Nevada. Statistical Research Technical Series No. 58. Boulder City, NV: Statistical Research: 35-77. 

Fenstermaker, L.F.; McDonald, E.V.; Webb, R.H. 2009. Regional threats to the Mojave Desert. In: Webb, 

R.H.; Fenstermaker, L.F.; Heaton, J.S.; [and others]. (eds.). The Mojave Desert: ecosystem processes 

and sustainability. Las Vegas, NV: University of Nevada Press: 7-10.

Fleishman, E.; Austin, G.T; Murphy, D.D. 2001. Biogeography of Great Basin butterflies: revisiting patterns, paradigms, and climate change scenarios. Biological Journal of the Linnean Society. 74:501-515.

Folke, C.; Carpenter, S.; Elmqvist, T.; [and others]. 2002. Resilience and sustainable development: building adaptive capacity in a world of transformations. Scientific background paper on resilience for the 

process of The World summit on sustainable development on behalf of The Environmental Advisory 

Council to the Swedish Government. Stolkholm, Sweden: Ministry of the Environment. 74 p.

Folke, C.; Carpenter, S.; Walker, B.; [and others]. 2004. Regime Shifts, Resilience, and Biodiversity in 

Ecosystem Management. Annual Review of Ecology, Evolution, and Systematics. 35:557-581.

Forister, M.L.; Fordyce, J.A; Shapiro, A.M. 2004. Geological barriers and restricted gene flow in the holarctic skipper Hesperia comma (Hesperiidae). Molecular Ecology. 13: 3489-3499.

Harper, C.; Ahlstrom, R.V.N.; Eskenazi, S. 2006. Introduction. In: Harper, C. (ed.). A room with a view: 

Data recovery of an early historical rockshelter site located in the Upper Moapa Valley, Clark County, 

Nevada. HRA Papers in Archaeology No. 5. Las Vegas, NV: HRA. 1-14.

Holling, C.S. 1973. Resilience and stability in ecological systems. Annual Review of Ecology and 

Systematics. 4:1-23.

Hughson, D.L. 2009. Human population in the Mojave Desert: Resources and sustainability. In: Webb, 

R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, E.V; Miller, D.M. eds. The Mojave 

Desert: Ecosystem processes and sustainability. Las Vegas, NV: University of Nevada Press: 57-77.

Kotler, B.P.; Brown, J.S. 1988. Environmental heterogeneity and the coexistence of desert rodents. Annual 

Review of Ecology and Systematics. 19:281-307.

Loarie, S.R.; Duffy, P.B.; Hamilton, H.; [and others]. 2009. The velocity of climate change. Nature. 

462:1052-1055.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 15

Lyneis, M.M. 1995. The Virgin Anasazi, far western Puebloans. Journal of World Prehistory. 

9(2):199-241.

Meyer S.E.; Garvin, S.C.; Beckstead, J. 2001. Factors mediating cheatgrass invasion of intact salt desert shrubland. In: McArthur D.E.; Fairbanks, D.J. Comps. Shrubland Ecosystem Genetics and Biodiversity: Proceedings. Proc RMRS-P-21. Ogden UT: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station: 224-232.

Milchunas, D.G.; Sala, O.E.; Lauenroth, W.K. 1988. A generalized model of the effects of grazing by large 

herbivores on grassland community structure. American Naturalist. 132:87-106.

Miller, R.R. 1950. Speciation in fishes of the genera Cyprinodon and Empetrichtys, inhabiting the Death 

Valley region. Evolution. 4:155-163.

Pase, C.P.; Brown, D.E. 1982. Rocky Mountain (petran) and madrean montane coniferous forests. In: 

Brown, D.E., (ed.). Biotic communities of the American Southwest-United States and Mexico. Desert 

Plants. 4(1/4):43-48. 

RECON (Regional Environmental Consultants, Inc.). 2000. Final Clark County Nevada multiple species 

habitat conservation plan and environmental impact statement. Prepared for Clark County Administrative Services. 550 p. plus appendices.

Shoenherr, A.A. 1992. A natural history of California. Berkeley, CA: University of California Press. 772 p.

Sterner, M.A.; Ezzo, J.A. 1996. Religion, ranching, and railroads: the history of the Muddy and Virgin 

River Valleys. In: Ezzo, J.A. (ed.). A Class I cultural resources survey of the Moapa and Virgin Valleys, Clark County, Nevada. Statistical Research Technical Series No. 58, Boulder City, NV: Statistical 

Research: 79-130.

Spaulding, W.G. 1990. Vegetational and climate development of the Mojave Desert: the last glacial maximum to the present. In: Betancourt, J.L.; Van Devender, T.R.; Martin, P.S. (eds.). Packrat middens: the 

last 40,000 years of biotic change. Tucson: University of Arizona Press: 166-199.

Turner, K.; LaVoie, A.M.; Ronning, C.J.; [and others]. 2009. SNAP Science and Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/SNAP-S-R-Strategy-2009r.

pdf. [2011, April 6].

U.S. Environmental Protection Agency. 2002. Level III ecoregions of the continental United States. Derived from Omernik,J.M. 1987 Ecoregions of the conterminous United States. Map (scale 1:7,500,000). 

Annals of the Association of American Geographers 77(1): 118-125. Corvallis, OR: U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory. Map M-1, 

various scales.

U.S. Environmental Protection Agency. 2010. Ecoregions of Nevada. Western Ecology Center. Online: 

http://www.epa.gov/wed/pages/ecoregions/nv_eco.htm#Ecoregions. [2011, 5 April].

Van de Koppel, J.; Reitkerk, M.; Langevelde, F.V.; [and others]. 2002. Spatial heterogeneity and irreversible vegetation change in semiarid grazing systems. American Naturalist. 159:209-218.

Van Devender, T.R. 1977. Holocene woodlands in the southwestern deserts. Science. 198:189-192.

Van Devender, T.R.; Spaulding, W.G. 1979. Development of vegetation and climate in the Southwestern 

United States. Science. 204:701–710.

Walker B.H.; Kinzig A.; Langridge J. 1999. Plant attribute diversity, resilience, and ecosystem function: 

the nature and significance of dominant and minor species. Ecosystems. 2:1-20.

Western Regional Climate Center. 2011. Online: http://www.wrcc.dri.edu/index.html. [2011, 5 April].

Wisdom, M.J.; Chambers, J.C. 2009. Concepts for ecologically-based management of Great Basin shrublands. Restoration Ecology. 17:740-749. 
16 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 17

Chapter 2

Ecosystem Stressors in Southern Nevada 

Burton K. Pendleton, Jeanne C. Chambers, 

Matthew L. Brooks, and Steven M. Ostoja

Introduction

Southern Nevada ecosystems and their associated resources are subject to a number 

of global and regional/local stressors that are affecting the sustainability of the region. 

Global stressors include elevated carbon dioxide (CO2) concentrations and associated 

changes in temperature and precipitation patterns and amounts, solar radiation, and 

nutrient cycles (Smith and others 2009b). Global stressors are ubiquitous in nature 

and interact both directly and indirectly with regional or local stressors. Regional/local 

stressors in southern Nevada include: population growth and urbanization and associated 

increases in nitrogen deposition, energy development, water development, and recreation; increased effects of insects and disease; ongoing effects of livestock, wild horse 

and burro grazing; new and expanding invasive species; and altered fire regimes. This 

chapter provides background information on the stressors affecting southern Nevada’s 

ecosystems that is needed to address Goal 1.0 in the SNAP Science Research Strategy, 

which is to restore, sustain, and enhance southern Nevada’s ecosystems (Turner and 

others 2009).

Human population growth and changes in land use strongly affect the type and 

magnitude of local/regional stressors. From 1960 to 2010, Nevada’s growth rate was 

the highest in the nation (www.census.gov/prod/cen2010/briefs/c2010br-01.pdf). Clark 

County has experienced particularly high growth, with a population increase of greater 

than 40 percent since the 2000 census. Factors like land ownership, historic and current 

land use, proximity to human and energy developments, and desirability for recreation 

all influence the level of human-caused stress. 

The strong elevation/climate gradients and large differences in the environmental 

characteristics of southern Nevada ecosystems (fig. 1.2; Chapter 1) have a major influence 

on both patterns of land use and the dominant stressors for different ecosystem types. 

Shifts in land use related to population growth, urbanization, and energy development 

are largely focused in lower elevation ecosystems including sagebrush, blackbrush 

and shadscale, and Mojave Desert scrub. Water diversions influence riparian/aquatic 

ecosystems and springs, while groundwater pumping also has the potential to affect 

ecosystems that characterize lower valleys including Mojave Desert scrub. Recreational 

uses influence all ecosystems, and wild horse and burro use and livestock grazing affect 

all but alpine and subalpine ecosystems. Insects and disease, as well as invasive species 

are widespread stressors. Fire is limited to ecosystems with sufficient fuels to carry fire 

and is strongly influenced by invasive species in lower elevation Mojave Desert scrub, 

blackbrush and shadscale, and sagebrush ecosystems. 

This chapter addresses aspects of several of the Goals and Sub-goals listed in the 

SNAP Science Research Strategy (table 1.3; Turner and others 2009). Altered fire regimes, invasive species, land use practices, and management actions are addressed in 

Goal 1—Sustain, Restore, and Enhance Southern Nevada’s Ecosystems. The effects of 
18 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

these stressors on sensitive species and habitats are specifically addressed in Sub-goal 

1.4—Sustain and Enhance Southern Nevada’s Biotic Communities to Preserve Biodiversity and Maintain Viable Populations. Anthropogenic factors, such as recreation 

and urbanization, are referred to in Goal 2—Provide for Responsible Use of Southern 

Nevada’s Lands in a Manner That Preserves Heritage Resources and Promotes an Understanding of Human Interaction with the Landscape.

Global Stressors

Climate Change and Elevated CO2 Concentrations

Natural disturbance regimes of arid systems are characterized by resource pulses. 

Rainfall is infrequent and variable in amount, while fire and drought can temporarily 

increase available soil nitrogen (White and others 2006). Changes in the frequency 

and/or magnitude of these pulses associated with altered precipitation patterns may 

have profound effects on vegetation (Smith and others 2009a). For example, climate 

predictions include an increase in intense, short-duration rainfall events, which could 

temporarily increase plant productivity, facilitate plant invasions (Chapter 4), and episodically promote the spread of fire (Chapter 5). Similarly, enhanced levels of CO2 may 

increase the rate and extent of invasive annual grass invasions, leading to unprecedented 

frequency in wildfires (Smith and others 2009b). Increasing levels of CO2 are continuous and cumulative, representing a fundamentally different kind of stress from pulsed 

disturbance regimes (Smith and others 2009a; Stohlgren and others 2000). 

Climate regimes are defined by patterns of both temperature and precipitation. Bioclimatic modeling has been used to estimate both the effects of climate change on the 

distribution of vegetation types, as well as to predict future distribution of individual 

species. Loarie and others (2009) predict shifts in plant community climate regimes 

based on temperature on the order of 1.26 km yr-1 (0.78 mi yr-1) upward in elevation 

or latitude for desert systems. Work by Notaro and others (2012) project a region-wide 

decline in vegetation cover, a reduction in plant species richness in high-elevation 

evergreen forests, and a northward shift of the Sonoran Desert. Rehfeldt and others 

(2006) modeled current and projected climate profiles for 25 biotic communities of the 

western United States. Projections estimate that by the end of the century, 55 percent of 

western land area would not support present-day vegetation communities (as described 

by Brown and others 1998). Projections for individual species, however, do not necessarily follow those of the community as a whole. Consequently, community types (associations) that remain may not be comprised of the same species as are present today 

and may not have historical analogs (Williams and Jackson 2007). For example, arid 

shrublands may remain the same shrubland vegetation formation type but be comprised 

of different dominant species (vegetation alliances) or combinations of dominant and/or 

sub-dominant species (vegetation associations). Also, approximately half of the western 

United States, including most of southern Nevada, may have climate regimes not currently found there, likely resulting in completely novel community types (Rehfeldt and 

others 2006).

Atmospheric CO2 increased approximately 32 percent during the last century 

(Wagner 2009), and is expected to double from today’s levels by the end of the current 

century (Houghton and others 2001). This rise is predicted to affect ecosystems in two 

separate ways, through direct effects on plant physiology and indirect effects on the global 

climate (Smith and others 2009a). Increased concentrations of CO2 have been shown 

to increase the rate of carbon assimilation by plants through photosynthesis, while 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 19

decreasing water loss through transpiration (Smith and others 2009b and references 

therein). The net effect is one of increased water-use efficiency, potentially resulting in 

increased productivity of arid systems. However, potential gains in productivity will 

likely be mitigated by changes in climate. For example, plants are less responsive to 

elevated levels of CO2 when soils are dry.

By far the most problematic effect of the rising atmospheric CO2 concentration is its 

linkage to global warming and climate change. Over the last 150 years, average temperatures have risen globally in tandem with increasing CO2 (Smith and others 2009a). 

Temperatures in the American Southwest are estimated to have risen 1.2-1.7 oC (2.2-

3.1 oF) during the last century (Sprigg and others 2000), outpacing the global average. 

Data for Nevada show even greater warming, with temperatures having risen 2.0 oC 

(3.6 oF) since 1908 (Saunders and others 2008). Regional projections of climate change, 

based on general circulation models (GCMs), predict a further increase of 2-6 oC (3.6-

10.8 oF) by the year 2100 (Saunders and others 2008; Wagner 2009). Moreover, nighttime temperatures have risen more than daytime maxima and will likely continue to 

do so (Wagner 2009). Nighttime temperatures limit the northern distribution of many 

warm-desert species (Beatley 1974; Pockman and Sperry 1997). Consequently, the 

potential range of these species is projected to expand northward (Smith and others 

2009a). Temperature also influences snow pack accumulation, water storage, and the 

timing of spring runoff (Mote and others 2005). 

Precipitation patterns also are influenced by rising levels of atmospheric CO2 through 

changes in oceanic temperatures and global circulation patterns such as El Niño events. 

As global warming continues, longer and more intense droughts (Saunders and others 

2008), and an increase in the frequency and intensity of extreme weather events (Archer 

and Predick 2008) are expected to occur throughout the West. Simulation model projections for the Mojave region vary, but many suggest reduced precipitation in general 

for the Southwest (Seager and others 2007; Wagner 2009). Other models predict an 

increase in El Niño events as well as increased summer precipitation (Smith and others 

2009b). However, evapotranspiration will increase with increasing temperatures, likely 

resulting in overall drier conditions and an increase in the Palmer Drought Severity 

Index. In addition to expected changes in the amount and timing of precipitation, rising 

temperatures will likely decrease snowpack levels and increase the rate of snow-melt, 

resulting in lower mid-summer stream flows (McCabe and Wolock 2009). As of 2008, 

Lake Mead was only 50 percent full following consecutive years of below-average 

inflow (Saunders and others 2008). Continued drought and reduced runoff will result 

in increased competition for the limited water resources of southern Nevada.

Local and Regional Stressors

Population Growth and Urbanization

Nevada is currently the fastest growing state in the country. According to the 2010 

U.S. Census, the population grew by 35 percent since 2000 and by 66 percent during the 

previous decade (1990-2000). In addition, Nevada is the only state that has maintained 

an average growth rate of 25 percent or greater over the last three decades, and is the 

fastest growing state for five straight decades (http://www.census.gov/prod/cen2010/

briefs/c2010br-01.pdf). In southern Nevada, the population of Clark County in 2010 

(1,951,269) was 42 percent higher than the 2000 census. The cities of Las Vegas, Henderson, and North Las Vegas have all posted impressive growth rates since 2000. Even 

the smaller, more rural communities of Mesquite, Pahrump, Overton, and Boulder City 

have had significant populations increases during this time frame (Chapter 10).
20 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Rapid growth does not happen without significant impacts on the flora and 

fauna of native ecosystems. The vast majority of urban development has taken place 

in the Mojave Desert scrub ecosystem. Between 2001 and 2007, Clark County lost 

56,512 acres of native ecosystems to urban development (Clark County 2008). Also, a 

significant amount of salt desert scrub located in Henderson/Green Valley and in northwest Las Vegas has been lost to urbanization (Burton Pendleton, personal observation 

of urbanization patterns since the 1960s in the Las Vegas Valley, Nevada).

The soil and vegetation disturbances taking place at the urban-desert interface and 

beyond constitute a major problem for public land managers. Issues created include 

dust generation, trash and materials dumping, off-road travel and resulting unauthorized 

roads, destruction of cultural resources, creation of dispersal corridors for invasive species, human-caused wildfires, and land degradation caused by uncontrolled recreation 

and ORV (off road vehicle) use. Vegetation communities at higher elevations are not 

as directly impacted by urbanization, but are impacted by recreational activities of the 

large urban population.

Nitrogen Deposition

Industrialization and urbanization have led to increased production of atmospheric 

nitrogen emanating from coal-fired power plants and vehicle exhaust along major 

highways and in metropolitan areas and deposited across broad regions downwind 

from their sources. Deposition levels near major cities like Las Vegas can be as high 

as 40 kg ha-1 yr-1 (35.2 lbs acre-1 yr-1; Smith and others 2009b). Levels away from 

metropolitan areas are on the order of 3-12 kg ha-1 yr-1 (2.6-10.6 acre-1 yr-1; Allen and 

others 2006). After water, productivity of desert systems is most limited by nitrogen. 

Increased levels of nitrogen may result in higher biomass production if accompanied by 

sufficient moisture. Invasive annual grasses are particularly responsive to increased levels 

of nitrogen. Allen and others (2006), working at Joshua Tree National Park, reported 

increased biomass of invasive grasses following even low levels of N-fertilization 

and theorized that continued N-deposition could cause a community shift from shrubland 

to one dominated by invasive grasses. Brooks (2003) also found increased biomass of 

invasive grasses following N-fertilization in a Mojave Desert ecosystem. Increased 

levels of soil N are also expected to alter nutrient cycling, but little empirical data are 

available to evaluate this potential effect.

Urbanization and human-caused disturbances also affect air quality in southern 

Nevada. Dust and other pollutants from energy development, housing development, 

and recreation result in increases in particulate matter. Of particular concern to humans 

and wildlife are particles smaller than 10 micrometers in diameter (PM-10). Particles of 

this size, when breathed into the lungs, can cause serious health effects (http://epa.gov/

air/particlepollution/basic.html). In southern Nevada, most particulate emissions come 

from wildfires and windblown dust. A study by the Desert Research Institute found that 

windblown dust accounted for 89-90 percent of the PM-10 occurring in Clark County 

(http://www.clarkcountynv.gov). Control measures currently being implemented are 

expected to offset increases in vehicular and construction project dust emissions that 

accompany population growth.

Energy Development

There is an almost universal consensus among the international scientific community 

that greenhouse gas emissions must be reduced in order to slow the rate of global warming (Abbasi and Abbasi 2010; Dincer 2000). As fossil fuel costs and the impact of their 

use have become more readily apparent, there has been increased industry investment 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 21

and government support for the development of renewable energy sources (Kunz and 

others 2007). Southern Nevada has been the focus of many recent renewable energy 

projects, partially due to the abundance of sun and wind needed as energy sources for 

the generation of electricity.

Solar Energy—The arid Southwest contains a large amount of Federal lands that receive significant amounts of solar radiation, and the majority of large-scale solar facilities in the United States are slated for development on these lands. All energy development requires water, and the amount varies with the type of energy facility (Sovacool 

and Sovacool 2009). There are two types of utility-scale solar energy developments: 

solar voltaic and concentrating solar. Solar voltaic facilities require minimal water use 

(3.8-7.6 liters or 1-2 gallons per MWhe). In contrast, concentrating solar facilities concentrate solar energy to generate steam for power production and require 2,850 liters 

(750 gallons) of water per MWhe (Pate and others 2007), an amount four times as 

much as a natural gas-fueled power plant and twice as much as a coal-fired or nuclear 

plant (Glennon 2009). Two new solar facilities slated for construction on BLM land 

in southern Nevada were approved in fall of 2010 (BLM 2011a). The Amargosa Farm 

Road Solar Project, a concentrating solar facility, will occupy 2,558 ha (6,320 acres) 

just east of Amargosa, Nevada, and will consume significantly more water resources 

than existing photovoltaic systems operating in southern Nevada. Construction of the 

Silver State North Project is almost complete and occupies 250 ha (618 acres) east of 

Primm, Nevada. Both are located in Mojave Desert scrub. An additional project, Silver 

State South, is undergoing environmental analysis with a decision anticipated in 2012. 

Both Silver State Projects use photovoltaic technology.

Boulder City has developed a 3,200-ha (8,000-acre) solar energy zone in Eldorado 

Valley, an area southwest of the town but within the city limits. The largest two operational utility scale solar facilities in southern Nevada are located in this zone (Acciona 

Solar’s Solar One concentrated solar facility and Sempra Generation’s Copper Mountain 

photovoltaic solar facility). Additional facilities are planned for this area (BLM 2011a). 

Grouping all of the solar facilities in one area creates a larger impact locally, but reduces 

energy sprawl, fragmentation of habitat, and impacts from transmission lines and service 

roads on a landscape level. The BLM is examining a similar approach and is coordinating public input in an effort to determine appropriate areas to locate solar energy zones 

(BLM 2011a). An updated list of operational and proposed alternative energy facilities 

in Nevada is located under alternative energy on the BLM website (www.blm.gov/nv).

While new solar facilities produce far fewer CO2 emissions than traditional power 

plants, their construction and operation are not without environmental impacts. These 

facilities also can use tremendous amounts of already limited groundwater. The Nation’s 

limited experience with large-scale solar facilities means that there is little on-the-ground 

understanding of potential impacts (McDonald and others 2009; Tsoutsos and others 

2005; Turner 1982). Attention during the planning, construction and operational phases 

could help to minimize the potential environmental impacts listed below (Tsoutsos and 

others 2005).

• Facilities must be kept free of vegetation for worker safety and to prevent 

the possibility of heat-induced wildfires. This results in large areas devoid of 

vegetation.

• Dust emissions from construction, resulting in un-vegetated areas, and roads 

will likely increase, even though chemical dust-control agents may reduce the 

total amount generated. Little is known regarding potential off-site movement 

of chemical dust-control agents or their effect on surrounding vegetation.
22 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

• The impact of solar energy development on wildlife has not been well studied. 

Effects on migration corridors and genetic linkages, as well as effects on resident 

species are largely unknown (USGS 2010).

• Maintenance roads may serve as corridors for dispersal of invasive plant species, increased unsupervised recreational uses, and augmented food supply for 

ravens.

Wind Energy—Wind energy is increasingly important as a means of alternative energy production. As with solar installations, new and much larger wind farms are planned 

or under development. For example, the Searchlight Wind facility is planned for 780 

acres of BLM land east of Searchlight, Nevada, and if approved, would include 89 

wind turbines and a substation (draft EIS not yet released).

The technology to develop energy from wind on a large scale is a more mature 

technology than that of large-scale solar development. However, our understanding of 

potential ecosystem impacts of proposed large-scale wind farms in southern Nevada 

is severely lacking (Drewitt and Langston 2006). Studies on the effects on wildlife are 

particularly lacking (Lovich and Ennen 2011). Habitat types most likely affected by wind 

energy production in southern Nevada are Mojave Desert scrub and adjacent sparsely 

vegetated rocky foothill habitats. As with fossil fuel production, impacts on wildlife 

from wind turbines will largely come from habitat fragmentation, wildlife avoidance 

behavior, and bird and bat mortality, rather than from direct effects from installation 

(McDonald and others 2009). Recent monitoring studies indicate large numbers of bat 

fatalities associated with wind energy facilities (Kunz and others 2007). Potential effects on birds, including raptors and eagles, are collision mortality, displacement due to 

disturbance, alteration or loss of migration flyways and local flight paths, and habitat 

change or loss (Drewitt and Langston 2006). To date, there have not been multi-region 

studies of bat and bird deaths related to wind power generation.

Water Development

Water is a very critical resource in the southwest, and in southern Nevada. The municipal and county water districts in southern Nevada united to form the Southern Nevada 

Water Authority (SNWA) in 1991, with the goal of managing existing water resources, 

developing new ones, and promoting conservation (SNWA 2009). Ninety percent of the 

water provided by the Las Vegas Valley Water District is from Colorado River water 

impounded in Lake Mead. Ten percent of the water budget comes from approximately 

100 municipal groundwater wells (Cohen 2011). Ongoing drought conditions have 

reduced the amount of flow into Lake Mead, reducing the amount of stored water to 52 

percent of capacity by early 2009 (SNWA 2009). Since then, the water level of Lake 

Mead has continued to fall and was at 51.22 percent of a full pool on October 30, 2012 

(http://lakemead.water-data.com). Climate change is expected to further deplete reservoirs due to decreased streamflow and increased evaporation rates. Based on current 

and projected demands, a long-term non-Colorado River water supply is needed. 

The Water Resource Plan projects the need for additional groundwater resources to 

be brought on-line by 2020 (SNWA 2009). This has prompted the SNWA to seek further 

development of in-state groundwater resources, including applications to the BLM to 

construct a 525-km (326-mile) pipeline and drill additional groundwater wells to extract 

approximately 217 billion liters (57 billion gallons) of water per year from north-eastern 

central Nevada. The application and approval process for developing and transporting 

this water began in 2003. The aquifers in question are deep and extend across state lines. 

There are questions as to what effect groundwater pumping to provide additional water 

to southern Nevada will have on wells that service central Nevada and western Utah, 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 23

as well as effects to surface vegetation and the wildlife that depend on this resource. 

Groundwater development studies are underway. The 90-day review of the draft is 

scheduled to be completed by spring 2013. Date for the final EIS publication has not 

yet been determined (BLM 2011b). In 1997, the SNWA developed the Las Vegas Valley Groundwater Management Program to protect and manage groundwater resources. 

Activities include development of a permanent recharge program, plugging unused wells 

in the valley, conservation education and increased groundwater quality monitoring. 

Conservation and management activities have led to a reduction in per capita water use. 

Between 1990 and 2008, use declined from 1,317 to 912 liters (348 to 241 gallons) per 

capita per day (Cohen 2011). The SNWA has adopted a goal of 753 liters (199 gallons) 

per capita per day by 2,035, a 17 percent decrease, yet total water usage is still projected 

to increase some 40 percent by that date due to population growth (SNWA 2009). 

Colorado River basin water, utilized by much of the southwest, is not adequate 

to support increased regional populations, especially during a period of increased 

temperature and more frequent drought. This will put pressure on other water resources, 

including aquifers that support southern Nevada springs. There are three classes of aquifers in the SNAP area, mountain block, local, and regional. The three are not equally 

affected by ground water pumping, but all are affected by a number of above-ground 

stressors. The Clark County, Nevada, MSHCP Ecosystem Health Workshop, sponsored 

by the Desert Research Institute, was held January 29-31, 2008, in Las Vegas. Workshop 

participants developed a list of stressors based on previous research, past workshops, and 

the combined experience of the managers and researchers in attendance (Sada 2008). 

Most important stressors by aquifer type are given below.

• Mountain block aquifers: freezing, periodic drying from drought, low seasonal 

flow, avalanche, fire, and compaction and trampling by animal and human 

activity. 

• Local aquifers: trampling and compaction by human activity and animals, water 

diversion, human recreational activity, and ground water removal.

• Regional aquifers: agricultural activities, pesticide contamination, water diversion, ground water pumping, grazing, and non-native aquatic species.

Work by a number of scientists in the last decade has been synthesized by Sada (2008) 

into a comprehensive system for prioritizing the management and restoration of 

Nevada springs. The Forest Service is currently developing a similar program (Solem 

and others 2012).

In 2010, the Spring Mountains National Recreation Area, Humboldt-Toiyabe National 

Forest, initiated a comprehensive Level II survey of the springs in the SMNRA. Fortyseven springs were surveyed in 2010 and 2011. This work identified over 25 types of 

disturbance, all of which stress the system. The most common disturbances, those found 

at a minimum of 30 percent of the springs sampled, consisted of:

• Soil compaction, including animal and human trails, trampling, and other ground 

disturbance;

• Erosion around springs and water channels;

• Large mammal disturbance from grazing (cattle are absent from the SMNRA), 

hoof disturbance (horses and elk), and other wild animal disturbance; and

• Water extraction effects on water availability.

There were a number of other disturbances that occurred at over 15 percent of the springs 

sampled, including fire, vehicle tracks, tree cutting, and flooding. The complete results 

are reported in Solem and others (2012).
24 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

The Mojave Inventory and Monitoring Network of the National Park Service is also 

beginning to monitor springs on Park Service land within the SNAP area. This work 

will also document stressors as more springs are sampled. 

Recreation

The emergence of Las Vegas as a metropolitan area created significant needs for public 

lands to meet public uses. As the population in southern Nevada continues to grow, so 

too will the use of public lands, especially for recreation. Meeting recreational needs 

of both citizens and visitors to the area must be balanced with maintaining natural and 

cultural resources, conserving the unique biodiversity of southern Nevada’s ecosystems, 

and maintaining the very qualities that are attractive for recreation. The majority of 

southern Nevada’s population is concentrated in the major cities of Las Vegas, North 

Las Vegas, Henderson, Mesquite, Overton, Pahrump, and Boulder City. Public lands 

near these cities, such as the Spring Mountains and Lake Mead National Recreation 

Areas, and the urban/desert interface experience intense use. 

According to the SNAP Recreation Team report, the most popular recreation activities 

are hiking, camping, viewing natural features and wildlife, and rock climbing (Holland 

and others 2010). Popular water activities are swimming, fishing, and boating (NPS 

2009). Unregulated ATV (all-terrain vehicle) and ORV (off road vehicle) use are also 

favorite desert activities. A more complete review of southern Nevada’s recreational 

opportunities is given in Chapter 10.

Population growth and accompanying increases in use of public lands for recreation 

puts added strain on Nevada’s natural and cultural resources. The impacts of unrestricted 

use can be considerable, but determination of sustainable use levels is problematic, particularly under a changing climate. Insufficient funds for adequate management, staffing, 

and educational programs compound the problem. The most cost-efficient means of 

mitigating environmental damage are two-fold: the development and implementation 

of sound management plans and public education. For example, the BLM develops 

Recreation Area Management Plans (RAMPs) that identify goals and actions for recreation in designated areas. The Nevada Division of State Parks regularly updates its 

Comprehensive Outdoor Recreation Plan (DeLoney 2004). Public involvement helps to 

identify facility, infrastructure, and interpretive needs to accommodate the ever-increasing 

use levels. The difficulty is in providing reasonable access while still protecting cultural 

and natural resources. Problems accompanying recreational use include:

• Erosion from trail cutting;

• Human waste and trash from camping in undesignated areas;

• Declines in wildlife populations due to habitat fragmentation and avoidance 

behavior;

• Dispersal of invasive species;

• Land degradation due to off-road vehicle use and unrestricted camping; and

• Competition for scarce water resources.

Of major concern is rampant degradation from unrestricted camping and ORV use, 

particularly in Mojave Desert scrub. The BLM, NPS, FWS, and USFS all consider this 

issue of high importance (see Chapter 10). Programs are needed to educate those who 

consider the desert areas to be ‘wasteland’ of no particular value. Although ORV use 

is restricted to existing roads and trails in many areas, and existing roads, trails, and 

dry washes in some areas with specific regional restrictions), illegal ORV use occurs 

and damages vegetation and destroys biological soil crusts that hold the soil in place. 

Disturbing desert soils generates dust, reducing visibility and creating health problems. 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 25

Additionally, ORV use causes erosion, disperses invasive species, and fragments habitat 

for wildlife.

Public education and outreach programs are instrumental in teaching visitors about 

the importance and fragility of the desert environment. Most recreationists care about the 

environment and understand the need to balance recreation with resource conservation 

(DeLoney 2004). Given sufficient information, most will observe good visitor practices. 

For those that don’t, additional monitoring and mitigation, as well as enforcement of 

regulations, are needed.

Insects and Disease

Insect and disease issues are not currently among the primary concerns of land managers in southern Nevada. The presence of pneumonia in Nevada populations of Desert 

bighorn sheep (Ovis canadensis nelsoni) was first reported in 1978 (McQuivey 1978). 

The disease appears to affect both native and domestic sheep, though not to the same 

extent. Stress from blowing dust and human proximity may aggravate the symptoms 

(Jessop 1981). Chronic wasting disease in deer and white nose syndrome in bats have 

the potential to occur in southern Nevada, but have not been detected within the state. 

Upper respiratory tract disease in the desert tortoise (Gopherus agassizii) is one of 

several factors contributing to the population decline of this threatened species. Issues 

associated with the decline and recovery of the desert tortoise are discussed in Chapter 6.

Mistletoe and rust diseases affect conifer species in mountain areas, with white fir being 

the hardest hit (Guyon and Munson 1998). White-spored gall rust, found only in the 

Spring Mountains, affects the ponderosa pine growing there, complicating management 

of that species (Guyon and Munson 1998). Bark beetles cause the most insect damage, 

affecting bristlecone pine (Pinus longaeva), singleleaf piñon pine (Pinus monophylla), 

twoneedle pine (Pinus edulis), ponderosa pine (Pinus ponderosa), and white fir (Abies 

concolor). In 2009, the Humboldt-Toiyabe National Forest conducted an aerial survey 

of bark beetle damage. Of the over 80,000 ha (200,000 acres) surveyed, tree mortality 

from mountain pine beetles occurred on 47 ha (117 acres), from western pine beetles on 

5 ha (13) acres, and from piñon ips beetle on 1.6 ha (4 acres). Tree mortality from the 

fir engraver beetle decreased from 184 ha (461 acres) in 2007 to only 4.8 ha (12 acres) 

in 2009 (USFS 2009). The Humboldt-Toiyabe Aerial Insect Disease Detection Survey 

of 2011 (http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5349313.

pdfcitation) also found a limited number of trees with indications of insect damage. 

Less than 210 ponderosa pines in 15 locations exhibited signs of bark beetle damage. 

Less than 30 true firs at two locations were damaged by fir engraver beetles. Given the 

large forested area of the SMNRA, these numbers did not indicate a significant insect 

problem in early 2011. However, during the fall of 2011, SMNRA and I&M staff noted 

a large number of newly infected trees within the Kyle and Lee fuel treatment areas. 

The extent of this beetle outbreak should be quantified during the 2012 Aerial Insect 

Disease Detection Survey. 

In all cases, mortality increases when trees are under stress, particularly drought stress. 

Projected increases in temperature may allow more beetles to overwinter or complete 

two life cycles in one year (Lange and others 2006; Raffa and others 2008). High temperatures and prolonged drought conditions will create conditions under which outbreaks 

are more likely to occur. Bark beetle and rust in conifers are of greatest concern in the 

Spring Mountains as plant communities migrate up in elevation. Conifer communities 

of the future may contain species not currently found together, putting disease vectors or 

insect pests into new context. Plants and pathogens that have been previously separated 

by distance may come into contact (Flores 2008). The potential for large-scale die-offs 

of key species and the consequences for ecosystems can be illustrated by the recent 
26 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

widespread mortality of two needle piñon. In 2002-2003, 40-80 percent of piñons in a 

four-state region died following prolonged drought and unusually high temperatures 

(Breshears and others 2009). Mortality was apparently driven by protracted water stress, 

leading to carbon starvation and an associated increase in susceptibility to beetles (Breshears and others 2009). Regional mortality of key species has the potential to rapidly 

alter vegetation composition and associated ecosystem properties for decades. 

Grazing

The Mojave Desert has not supported large numbers of native grazing animals since 

horses and other ungulates became extinct at the end of the Pleistocene, approximately 

10,000 to 14,000 years before present (Grayson 1993; Thorne 1986). Horses first reappeared in North America as domesticated European stock with the second voyage of 

Christopher Columbus in 1493, and introductions continued in earnest throughout the 

Spanish colonial period through the 1700s (De Steiguer 2011). Cattle and sheep were 

also introduced during the same time period. At the beginning of the 1800s, bands of 

free roaming horses associated with the Spanish missions and rancheros in California 

had grown so large that efforts were initiated to reduce their numbers to protect forage 

for the emerging livestock industry. Western explorers, such as Lewis and Clark and 

Jedediah Smith, noted many bands of wild horses during the first decades of the 1800s, 

although their sightings were mostly from the northern Great Plains and Intermountain 

West. Thus, it appears that horses and livestock have likely been present in western 

North America for at least the past 200 years, although their historical abundance in the 

Mojave Desert is less well documented.

It is generally agreed that present day Mojave ecosystems did not evolve with significantly selective pressure from large-bodied herbivores (Beever and others 2003; 

Brown and McDonald 1995; Grayson 1987; Hall 1946), and desert vegetation is very 

slow to recover if overgrazed or disturbed (Abella and others 2007; Tueller 1989). 

Grazing, regardless of source, produces impacts on the ecosystems within the SNAP 

agencies’ boundaries, and the greater the number of animals, the more extensive the 

impacts. Some disturbance impacts are common to all grazers, while others are unique 

to the particular grazer. These impacts are not uniform in their severity or in associated 

recovery times. The most significant impacts of both past and present grazing within 

the SNAP agencies’ boundaries are disruption of soil crusts, alteration of carbon and 

nitrogen cycles, soil compaction, changes in vegetation cover and composition, reduction in soil seed banks, and disturbance of soil around springs (Beever and others 2003). 

Springs are particularly susceptible to disturbance effects. A more detailed discussion 

of these issues is contained in the following sections.

Livestock—Currently, livestock (cattle and sheep) grazing in the SNAP area is extremely limited and stocking rates on the few remaining allotments are well below allowable numbers. Few long-term impacts would be expected from the limited grazing 

occurring under current permits. No grazing is allowed in critical desert tortoise habitat 

(USFWS 2011). However, trespass grazing continues to be a problem in some areas (Fred Edwards, personal communication).

Despite the limited amount of grazing currently allowable, the area does carry a 

legacy of effects from past grazing practices when large numbers of cattle and sheep 

were introduced into southern Nevada. Determination of the effects of past grazing history in the Mojave can be difficult. Very few areas of truly ungrazed land exist; most 

areas have been extensively grazed in the past and records are either incomplete or 

nonexistent (Beever and Brussard 2000). Protected areas, such as military bases, can 

provide a reference frame for assessing the effects of historic grazing (Tueller 1989). 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 27

Historic photos and records also provide some context. Exclosures can be used to monitor recovery (e.g. Brooks 1995; Courtois and others 2004), but carry the legacy of past 

grazing, limiting their usefulness (Fleishchner 1994). Although most researchers agree 

that grazing negatively impacts desert ecosystems, there is some disagreement as to the 

level of these impacts (Brown and McDonald 1995 and references therein; Courtois and 

others 2004). This may be attributed, at least in part, to the reference community used 

by each author. For example, not all southwestern deserts are the same ecologically as 

the Mojave, and there are even subtle differences within sections of the Mojave. Also, 

impacts vary depending on grazing intensity (Brown and McDonald 1995).

Although the large-scale effects of grazing are typically of greatest concern, available information about livestock grazing in the Mojave Desert is in relation to localized 

effects (Brooks and others 2006). Grazing affects composition and production of the 

vegetative plant community through selective foraging. For example, at the Nevada Test 

Site, where grazing has been excluded for over 50 years, the blackbrush community has 

a healthy understory of desert needlegrass (Stipa speciosa) that is lacking in blackbrush 

sites that have been grazed (Tueller 1989). An early study by Webb and Stielstra (1979) 

described deteriorating range conditions due to sheep grazing, including a 60 percent 

reduction in understory herbaceous biomass and disruption of the soil surface. Brooks 

(1995) also reported increased forb biomass, shrub cover, and seed biomass following 

12-14 years of livestock exclusion at the Desert Tortoise Research Natural Area. Densities of small mammals, lizards, and insects can also be affected (Fleischner 1994 and 

references therein; Brooks 1995). 

Water sites are centers of grazing activity and are typically completely denuded of 

vegetation and have highly compacted and eroded soils. The effects beyond this high 

impact zone can extend hundreds of meters into the surrounding desert in roughly concentric gradients of impact referred to as a piosphere. In the west-central Mojave Desert, 

cover of invasive annual plants was shown to increase with proximity to watering sites, 

whereas cover and species richness of native annual and perennial plants decreased 

(Brooks and others 2006). Effects were most pronounced within 200 m of the watering 

sites, suggesting that control of invasive annual plants and restoration of native plants 

should be focused within the central part of the piosphere. A similar study was conducted 

to evaluate effects of piospheres on ant communities in the eastern Mojave Desert, but 

other than finding that total ant abundance was higher immediately at the high impact 

zone within the watering site, no gradient away from those sites was detected (Nash 

and others 2004). 

A significant and long-lasting effect of grazing comes from soil compactions and 

disruption of the cryptobiotic soil crust, leading to erosion and disruption of nitrogen and 

carbon cycles. Biological soil crusts, present on desert soils, contribute to soil stability, 

nitrogen fixation, and water-holding capacity. These crusts are extremely susceptible 

to surface disturbance, including trampling by livestock. The recovery rate from disturbance, trampling, and compaction is long and can exceed 100 years (Belnap and Lange 

2003). 

Given changes in vegetative cover as described above, concurrent loss of seed banks 

(Brooks 1995), the advent of invasive weeds (Abella 2008), and accompanying fires 

(Brooks and Chambers 2011), these systems may have passed a threshold such that 

recovery to a pre-settlement condition is impossible, no matter how long grazing is 

excluded (Tueller 1989).

Wild Horses and Burros—There are five active wild horse and burro herd management areas (HMAs) in the BLM Southern Nevada District (BLM 2012). Muddy 

Mountain and Gold Butte HMAs have burros only, the Nevada Wild Horse Range has 
28 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

horses only, and the Johnnie and Red Rock HMAs have both horses and burros. The 

Muddy Mountain and Gold Butte HMAs, managed by the BLM, are adjacent to Lake 

Mead NRA, and the Wild Horse and Burro Protection Act does not apply to lands 

managed by the National Park Service (NPS). The NPS does not recognize HMAs and 

sets management prescriptions for minimal burro use on NPS lands. The NPS recognizes, however, that a certain amount of incidental use occurs from adjacent HMAs, 

and coordinates with the BLM on joint activities for burro management on NPS lands 

under the 1995 Lake Mead Burro Management Plan. The Nevada Wild Horse Range 

lies within the Nellis Air Force Test and Training Range, but is administered by the Las 

Vegas BLM Pahrump Field Office.

On BLM and USFS public lands, wild horses and burros are managed as selfsustaining populations of healthy animals with the goal of maintaining a balance with 

other multiple uses, including providing critical habitat for focal, threatened, and endangered species This is also called minimal management since resources are not added to 

the HMA in order to maintain a herd (Wild Horse and Burro Act of 1971). The issue in 

southern Nevada is not one of maintaining herds but rather herd overpopulation. Wild 

horses and burros have very high reproductive rates of 17-20 percent per year, and 

herds can double in size every 4 to 5 years. West-wide, as of February 2012, the BLM 

estimated wild horse and burro numbers at 37,300 (BLM 2012), nearly 11,000 more 

than the existing appropriate management level (AML). Funding for gathers (roundups) 

must be appropriated by Congress. Insufficient funding means that horse and burro 

numbers multiply beyond appropriate management levels. Also, public opinion generally 

runs against wild horse gathers, generating negative publicity (Resource Concepts, Inc. 

2001). In a relatively new effort to control horse numbers, on March 3, 2011, the BLM 

announced the initiation of a 4-year study of the birth control vaccine PZP to test if the 

effects of the vaccine can be extended from 22 months to 3 to 4 years (BLM 2011c).

Although wild horses and burros are managed as a part of the cultural landscape, 

they can also have impacts that may threaten other resources. Their status as non-native 

species, and their potential to impact native natural resources, could lead to them being 

considered invasive species (Chapter 4). Wild horses and burros primarily consume 

herbaceous vegetation and some parts of woody vegetation in a wide variety of vegetation 

types in the Mojave Desert (Abella 2008), with use in southern Nevada concentrating 

at springs/seeps in the SMNRA. Their means of foraging differs from that of domestic 

livestock in a number of ways. Horses and burros are less selective in diet than domestic 

cattle, consuming a broad spectrum of plant species (Beever and others 2003). They are 

able to crop forage much closer to the ground than cattle due to the presence of upper 

front incisors (Beever and others 2003). Their use of lower quality forage may result 

in the consumption of 20-65 percent more forage than a cow of similar body mass 

(Hanley 1982; Menard and others 2002). Excessive use of grasses and forbs decreases 

the regeneration capability of these plants, resulting in decreased forage availability in 

successive years. Effects are concentrated at watering sites, decreasing vegetative cover 

by up to 90 percent and species richness by 70 percent (Beever and Brussard 2000; 

Beever and others 2008).

Wild horses and burros also differ in the amount of territory covered, often roaming 

over large areas (Abella 2008; Beever and Brussard 2000). Horses are known to roam 

farther from water than cattle, utilizing ridge tops and steeper slopes and making conspicuous trails (Beever and Brussard 2000). Beever and others (2003) found that several 

disturbance-related variables, including soil surface hardness and total plant cover, 

distinguished horse-occupied and non-occupied sites better than presence of palatable 

plant species. Ground disturbance caused by trampling, particularly in areas surrounding sensitive springs and seeps, creates conditions favorable to invasive species such as 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 29

cheatgrass or red brome, or noxious weeds such as knapweed or perennial pepperweed. 

These weedy species out-compete native species and alter ecosystem function (BLM 

2012; Cummings 2010; ENTRIX, Inc. 2008). 

Non-native ungulates affect ecosystems in other ways as well, including nutrient 

cycling (Hobbs 1996) and diversity of small mammals and reptiles (Beever and 

Brussard 2004). The lack of time for ecosystems, particularly springs, to recover from 

the high pre-gather herd numbers is also of concern.

Wild horse and burro management is a difficult challenge and will likely be made 

more difficult in coming years. An examination of multiple climate change models for 

the southwest reveals almost universal agreement that the area managed by SNAP 

agencies will be warmer and dryer in the coming decades. Longer periods of drought 

are also predicted (Notaro and others 2012). In the context of these drying and warming trends, managers must address two relatively recent phenomenon that significantly 

impact the resources available for wild horse and burro herds: an increase in the biomass 

of exotic annual grasses and the accompanying changes in the size and frequency of 

wildfires. 

Elk—Elk were introduced to the Spring Mountains beginning in the 1930s, with subsequent releases in the 1980s. Elk are found at higher elevations in piñon-juniper, mixed 

conifer, and bristlecone pine vegetation types. They prefer grasses and forbs, which are 

common on burned areas. Elk create trampled areas around springs and seeps, which 

are home to a number of rare species. Elk-created disturbance, therefore, has the potential to impact rare snails, moonworts, and other rare species (Solem and others 2011). 

Elk populations within the SMNRA were estimated at 246 in 1996, but subsequently 

declined to 130 in 2009. Reasons cited for the decline include increased recreational 

and off-road vehicle (ORV) use within the herd unit area, habitat degradation caused 

by excessive numbers of horses and burros, and extended periods of drought (Nevada 

Department of Wildlife 2011). An aerial survey conducted in 2010 reported sighting 

only 122 elk. The level of reproduction currently appears insufficient to sustain the 

population.

Invasive Species

Invasive Plants—Non-native invasive plants often produce large numbers of seeds 

that can spread rapidly across the landscape along road corridors, in contaminated 

animal feed, and by wind, animal, and human dispersal (Chapter 4). Invasive plants 

out-compete native species due to an ability to thrive on many different soil types and 

to utilize increased CO2 and higher nitrogen levels that result from nitrogen deposition (Allen and others 2006; Ziska and others 2003). Invasive plants produce biomass 

and fine fuels that will carry fire in the interspaces between shrubs, resulting in large, 

relatively frequent wildfires in desert shrub ecosystems that are not fire adapted 

(Chapter 5). Many invasive plants respond positively and quickly after fire, limiting 

the recovery of the native community (Abella 2009). In addition, invasive species can 

alter wildlife habitat and decrease native forage species (Brooks and Pyke 2001; Chapter 4). Restoration of communities dominated by invasives is difficult and costly. In the 

Mojave, management of invasive plants and fire must be integrated due to the linkages 

between the two issues (Brooks and Pyke 2001).

Wetland and Aquatic Invasives—The problem of wetland and aquatic invasive species is on the rise in southern Nevada (Chapter 4). Saltcedar (Tamarix spp.) and other 
30 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

riparian weeds alter streambanks and lower water tables, reducing the biodiversity of 

critical wetland communities (Sada 2008; Howell 2011). The release of nonnative fish 

into springs, quagga mussels (Dreissena rostriformis) into lakes, and nonnative bullfrogs (Lithobates catesbeianus) and crayfish (Procambaras clarkia) into lakes, rivers, 

and springs are impacting the native and endemic fish, amphibians, and snail species 

(Sada 2008). Removal of these problematic nonnatives is often not possible, and always extremely difficult and expensive (Chapter 4).

Altered Fire Regimes

Altered fire regimes are a significant cause of concern to managers in southern 

Nevada. In 2005, over 400,000 ha (1 million acres) of the Mojave Desert burned, much 

of it in southern Nevada (Brooks and Matchett 2006; McKinley and others, in press). 

The introduction of non-native invasive grasses has provided the fine fuel biomass 

needed to carry fire across large areas of Mojave Desert scrub, including blackbrush 

and Joshua tree communities. The size and frequency of these wildfires are a function 

of precipitation and the resulting annual invasive grass fuel load. Years of high winter 

and spring precipitation result in a flush of invasive annual grass biomass. The shrub 

communities of the Mojave Desert are generally not well adapted to large-scale fire 

(Chapter 5). Some species, such as blackbrush, do not form a persistent seedbank (Meyer 

and Pendleton 2005), requiring seeds to disperse from unburned patches of surviving 

individuals and hindering their recovery following fires. Only a small proportion of shrub 

species are physiologically able to resprout following fire, and their ability to resprout 

is further affected by fire temperature, soil moisture levels prior to fire, and post-fire 

drought (Brooks and Minnich 2006; Chapter 5). In contrast to native shrubs, invasive 

annual grasses can more easily survive fires as seeds, especially when they are lying on 

the surface of the mineral soil with little to no fuels immediately adjacent to them. The 

post-fire shrub community is less diverse with increased fine fuel loads that are prone 

to more frequent fire, and thus can reset the fire cycle outside of the timeframe under 

which these communities evolved. 

Several factors complicate post-fire revegetation efforts. Aerial seeding has had limited 

success, in part due to the variability and timing of precipitation (Brooks and Klinger 

2012; Chapters 5 and 7). Native seed is often not available as needed for large-scale 

restoration projects or may be cost-prohibitive. Post-fire reduction in the number of 

small mammals and other species that disperse seeds also inhibits natural reestablishment of pre-fire shrub communities (Beatley 1976). Thus, restoration of the post-fire 

landscape is problematic. Seeding success is species and situational specific (Abella and 

Newton 2009). Research on both the establishment needs of desert restoration species 

and techniques/equipment for planting and seeding is sorely needed. A comprehensive 

review of Mojave Desert restoration and rehabilitation is discussed in Chapter 7. 

Suppression of naturally occurring fires at upper elevations also has created a 

problem for land managers. Some of the high elevation ecosystem types within the 

southern Nevada mountain ranges are fire-adapted (Provencher 2008; Chapters 5 and 7), 

and have been affected by fire exclusion. Fire suppression efforts have been particularly 

aggressive in the Spring Mountains because of the number of residences located within 

the canyons. Fire within steep canyons can pose a significant danger to residents as 

there is typically only one egress route down-slope. A hazardous fuels reduction project 

was proposed in 2007 to reduce fuels adjacent to the Spring Mountain communities 

and to facilitate the protection of important resource values. The fuels reduction project was conducted from 2008 through 2010. An implementation and monitoring audit 

conducted in the fall of 2010 looked at how closely the objectives were achieved. The 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 31

recommendations will be useful in implementing the 10-Year Multiagency Fuel Treatment Plan, which was completed in 2010 (METI 2010). Under this plan, six areas of 

the SMNRA have been identified for future fuel treatment projects. The objectives for 

future projects include (1) coordinate treatment of right of ways and private facilities; (2) 

improve egress for residents, visitors, and staff and ingress for fire crews and equipment; 

(3) slow or prevent the spread of fires ignited along roadways; and (4) reduce the fuel 

loads in chaparral and mesquite so that fire can be reintroduced as a management tool 

(METI 2010). Understanding fire’s history and behavior in the region under different 

conditions would help managers effectively and efficiently manage future wildland fires 

and provide insight regarding the role of fire within upper-elevation communities. See 

Chapter 5 for a more complete discussion of fire issues and Chapter 7 for restoration 

associated issues.

Knowledge Gaps and Management Implications

Southern Nevada is experiencing both a novel suite of stressors and a historically 

unprecedented rate of climate change. With the introduction of new stressors, rapid climate change, and increased frequency and size of disturbances, the interactions among 

all of these stressors will drive ecosystem change in potentially unknown directions. 

Managers are faced with situations for which we have no current answers. 

• What can be done to control the new and existing invasive species? 

• How should we manage fire size and frequency? 

• Where should we try revegetation and what plant materials do we use given 

estimates of species migration due to climate change? 

• How will human impacts on water use, recreation, and energy development 

affect regional ecosystem stability? 

• How can we prevent the loss of endemic species that have specific habitat requirements such as desert springs and “Sky Islands” in the Spring and Sheep 

Mountains? 

• Are species resilient enough, genetically variable enough, or are their specialized habitats protected enough for them to persist in place? 

• Do they have life history features that will enable them to move with changing 

conditions? 

These questions embody some of the big issues facing managers and provide a general 

overview of knowledge gaps. Gaps are discussed in more detail in subsequent chapters. 

Additional information needs that can be obtained through research and monitoring are:

• Species-specific climate profiles and projected ranges under different climate 

change scenarios; methods to detect geographic shifts in plant communities 

and individual species.

• Effects of drought, warmer winter temperatures, and changes in precipitation 

amount and timing on the type and extent of insect and disease outbreaks.

• Interactive effects of naturally occurring disturbances with global change drivers 

such as rising levels of CO2 and N deposition. 

• Effects of N deposition and increased CO2 levels on biogeochemical cycles 

including biological soil crust function.

• Appropriate plant materials and planting techniques for use in reclamation and 

restoration of disturbed sites under expected climate change scenarios.

• Criteria for selecting the most appropriate and least deleterious sites for energy 

development.
32 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

• Information on the environmental impacts of large-scale power development 

(including wind and solar) on animal mortality, migration corridors, seed movement, and potential off-site effects of dust and chemical dust control agents.

• Improved techniques for tracking available forage given the increase in the 

biomass of exotic annual grasses and the accompanying changes in the size 

and frequency of wildfires. 

Development of education programs has the potential to mitigate many of the stressors caused by human activity. Education can point out rather simple and strait forward 

approaches that can minimize human impacts on the desert, while still permitting the 

recreational activities citizens enjoy. Educational outreach to teach citizens the economic 

and ecological value of energy efficiency and conservation is a step toward reducing the 

sprawl of energy developments in the western United States. Educational approaches 

in which the benefits of behavior changes are placed in an ecological context—for 

example, how the pieces, including humans, fit together to form the ecosystem—can 

instill a better sense of stewardship and a more developed conservation ethic.

References

Abbasi, T.; Abbasi, S.A. 2010. Biomass energy and the environmental impact associated with its production and utilization. Renewable and Sustainable Energy Reviews. 14:919-937.

Abella, S.R. 2008. A systematic review of wild burro grazing effects on Mojave Desert Vegetation, USA. 

Environmental Management. 41:809-19.

Abella, S.R. 2009. Post-fire plant recovery in the Mojave and Sonoran Deserts of western North America. 

Journal of Arid Environments. 73:699-707.

Abella, S.R.; Newton, A.C. 2009. A systematic review of species performance and treatment effectiveness 

for revegetation in the Mojave Desert, USA. In: Bernal-Fernancez, A.; De La Rose, M.S., eds. Arid 

environments and wind erosion. Hauppauge, NY: Nova Science Publishers, Inc.: 45-74. 

Abella, S.R.; Newton, A.C.; Bangle, D.N. 2007. Plant succession in the eastern Mojave Desert: an example from Lake Mead National Recreation Area, southern Nevada. Crossosoma. 33:45-55.

Allen, E.B.; Bytnerowicz, A.; Fenn, M.E.; Minnich, R.A.; Allen, M.F. 2006. Impact of anthropogenic N 

deposition on weed invasion, biodiversity and the fire cycle at Joshua Tree National Park. Final Report 

to the National Park Service, PMIS Number 72123. Washington, DC: U.S. Department of the Interior, 

National Park Service. 40 p.

Archer, S.R.; Predick, K.I. 2008. Climate change and ecosystems of the Southwestern United States. 

Rangelands. 30:23-28.

Beatley, J.C. 1974. Effects of rainfall and temperature on the distribution and behavior of Larrea tridentata (creosote-bush) in the Mojave Desert of Nevada. Ecology. 55:245-261.

Beatley, J.C. 1976. Environments of kangaroo rats (Dipodomys) and effects of environmental change on 

populations in southern Nevada. Journal of Mammalogy. 57:67-93.

Beever, E.A.; Brussard, P.F. 2000. Examining ecological consequences of feral horse grazing using exclosures. Western North American Naturalist. 60:236-254.

Beever, E.A.; Brussard, P.F. 2004. Community- and landscape-level responses of reptiles and small mammals to feral horse grazing in the Great Basin. Journal of Arid Environments. 59:271-297.

Beever, E.A.; Tausch, R.J.; Brussard, P.F. 2003. Characterizing grazing disturbance in semiarid ecosystems across broad scales, using diverse indices. Ecological Applications. 13:119-136.

Beever, E.A.; Tausch, R.J.; Thogmartin, W.E. 2008. Multi-scale response of vegetation to removal of 

horse grazing from Great Basin (USA) mountain ranges. Plant Ecology. 196:163-184.

Belnap, J.; Lange, O.L., eds. 2003. Biological soil crusts: structure, function, and management. Heidelberg: Springer-Verlag. 503 p.

Breshears, D.D.; Myers, O.B.; Meyer, C.W.; Barnes, F.J.; Zou, C.B.; Allen, C.D.; McDowell, N.G.; Pockman, W.T. 2009. Tree die-off in response to global change-type drought: mortality insights from a 

decade of plant water potential measurements. Frontiers in Ecology and Environment. 7:185-189.

Brooks, M.L. 1995. Benefits of protective fencing to plant and rodent communities of the western Mojave 

Desert, California. Environmental Management. 19:65-74.

Brooks, M.L. 2003. Effects of increased soil nitrogen on the dominance of alien annual plants in the 

Mojave Desert. Journal of Applied Ecology. 40: 344-353.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 33

Brooks, M.L.; Chambers, J.C. 2011. Resistance to invasion and resilience to fire in desert shrublands of 

north America. Rangeland Ecology and Management. 64:431-438.

Brooks, M.L.; Klinger R.C. 2012. Establishment of plants from postfire aerial seeding treatments implemented 1993 to 2007 in the eastern Mojave Desert. Report to the Bureau of Land Management, Ely 

District Office. Ely, NV: U.S. Department of the Interior, Bureau of Land Management. 34 p.

Brooks, M.L.; Matchett, J.R. 2006. Spatial and temporal patterns of wildfires in the Mojave Desert, 190-

2004. Journal of Arid Environments. 67:148-164.

Brooks, M.L; Matchett, J.R.; Berry, K.H. 2006. Effects of livestock watering sites on alien and native 

plants in the Mojave Desert, USA. Journal of Arid Environments. 67:125-147.

Brooks, M.L; Minnich, R.A. 2006. Southeastern deserts bioregion. In: Sugihara, N.G.; van Wagtendonk, 

J.W.; Shaffer, K.E.; Fites-Kaufman, J.; Thode, A.E. (eds.) Fire in California’s ecosystems. Berkeley, 

CA: University of California Press: 391-414.

Brooks, M.L.; Pyke, D.A. 2001. Invasive plant and fire in the deserts of North America. In: Galley, 

K.E.M.; Wilson, T.P. (eds.) Proceedings of the invasive species workshop: the role of fire in the control 

and spread of invasive species. Fire Conference 2000: The first national congress on fire ecology, prevention, and management. Miscell.Publ.No. 11. Tallahassee, FL: Tall Timbers Research Station: 1-14.

Brown D.E.; Reichenbacher F.; Franson, S.E. 1998. A classification of North American biotic communities. Salt Lake City, UT: University of Utah Press. 141 p.

Brown, J.H.; McDonald, W. 1995. Livestock grazing and conservation on southwestern rangelands. Conservation Biology. 9:1644-1647.

Bureau of Land Management (BLM). 2011a. Renewable energy projects in Nevada. Online: energy.state.

nv.us/documents/renewable-energy-projects.pdf [2011, June 9].

Bureau of Land Management (BLM). 2011b. Clark, Lincoln, and White Pine Counties Groundwater Development Project. Online: http://www.blm.gov/nv/st/en/prog/planning/groundwater_projects/snwa_

groundwater_project.html [2012, June 5].

Bureau of Land Management (BLM). 2011c. BLM begins four-year research study into longer-duration 

fertility control for wild horse mares. Bureau of Land Management News Release 2011-20. Online: 

C: http://www.blm.gov/nv/st/en/info/newsroom/state_office_news/2011/march/blm_begins_four-year.

html [21 March, 2013].

Bureau of Land Management (BLM). 2012. Bureau of Land Management National Wild Horse and Burro 

Program. Online: http://www.blm.gov/wo/st/en/prog/whbprogram.html [2012, June 6].

Clark County, Department of Air Quality and Environmental Management. 2008. Land use trends tracking system. Report to Science Advisor. Las Vegas, NV: Clark County, Department of Air Quality and 

Environmental Management, Desert Research Institute. 11 p.

Cohen, M.J. 2011. Municipal deliveries of Colorado River Basin Water. Oakland, CA: Pacific Institute. 

63 p.

Courtois, D.R.; Perryman, B.L.; Hussein, H.S. 2004. Vegetation change after 65 years of grazing and grazing exclusion. Journal of Range Management. 57:574-582.

Cummings, P. 2010. Unit 262 Spring Mountains. In: Cox, M.; Wasley, T.; Dobel, M.; Gilbertson, L.; 

Kimble, S.; Lansford, K.; Carter, D. (comps., eds.). Nevada Department of Wildlife 2009-2010 big 

game status: 76-77. Online: http://www.ndow.org/about/pubs/reports/10_bg_status.pdf [2012, Oct 30].

De Steiguer, J.E. 2011. Wild horses of the West: history and politics of America’s mustangs. Tucson, AZ: 

University of Arizona Press. 296 p.

DeLoney, J.A. 2004. Nevada’s 2003 statewide comprehensive outdoor recreation plan – assessment and 

policy plan. Carson City, NV: Nevada Division of State Parks, Department of Conservation and Natural 

Resources. 288 p.

Dincer, I. 2000. Renewable energy and sustainable development: a crucial review. Renewable and Sustainable Energy Reviews. 4:157-175.

Drewitt, A.L.; Langston, R.H.W. 2006. Assessing the impacts of wind farms on birds. Ibis. 148:29-42.

Edwards, Fred. 2012. [Personal communication within review comments for this document transmitted 

to Burton Pendleton] May 19. Complete comments on file at USDA, Forest Service, Albuquerque Lab, 

Albuquerque, NM. GSD Program.

ENTRIX, Inc. 2008. Spring Mountains National Recreation Area landscape analysis. Report to USDA 

Forest Service, Humboldt-Toiyabe National Forest, Las Vegas, NV. 673 p.

Fleischner, T.L. 1994. Ecological costs of livestock grazing in western North America. Conservation Biology. 8:629-644.

Flores, M. 2008. Mixed conifer. In: Report from Clark County Nevada MSHCP Ecosystem Health Workshop, Las Vegas, NV, January 29-31, 2008. Reno, NV: Desert Research Institute: 24-29.

Glennon, R. 2009. Is solar power dead in the water? The Washington Post, Sunday, June 7, 2009. 

Grayson, D.K. 1987. The biogeographic history of small mammals in the Great Basin: observations on the 

last 20,000 years. Journal of Mammalogy. 68:359-375.
34 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Grayson, D.K. 1993. The desert’s past: a natural prehistory of the Great Basin. Washington, DC: 

Smithsonian Institution Press. 356 p.

Guyon, J.; Munson, S. 1998. Spring Mountain insect and disease survey. Report to the Humboldt-Toiyabe 

National Forest. 20 p.

Hall, E.R. 1946. Mammals of Nevada. Berkeley, CA: University of California Press. 710 p.

Hanley, T.A. 1982. The nutritional basis for food selection by ungulates. Journal of Range Management. 

35:146-151.

Holland, J.: Peterson, M.: Reardon, D.; Tanner, A.; White, E.; Yost, A. 2010. Understanding visitors to 

public lands in Clark County, Nevada. Southern Nevada Agency Partnership Recreation Team. Southern Nevada Visitor Use Monitoring. On file at: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station, Albuquerque, NM. 4 p.

Hobbs, N.T. 1996. Modification of ecosystems by ungulates. Journal of Wildlife Management. 

60:695-713.

Houghton, J.T.; Ding, Y.; Griggs, D.J.; Noguer, M.: van der Linden, P.J.; Dai, X.; Maskell, K.; Johnson, 

C.A. 2001. Climate change 2001: the scientific basis. Cambridge, UK: Cambridge University Press. 

892 p.

Howell, C. 2011. Humboldt-Toiyabe National Forest climate change vulnerability report: April 2011. 

Unpublished document in U.S. Forest Service files. 17 p.

Jessop, D.A. 1981. Pneumonia in bighorn sheep: effects on populations. Cal-Nev Wildlife Transactions. 

1981:72-98.

Kunz, T.H.; Arnett, E.B.; Erickson, W.P.; Hoar, A.R.; Johnson, G.D.; Larkin, R.P.; Strickland, M.D.; 

Thresher, R.W.; Tuttle, M.D. 2007. Ecological impacts of wind energy development on bats: question, 

research needs, and hypotheses. Frontiers in Ecology and Environment. 5:315-324.

Lange, H.; Økland, B.; Krokene, P. 2006. Thresholds in the life cycle of the spruce bark beetle under climate change. International Journal of Complex Systems. 1648:1–10.

Loarie, S.R.; Duffy, P.B.; Hamilton, H.; Asner, G.P.; Field, C.B.; Ackerly, D.D. 2009. The velocity of 

climate change. Nature. 462:24-31.

Lovich, J.E.; Ennen, J.R. 2011. Wildlife conservation and solar energy development in the desert Southwest, United States. Bioscience. 62:982-992.

McCabe, G.J.; Wolock, D.M. 2009. Recent declines in western U.S. snowpack in the context of twentiethcentury climate variability. Earth Interactions. 13:1-15.

McDonald, R.I.; Fargione, J.; Kiesecker, J.; Miller, W.M.; Powell, J. 2009. Energy sprawl or energy efficiency: climate policy impacts on natural habitat for the United States of America. PLoS ONE. 4:e6802.

McKinley, R.A., M.L. Brooks, R.C. Klinger. [In press]. Fire History of Clark and Lincoln Counties in 

Southern Nevada. Open File Report. Sioux Falls, SD: U.S. Geological Survey. 62 p.

McQuivey, R. 1978. The desert bighorn sheep of Nevada. Biological Bulletin No. 6. Reno, NV: Nevada 

Department of Wildlife. 81 p.

Menard, C.; Duncan, P.; Fleurance, G.; Georges, J.-Y.; Lila, M. 2002. Comparative foraging and nutrition 

of horses and cattle in European wetlands. Journal of Applied Ecology. 39:120-133.

METI, Inc. 2010. Implementation and monitoring audit: mechanical hazardous fuel treatments and wildland fire supression and restoration. Report to the Spring Mountains National Recreation Area, Las 

Vegas Range District, Humboldt-Toiyabe National Forest. El Paso, TX: METI, Inc. 27 p.

Meyer, S.E.; Pendleton, B.K. 2005. Factors affecting seed germination and seedling establishment of a 

long-lived desert shrub (Coleogyne ramosissima: Rosaceae). Plant Ecology. 178:171-187.

Mote, P.W.; Hamlet, A.F.; Clark, M.P.; Lettenmajer, D.P. 2005. Declining mountain snowpack in western 

North America. Bulletin of the American Meteorological Society. 86:39-49.

Nash, M.S.: Bradford, D.F.; Franson, S.E.; Neale, A.C.; Whitford, W.G.; Heggema, D.T. 2004. Livestock 

grazing effects on ant communities in the eastern Mojave Desert, USA. Ecological Indicators. 

4:199-213

National Park Service (NPS). 2009. Comparison of Lake Mead and Lake Mojave in Clark County, NV. 

Single Agency Report. Southern Nevada Agency Partnership, Southern Nevada Visitor Use Monitoring. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 

Albuquerque, NM. 76 p.

Nevada Department of Wildlife. 2011. Time to listen and look for elk Online: http://ndow.org [2011, 

Feb 24].

Notaro, M.; Mauss, A.; Williams, J.W. 2012. Projected vegetation changes for the American Southwest: combined dynamic modeling and bioclimatic-envelope approach. Ecological Applications. 

22:1365-1388.

Pate, R.; Hightower, M.; Cameron, C.; Einfeld, W. 2007. Overview of energy-water interdependencies 

and the emerging energy demands on water resources. Report # SAND 2007-1349C. Albuquerque, 

NM: Sandia National Laboratories. 20 p.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 35

Pockman, W.T.; Sperry, J.S. 1997. Freezing-induced xylem cavitation and the distribution of Sonoran 

Desert vegetation. American Journal of Botany. 87:1287-1299. 

Provencher, L. 2008. Fire regime condition class mapping for the Spring Mountains southern Nevada. 

Draft report to the U.S. Forest Service Spring Mountains National Recreation Area. USDA Forest Service Solicitation AG-9360-S-08-004. Reno, NV: The Nature Conservancy of Nevada. 333 p.

Raffa, K.F.; Aukema, B.H.; Bentz, B. J.; Carroll, A.L.; Hicke, J.A.; Turner, M.G.; Romme, W.H. 2008. 

Cross-scale drivers of natural disturbances prone to anthropogenic amplification: the dynamics of bark 

beetle eruptions. Bioscience. 58:501-517.

Rehfeldt, G.E.; Crookston, N.L.; Warwell, M.C.; Evans, J.S. 2006. Empirical analyses of plant-climate 

relationships for the western United States. International Journal of Plant Science. 167:1123-1150.

Resource Concepts, Inc. 2001. Nevada grazing statistics report and economic analysis for federal lands in 

Nevada. Report to the State of Nevada, Department of Agriculture. 73 p.

Sada, D. 2008. Springs and riparian ecosytems. In: Report from the Clark County MSHCP Ecosystem 

Health Workshop; January 29-31, 2008; Las Vegas, NV. Reno, NV: Desert Research Institute: 5-16.

Saunders, S.; Montgomery, C.; Easley, T.; Spencer, T. 2008. Hotter and drier: the West’s changed climate. 

Rocky Mountain Climate Organization and the Natural Resources Defense Council. Online: http://

www.rockymountainclimate.org [2012, Nov 1].

Seager, R.; Ting, M. F.; Held, I.; Kushnir, Y., Lu, J.; Huei-ping Huang, Gabriel.; Harnik, Nili; Leetmaa, 

Ants; Cheung lau, N.; Li, C.; Velex, J.; and Naik, N. 2007 Model projections of an imminent transition 

to a more arid climate in southwestern North America. Science 316: 1181-1184.

Smith, M.D.; Knapp, A.K.; Collins, S.L. 2009a. A framework for assessing ecosystem dynamics in reponse to chronic resource alterations induced by global change. Ecology. 90:3279-3289.

Smith, S.D.; Charlet, T.N.; Fenstermaker, L.F.; Newingham, B.A. 2009b. Effects of global change on Mojave Desert ecosystems. In: Webb, R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, 

E.V.; Miller, D.M. (eds.). The Mojave Desert. Reno, NV: University of Nevada Press: 31-56.

Solem, S.J.; Pendleton, B.K.; Coles-Ritchie, M.; Ledbetter, J.; McKelvey, K.S.; Berg, J.; Nelson, K.; Menlove, J. 2011. 2010 Annual Report: monitoring and evaluation for conserving biological resources of the 

Spring Mountains National Recreation Area. El Paso, TX: Management and Engineering Technologies 

International, Inc. (METI); Albuquerque, NM: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 117 p.

Solem, S.J.; Pendleton, B.K.; Woldow, J.A.; Coles-Ritchie, M.; Ledbetter, J.; McKelvey, K.S.; Berg, J.; 

Gilboy, A.; Menlove, J.; Woodlief, C. 2012. 2011 Annual Report: monitoring and evaluation for conserving biological resources of the Spring Mountains National Recreation Area. El Paso, TX: Management and Engineering Technologies International, Inc. (METI); Albuquerque, NM: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 160 p.

Southern Nevada Water Authority (SNWA). 2009. Water resource plan 2009. Online: www.snwa.com/

html [2011, June 8].

Sovacool, B.K.; Sovacool, K.E. 2009. Identifying future electricity-water tradeoffs in the United States. 

Energy Policy. 37:2763-2773.

Sprigg, W.A.; Hinkley, T.; Bernal, J. 2000. Preparing for a changing climate: the potential consequences 

of climate variability and change – southwest. Report of the Southwest Regional Assessment Group, 

University of Arizona. Tucson, AZ: U.S. Global Change Research Program. 60 p.

Stohlgren, T.J.; Owen, A.J.; Lee, M. 2000. Monitoring shifts in plant diversity in response to climate 

change: a method for landscapes. Biodiversity and Conservation. 9:65-86.

Thorne, R.F. 1986. A historical sketch of the vegetation of the Mojave and Colorado Deserts of the American southwest. Annals of the Missouri Botanical Garden. 73:642-651.

Tsoutsos, T.; Frantzeskaki, N.; Gekas, V. 2005. Environmental impacts from the solar energy technologies. 

Energy Policy. 33:289-296.

Tueller, P.T. 1989. Vegetation and land use in Nevada. Rangelands. 11:204-210.

Turner, F.B., ed. 1982. Environmental effects of solar-thermal power systems: ecological observations 

during early testing of the Barstow 10-MWe pilot STPS. Technical Report UCLA-12/1385. Los Angeles, CA: University of California, Los Angeles, Laboratory of Biomedical and Environmental Sciences. 

54 p.

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. Southern Nevada 

Agency Partnership (SNAP) science and research strategy. Las Vegas, NV: SNAP. 150 p.

U.S. Fish and Wildlife Service, (USFWS) Pacific Southwest Region. 2011. Revised recovery plan for 

the Mojave population of the Desert Tortoise (Gopherus agassizii). Sacramento, CA: U.S. Fish and 

Wildlife Service. 200 p.

U.S. Fish and Wildlife Service (USFWS). 1998. Conservation Agreement for the Spring Mountains National Recreation Area, Clark and Nye Counties, Nevada. 49 p.

U.S. Fish and Wildlife Service (USFWS), Region 4. 2009. Aerial detection survey results. Internal document. 8 p.
36 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

U.S. Geological Survey (USGS). 2010. Natural resource needs related to climate change in the Great 

Basin and Mojave Desert. Workshop, 20-22 April 2010, Las Vegas, NV. Online: www.wr.usgs.gov/

workshops/ccw2010/abstracts.html [2010, Dec 1].

Wagner, F.H. 2009. Climate warming and environmental effects in the West. In: Wagner, F.H., ed. Climate 

warming in Western North America. Salt Lake City, UT: University of Utah Press: 143-160.

Webb, R.H.; Stielstra, S.S. 1979. Sheep grazing effects on Mojave Desert vegetation and soils. Environmental Management. 3:517-529.

White, C.S.; Pendleton, R.L.; Pendleton, B.K. 2006. Response of two semiarid grasslands to a second fire 

application. Rangeland Ecology and Management. 59:98-106.

Williams, J.J.; Jackson, S.T. 2007. Novel climates, no-analog communities, and ecological surprises. 

Frontiers in Ecology and the Environment. 5:475-482.

Ziska, L.H.; Gebhard, D.E; Frenz, D.A.; Faulkner, S.; Singer, B.D.; Straka, J.G. 2003. Cities as harbingers 

of climate change: common ragweed, urbanization and public health. Journal of Allergy Clinical Immunology. 111:290-295.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 37

Chapter 3

Water and Water Use in Southern Nevada

Wayne R. Belcher, Michael J. Moran, and Megan E. Rogers

Introduction

Water and water use in southern Nevada is an important issue. The scarcity of water 

resources for both human and biologic communities often leads to intense competition 

for both surface and groundwaters. Anthropogenic and climate change impacts on scarce 

water resources need to be understood to assess human and ecosystem health for the 

study area.

This chapter outlines the state of the science for hydrology in southern Nevada—

groundwater, surface water, and water quality. A brief summary of the knowledge of 

hydrology of southern Nevada is presented and recommendations for filling gaps in 

knowledge of the hydrology are proposed. This chapter serves as a synthesis of information to aid in meeting Sub-Goal 1.3 of the SNAP Science and Research Strategy, 

which is to restore and sustain proper function of Southern Nevada’s watersheds and 

landscapes (table 1.3; Turner and others 2009).

Habitats greatly influenced by groundwater in the Mojave Desert include streams, 

riparian areas, and wetlands. These habitats are a relatively small fraction of the landscape, 

but are extremely important by any biologic measure (Miller and others 2007). These 

“wet” habitats contain a great deal of biodiversity, possess a relatively high vegetative 

density, are relied on by terrestrial mammals, and support diverse aquatic species. The 

conceptual model of these habitats in the Mojave Desert is that they are largely supported by groundwater (Miller and others 2007). 

Study Area

The Southern Nevada Agency Partnership (SNAP) study area lies within the southern 

part of the Basin and Range physiographic province (Planert and Williams 1995) with 

most of the study area being within the internally drained Great Basin subprovince 

(Fenneman 1931). The very eastern edge is in the Colorado River drainage formed by 

the Virgin, Muddy, and Colorado Rivers (fig.1.1). The SNAP study area includes several 

large valleys, including the Amargosa Desert, Pahrump Valley, Las Vegas Valley, and 

Pahranagat Valley. The region also includes several major mountain ranges including the 

Spring Mountains, the Sheep and Pahranagat Ranges. Late Cenozoic tectonic activity 

accounts for much of the observed topographic relief across the study area (Grose and 

Smith 1989).

The relief between valleys and adjoining mountains locally exceeds 1,500 m (Bedinger 

and others 1989). Principal mountain ranges in the southern one-half of the study area 

trend northwest-southeast. Throughout the study area the trends of intermediate-scale 

topographic features are quite variable (fig.1.1). 
38 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Land Use

Most of the land in southern Nevada is owned by the U.S. Government and is administered by numerous Federal agencies, such as the Bureau of Land Management, the 

U.S. Fish and Wildlife Service, the National Park Service, the U.S. Forest Service, the 

Department of Energy, and the Department of Defense. Privately owned land is scattered 

throughout the region, but most private ownership is concentrated near the urban areas 

of Las Vegas Valley and agricultural centers of Amargosa Desert and Pahrump Valley. 

The major land-use activities in the region are recreation, mining and agriculture along 

the river corridors. 

From January 1951 through September 1992, 828 underground nuclear tests were 

conducted at the Nevada National Security Site (NNSS; formerly the Nevada Test 

Site). Depths of these tests ranged from 30 to 1,500 meters below the ground surface 

with approximately one-third of these tests being at or below the groundwater table. 

This resulted in some radioactive contamination of the groundwater at the NNSA. The 

Department of Energy’s (DOE) National Nuclear Security Administration (NNSA) 

has funded the Underground Test Area (UGTA) program to assess the nature, extent, 

and future migration of contaminants at the NNSS. Since there is no feasible method 

to remediate deep groundwater contamination at the NNSS, the UGTA program has a 

long-term strategy consisting of developing computer models to simulate groundwater 

flow and contaminant migration, developing a groundwater monitoring system, and 

establishing institutional control to limit access to contaminated groundwater in and 

around the NNSS.

Water Use

Water in southern Nevada is used mostly for domestic, commercial, and to a lesser 

extent agricultural, wildlife groundwater, military, and mining purposes. Water resources 

in the SNAP area include water resources for biological resources with adjudicated 

water rights for their protection. A significant example is the endangered Devils Hole 

pupfish (Cyprinidon diabolis) whose continued existence depends on naturally occurring 

spring discharges and stable pool levels in Devils Hole within Death Valley National 

Park. Water resources also include a number of local and regional spring sources that 

add greatly to the biodiversity of the area.

The study area is subdivided into hydrographic areas that generally consist of valleys 

separated by surface-water drainage divides (Rush 1968). The USGS and the NDWR 

systematically delineated hydrographic areas in Nevada for scientific and administrative 

purposes (Cardinalli and others1968; Rush 1968) for both surface water and groundwater. 

Official hydrographic-area names, numbers, and geographic boundaries continue to be 

used in USGS and other agency’s scientific reports and NDWR administrative activities 

pertaining to Nevada.

Ground-water rights in Nevada are assigned according to these hydrographic areas. 

Where perennial yield is less than the water use, certain hydrographic areas have been 

“designated,” meaning that certain administrative strategies have been applied to these 

“over allocated” (pumping is greater than the perennial yield) basins. Table 3.1 presents 

the hydrographic areas in the SNAP area with The Nevada State Engineer’s estimated 

perennial yield, water use, and designation status for ground water.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 39

Table 3.1. Water Use for Southern Nevada Agency Partnership Study Area by Hydrographic Area.

 Annual Annual Annual Annual

 perennial perennial water water

Hydrographic yield yield use use

Area No. Hydrographic Area Name Designated? (acre ft) use (m^3) (acre ft) (m^3)

141 RALSTON VALLEY Y (all) 6,000 7,401,715 4,306 5,311,409

145 STONEWALL FLAT N 100 123,362 12 14,532

146 SARCOBATUS FLAT Y (all) 3,000 3,700,858 3,535 4,361,362

147 GOLD FLAT N 1,900 2,343,876 414 510,792

148 CACTUS FLAT N 300 370,086 248 306,160

149 STONE CABIN VALLEY Y (all) 2,000 2,467,238 11,532 14,226,528

157 KAWICH VALLEY N 2,200 2,713,962 0 0

158A EMIGRANT VALLEY-GROOM LAKE VALLEY N 2,800 3,454,134 12 15,198

158B EMIGRANT VALLEY-PAPOOSE LAKE VALLEY N 10 12,336 0 0

159 YUCCA FLAT N 350 431,767 0 0

160 FRENCHMAN FLAT N 100 123,362 0 0

161 INDIAN SPRINGS VALLEY Y (portion) 500 616,810 1,392 1,717,124

162 PAHRUMP VALLEY Y (all) 12,000 14,803,430 62,597 77,220,713

163 MESQUITE VALLEY (SANDY VALLEY) Y (all) 1,500 1,850,429 386 476,004

164A IVANPAH VALLEY-NORTHERN PART Y (all) 700 863,533 1,913 2,359,988

164B IVANPAH VALLEY-SOUTHERN PART Y (all) 250 308,405 781 963,148

165 JEAN LAKE VALLEY Y (all) 50 61,681 340 419,875

166 HIDDEN VALLEY (SOUTH) Y (all) NA NA 67 82,541

167 ELDORADO VALLEY Y (all) 500 616,810 2,256 2,783,094

168 THREE LAKES VALLEY (NORTHERN PART) N 3,700 4,564,391 3,700 4,564,391

169A TIKAPOO VALLEY-NORTHERN PART N 2,600 3,207,410 2,594 3,199,626

169B TIKAPOO VALLEY-SOUTHERN PART N 1,700 2,097,153 1,700 2,097,153

170 PENOYER VALLEY (SAND SPRING VALLEY) Y (all) 4,000 4,934,477 15,083 18,606,247

171 COAL VALLEY N 6,000 7,401,715 32 38,958

172 GARDEN VALLEY N 6,000 7,401,715 558 688,804

173A RAILROAD VALLEY-SOUTHERN PART N 2,800 3,454,134 3,931 4,849,382

181 DRY LAKE VALLEY N 12,700 15,666,964 1,066 1,314,495

182 DELAMAR VALLEY N 2,550 3,145,729 7 8,931

197 ESCALANTE DESERT N 1,000 1,233,619 71 87,698

203 PANACA VALLEY Y (all) 25,000 30,840,480 29,201 36,022,729

204 CLOVER VALLEY N 25,000 30,840,480 2,768 3,414,843

205 LOWER MEADOW VALLEY WASH Y (all) 25,000 30,840,480 21,483 26,501,261

206 KANE SPRINGS VALLEY N 1,000 1,233,619 1,000 1,233,619

208 PAHROC VALLEY N 21,000 25,906,003 39 48,037

209 PAHRANAGAT VALLEY NA 25,000 30,840,480 12,800 15,790,498

210 COYOTE SPRING VALLEY Y (all) 1,900 2,343,877

 to to

 1,8000 22,205,146 16,200 19,984,631

211 THREE LAKES VALLEY (SOUTHERN PART) Y (portion) 4,500 5,551,286 4,500 5,551,619

212 LAS VEGAS VALLEY Y (all) 25,000 30,840,480 95,631 117,971,794

213 COLORADO VALLEY Y (all) 200 246,724 4,557 5,621,023

214 PIUTE VALLEY Y (all) 300 370,086 5,039 6,216,331

215 BLACK MOUNTAINS AREA Y (all) 1,300 1,603,705 6,048 7,460,509

216 GARNET VALLEY Y (all) 400 493,448 3,366 4,151,795

217 HIDDEN VALLEY (NORTH) Y (all) 200 246,724 2,275 2,805,953

218 CALIFORNIA WASH Y (all) 2,200 2,713,962 10,568 13,036,283

219 MUDDY RIVER SPRINGS AREA (UPPER) Y (all) 100 123,362

 to to

 3,6000 44,410,291 14,557 17,958,399

220 LOWER MOAPA VALLEY Y (all) 50 61,681 5,721 7,057,930

221 TULE DESERT N 2,100 2,590,600 5,004 6,172,562

222 VIRGIN RIVER VALLEY Y (all) 3,600 4,441,029 12,343 15,226,056

223 GOLD BUTTE AREA N 500 616,810 1 1,382

224 GREASEWOOD BASIN N 300 370,086 4 4,996

225 MERCURY VALLEY N 24,000 29,606,861 0 0

226 ROCK VALLEY N 24,000 29,606,861 0 0

227A FORTYMILE CANYON-JACKASS FLATS N 24,000 29,606,861 58 71,969

227B FORTYMILE CANYON-BUCKBOARD MESA N 24,000 29,606,861 0 0

228 OASIS VALLEY Y 24,000 29,606,861 1,296 1,598,869

229 CRATER FLAT N 24,000 29,606,861 681 840,539

230 AMARGOSA DESERT Y (portion) 24,000 29,606,861 25,479 31,431,211
40 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Groundwater

The current understanding of regional groundwater flow in the Great Basin came 

from the basin studies done under the U.S. Geological Survey and the State of Nevada 

cooperative groundwater program. Maxey and Eakin (1949) compared recharge and 

discharge estimates of individual basins and realized that many basins were not closed 

to groundwater transfer to or from adjacent basins. Eakin (1966) identified a system 

of interconnected basins of the White River and Muddy River springs area. The water 

budget imbalances within and between basins was useful in discerning interbasin flow 

and defining the basins of the White River flow system (part of the Colorado River flow 

system).

In southern Nevada, groundwater flow is strongly influenced by the physical framework 

of the system, which is characterized by aquifers, confining units, and flow barriers. 

Groundwater flows through a diverse assemblage of rocks and sediments in the region, 

and geologic structures exert significant control on groundwater movement as well 

(Faunt and others 2010).

The groundwater hydrology of southern Nevada, as in all flow systems, is influenced 

by geology and climate and varies with time. In general, groundwater moves through 

permeable zones under the influence of hydraulic gradients from areas of recharge to 

areas of discharge in the regional system. The topography produces numerous local 

subsystems within the major flow system (Freeze and Cherry 1979). Water that enters 

the flow system in a recharge area may be discharged in the nearest topographic low, or 

it may be transmitted to a regional discharge area (Faunt and others 2010).

Aquifers

An aquifer is “a geologic unit that can store and transmit water at rates fast enough to 

supply reasonable amounts to wells” (Fetter 2001: 95). The Basin and Range aquifers 

are located in an area that comprises most of Nevada. The water-yielding materials in 

this area are in valleys and basins, and consist primarily of unconsolidated alluvial-fan 

deposits, although locally flood plain and lacustrine (lake) beach deposits may yield 

water to wells. Also, the consolidated volcanic and carbonate rocks that underlie the 

unconsolidated alluvium are a source of water if the consolidated rocks are sufficiently 

fractured or have solution openings. Many of these valleys and basins are internally 

drained; that is, water from precipitation that falls within the basin recharges the aquifer 

and ultimately discharges to the land surface and evaporates within the basin. Groundwater 

is generally unconfined at the margins of the basins, but as the unconsolidated deposits 

become finer grained toward the centers of the basins, the water becomes confined. 

The current conceptual model of interbasin flow suggests that basins are hydraulically 

connected in the subsurface by fractures or solution openings in the underlying bedrock. 

These multiple-basin systems end in a terminal discharge area, or sink, from which 

water leaves the flow system by evapotranspiration. Also, several basins or valleys may 

develop surface-water drainage that hydraulically connects the basins, and groundwater 

flows between the basins, mostly through the unconsolidated alluvial stream/floodplain 

sediments (Planert and Williams 1995).

Three principal aquifer types exist within southern Nevada: volcanic-rock aquifers, which are primarily tuff, rhyolite, or basalt of Tertiary age; carbonate-rock 

aquifers, which are primarily limestones and dolomites of Mesozoic and Paleozoic 

age; and basin-fill aquifers, which are primarily unconsolidated sand and gravel 

of Quaternary and Tertiary age. Any or all three aquifer types may be in, or underlie, a particular basin and constitute three separate sources of water; however, the 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 41

aquifers may be hydraulically connected to form a single source. Other rock types 

within the region have low permeability and act as boundaries to the flow of fresh 

groundwater (Planert and Williams 1995).

Regional Groundwater Flow Systems

The ground-water flow systems of southern Nevada are in individual basins and/or 

more hydraulically connected basins through which groundwater flows to a terminal 

discharge point or sink. Except for relatively small areas that drain to the Colorado 

River, water is not discharged to major surface-water bodies but is lost primarily through 

evapotranspiration. Each basin has essentially the same characteristics: the impermeable 

rocks of the mountain ranges serve as boundaries to the flow system, and the majority 

of the groundwater flows through basin-fill deposits and permeable rock formations of 

the mountain ranges. In the area where carbonate rocks underlie the basins, substantial 

quantities of water can flow between basins through the carbonate rocks and into the 

basin-fill deposits, but this water also is ultimately discharged by evapotranspiration. 

Most recharge to the basin-fill deposits originates in the mountains as snowmelt, and, 

where the mountain streams emerge from bedrock channels, the water infiltrates into 

the alluvial fans and replenishes the basin-fill aquifer. Intense thunderstorms may provide some direct recharge to the basin-fill deposits, but, in most cases, any rainfall that 

infiltrates the soil is either immediately evaporated or taken up as soil moisture. Thus, 

little water percolates downward through the unsaturated zone to reach the water table 

in the valleys. In mountain areas underlain by permeable carbonate rocks, most of the 

recharge may enter the carbonate rocks and little water remains to supply runoff (Planert 

and Williams 1995).

Groundwater flow in southern Nevada is dominated by interbasin flow with several 

relatively shallow and local flow systems that are superimposed on deeper intermediate and regional flow systems (fig. 3.1). The regional groundwater flow patterns do not 

coincide with local topographic basins. Regional groundwater flow generally follows 

the regional topographic gradient as water moves toward the lowest point in the region 

at Death Valley, California, for groundwater flow systems in the Great Basin (Faunt and 

others 2010) or toward the Colorado River for those groundwater flow systems in the 

Colorado River drainage (Harrill and others 1988).

Interbasin flow has been established by scientific studies over the past century. Interbasin flow, although it is not uniform between all basins, is common and is a function 

of the hydraulic gradient between basins and hydraulic conductivity of the intervening 

rocks. Several decades of geologic and hydrologic work in the Great Basin province 

led to the conclusion that groundwater flow results from an interconnected, complex 

groundwater flow system (Carpenter 1915; Eakin 1966; Eakin and Moore 1964; Eakin 

and Winograd 1965; Harrill and others 1988; Hunt and others 1966; Mendenhall 1909; 

Mifflin 1968; Mifflin and Hess 1969; Winograd and Thordarson 1975). Knowledge 

of interbasin groundwater flow through bedrock and basin-fill deposits of the region 

is the basis for regional groundwater management and water-resource planning in the 

Great Basin province. The concept and development of interbasin flow is summarized 

in Belcher and others (2009).

In the prevailing conceptual model of interbasin flow, water enters the system as 

interbasin underflow and as recharge from precipitation in upland areas. Because 

of present-day arid conditions, present-day recharge is restricted to higher altitudes; 

virtually no recharge occurs and no perennial surface water flows in the lowlands and 

valley floors (Winograd and others 2005). Groundwater flow paths within the system 

diverge from the highlands and are superimposed on deeper regional flow paths that 

are controlled largely by flow in the regional carbonate-rock aquifer. The SNAP area 
42 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

is contained within two regional groundwater flow systems: the Death Valley flow 

system and the Colorado flow system (Harrill and others 1998; fig. 3.2). The Death 

Valley flow system is located in the southern part of the Great Basin province and is 

approximately 100,000 km2 in area; it consists of recharge areas in the mountains of 

central and southern Nevada and discharge areas of wet playas and springs south and 

west of the Nevada National Security Site and in Death Valley, California. The Colorado 

flow system is located in the Colorado River drainage system just east of the southern 

part of the Great Basin and is approximately 42,000 km2 in area. Recharge areas are 

in some mountainous areas within the flow system, but recharge to the system is also 

from groundwater flow from adjacent flow systems. The Virgin and Colorado Rivers 

are the major discharge areas of the system.

Water Budgets

A basic way to evaluate the occurrence and movement of groundwater in an aquifer 

system is to develop a water budget accounting for the aquifer system’s inflows (recharge) 

and outflows (discharge) (Laczniak and others 2007). A water budget is developed to 

evaluate the balance between the flow into and flow out of a groundwater flow system. 

The primary components of a regional water budget are natural discharge (evapotranspiration and spring flow), pumpage, recharge, and lateral flow into and out of an area 

(estimated by using Darcy calculations or existing water budgets). The introduction of 

pumping as a discharge from the flow system initially decreases hydraulic heads and 

ultimately affects one or more flow components by decreasing natural discharge or by 

increasing recharge, as well as by removing groundwater from aquifer storage (San Juan 

and others 2010).

Figure 3.1—Schematic block diagram illustrating the structural relations between mountain 

blocks, valleys, and groundwater (interbasin) flow (Faunt and others 2010; modified from Eakin 

and others 1976).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 43

The relation between precipitation and evapotranspiration is a major factor in water 

availability. Generally, if annual precipitation exceeds annual potential evapotranspiration, then there is a net surplus of water and streamflow is perennial. However, annual 

potential evapotranspiration can exceed annual precipitation, which causes a net deficit 

of water. A net annual moisture deficit occurs almost everywhere in Nevada. Water is 

available to recharge aquifers only at times when precipitation or snowmelt is greater 

than actual evapotranspiration (Planert and Williams 1995).

Current sources of groundwater flow in the region are (1) recharge from precipitation in 

the mountains (usually winter storms) within the model domain, and (2) lateral flow into 

the study area, predominantly through the carbonate-rock aquifer via interbasin flow. Most 

groundwater recharge results from infiltration of precipitation and runoff on the mountain 

ranges (Bedinger and others 1989). Water may infiltrate from melting snowpack in the 

mountains primarily on volcanic or carbonate rocks or adjacent to the mountains from 

streams flowing over alluvium (fans and channels) (Harrill and Prudic 1998).

Figure 3.2—The Death Valley and Colorado regional groundwater flow 

systems (Harrill and others 1998).
44 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Groundwater discharge in the region is from:

1. seeps and spring flow from the regional carbonate-rock aquifer and local systems; 

2. evapotranspiration (ET);

3. pumpage for irrigation, mining, public supply, commercial, and domestic uses; 

and 

4. subsurface flow in or out of the groundwater basins of the study area (Harrill 

and others 1988).

Most natural groundwater discharge today originates as spring or seep flow caused 

by variations in permeability created by geologic structures and varying lithologies 

(Winograd and Thordarson 1975). In particular, many of the regional (larger volume and 

higher temperature) springs occur along major faults. For example, at Ash Meadows, a 

high concentration of springs exists. More than 30 springs and seeps are aligned in an 

approximate linear pattern spanning about 10 miles. Spring discharge varies substantially 

across the area with a maximum measured discharge of nearly 3,000 gal/min at Crystal 

Pool. The combined measured discharge has been estimated at about 10,500 gal/min. 

More than 80 percent of the measured springflow discharges from nine of the springs 

(Laczniak and others 1999). Groundwater flow is impeded by the presence of one or 

more buried faults (Gravity fault) that down drop the carbonate bedrock block beneath 

and west of Ash Meadows. The contrast in hydraulic properties between the more permeable faulted and fractured carbonate rock and the juxtaposed, less permeable basin-fill 

deposits hinders southwestwardly flowing groundwater forcing it upward to the surface, 

producing the springs at Ash Meadows (Winograd and Thordarson 1975). Pohlmann and 

others (1998) concluded that springs in Black Canyon south of Hoover Dam included 

components from local, sub-regional, and Lake Mead sources. These local springs are 

unrelated to large, regional groundwater flow systems like those in the carbonate-rock 

aquifer. Justet and others (in preparation) reach similar conclusions with these springs 

being from locally derived groundwater most likely driven by the hydrostatic pressure 

of Lake Mead.

Most regional spring discharge is ultimately consumed by evapotranspiration. Major 

discharge areas primarily occur in the lower part of intermontane valleys where the 

potentiometric surface is near or above land surface.

In addition to direct spring flow measurement, natural groundwater discharge in the 

SNAP area is estimated by calculating ET. The underlying assumption of this approach 

is that most of the groundwater issuing from springs and seeps within a discharge area 

ultimately is evaporated or transpired locally and therefore is accounted for in estimates 

of ET. Evapotranspiration (ET) refers to water evaporated or transpired from the regional 

groundwater flow system, not water evapotranspired from precipitation infiltrating into 

the shallow flow system. ET estimates in the SNAP area includes work presented in 

reports by Laczniak and others (1999, 2001) and DeMeo and others (2003, 2006) for 

Ash Meadows and the Death Valley flow system and DeMeo and others (2008) for 

the Colorado River flow system. These investigations were similar in that continuous 

micrometeorological data were collected to estimate local ET rates, and remotely sensed 

multispectral data were used to distribute measured ET rates over the area evaluated.

Discharge also occurs as pumping for irrigation, mining, public supply, commercial, 

and domestic uses (Bedinger and others 1989; Moreo and Justet 2008; Moreo and others 

2003). Since 1959, pumpage inventories have been conducted almost annually by the 

NDWR in Pahrump Valley, and since 1983, almost annually in all valleys with irrigation (NDWR 2011, http://water.nv.gov/data/pumpage/, last accessed May 26, 2011). 

Moreo and Justet (2008) compiled pumpage estimates for the Death Valley regional 

flow system, which comprises a large part of the SNAP study area.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 45

Lateral flow from one basin to another (interbasin flow) has been compiled by 

Harrill and others (1988) based on the series of reconnaissance reports done under the 

U.S. Geological Survey and the State of Nevada cooperative groundwater program.

Surface Water

In the study area, perennial streamflow is sparse, with the exception of the Colorado 

River drainage. Most surface water in the region is either runoff or spring flow discharge. Precipitation falling on the slopes of the mountains forms small, intermittent 

streams that quickly disappear and infiltrate as groundwater recharge. In addition, several 

streams originate from snowmelt in the high altitudes of the Spring Mountains. Both 

of these types of streams have highly variable base flows and in dry years have almost 

imperceptible discharges. Springs maintain perennial flow for short distances in some 

of the drainages.

Fluvial Systems

In most of Nevada, nearly all the streams that originate in the mountains are ephemeral and lose flow to alluvial aquifers as the streams emerge onto the valley floors. In 

southern Nevada, there are three main fluvial systems: The Colorado River (Lakes Mead 

and Mohave), the Virgin and Muddy Rivers, and the Las Vegas Wash (fig. 3.3). The 

Colorado River is supplied primarily by runoff from the Rocky Mountains. The Virgin 

and Muddy Rivers and the Las Vegas Wash are all tributaries to the Colorado River. 

The Muddy River begins as a series of regional springs in Moapa Valley and drains 

into the northern arm of Lake Mead (Colorado River). The Virgin River originates in 

Navajo Reservoir in southwestern Utah and enters Lake Mead from the north (forming 

the northern arm of the lake). Prior to the construction of the Hoover Dam, the Muddy 

River joined the Virgin River. The Las Vegas Wash drains Las Vegas Valley and largely 

contains urban runoff, shallow groundwater, reclaimed water, and storm water runoff. 

The Las Vegas Wash supports a large wetland. USGS measures discharge on all four of 

these rivers.

Flow in the Colorado River and its tributaries (Muddy and Virgin Rivers) is monitored 

by entitlement holders, the Bureau of Reclamation, and the USGS. The flow is monitored 

to assess the amount of Colorado River that is diverted, returned, and consumptively 

used to determine whether individual users have exceeded their entitlement of water 

(Matuska 2011). The Southern Nevada Water Authority and the USGS have measured 

water quality on the Muddy River at various times as part of tributary inflow to Lake 

Mead. The USGS has monitored water quality (temperature, specific conductance, 

sediment concentration, and chemical analyses) on the Virgin River since 1948 to assess salt-loading problems by establishing baseline loading conditions over a variety 

of hydrologic conditions.

The Colorado River drainage is the main source of water for southern Nevada. Approximately 90 percent of southern Nevada’s water resources are obtained from the 

Colorado River and its tributaries (Southern Nevada Water Authority 2011, http://www.

snwa.com/html/wr_index.html, last accessed May 26, 2011). The state of Nevada is 

permitted, by the Colorado River Compact of 1922 and the Boulder Canyon Project 

Act of 1928, an allotment of 300,000 acre-feet per year from the Colorado River and 

its tributaries.
46 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Springs

A spring is where groundwater flows to the land surface. Spring discharge can form 

pools or creeks and can provide water to plants and animals. Most of the groundwater 

discharged naturally in southern Nevada flows from springs and seeps. Springs also 

are an important and complex component of the groundwater budget. Spring discharge 

can originate from a local or regional source, or a mixture of more than one source. 

Geography, geology, and precipitation control spring discharge. Discharge from springs 

can flow along the land surface, infiltrate back into the groundwater system, evaporate, 

be transpired, or undergo a combination of these processes. Measurable properties of 

spring discharge reflect these sources, controls, and processes, and therefore can be used 

to estimate local or regional components of the study area groundwater budget.

Figure 3.3—Perennial fluvial system in southern Nevada.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 47

In southern Nevada, springs are an important water resource. Historically, Native 

Americans, early pioneers, miners and settlers, and modern residents (including farmers 

and ranchers) have used spring water for drinking, bathing, agriculture, mining, and 

recreational purposes. Many of the settlements and towns in the study area are located 

near larger springs that have been a source of water for humans since Native Americans 

began utilizing them thousands of years ago. Springs in southern Nevada support a 

large amount of the aquatic and riparian species in arid regions (Fisher and others 1972; 

Gubanich and Panik 1986; Myers and Resh 1999; Williams and Koenig 1980).

Because springs are sourced ultimately in groundwater, increased groundwater 

pumping from existing wells and new points of diversion, could impact nearby waterdependent ecosystems by reducing the amount of groundwater discharge and decreasing 

shallow water tables. Increased pumping could result from increasing water supplies for 

population growth and from the development of solar power plants. Springs emanating from perched aquifer systems in the higher mountain ranges in the study area are 

threatened by climate change.

Springs help sustain unique aquatic, riparian, and phreatophytic ecosystems, some 

of which support threatened or endangered species endemic to the region. Some of the 

more recognizable threatened or endangered species include the Devils Hole pupfish 

(Cyprinodon diabolis), the Ash Meadows Amargosa pupfish (Cyprinodon nevadensis 

mionectes), and the Moapa dace (Moapa coriacea) (http://www.fws.gov/endangered/, 

last accessed Sept. 1, 2011).

Groundwater discharges at the Ash Meadows National Wildlife Refuge, Pahranagat 

National Wildlife Refuge, the Moapa Valley, at numerous springs and seeps in the 

mountainous areas, and along parts of the Amargosa River. Additionally, groundwater 

is intersected at Devils Hole, a fissure in the regional carbonate-rock aquifer in the Ash 

Meadows area. Several hundred springs are scattered throughout Clark County and 

basic environmental and biological characteristics of the larger discharge springs have 

been inventoried (Sada 2000; Sada and Nachlinger 1996, 1998). The MSHCP reported 

506 springs in Clark County, although most of these springs dry frequently and fewer 

than 200 springs occur persistently in Clark County (Sada, 2000; Sada and Nachlinger 

1996, 1998). Most springs can be classified as local (low discharge and cool temperatures) or regional (high discharge and warmer temperatures). 

Local Springs—Local springs are generally low volume, low temperature springs that 

mostly discharge from areas within the mountain ranges of southern Nevada. These 

local springs are believed to be derived from local recharge from precipitation. Local springs occur both at higher altitudes in mountainous areas and at lower altitudes 

adjacent to mountain fronts. The higher altitude springs are less susceptible to impacts 

from pumping than their lower altitude counterparts. Because these local springs are 

dependent on local recharge from precipitation, changes in precipitation patterns as 

a result of climate change could impact their discharge. In most cases, only the locations of the springs (derived from the USGS National Hydrologic Dataset) are available. Discharge and water quality information is not routinely collected for most local 

springs by the USGS or any other Federal, state, or local agency. The Nevada Natural 

Heritage Program classifies one wetland in the extreme southern part of the study area 

as a “priority wetland” for conservation: Mojave riparian wetlands along the Colorado 

River below Davis Dam (Skudlarek 2008).

In the Spring Mountains, water moving laterally from bedrock and alluvial aquifers 

to the surface form the over 100 surveyed springs (Hershey 1989; Purser 2002; Sada and 

Nachlinger 1998). Spring discharge varies from year to year with some springs drying 

up annually, some drying only after extended droughts, and others flowing continuously 
48 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

(Sada and others 2005). A few perennial streams (such as Carpenter Canyon, Clark Canyon, Cold Creek, Deer, McFarland, Santa Cruz, Sawmill, and Willow) are associated 

with large springs and/or spring complexes (Hughes 1966; Maxey and Jameson 1948; 

Nachlinger and Reese 1996).

Regional Springs—Regional high-volume springs having flows greater than 1,500 

cubic meters per day (m3/d) discharge in Ash Meadows (60,000 m3/d), Manse Spring 

in Pahrump Valley (5000 m3/d), Pahranagat Valley (60,000 m3/d from Hiko, Ash, and 

Crystal Springs), the Muddy River springs area in Moapa Valley (10,500 m3/d), and 

Rogers and Blue Point Springs along Lake Mead in the Muddy Mountains (4,200 m3/d 

and 1,400 m3/d, respectively) (fig. 3.4). Typically, these regional springs discharge water with temperatures greater than 30 degrees Celsius (°C) directly from the rocks that 

make up the regional carbonate-rock aquifer (Harrill and Prudic 1998; San Juan and 

others 2010). Discharge from these large springs is typically taken up by evapotranspiration. The exception to this is Muddy Springs in Moapa Valley, which discharge into 

the Muddy River (Harrill and Prudic 1998). Discharge from these regional springs is 

measured by the USGS and cooperating agencies and entered into NWIS.

Figure 3.4—Regional spring discharge areas in southern Nevada (Harrill 

and others 1988).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 49

In some areas in southern Nevada (Ash Meadows in the Death Valley regional system 

and the Virgin River in the Colorado River system), diffuse discharge has been estimated by using micrometerological stations and remote sensing to estimate the amount 

of regional evapotranspiration from some major discharge areas in southern Nevada 

(DeMeo and others 2008; Laczniak and others 2001).

Water Chemistry

Water chemistry issues within the Lake Mead National Recreation Area (LAME) 

probably have the greatest visibility in Southern Nevada. Lake Mead is the largest and 

one of the most intensely used reservoirs in the western United States. Many human 

activities can affect the chemistry of water in Lake Mead such as boating and fishing, 

runoff from agricultural lands, inflows of treated wastewater, and urban runoff. Many 

of the water chemistry issues that affect LAKE have been summarized in a U.S. Geological Survey (USGS) Circular titled Lake Mead National Recreation Area Aquatic 

Ecosystem (Rosen and others 2012). 

Perchlorate and mercury are two contaminants that have been found in LAME 

that have anthropogenic sources (Shimshack and others 2007; USEPA 2001). Studies suggest that perchlorate and mercury may have health effects on fish populations 

in LAME (Cizdziel and others 2003; Crouch 2003; Kramer 2009; Snyder and others 

2002). Concentrations of organic contaminants have been high enough in Lake Mead 

to cause toxicity or endocrine disruption to aquatic organisms (Advanced Concepts and 

Technologies International 2010). Better understanding of the sources, transport, and 

fate of contaminants is important to understanding their effects on aquatic organisms 

and the overall aquatic ecosystem of LAME.

Water chemistry has been studied in several rivers in the southern Nevada, most 

notably the Muddy and Virgin Rivers. The USGS has analyzed a variety of chemical 

constituents in samples from these rivers including major ions, nutrients, and pesticides. 

Although these data have not been analyzed, the results suggest that anthropogenic 

activities influence the chemistry of water in these rivers. In desert landscapes common in Southern Nevada, springs provide the only reliable source of water and support 

unique ecosystems. The chemistry of water from springs is critical to the abundance 

and diversity of species found at springs (Sada and others 2005). For example, spring 

snails are restricted to portions of springs that provide suitable physical and chemical 

conditions (Sada 2008). In general, human disturbances of the natural ecosystems at 

springs have been limited to livestock trampling and recreation and have not resulted 

in significant changes in the water chemistry of springs.

The USGS has conducted several intensive studies of the water chemistry of springs 

in several areas of Southern Nevada region. Samples from 28 springs throughout Clark 

County were collected from July 2008 to September 2010 and analyzed for a variety 

of chemical constituents. Results indicate that the groundwater from these springs is 

derived from various aquifers in the region. In Black Canyon south of Hoover Dam, 

springs support unique riparian ecosystems. Using geologic and geochemical methods, 

it was determined that the source of water to springs in Black Canyon is locally derived 

groundwater most likely driven by the hydrostatic pressure of Lake Mead (Justet and 

others, in preparation). 
50 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Hydrologic and Water Quality Data Collection

The USGS investigates the occurrence, quantity, quality, distribution, and movement 

of surface and groundwater and disseminates the data to the public: Tribal, state, and 

local governments; public and private utilities; and other Federal agencies involved with 

managing Nevada’s water resources. In 1889, the U.S. Geological Survey established 

its first gaging station in Nevada that provides data to the public about Nevada’s water 

resources.

The USGS has a distributed water database that is locally managed within the Nevada 

Water Science Center. Surface water, groundwater, and water quality data are compiled 

from these local, distributed databases into a national information system. Data collected 

on behalf of or by cooperating agencies is compiled, quality-assured, and entered into 

the database. Information from these sites is served on the Internet through NWISWeb, 

the National Water Information System Web Interface. NWISWeb provides all USGS 

water data that are approved for public release. 

The USGS also collects and analyzes chemical, physical, and biological properties 

of water, sediment, and tissue samples. The NWISWeb discrete sample database is a 

compilation of over 4.4 million historical water quality analyses in the USGS district 

databases through September 2005. The discrete sample data is a large and complex set 

of data that has been collected by a variety of projects ranging from national programs to 

studies in small watersheds. At selected surface-water and groundwater sites, the USGS 

maintains instruments that continuously record physical and chemical characteristics 

of the water including pH, specific conductance, temperature, dissolved oxygen, and 

percent dissolved-oxygen saturation. Supporting data such as air temperature and barometric pressure are also available at some sites. Published and provisional hydrologic 

and water quality data collected or compiled by the USGS are available online: http://

waterdata.usgs.gov/nv/nwis/nwis.

The USGS and various DOE contractors routinely collect groundwater levels at the 

NNSS to aid in the development of the groundwater models. USGS collected data is 

entered into NWIS, but much of the information collected by DOE contractors is not. 

Data from the USGS NNSS programs, in addition to being available in NWIS, are 

available at: http://nevada.usgs.gov/doe_nv/. While budget constraints at the DOE for 

monitoring has resulted in a reduced monitoring network, many Federal agencies still see 

value in continuing to collect this information. Many wells from the old Yucca Mountain 

monitoring network have been picked up for continued water-level data collection by 

Interior agencies (USGS, BLM, and FWS) and Nye County.

To assist with these efforts to better understand the dynamics of Lake Mead, the 

USGS, in cooperation with the National Park Service, Southern Nevada Water Authority, and Clark County Water Reclamation, collects water-quality, water-velocity, 

and meteorological data as part of its Lake Mead Monitoring Network. Studies are 

currently underway to determine temporal changes and spatial distributions of natural 

and anthropogenic chemical compounds in Lake Mead. The USGS currently maintains 

one monitoring station on the lake in Boulder Basin south of Sentinel Island. The 

Sentinel Island station records depth-dependent measurements of water temperature 

and specific conductance and hourly averaged meteorological data (air temperature, 

relative humidity, solar and net radiation, and wind speed and direction). The Black 

Canyon station records depth-dependent measurements of water temperature, specific conductance, dissolved oxygen, pH, and turbidity. The water-quality data are 

collected every 6 hours beginning each day just after midnight. Both stations are 

equipped to record hourly water-velocity data.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 51

The Southern Nevada Water Authority (SNWA) collects water-quality data from 

source water as well as finished drinking water as part of providing a safe drinking water 

supply to the Las Vegas metropolitan area. This includes collecting water-quality data 

from Lake Mead, the largest source of drinking water for Las Vegas. The USGS cooperates with SNWA to collect water-quality data from Lake Mead as well as other areas of 

southern Nevada including the Virgin River and Colorado River below Hoover Dam. 

Other Federal, state, and local agencies collect water-quality data in southern Nevada 

including the U.S. Bureau of Reclamation (BOR), the U.S. Environmental Protection 

Agency (EPA), the Clark County Water Reclamation District (CCWRD), the City of 

Las Vegas, and the City of Henderson. The BOR collects water-quality data from Lake 

Mead while the EPA collects water-quality data below Hoover Dam. The CCWRD, 

City of Las Vegas, and City of Henderson cooperate to collect water-quality data at a 

number of sites in the Las Vegas Wash and from Lake Mead.

Knowledge Gaps and Management Implications

As climate change and increasing populations potentially reduce available water 

supplies for both human and biologic communities, the collection and interpretation of 

information to define and assess local and regional hydrologic conditions becomes vital. 

Assessing the information that is regularly collected by Federal agencies in southern 

Nevada has indicated that there are several gaps in data collection. Since there tends 

to be a project by project approach to data collection, at times there is no long term 

program(s) to collect data. Data are collected for the goals of a certain project and once 

the project is completed, data collection ends. There is very little long-term continuity 

or planning on basic data collection that could be used to assess the hydrologic and 

biologic health of the study area.

Base Conditions of Springs and Rivers

Base conditions of springs and rivers just prior to settlement of southern Nevada are 

largely unknown. A qualitative assessment of these conditions could be accomplished 

by examining historical records (such as early settler diaries and journals, military 

exploration reports, and 19th century scientific reports) and compiling observations of 

streamflow and springs conditions.

Water Levels

Water levels are currently collected by a variety of agencies over the SNAP area for a 

variety of purposes. This work is primarily project based. Collection of water-level data 

is concentrated in few areas (for example, Las Vegas Valley, Pahrump Valley, Amargosa 

Desert, and the Nevada National Security Site). For some hydrographic areas there is 

very little or no water-level data. The water level data is essential to establishing baseline conditions of and estimating amounts of regional groundwater flow. Work could 

be done to establish areas where a paucity of data exist and then canvass these areas for 

existing wells that could be used to collect water levels. In areas where no wells exist, 

it may be necessary to drill wells to be able to obtain water-level information.

Pumping Inventories

Currently, the pumping inventories in the study area are estimated by Nevada Division of Water Resources (NDWR) in irrigated valleys, along with some project specific 

work (such as the Death Valley regional flow system). A systematic method of estimating pumping using the existing inventories, along with remote sensing for the entire 
52 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

SNAP study area on an annual basis would aid in estimating water budgets. Updating 

the water use data base would involve:

1. Acquisition and processing of Thematic Mapper imagery to estimate irrigated 

acreage;

2. Compiling State Pumpage Inventories;

3. Estimating, by user and location, annual groundwater pumpage; and

4. Entering annual pumpage estimates into a database.

Evapotranspiration Estimates

Estimates of evapotranspiration (ET) are performed by government and (or) scientific 

organizations on a project-by-project basis and rarely as a comprehensive program. 

Estimates of ET could be performed to assess the amount of water discharging from the 

regional groundwater system over the entire study area. These estimates could be repeated 

every few years to assess potential impacts of changing recharge due to climate change. 

High-resolution multi-spectral imagery will be used to delineate the extent, density, and 

diversity of riparian vegetation within groundwater discharge areas. Discharge area 

mapping techniques would be based on land-cover classification methods and defined 

vegetation index threshold values. The accuracy of these mapped discharge areas will be 

assessed with field-based ground-truth observations. Atmospheric and water-level data 

would be measured with micrometeorological stations consisting of eddy-covariance and 

energy-balance sensors. Each ET site will also be equipped with rain gages to measure 

precipitation, and a monitoring well equipped with a pressure transducer to monitor 

daily and seasonal groundwater-level fluctuations. Periodic collection of samples and 

additional field measurements will be needed to partition between phreatophytic consumptive use of groundwater, precipitation, and periodic surface water flow. At each ET 

site, precipitation, plant-stem water, soil water, groundwater, and surface water flow, if 

available, could be sampled quarterly and analyzed for stable hydrogen- and oxygenisotope concentrations. The isotope data will be used as a tracer to evaluate the relative 

proportion of source waters (precipitation, groundwater, and possibly surface water) 

contributing to the measured ET. Soil-water content could be measured quarterly using a 

neutron-moisture probe to document seasonal changes in soil-water storage (upper 1 m) 

that occur in response to precipitation, surface water flow, and ET.

Recharge Estimates

Knowing the amount of recharge in the mountainous areas is an important component 

of a water budget. In the past, recharge amounts have been estimated using a variety of 

methods, with generally more sophisticated methods utilized as the processes involved 

in recharge became better known. Recently, more sophisticated methods of estimating 

the amount of recharge to the groundwater system have been developed. These newer 

methods should be used to get more accurate estimates of recharge for water budgets. 

Net infiltration has been used as a proxy for groundwater recharge from infiltration 

(San Juan and others 2010). Net infiltration for the DVRFS was estimated using a 

distributed-parameter method, INFILv3, described by Hevesi and others (2003). As an 

extension and improvement of this method, these existing estimates were refined and 

updated using the more recent Basin Characterization Model (BCM) that has been used 

in the Great Basin (Flint and others 2011). Direct measurement or improved estimates 

of precipitation could be helpful in refining these estimates of recharge. Additionally, 

both INFILv3 and BCM use streamflow estimates as calibration points; collection of 

more streamflow discharge could help to constrain the model.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 53

Interbasin Flow

Knowing the amount of recharge from underflow from adjacent basins would help 

to refine water budgets and assess natural resource damage in a hydrographic basin 

from activities in adjacent basins. Currently there are rough estimates from the NDWR 

Reconnaissance Reports and from several regional groundwater models constructed 

for various uses in southern Nevada. A review of the existing hydrologic and geologic 

data and results from numerical models for both the Death Valley and Colorado flow 

systems could help to refine the amount of interbasin flow in the study area.

Spring Discharges

Establishing baseline conditions for spring discharge and water quality would be useful 

for restoration work, management guidelines and to better understand effects of climate 

change and other anthropogenic impacts to these ecosystems. Currently, several springs 

in the study area are monitored by various Federal agencies using full continuous stage/

discharge streamgages or biennial or quarterly direct discharge measurements. These 

springs are mostly regional springs emanating from the carbonate-rock aquifer. While 

the regional springs play a significant role in evaluating overall water resource viability 

in the study area, more data are needed on important local springs in mountainous areas. 

These data would be useful for assessing water budgets and the potential for climate 

change associated with lessening recharge.

The collection of continuous stage/discharge data is required for calculating spring 

output and assessing seasonal and overall trends. For instance, a drop in stage and discharge at a given spring could indicate potential drawdown from pumping nearby. Not 

every local spring is large enough to support a full streamgage; field reconnaissance to 

assess target springs must be completed.

On those springs that support sensitive species of fish and other animals, water quality 

data are needed to establish baselines and direct conservation efforts. At the very least, 

simple water temperature probes can be installed for monitoring continuous water temperature data. For a more robust solution, continuous water quality probes that collect 

many different chemical parameters (i.e. temperature, conductance, pH, and turbidity) 

can also be considered. Historical baseline conditions of springs could be obtained by 

searching historical records from the 19th and early 20th centuries. Mendenhall (1909) 

has descriptions of springs in the Mojave Desert from the late 19th and early 20th 

centuries.

Streamgaging

Direct measurement of peak flows in natural streams presents a unique challenge in 

the desert environment. During summer monsoons, rain can be localized and peak flows 

on streams can last 30 minutes or less. A worker must essentially be on-site when the 

rain begins in order to measure summer peak flows. During winter rains, peak flows 

can last from several hours to several days but often contain very high sediment and 

debris loads, which make direct measurements extremely difficult and unsafe to attain. 

Acoustic Doppler profiling technology is favored for quickly measuring highly unstable 

elevated flows as measurements can be obtained in as little as 12 minutes. Recent advances in Doppler technology have made it more useful for measuring discharges with 

high sediment loads. Conventional current meter methods can also be used to measure 

discharge in those streams where Doppler would be impractical. Direct measurement 
54 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

of peak flows coupled with long term flow monitoring would greatly aid in assessing 

a more accurate total water budget for surface water. Although less preferable than 

long-term flow monitoring, short-term studies focusing on synoptic streamgaging (i.e. 

performing multiple discharge measurements on the same stream at the same time to 

provide a “snapshot” of conditions) would help improve understanding of where the 

streams lose or gain flow from the groundwater system.

Measurements of peak flows can be made either from a bridge or cableway or by 

wading. Wading is typically very unsafe in desert washes where the water can rise from 

a trickle flow to several feet deep in a short period of time. However, many streamgaging 

sites are located in areas where a bridge or cableway does not exist. In cases where a 

worker cannot enter the water to directly measure, an indirect measurement of discharge 

must be done after the water has receded. High water marks such as debris piles, mud 

lines, and cut marks are flagged and surveyed and an approximate discharge for the 

flood is computed. Indirect methods can be accurate to within 5 percent of true peak 

discharge, but often are only within 20 percent of the peak. More cableways must be 

funded and installed in areas where bridges do not exist.

While channel-mounted up-looking acoustic devices can work well for directly measuring discharge in unwadeable stable channels (for instance, concrete-lined irrigation 

ditches), they do not work well for most natural channels in southern Nevada due to 

scour and fill processes occurring in the channel during flow. Instrumentation installed 

in concrete-lined urban channels in the Las Vegas Valley have issues with vandalism, 

theft, and the potential for urban debris striking and damaging or destroying expensive 

equipment during periods of flow. Additionally, these urban channels undergo annual 

or semi-annual cleaning during which debris is scraped from the channel using heavy 

machinery. Any instrumentation placed in the channel has the potential to be damaged 

during these operations.

Should cableway installation be impractical and direct measurement of discharge 

impossible, a series of crest stage gages (CSGs) could be installed in selected indirect 

measurement reaches. A CSG is a piece of pipe with caps on the top and bottom vertically 

anchored next to a stream. There are a series of holes in the sides of the caps, a wooden 

stick inside the pipe, and powdered cork in a reservoir in the bottom cap. During high 

flows, water enters the bottom of the pipe through the holes in the cap and carries the 

powdered cork up as it rises inside the pipe. As the water recedes a cork line is left on 

the stick, which provides a very reliable high water mark from the flood. High water 

marks in CSGs are more accurate than those determined by debris piles, mud lines, or 

cut marks and help reduce the uncertainty in indirect discharge measurement computations. If several CSGs are installed in a given gaged reach, an accurate high water mark 

profile and slope can be determined. These, in turn, would be used to determine the 

amount of stream discharge that could be used to improve long-term monitoring efforts.

Water Chemistry and Quality

Numerous gaps in water-quality information exist in Southern Nevada and the data 

needed are dependent on the area of interest and the scientific question to be answered. 

An example of a data gap is the lack of information on stable isotopes of hydrogen and 

oxygen in precipitation water. Understanding the modern signature of stable isotopes in 

precipitation relative to groundwater is important in delineating modern from ancient 

recharge and enhances understanding of the sources and flow paths of groundwater and 

the sustainability of groundwater resources. 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 55

Data Repositories

While the USGS maintains a large database on hydrologic information (NWIS), there 

are hydrologic data collected by various governmental and scientific organizations that 

are not contained within these national databases and thus cannot be used for answering questions concerning management of the natural and cultural resources of the study 

area. Some effort needs to be put forth to capture these data and enter them into NWIS 

for use by scientists working in southern Nevada, as well as the general public.

References

Advanced Concepts and Technologies International. 2010. Las Vegas Wash monitoring and characterization study: ecotoxicologic screening assessment of selected contaminants of potential concern in sediment, whole fish, bird eggs, and water, 2007-2008. Prepared for: Southern Nevada Water Authority; 

Department of the Interior, Bureau of Reclamation; Department of the Interior, U.S. Fish and Wildlife 

Service. Online: http://www.lvwash.org/html/resources_library_ecology.html. [2011, Feb 26].

Bedinger, M.S.; Langer, W.H.; Reed, J.E. 1989. Ground-water hydrology. In: Bedinger, M.S.; Sargent, 

K.A.; Langer, W.H., eds. Studies of geology and hydrology in the Basin and Range Province, southwestern United States, for isolation of high-level radioactive waste - characterization of the Death Valley Region, Nevada and California. Professional Paper 1370–F. U.S. Department of the Interior, U.S. 

Geological Survey: 28-35.

Belcher, W.R.; Bedinger, M.S.; Back, J.T.; Sweetkind, D.S. 2009. Interbasin flow in the Great Basin with 

special reference to the southern Funeral Mountains and the source of Furnace Creek springs, Death 

Valley, California, U.S. Journal of Hydrology. 369:30-43. 

Benotti, M.J.; Stanford, B.D.; Snyder, S.A. 2010. Impact of drought on wastewater contaminants in an 

urban water supply. Journal of Environmental Quality. 39:1196-1200.

Bevans, H.E.; Goodbred, S.L.; Miesner, J.F.; Watkins, S.A.; Gross, T.S.; Denslow, N.D.; Schoeb, T. 1996. 

Synthetic organic compounds and carp endocrinology and histology in Las Vegas Wash and Las Vegas 

and Callville Bays of Lake Mead, Nevada, 1992 and 1995. Water-Resources Investigations Report 

96–4266. U.S. Department of the Interior, U.S. Geological Survey. 12 p.

Cardinalli, J.L.; Roach, L.M.; Rush, F.E.; Vasey, B.J., comps. 1968. State of Nevada hydrographic areas: 

Nevada Division of Water Resources map, 1:500,000 scale. In: Rush, F.E. Index of hydrographic areas 

in Nevada. Information Report 6. Nevada Division of Water Resources. 38 p.

Carpenter, E. 1915. Ground water in southeastern Nevada. Water-Supply Paper 365. U.S. Department of 

the Interior, U.S. Geological Survey. 86 p.

Cizdziel, J.V.; Hinners, T.A.; Cross, C.L.; Pollard, J.E. 2003. Distribution of mercury in the tissues of five 

species of freshwater fish from Lake Mead, USA. Journal of Environmental Monitoring. 5:802–807.

Crouch, N.T. 2003. Investigation of the effects of perchlorate on thyroid and reproductive system functions in goldfish. University Park, PA: Pennsylvania State University. 40 p. Thesis.

DeMeo, G.A.; Laczniak, R.J.; Boyd, R.A.; Smith, J.L.; Nylund, W.E. 2003. Estimated ground-water discharge by evapotranspiration from Death Valley, California, 1197-2001: Water-Resources Investigations Report 03-4254, 27 p. Available at: http://pubs.usgs.gov/wri/wrir034254/wrir034254.pdf.

DeMeo, G.A.; Smith, J.L.; Damar, N.A.; Darnell, Jon. 2008. Quantifying ground-water and surface-water 

discharge from evapotranspiration processes in 12 hydrographic areas of the Colorado regional groundwater flow system, Nevada, Utah, and Arizona. Scientific Investigations Report 2008-5116. U.S. Department of the Interior, U.S. Geological Survey. 22 p. 

Eakin, T.E. 1966. A regional interbasin ground water system in the White River area, southeastern Nevada. Water Resources Research. 2(2):251-271.

Eakin, T.E.; Moore, D.O. 1964. Uniformity of discharge of Muddy River springs, southeastern Nevada, 

and relation to interbasin movement of ground water. In: Geological survey research. 1964. Professional Paper 501-D. U.S. Department of the Interior, U.S. Geological Survey: D171–D176.

Eakin, T.E.; Winograd, I.J. 1965. Interbasin movement of ground water in south-central Nevada: some 

implications. [Abstract]. In: 1964 Geological Society of America: Special Paper 82. 52 p.

Faunt, C.C.; D’Agnese, F.A.; O’Brien, G.M. 2010. Hydrology. In: Belcher, W.R.; Sweetkind, D.S., eds. 

Death Valley regional groundwater flow system, Nevada and California: Hydrogeologic framework 

and transient groundwater flow model. Professional Paper 1711. U.S. Department of the Interior, U.S. 

Geological Survey. 137-159.

Fenneman, N.M. 1931. Physiography of western United States. New York: McGraw-Hill Book Company, 

Inc. 534 p.
56 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Fetter, C.W. 2001. Applied hydrogeology. 4th ed. Upper Saddle River, NJ: Prentice-Hall. 598 p.

Fisher, C.D.; Lingren, E.; Dawson, W.R. 1972. Drinking patterns and behavior of Australian desert birds 

in relation to their ecology and abundance. Condor. 74:111-136. 

Fleishman, E.; Murphy, D.D.; Sada, D.W. 2006. Effects of environmental heterogeneity and disturbance 

on the native and non-native flora of desert springs. Biological Invasions. 8:1091-1101.

Flint, A.L; Flint, L.E.; Masbruch, M.D. 2011, Appendix 3: Input, calibration, uncertainty, and limitations 

of the Basin Characterization Model. In: Heilweil, V.M.; Brooks, L.E. (eds.). Conceptual model of the 

Great Basin carbonate and alluvial aquifer system. Scientific Investigations Report 2010-5193. U.S. 

Department of the Interior, U.S. Geological Survey. 6 p.

Freeze, R.A.; Cherry, J.A. 1979. Groundwater. Englewood Cliffs, NJ: Prentice-Hall. 604 p.

Goodbred, S.L.; Leiker, T.J.; Patino, R.; Jenkins, J.A.; Denslow, N.D.,; Orsak, E.; Rosen, M.R. 2007. 

Organic chemical concentrations and reproductive biomarkers in common carp (Cyprinus carpio) collected from two areas in Lake Mead, Nevada, May 1999 – May 2000. Data Series Report 286. U.S. 

Department of the Interior, U.S. Geological Survey. 18 p. Online: http://pubs.er.usgs.gov/usgspubs/ds/

ds286 [2012, Jan. 18].

Grose, T.L.; Smith, G.I. 1989. Geology. In: Bedinger, M.S.; Sargent, K.A.; and Langer, W.H. (eds.). Studies of geology and hydrology in the Basin and Range Province, southwestern United States, for isolation of high-level radioactive waste. Professional Paper 1370-F. U.S. Department of the Interior, U.S. 

Geological Survey: 5-19. 

Gubanich, A.A.; Panik, H.R. 1986. Avian use of waterholes in pinyon-juniper. In: Everett, R.L. (comp.) 

Proceedings of the pinyon-juniper conference. Gen. Tech. Rep.INT-215. Ogden, UT: U.S. Department 

of Agriculture, Forest Service, Intermountain Research Station: 534-540.

Harrill, J.R.; Gates, J.S.; Thomas, J.M. 1988. Major ground-water flow systems in the Great Basin region 

of Nevada, Utah, and adjacent states. U.S. Geological Survey Hydrologic Investigations Atlas HA694-C. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey. 1:1,000,000; [Projection 

unknown]; colored. 2 sheets. [Online]. Available: http://pubs.er.usgs.gov/publication/ha694C. [2012, 

Oct 29].

Harrill, J.R.; Prudic, D.E. 1998. Aquifer systems in the Great Basin region of Nevada, Utah, and adjacent 

states. Professional Paper 1409-A. U.S. Department of the Interior, U.S. Geological Survey. 66 p.

Hershey, R. L. 1989. Hydrogeology and hydrogeochemistry of the Spring Mountains, Clark County, Nevada. Las Vegas, NV: University of Nevada. Thesis.

Hevesi, J.A.; Flint, A.L.; Flint, L.E. 2003, Simulation of net infiltration and potential recharge using a 

distributed-parameter watershed model of the Death Valley Region, Nevada and California. WaterResources Investigations Report 03-4090. U.S. Geological Survey. 161 p.

Hinck, J.E.; Blazer, V.S.; Denslow, N.D.; Echols, K.R.; Gross, T.S.; May, T.W.; Anderson, P.J.; Coyle, J.J.; 

Tillitt, D.E. 2007. Chemical contaminants, health indicators, and reproductive biomarker responses in 

fish from the Colorado River and its tributaries. Science of the Total Environment. 378:376-402.

Hughes, J.L. 1966. Some aspects of the hydrogeology of the Spring Mountains and Pahrump Valley, 

Nevada, and environs, as determined by spring evaluation. Reno, NV: University of Nevada, Reno, 

Mackay School of Mines. Thesis.

Hunt, C.B.; Robinson, T.W.; Bowles, W.A.; Washburn, A.L. 1966. Hydrologic basin Death Valley California. Professional Paper 494-B. U.S. Department of the Interior, U.S. Geological Survey: B1–B147.

Justet, L.; Paces, J.B.; Beard, L. Sue; Wilson, J.W. [In preparation]. Investigating the sources of groundwater to springs in Black Canyon, south of Hoover Dam, Lake Mead National Recreation Area, Nevada 

and Arizona. Scientific Investigations Report. Reston, VA: U.S. Department of the Interior, U.S. Geological Survey. 

Kramer, J.L. 2009. Mercury concentrations in muscle tissue from sportfish in Lake Mead, Nevada. Las 

Vegas, NV: University of Nevada, Las Vegas. Thesis. 

Laczniak, R.J.; Smith, J.L.; DeMeo, G.A. 2006. Annual ground-water discharge by evapotranspiration 

from areas of spring-fed riparian vegetation along the eastern margin of Death Valley, 2000-02: U.S. 

Geological Survey Scientific Investigations Report 2006-5145, 36 p. Available at: http://pubs.water.

usgs.gov/sir2006-5145.

Laczniak, R.J.; DeMeo, G.A.; Reiner, S.R.; Smith, J.L.; Nylund, W.E. 1999. Estimates of ground-water 

discharge as determined from measurements of evapotranspiration, Ash Meadows Area, Nye County, 

Nevada. Water-Resources Investigations Report 99-4079. U.S. Department of the Interior, U.S. Geological Survey. 70 p.

Laczniak, R.J.; Flint, A.L.; Moreo. M.T.; Knochenmus, L.A.; Lundmark, K.W.; Pohll, Greg; Carroll, 

R.W.H.; Smith, J.L.; Welborn, T.L.; Heilweil, V.M.; Pavelko, M.T.; Hershey, R.L.; Thomas, J.M.; Earman, Sam; Lyles, B.F. 2007. Ground-water budgets. In: Welch, A.H.; Bright, D.J.; Knochenmus, L.A., 

eds. Water resources of the Basin and Range carbonate-rock aquifer system, White Pine County, Nevada, and adjacent areas in Nevada and Utah. Scientific Investigations Report 2007-5262. U.S. Department of the Interior, U.S. Geological Survey. 96 p.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 57

Laczniak, R.J.; Smith, J.L.; Elliott, P.E.; DeMeo, G.A.; Chatigny, M.A.; Roemer, G.J. 2001. Ground-water 

discharge determined from estimates of evapotranspiration, Death Valley regional flow system, Nevada 

and California. Water-Resources Investigations Report 2001-4195. U.S. Department of the Interior, 

U.S. Geological Survey. 51 p.

Leiker, T.J.; Abney, S.R.; Goodbred, S.L.; Rosen, M.R. 2009. Identification of methyl triclosan and halogenated analogues in both male common carp (Cyprinus carpio) from Las Vegas Bay and semipermeable 

membrane devices from Las Vegas Wash, Nevada. Science of the Total Environment. 407:2102-2114. 

Linder, G.; Little, E.E. 2009. Competing risks and the development of adaptive management plans for 

water resources: field reconnaissance investigation of risks to fishes and other aquatic biota exposed 

to endocrine disrupting compounds (EDCs) in Lake Mead, Nevada, USA. In: Proceedings, World environmental and water resources congress 2009; May 17-21, 2009; Kansas City, MO. Reston, VA: 

American Institute of Civil Engineers. 567 p.

Matsuka, Paul. 2011. Colorado River accounting and water use report Arizona, California, and Nevada 

Calendar Year 2010. Boulder City, NV: U.S. Department of the Interior, Bureau of Reclamation. 50 p.

Maxey, G.B.; Jameson, C.H. 1948. Geology and water resources of Las Vegas, Pahrump, and Indian 

Springs Valleys: Nye and Clarke Counties, Nevada. Water Resources Bulletin 5. Carson, NV: State of 

Nevada, Office of the State Engineer.

Maxey, G.B.; Eakin, T.E. 1949, Ground water in White River Valley, White Pine, Nye, and Lincoln Counties, Nevada. Water Resources Bulletin Number 8. Carson, NV: Nevada State Engineer. 59 p. 

Mendenhall, W.C. 1909. Some desert watering places in southeastern California and southwestern Nevada. Water-Supply Paper 224. U.S. Department of the Interior, U.S. Geological Survey. 86 p.

Mifflin, M.D. 1968. Delineation of ground-water flow systems in Nevada. Technical Report Series H-W: 

Hydrology and water resources publication No. 4. Reno, NV: Desert Research Institute, University of 

Nevada System. 103 p.

Mifflin, M.D.; Hess, J.W. 1969. Regional carbonate flow systems in Nevada. Journal of Hydrology. 

43:217-237.

Miller, D.M.; Esque, T.C.; Bedford, D.R.; Finn, S.; Webb, R.E.; Hughson, D.L. 2007. Appendix G – Ecological conceptual models. In: Chung-MacCoubrey, A.L.; Truitt, R.E.; Caudill, C.C.; Rodhouse, T.J.; Irvine, K.M.; Siderius, J.R.; Chang, V.K. 2008. Mojave Desert Network vital signs monitoring plan. NPS/

MOJN/NRR—2008/057. Fort Collins, CO: U.S. Department of the Interior, National Park Service. 

Moran, M.J.; Veley, R.J. [In preparation]. Evaluating lake stratification and temporal trends using nearcontinuous water-quality data from automated profiling systems for water years 2005-2009, Lake 

Mead, Nevada and Arizona. Scientific Investigations Report 2011-XXXX. U.S. Department of the Interior, U.S. Geological Survey. XX p. 

Moreo, M.T.; Halford, K.J.; La Camera, R.J.; Laczniak, R.J. 2003. Estimated ground-water withdrawals 

from the Death Valley regional flow system, Nevada and California, 1913-98. Water-Resources Investigations Report 2003-4245. U.S. Department of the Interior, U.S. Geological Survey. 28 p. Online: 

http://pubs.usgs.gov/wri/wrir034245/. [2012, February 8].

Moreo, M.T.; Justet, Leigh. 2008. Update to the ground-water withdrawals database for the Death Valley 

regional ground-water flow system, Nevada and California, 1913-2003. U.S. Geological Survey Data 

Series 340. 10 p. U.S. Department of the Interior, U.S. Geological Survey. Online: http://pubs.usgs.gov/

ds/340/. [2012, Oct 29].

Myers, M.J.; Resh, V.H. 1999. Spring-formed wetlands of the arid west: Islands of aquatic invertebrate 

biodiversity. In: Batzer, D.B.; Radar, R.B.; Wissiner, S.A.,eds. Invertebrates in freshwater wetlands of 

North America: ecology and management. New York, NY: John Wiley and Sons: 811-828.

Nachlinger, J.L.; Reese.G.A. 1996. Plant community classification of the Spring Mountains National Recreation Area, Clark and Nye Counties, Nevada. Submitted to USDA Forest Service, Humboldt-Toiyabe 

National Forest, Spring Mountains National Recreation Area, Las Vegas, NV. Reno, NV: The Nature 

Conservancy, Northern Nevada Office.

Nevada Department of Wildlife. 2011. Fish Nevada, mercury in the environment. Online: http://ndow.org/

fish/health/#southern. [2011, June 2].

Osemwengie, L.I.; Gerstenberger, S.L 2004. Levels of synthetic musk compounds in municipal wastewater for potential estimation of biota exposure in receiving waters. Journal of Environmental Monitoring. 

6:533-539.

Patiño, R.; Goodbred, S.L.; Draugelis-Dale, R.; Barry, C.E.; Foott, J.S.; Wainscott, M.R.; Gross, T.S.; 

Covay, K.J. 2003. Morphometric and histopathological parameters of gonadal development in adult 

common carp from contaminated and reference sites in Lake Mead, Nevada. Journal of Aquatic Animal 

Health. 15:55-68. 

Planert, M.; Williams, J.S. 1995. Ground water atlas of the United States, Segment 1, California, Nevada. 

Hydrologic Investigations Atlas 730-B. U.S. Department of the Interior, U.S. Geological Survey. 28 p. 
58 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Pohlmann, K.F.; Campagna, D.J.; Chapman, J.B.; Earman, S. 1998. Investigation of the origin of springs 

in the Lake Mead National Recreation Area. Publication 41161. Las Vegas, NV: Desert Research Institute. 83 p. 

Purser, M.D. 2002. Spring Mountains National Recreation Area: an update on selected springs from the 

Springs Restoration Project. U.S. Department of Agriculture, Forest Service, Humboldt-Toiyabe National Forest.

Rosen, M.R.; Turner, K.; Goodbred, S.L.; Miller, L.M., eds. 2012. A synthesis of aquatic science for 

management of Lakes Mead and Mohave: U.S. Geological Survey Circular 1381, 162 p. Available at: 

http://pubs.usgs.gov/circ/1381/.

Rosen, M.R.; Alvarez, D.A.; Goodbred, S.L.; Leiker, T.J.; Patiño, R. 2010. Sources and distribution of 

organic compounds using passive samplers in Lake Mead National Recreation Area, Nevada and Arizona, and their implications for potential effects on aquatic biota. Journal of Environmental Quality. 

39(4):1161-1172. 

Rosen M.R.; Van Metre, P.C. 2010. Assessment of multiple sources of anthropogenic and natural chemical 

inputs to a morphologically complex basin, Lake Mead, USA. Palaeogeography, Palaeoclimatology, 

Palaeoecology. 294:30-43.

Rush, F.E. 1968. Index of hydrographic areas in Nevada. Information Report 6. Nevada Division of Water 

Resources. 38 p.

Sada, D.W. 2008. Synecology of a springsnail (Prosobranchia: Family Hydrobiidae) assemblage in a 

western U.S. thermal spring province. The Veliger. 50:59-71.

Sada, D.W., Fleishman, E.; Murphy, D.D. 2005. Associations among spring-dependent aquatic assemblages and environmental and land use gradients in a Mojave Desert mountain range. Diversity and 

Distributions. 11:981-99.

Sada, D.W.; Nachlinger, J. 1998. Spring Mountains ecosystem: Vulnerability of spring-fed aquatic and 

riparian systems to biodiversity loss. Part II. Springs sampled during 1997. Unpublished report on file 

at: U.S. Bureau of Land Management, Las Vegas, NV. 

Sada, D.W.; Nachlinger, J.L. 1996. Spring Mountains ecosystem: vulnerability of spring-fed aquatic and 

riparian systems to biodiversity loss. Unpublished report on file at: U.S. Fish and Wildlife Service, Las 

Vegas, NV. 

San Juan, C.A.; Belcher, W.R.; Laczniak, R.J.; Putnam, H.M. 2010. Hydrologic components for model development. In: Belcher, W.R.; Sweetkind, D.S. (eds.) Death Valley regional ground-water flow system, 

Nevada and California: Hydrogeologic framework and transient ground-water flow model. Professional 

Paper 1711. U.S. Department of the Interior, U.S. Geological Survey: 95-132. 

Shimshack J.P.; Ward, M.B.; Beatty, T.K.M. 2007. Mercury advisories: information, education, and fish 

consumption. Journal of Environmental Economics and Management. 53(2):158-179.

Skudlarek, E., ed. 2008. 2007 Nevada priority wetlands inventory. Prepared for Nevada Division of State 

Parks. Carson City, NV. 51 p.

Snyder, E.; Kelly, K.; Van der Kraak, G.; Fitzgerals, S.; Crouch, N.; Snyder, S. 2002. Perchlorate in Lake 

Mead: field investigation of potential effects on fish thyroid and reproductive function. SETAC Annual 

Conference; November 16-20, 2002; Salt Lake City, UT (abstract). American Water Works Association.

Snyder, S.A.; Keith, T.L.; Verbrugge, D.A.; Snyder, E.M.; Gross, T.S.; Kannan, K.; Geisy, J.P. 1999. Analytical methods for detection of selected estrogenic compounds in aqueous mixtures. Environmental 

Science and Technology. 33:2814–2830.

U.S. Environmental Protection Agency. 2001. Mercury update: Impact of fish advisories. Fact Sheet. 

EPA-823-F-01-011. Washington, DC: Office of Water. 10 p. Online: http://nepis.epa.gov/Exe/ZyPURL.

cgi?Dockey=P1000QD9.txt [2012, Oct 29].

U.S. Geological Survey. [In preparation]. Lake Mead National Recreation Area aquatic ecosystem. In: 

Rosen, M.R.; Turner, K.; Goodbred, S.L. (eds.). Reston, VA: U.S. Geological Survey.

Williams, P.L.; Koenig, W.D. 1980. Water dependence of birds in a temperate oak woodland. Auk. 

97:339-350.

Winograd, I.J.; Fridrich, C.F.; Sweetkind, D.; Belcher, W.R.; Thomas, J.M. 2005. Comment on ‘‘Testing 

the interbasin flow hypothesis at Death Valley, California.” EOS, Transactions of the American Geophysical Union. 86:295–296.

Winograd, I.J.; Thordarson, W. 1975. Hydrologic and hydrochemical framework, south-central Great Basin, Nevada-California, with special reference to the Nevada Test Site. Professional Paper 712-C. U.S. 

Department of the Interior, U.S. Geological Survey: C1 - C126.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 59

Chapter 4

Invasive Species in Southern Nevada

Matthew Brooks, Steven Ostoja, and Jeanne Chambers

Introduction

Southern Nevada contains a wide range of topographies, elevations, and climatic 

zones emblematic of its position at the ecotone between the Mojave Desert, Great Basin, and Colorado Plateau ecoregions. These varied environmental conditions support 

a high degree of biological diversity (Chapter 1), but they also provide opportunities 

for a wide range of invasive species. In addition, the population center of the Las Vegas 

valley, and the agricultural areas scattered throughout Clark, Lincoln, and Nye counties, all connected by a network of roads and highways, plus ephemeral and perennial 

watercourses, provide abundant opportunities for new invaders to be transported into 

and within southern Nevada (Brooks 2009; Brooks and Lair 2009).

Invasive species are a concern for land managers because they can compete directly 

with native species (Brooks 2000; Chambers and others 2007; DeFalco and others 2003, 

2007; Mazzola and others 2010), change habitat conditions (Brooks and Esque 2002; 

Esque and others 2010; Miller and others 2011), and alter ecosystem properties (Brooks 

and Matchett 2006; Brooks and Pyke 2001; Evans and others 2001). Many invasive 

species have already established and spread to the point that they are now considered 

to pose significant problems in southern Nevada. However, there are likely many more 

that have either not been transported to or colonized the region, or have established but 

for various reasons not spread or increased in abundance to the point where they have 

a significant impact. Land managers must understand both current and potential future 

problems posed by invasive species to appropriately prioritize management actions.

This chapter addresses Sub-goal 1.2 in the SNAP Science Research Strategy 

(table 1.3; Turner and others 2009), which is to protect southern Nevada’s ecosystems 

from the adverse impacts of invasive species. It provides a brief overview of the key 

concepts associated with the ecology and management of invasive species, and includes 

information relevant to all five strategic goals identified by the National Invasive Species Council: prevention, early detection and rapid response, control and management, 

restoration, and organizational collaboration (National Invasive Species Council 2001, 

2008). Restoration also is discussed in a broader context in Chapters 5 and 7. This 

chapter does not present a comprehensive review of all invasive species or associated 

land management issues in southern Nevada, but rather uses key species of concern to 

illustrate invasion ecology concepts and management strategies. It is focused on terrestrial 

and aquatic plants and animals, and does not address potential invasive taxa from the 

other Kingdoms. The information presented herein is intended to provide a foundation 

upon which land management plans can be developed and project-level decisions can 

be made relative to the management of invasive species in southern Nevada.
60 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Overview of Invasive Species Management

Executive Order 13112 issued by President Clinton in 1999 called for the establish-

ment of the inter-departmental National Invasive Species Council (NISC) and directed 

its members to create a national plan to serve as a comprehensive blueprint for Federal 

action on invasive species. This plan was published in 2001 (National Invasive Species 

Council 2001) and was updated in 2008 (National Invasive Species Council 2008). It 

identifies five strategic goals: prevention, early detection and rapid response, control 

and management, restoration, and organizational collaboration. It also includes priority 

strategic action plans with objectives and implementation tasks for 2008 through 2012. 

These documents provide the guiding principles and priorities for invasive species 

management on Federal lands, including those in southern Nevada.

Invasive species are defined as “a species that is 1) non-native (or alien) to the 

ecosystem under consideration and 2) whose introduction causes or is likely to cause 

economic or environmental harm or harm to human health” (National Invasive Species 

Council 2001). Many non-native species do not cause harm, and are actually beneficial 

to humans (e.g., crop species). Others are clearly invasive and harmful outside of their 

native range (e.g., European starling). Still other non-native species are considered in-

vasive by some, but beneficial or otherwise desirable by others (e.g., some ornamental 

plants, wild and free roaming horses and burros). Land managers, policy makers, and 

society in general must determine which non-native species are invasive and pose the 

greatest threats, and which are the most important to actively manage.

Species invasions proceed through the general phases of transport (long distance 

dispersal), colonization, establishment, and spread (Booth and others 2010). Each stage 

presents unique challenges and opportunities for management actions to control invasive 

species. As a general rule, preventing transport and colonization of potential invaders 

is the most effective approach to invasive species management. This is accomplished 

by state and Federal noxious species lists and associated quarantine and inspection 

processes preventing the import and sale of these species as a first and most effective 

line of defense.

There is also a need for early detection, prioritization, and rapid response to man-

age invading species that slip through the inspection and prevention cracks. Because 

there are more species than can be managed, a prioritization process is key to refining 

early detection plans and to improving the detectability of the highest priority species. 

Depending on the types of existing information and resources available to process the 

information, a generalized, prioritized, or optimized monitoring plan can be developed 

to improve the efficacy of monitoring efforts (Brooks and Klinger 2009; fig. 4.1). These 

same concepts can be used to prioritize sites and species for control efforts. Species 

invasions often stall at the establishment phase when spread of local populations may 

be constrained by dispersal and/or environmental barriers (Richardson and others 2000). 

This lag in spread may persist for decades, offering the best opportunity to prioritize 

and control locally established populations.

Understanding the mechanisms of propagule pressure and resource availability 

can facilitate both detection and control efforts (Brooks 2009; Mazzola and others 

2010; fig. 4.2). Propagule pressure is related to the number or density of seeds and 

other plant parts capable of dispersing and establishing. Resource availability refers to 

amount of resources necessary for plant growth. A generalized monitoring plan can be 

developed with a basic understanding of where propagule pressure is likely to be 

highest (e.g., along roadsides, near urban or agricultural centers) and where resource 

availability is highest (e.g. riparian areas, mid elevation ecosystems, intermittent 

washes, roadsides) (Brooks 2009). In addition, depending on the relative significance 

of propagule pressure or resource availability, management actions can either focus 

on reducing numbers of plants and propagules (e.g., herbicides, mechanical thinning) 

or reducing resource availability (e.g., increasing nutrient uptake by soil microbes or 

promoting the growth of competitive plants).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 61

Figure 4.1—Steps for developing 

early detection monitoring plans 

(reprinted with permission from 

Brooks and Klinger 2009).

Figure 4.2—Main factors affecting plant invasions and management responses (modified with 

permission from Brooks and 

Lusk 2008).
62 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

The Interagency Weed Sentry Project in Clark County, Nevada, was a significant 

early detection effort that began in 2004 with protocol development and lasted through 

2009. It was focused on surveying roadsides, trails, and shorelines (Lake Mead and 

Lake Mojave) to detect and record the location of new plant invaders (Abella and 

others 2009). These survey areas represent centers of propagule dispersal and locally 

high resource availability, and corridors of movement of species among regions 

(Brooks and Lair 2009). However, other recognized pathways of invasion in the 

Mojave Desert occur along riparian and dry wash corridors (Abella and others 2009; 

Brooks 2009), and it is possible that many species are missed by not surveying these areas. 

The Weed Sentry Program also focused search efforts on a subset of likely invaders with 

the most potential to cause the greatest management problems. Although this approach 

ignored established species, some of which cause the greatest management problems 

(e.g., Bromus spp. that alter fire regimes) (Brooks and Esque 2002; Brooks and Pyke 

2001), it provided for a more efficient survey approach for newly invading species 

(Abella and others 2009; Brooks and Klinger 2009). This early detection program was 

discontinued in 2010, but agencies have continued to inventory invasive species on their 

own lands through various methods including aerial surveys and incidental observations 

associated with other field efforts.

Once new populations of invading species are identified, they need to be prioritized for control efforts. Species prioritization is typically based on relative threats 

posed, dispersal and spread potential, current range and extent patterns, and in some 

cases feasibility of control (Warner and others 2003). Site prioritization considers the 

conservation value of the site, the location relative to other nascent populations (especially if it is on the leading edge of the invasion front), and feasibility of control at the 

site. Control efforts may include chemical, mechanical, or cultural treatments, alone 

or in combination with each other. Follow-up control treatments are often required to 

improve efficacy.

Although much of invasive species management is focused on detection, prioritization, and control efforts, the most efficient and effective way to manage these species 

is to restore or maintain resistance of southern Nevada ecosystems to invasion. For 

example, functional diversity of plants is positively correlated with resistance to invasion (Brooks and Chambers 2011), so managing ecosystems to restore or maintain a 

wide array of plant life forms can hinder plant invasions. More detailed discussion of 

this topic is presented in Chapters 1 and 7.

Invasive Plants

Uplands

What are upland invasive plants and how did they get here?—The majority of invasive plant species that dominate upland areas in southern Nevada are annual life forms 

(Brooks and Esque 2002). Annuals complete their entire lifecycle in 1 year, germinating, growing, reproducing, and dying, typically within the winter to spring time period. 

They are ideally suited to avoid the inhospitable arid conditions that characterize most 

of the year by remaining dormant as seeds in the seedbank. Seeds also provide an ideal 

mechanism for dispersal, allowing annual species to spread both within and among 

areas (Brooks 2009).

Invasive annual grasses are significant components of all southern Nevada ecosystem types except for the alpine and bristlecone pine ecosystem types. Cheatgrass 

(Bromus tectorum) is found mostly in the mixed conifer, piñon-juniper, sagebrush, 

and blackbrush/shadscale types. Within the Mojave Desert scrub ecosystem, red 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 63

brome (Bromus rubens) dominates the upper elevations, and Mediterranean split-grass 

(Schismus barbatus, Schismus arabicus) the lower elevations. The most widespread 

invasive forb is red-stemmed filaree (Erodium cicutarium), which occurs in significant 

numbers from the piñon-juniper, ecosystem all the way down to the lower elevations of 

Mojave Desert scrub. Other species of note include various mustard species (Brassica 

tournefortii, Hirshfeldia incana, Sisymbrium irio, Sisymbrium altissimum, Malcomia 

africana), which occur mostly within the Mojave Desert scrub type. Burr buttercup 

(Ceratocephala testiculata), prickly Russian thistle (Salsola tragus), and Russian 

knapweed (Acroptilon repens) are common invaders in sagebrush, piñon-juniper, and 

mixed-conifer ecosystems. The invasive perennial green fountaingrass (Pennisetum 

setaceum) also is escaping ornamental plantings and spreading by windblown and sheet 

flooded seed along dry washes much as it has done in the southern Mojave Desert and 

Sonoran Desert (Matthew Brooks, personal observation while living and working in the 

Las Vegas Valley during the 2000s). Specific locations of spread in southern Nevada 

are from ornamental planting in the Las Vegas valley and Laughlin areas into upland 

springs in the Newberry Mountains and along the shorelines of Lake Mohave and Lake 

Mead (C. Deuser, personal communication).

What are effects of upland invasive plants?—The greatest and most well documented threat that annual invasive plants pose to upland areas of southern Nevada is the 

alteration of fire regimes (Chapter 5). Most of southern Nevada is characterized by 

Mojave Desert scrub, which, because of its relatively low native plant cover, has experienced little historic fire. Accordingly, species that inhabit this ecosystem type have 

generally not evolved tolerance to fire (Brooks and Minnich 2006). Cheatgrass and 

red brome colonized North America during the late 1800s, have spread into southern 

Nevada, and since at least the 1930s have filled the interspaces between native perennial plants and persisted as standing fuels creating a continuous fuelbed that can carry 

fire. These same invasive grasses typically increase in dominance following fire and 

promote a shortened fire return interval that facilitates type-conversion of native shrublands into non-native invasive grasslands. Fire is considered one of the primary threats 

to the recovery of the desert tortoise (Gopherus agassizii), a Federally threatened species (USFWS 1994). Fire in Mojave Desert scrub also may have negative effects on 

forage production, aesthetic and recreational resources of value, and soil stabilization 

(Chapter 5).

Invasive plants also can outcompete individual native plants for limiting resources, 

especially in the seedling stage (e.g., Defalco and others 2003, 2007), although it is unknown what the net effects of competition are on native populations and communities. 

In addition, the seeds of some invasive plants (e.g., red brome, red-stemmed filaree) 

are eaten and also dispersed by native granivores, although these seeds may have differing nutritional quality compared to native species (Kelnick and MacMahon 1985). 

The desert tortoise will consume standing crops of red brome if there is little else to eat 

(Esque 1994), and this may cause physiological problems associated with potassium 

levels (Nagy and others 1998).

How can upland invasive plants be managed?—Annual plants are notoriously difficult to manage. Their seeds are easily dispersed and often remain viable for many 

years. Preventing their transport into new areas of southern Nevada is the best first line 

of defense, followed by eradication or containment of nascent populations (Brooks 

2009). Washing of equipment and removal of propagules from shoes and clothing 

before leaving infested areas also can help reduce dispersal rates (Brooks and Lusk 

2008). Repeated treatment over a period of years, typically with herbicides, is generally required until the soil seedbank becomes exhausted. Supplemental watering to 
64 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

stimulate seeds to germination may help expedite multi-year control efforts. However, 

repeated control treatments of the same type, especially herbicide treatments, may lead 

to selection for resistant invasive plant genotypes and thus complicate future control 

efforts (Radosevich and others 1997).

Management aimed at increasing the ecological condition of degraded ecosystems 

and restoring disturbed ecosystems also are viable strategies for managing invasive plant 

species (Chapters 5 and 7). Resistance to annual bromes is significantly increased by native perennial species, especially grasses and forbs, which are their strongest competitors 

(Allen and others 2002; Booth and others 2003; Chambers and others 2007). Because 

sagebrush, piñon-juniper, and mixed conifer ecosystems evolved with fire and periodic 

disturbance, vegetation management treatments that reinitiate succession and maintain 

high structural and functional diversity can increase resistance to invasion and prevent 

conversion to invasive species dominance following disturbances like fire or drought. 

Wildland use fire, prescribed fire, and mechanical treatments can be used to decrease 

woody species dominance, prevent high severity fire, and increase the competitive abilities of native grasses and forbs (Brown and others 2000; Pyke 2011). Due to inherently 

low resistance of Mojave Desert scrub ecosystems to invaders, management must focus 

on protection and eliminating or reducing stressors such as fire, dispersed recreational 

activities, ORV use, and overgrazing by wild horses, burros, and cattle.

Riparian/Aquatic and Springs

What are riparian/aquatic invasive plants and how did they get here?—Riparian 

and spring ecosystems are characterized by both annual and perennial invasive plant 

species but the most apparent are often perennials (Dudley 2009). Perennial species 

that have clonal or rhizomatous life forms or that are capable of root sprouting are 

ideally suited to survive the scouring floods and sediment deposition that often typify 

arid riparian ecosystems. These species also are often highly competitive with native 

riparian species. The most infamous perennial invader in southern Nevada is tamarisk 

or saltcedar (primarily Tamarix ramossisima, T. aphylla), which occurs in both riparian 

and spring ecosystems. This species was introduced to North America as an ornamental in the 1800s, and has subsequently spread throughout the continent (Dudley 2009). 

Most invasive species in these ecosystems are facultative or obligate riparian species 

that require elevated water tables for their establishment and persistence (USDA Plants 

Database 2012). Facultative or obligate riparian species in southern Nevada include the 

perennials, giant reed (Arundo donax), Russian olive (Elaeagnus angustifolia), camelthorn (Alhagi pseudalhagi), and perennial pepperweed (Lepidium latifolium), and the 

annual rabbitsfoot grass (Polypogon monspeliensis). Upland species that utilize seasonal increases in water availability or that occur at the periphery of these ecosystems 

include Russian knapweed (Acroptilon repens), invasive annual grasses such as ripgut 

brome (Bromus diandrus), red brome, and cheatgrass, and invasive mustards.

There are few aquatic plant invaders in southern Nevada, and those that are currently 

present do not pose serious threats. However, there are a few poised to invade that do 

pose real threats. Eurasian water-milfoil (Myriophyllum spicatum) has been reported 

along the Colorado River in the vicinity of Parker Arizona (Jacono and Richarson 2011) 

and giant salvinia (Salvinia molesta) has been reported farther downstream at the Imperial National Wildlife Refuge (Howard 2011).

What are the effects of riparian/aquatic invasive plants?—Because of their growth 

over many years, perennial species can attain large size, displace native vegetation, and 

significantly affect the physiographic structure of vegetation stands (Dudley 2009). 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 65

For example, conversion of native riparian vegetation to tamarisk stands can affect 

wildlife habitat quality and ecosystem properties associated with fire and hydrologic regimes (Dudley 2009). However, this ecosystem continues to support a diversity 

of species including two birds of conservation concern—the yellow-billed cuckoo 

(Coccyzus americanus) and the southwestern willow flycatcher (Empidonax traillii 

extimus)—that utilize tamarisk stands to forage and even nest in when native vegetation is unavailable (Bateman and Ostoja 2012). Giant reed, Russian olive, perennial 

pepperweed, Russian knapweed, and camelthorn can also significantly alter the structure of riparian communities, but are currently confined to a few localized populations 

in southern Nevada.

Eurasian water-milfoil and giant salvinia have the potential to choke out waterways, 

increase eutrophication, disrupt food webs, and otherwise significantly alter aquatic 

habitats of southern Nevada (Howard 2011; Jacono and Richarson 2011). These changes 

could threaten everything from endemic animals such as pupfish and spring snails, to 

game species such as sunfish, bass, and trout.

How can riparian/aquatic invasive plants be managed?—Challenges associated 

with controlling and managing riparian invasive plants differ from those of uplands. 

Many perennial species have persistent below-ground roots and rhizomes that make 

eradicating populations difficult (e.g., giant reed, perennial pepperweed). Also, seeds 

and other propagules are readily transported in flowing water and by the animals that 

utilized these ecosystems. Mechanical or prescribed fire treatments are often used initially to reduce aboveground biomass and stimulate resource re-allocation from belowground to aboveground tissue. Then, after regrowth has occurred, chemical treatments 

are used as a follow up to kill the plants. Treatment of resprouts may be necessary 

during subsequent years. Recently a biocontrol leaf eating beetle introduced to control 

tamarisk has spread into southern Nevada along the Virgin River corridor and is in 

the process of killing or at least reducing the vigor of tamarisk plants in that region 

(Bateman and others 2010). Long-term success of control treatments often requires 

restoration with native species and continued monitoring to detect reoccurring or new 

invasions.

Options for controlling aquatic plants are limited once the species have established 

local populations. Educational programs promoting watercraft washing and periodic 

inspections at entry points are potentially the most effective way to prevent transport 

and colonization of new waterways.

Invasive Animals

Terrestrial

What are terrestrial invasive animals and how did they get here?—While perhaps 

less conspicuous and less abundant than invasive plants, invasive animals can have 

significant ecological and economic consequences in southern Nevada. Small cryptic 

species like Argentine ants (Linepithema humile) and imported red fire ants (Solenopsis spp.) are difficult to detect and can be challenging to identify. Red imported 

fire ants, native to South America, were originally introduced to the southern United 

States between 1918 and 1930. While the ecological effects of this introduction are 

not fully known, existing data suggest cause for concern (Dowell and others 1997; 

Porter and others 1988). Native to Brazil and Argentina, Argentine ants are thought to 

have been originally introduced by coffee ships in the southern United States and have 

slowly moved west in landscape material and potted plants (Suarez and others 2001). 
66 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Africanized honey bees have also recently invaded southern Nevada from initial introductions in South America. Other non-native species like the heavily managed wild 

horses (Equus ferus) and burros (Equus asinus) represent a historical place holder for 

the American West and are thought by many to be a national cultural treasure, emblematic of the pioneer spirit of the West. In fact, the 1971 Wild Free-Roaming Horse and 

Burro Act (Public Law 92-195) specifically states, that “It is the policy of Congress 

that wild free-roaming horses and burros shall be protected from capture, branding, 

harassment, or death; and to accomplish this they are to be considered in the area where 

presently found, as an integral part of the natural system of the public lands...” Nonetheless, wild horses and burros come with an ecological cost (Abella 2008; Beever and 

Brussard 2004), and could potentially be categorized as invasive species as defined 

by the National Invasive Species Council (National Invasive Species Council 2001) if 

not for their specific exclusion from such distinction. Burros specifically were heavily 

used in the 1800s to assist with mining operations but were released or escaped and 

became wild as operations declined (Abella 2008). Effects of wild or otherwise free 

roaming cattle are also of concern especially near watering sites, and feral dogs (Canis 

familiaris) and cats (Felis catus) can pose significant threats to native animals near 

urbanized areas.

What are the effects of terrestrial invasive animals?—Argentine ants are successful and voracious predators in part because they will combine territories and attack other insects including native ant colonies, lizards, snakes, and small mammals 

(Grover and others 2008). Red imported fire ants compete with native fire ants, prey 

on invertebrates and vertebrates, and may affect plant assemblages by selective seed 

removal. In addition, red imported fire ants prey on solitary bees that pollinate native 

plant species (Vinson 1997). Because these ant species prefer relatively moist areas, 

their impacts will most likely be near urbanized areas and springs, seeps, and riparian 

areas.

Even though wild horses and burros maintain that iconic image of the American West 

and are protected on public lands under the 1971 Wild Free-Roaming Horse and Burro 

Act, some studies suggest they can cause significant ecological effects (Abella 2008; 

Beever and Brussard 2004). Heavy use by horses and burros can result in reduced plant 

cover and diversity and increased soil disturbance and potential erosion. Abella (2008) 

found that wild burros prefer grasses and forbs and are more likely to consume native 

Indian ricegrass (Achnatherum hymenoides) than would be expected by chance. Wild 

horses can cause damage by trampling vegetation, soil compaction, and overgrazing 

(Ostermann-Kelm and others 2008). Bighorn sheep (Ovis canadensis nelson) are reported 

to avoid water sources when wild horses are present and their densities are reduced by 

75% where horses are present (Ostermann-Kelm and others 2008).

The full impact of feral cats and dogs is not well known for southern Nevada, but 

due to extensive urban development there is a continuous supply of feral pets that have 

the potential to directly and indirectly impact native wildlife groups (Denny 1974; 

Lowry 1978). It is known that feral cats and dogs are among the main predators of the 

Federally protected desert tortoise (Bergman and others 2009) in addition to birds and 

other wildlife. Dogs hybridize with native canids (coyotes, Canis latrans, in the case 

for Southern Nevada) and the highest ratio of dog-coyote hybrids is near large human 

population centers (Mahan and others 1978). Packs of feral dogs also pose a direct 

threat to humans and could negatively affect recreational use of public lands in southern 

Nevada.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 67

How can terrestrial invasive animals be managed?—Control of invasive ants can 

be difficult. Aside from baiting and chemical control, few options exist and even these 

may have some residual impact to non-target groups. Because wild horses and burros 

are Federally protected on public lands under the Wild Horse and Burro Act, local resource managers need to review options and assess impacts against desired conditions 

when it comes to their control and management. Removals are conducted, but require 

continued monitoring and follow-up control efforts. Local exclosures can be used to 

protect critical habitat features and resources, and fertility control is a recent option 

that requires additional study. Feral cat and dog control can also be very tricky. Trapping is considered an effective control strategy for feral cats and dogs, but requires 

close coordination with adoption groups and is usually coupled with fertility control. 

(Barnett 1986). However these methods are difficult to implement due to negative public responses associated with animal rights concerns as well as complexity and costs.

Aquatic

What are aquatic invasive animals and how did they get here?—Several notable 

aquatic invasive species exist in southern Nevada including the quagga mussel (Dreissena rostriformis), bullfrogs (Rana catesbeiana), red swamp crayfish (Procambarus 

clarkii), and various species of fishes (Bradley and Deacon 1967). Quagga mussels 

are freshwater mollusks and are perhaps the most notorious aquatic invasive species 

in the region. This small zebra-shell-patterned mussel has spread across the western 

United States as larva in boat livewells and bilges and as adults when attached to boat 

hulls, engines, aquatic weeds, or other surfaces. Quagga mussels are present in Lake 

Mead and Lake Mojave and may have spread to various upland freshwater sources. 

The American bullfrog was introduced to southern Nevada in the 1920s (Jennings and 

Hayes 1994) and is now widespread in wetlands in Las Vegas Valley, Indian Springs 

Valley, and the Muddy and Virgin River valleys and in several upland springs in the 

region. The red swamp crayfish is native to the southeastern United States, is commonly used as bait by fishermen, and has become established in southern Nevada. 

Various species of fishes, including the mosquitofish (Gambusia spp.), red shiner 

(Notropis leutrensis), shortfin molly (Poecilia mexicana), cichlids (Oreochromis spp.), 

and tilapia (Tilapia spp.) have been introduced to southern Nevada. The mosquitofish 

was intentionally introduced to the region for control of mosquitos in ponds and other 

abandoned water sources (Bence 1988). Cichlids were introduced in various fresh water sites around Lake Mead NRA. Red shiners are thought to have been introduced 

through the emptying of bait buckets, but it is also a common aquarium fish (Nico and 

Fuller 2010; Nico and others 2011).

What are the effects of aquatic invasive animals?—Quagga mussels directly threatened water supplies and associated water diversion and management operations since 

they can clog pipes and compromise water intake systems. In addition, they can clog 

engines and encrust boats, docks, and associated facilities, alter the aquatic food web, 

impact sport fishing, and litter beaches with their small sharp shells. The economic cost 

associated with quaggas can easily reach millions of dollars.

Bullfrogs are aggressive and voracious predators of native toads and frogs, reptiles, 

small mammals, and birds; some of which are listed under the Endangered Species Act. 

Along the Muddy River, bullfrogs and red swamp crawfish are thought to be responsible 

for the elimination of the relict leopard frog (Bradford and others 2004) and have preyed 

on other amphibians in other regions (Gramradt and Kats 1996).
68 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

The mosquitofish, red shiner, and cichlids have adversely affected native invertebrates, amphibians, and fishes (USFWS 1995). Mosquitofish have been known to 

harm, kill, and outcompete other small fishes, including natives (Haynes and Cashner 

1995; Hubbs and Deacon 1964) and prey on native treefrog (Hyla regilla) tadpoles 

(Goodsell and Kats 1999). In addition, mosquitofish have been shown to contribute to 

algal blooms by directly preying on zooplankton grazers (Nico and others 2011), suggesting impacts on aquatic food webs. Shortfin mollies prey on larval fish including the 

Federally endangered Moapa dace (Moapa coriacea) and Moapa White River springfish (Crenichthys baileyi moapae) (Scoppettonne 1993). Information from the 1980s 

indicates that relict leopard frogs and cichlid fish coexisted in Blue Point and Rogers 

Springs (Courtenay and Deacon 1983), and although recent surveys indicate that relict 

leopard frogs still occur at these sites (collection sites 17 and 18; Bradford and others 

2004) there is evidence of substantial predation by cichlids and other non-native fishes 

on larval frogs and eggs (J. Jaeger, personal communication).

How can aquatic invasive animals be managed?—Prevention is the key to quagga 

mussel control because even if adults are killed the larvae have the ability to evade control measure, spread great distances, and later recolonize. It is important that all mud, 

plants, and aquatic organisms are cleaned and removed before vehicles or equipment 

are transported. Gear, equipment, and vehicles that come in contact with water should 

be drained, dried, and cleaned before moving (boat washing locations can be found on 

the internet). Bullfrog control can be difficult, but gigging has proven effective in some 

sites. Physical methods for control of bullfrogs and crayfish include de-watering and 

temporary habitat removal, but this can also affect native species. Because crayfish, 

and to some degree bullfrogs, are able to travel long distances over ground, physical 

methods have limited utility. However, an exclusion fence installed by the U.S. Bureau 

of Land Management around Perkins Pond in the Warm Springs area, following dewatering to remove bullfrogs, has been able to keep this frog from recolonizing. Crayfish 

moving up the Muddy River will likely threaten the pond in the future, but the hope is 

that the fence will also limit colonization by this species (J. Jaeger, personal communication). Chemical control methods include biocides, piscicides (e.g. rotenone), and 

pheromones, but the effective dosage required often kills other non-target organisms 

(McClay 2000; Oberg 1967).

Knowledge Gaps

Most invasive plant research from southern Nevada and the greater Mojave Desert 

has focused primarily on a few species, most notably red brome and cheatgrass in 

upland areas, tamarisk in riparian areas, and animal invaders in aquatic habitats. Even 

with this information, many key questions still remain relative to these well-studied 

species: (1) what are their net effects on native plants and animals; (2) what are the best 

combinations of control and restoration strategies to eradicate them and prevent their 

re-establishment, or at least minimize their dominance and negative effects; and (3) how 

will their abundance and effects change in the future? Very little is known about the 

potential effects of the vast majority of invasive plants, making it difficult to prioritize 

among them for early detection and rapid response control efforts. This information is 

especially urgent for some notable species, such as green fountaingrass, giant salvinia, 

and Eurasian water-milfoil, that are poised to colonize or spread from localized populations in southern Nevada.

Even less research has focused on the effects of invasive and non-native animals 

within the Mojave Desert; most information must be inferred from studies done in 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 69

other regions, which can pose extrapolation problems. For example, ecological effects 

of non-native wild horses, burros, and cattle may differ in the more arid Mojave Desert 

from elsewhere in the Intermountain West where most of the studies on these species 

have occurred. In contrast, some species that are generalist predators likely have similar 

effects wherever they occur. Species such as feral dogs may pose obvious threats to prey 

species such as individual desert tortoises, but it is much more difficult to estimate their 

effects on desert tortoise populations. In general, the net effects of invasive animals on 

natural resources of value are of ultimate concern, yet there is very little information 

available to make these predictions.

Among the five strategic goals for invasive species management identified by the 

National Invasive Species Council (2008), there is probably the least urgent need for new 

information regarding prevention and organizational collaboration. There is somewhat of 

a need for information on control and management, although numerous control studies 

from both within and beyond southern Nevada provide decent information on how to 

control some of the most problematic perennial invasive species (e.g., tamarisk). Effective 

control strategies for annual invasive species remain limited by soil seedbanks that often 

elude control treatments and ongoing stressors that promote the spread and persistence 

of these species. The greatest need is for information to help inform early detection and 

rapid response and restoration efforts including minimizing or eliminating stressors. 

The former requires knowledge of the areas that are most susceptible to invasion and 

an understanding of the potential effects of newly invading species to prioritize efforts 

to monitor and control them. Unfortunately, published literature may not always be the 

best source of data because species that are documented to cause significant problems 

in other ecosystems may or may not do the same in southern Nevada. Local assessments are clearly needed. Restoration treatments could provide the ultimate defense 

against invasions because robust native communities are more resistant to invasion 

than are depleted communities. Unfortunately, restoration actions have a high degree 

of failure in the Mojave Desert without significant investments of time and funding, 

which is often a limiting factor. The specific aspects of native communities that confer 

the greatest resistance to invasion are just beginning to be understood (e.g. Abella and 

Newton 2009; Abella and others 2012). Thus, information is most needed to address 

prioritization and restoration actions tailored for southern Nevada, and to understand 

how various stressors described in Chapter 2 interact with and affect species invasions.

Management Implications

Prevention is clearly the first line of defense against invasive species. The most effectively managed invasive species are those that are kept from being transported to, 

and colonizing within, southern Nevada. Species can be transported accidentally by 

people and equipment, and this mode of transport can be minimized by washing tools 

and vehicles, especially when leaving sites with known local infestations. Other species 

can be transported purposefully into a region, then spread on their own into wildland 

areas. These purposeful transportations can be discouraged by preventative regulations 

for state and Federal noxious species. Success may also be realized through public education and partnerships with the agricultural and ornamental horticultural community 

for other high priority species to help find less invasive alternative species.

Early detection and rapid response requires significant pre-planning to be effective. 

Prioritization is necessary to focus detection efforts on sites that are most invasible and 

species that are most likely to cause significant management problems if they are allowed to colonize, establish, and spread. Information provided in the introduction section 

explains how the effectiveness of early detection monitoring plans can be maximized.
70 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Control and management also require prioritization to triage nascent populations for 

rapid response control actions. It is also important to continue monitoring and retreating 

these areas for a few years to ensure there are no surviving individuals. Ideally, monitoring should be designed to evaluate the efficacy of control treatments, and adjust them 

accordingly in the future. If the ultimate objectives of control treatments are to benefit 

other species (e.g. natives), biodiversity (e.g. native species diversity), or ecosystem 

properties (e.g. reduce fire spread potential), then those factors should also be targeted 

for monitoring to determine if objectives are met.

Restoration of robust native ecosystems can increase the resilience of degraded areas 

to subsequent biological invasions. Unfortunately, the specific factors that increase resistance to invasion are poorly understood, so restoration guidelines are generally focused 

on maximizing characteristics like abundance and diversity of native species, diversity 

of functional types, and groups of species important for critical aspects of ecosystem 

function (e.g. nutrient cycling). All restoration projects should be carefully monitored 

to both determine if their restoration targets are achieved and to evaluate their effects 

on invasion resistance.

Organizational collaboration is required to effectively manage invasive species because 

they truly know no political boundaries, and if neighboring land owners are not doing 

their part, then efforts to prevent invasions and the problems that follow will often be in 

vain. Sharing resources and expertise by Federal and local agencies through cooperative 

agreements and through the interagency Southern Nevada Restoration Team can assist 

with the process of collaboration. Cooperative Weed Management Areas (CWMA) are 

formal groups that can also facilitate this process, especially in ensuring that species 

priorities are consistent across land management units and that coordinated management 

plans are maintained over time.

References

Abella, S.R. 2008. A systematic review of wild burro grazing effects on Mojave Desert Vegetation USA. 

Environmental Management. 41:809-819.

Abella, S.R.; Newton, A.C. 2009. A systematic review of species performance and treatment effectiveness 

for revegetation in the Mojave Desert, USA. In: Fernandez-Bernal, A.; De La Rosa, M.A. (eds.). Arid 

environments and wind erosion. Hauppauge, NY: Nova Science Publishers, Inc.: 45-74

Abella, S.R.; Craig, D.J.; Smith, S.D.; Newton, A.C. 2012. Identifying native vegetation for reducing 

exotic species during the restoration of desert ecosystems. Restoration Ecology. 20:781-787.

Abella, S.R.; Spenser, J.E.; Hoines, J.; Nazarchyk, C. 2009. Assessing and exotic plant surveying program in the Mojave Desert, Clark County, Nevada, USA. Environmental Monitoring and Assessment. 

151:221-230.

Allen, C.R.; Lutz, R.S; Demarais, S. 1995. Red imported fire ant impacts on northern bobwhite populations. Ecological Applications. 5:632-638.

Allen, C.D.; Savage, M.; Falk, D.A.; Suckling, K.F.; Swetnam, T.W.; Shulke, T.; Stacey, P.B.; Morgan, P.; 

Hoffman, M.; Klinger, J.T. 2002. Ecological restoration of southwestern ponderosa pine ecosystems: a 

broad perspective. Ecological Applications. 12:1418-1433.

Barnett, B. D. 1986. Eradication and control of feral and free-ranging dogs in the Galapagos Islands. Proceedings Vertebrate Pest Conference. 12:359-368.

Bateman, H.L.; Dudley, T.L.; Bean, D.W.; Ostoja, S.M.; Hultine, K.R.; Kuhn, M.J. 2010. A river system 

to watch: documenting the effects of saltcedar (Tamarix spp.) biocontrol in the Virgin River Valley. 

Ecological Restoration. 28:405-410.

Bateman, H.L.; Ostoja, S.M. 2012. Invasive woody plants affect the composition of native lizard and 

small mammal communities in riparian woodlands. Animal Conservation. 15:294-304.

Beever, E.A.; Brussard, P.F. 2004. Community- and landscape-level responses of reptiles and small mammals to feral-horse grazing in the Great Basin. Journal of Arid Environments. 59:271–297.

Bence, J.R. 1988. Indirect effects and biological control of mosquitoes by mosquitofish. Journal of Applied Ecology. 25:505-521.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 71

Bergman, D; Breck, S.; Bender, S. 2009. Dogs gone wild: feral dog damage in the United States. USDA 

National Wildlife Research Center—Staff Publications. Paper 862. Online: http://digitalcommons.unl.

edu/icwdm_usdanwrc/862 [2012, Oct 29].

Booth, B.D.; Murphy, S.D.; Swanton, C.J. 2010. Invasive plant ecology in natural and agricultural systems. Second ed. Oxfordshire, UK: CAB International. 214 p.

Booth, M.S.; Caldwell, M.M.; Stark, J.M. 2003. Overlapping resource use in three Great Basin species: 

implications for community invasibility and vegetation dynamics. Journal of Ecology. 91:36-48.

Bradford D.F.; Jaeger, J.R.; Jennings, R.D. 2004. Population status and distribution of a decimated amphibian, the relict leopard frog (Rana onca). Southwestern Naturalist. 49:218-228.

Bradley, W.G.; Deacon, J.E. 1967. The biotic communities of southern Nevada. Nevada State Museum 

Anthropological Papers. 13(Part 4): 201-273.

Brooks, M.L. 2000. Competition between alien annual grasses and native annual plants in the Mojave 

Desert. American Midland Naturalist. 144:92-108.

Brooks, M.L. 2009. Spatial and temporal distribution of non-native plants in upland areas of the Mojave 

Desert. In: Webb, R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, E.V.; Miller, D.M. 

(eds.) The Mojave Desert: ecosystem processes and sustainability. Reno, NV: University of Nevada 

Press: 101-124.

Brooks, M.L.; Chambers. J.C. 2011. Resistance to invasion and resilience to fire in desert shrublands of 

North America. Rangeland Ecology and Management. 64:431-429.

Brooks, M.L.; Esque, T.C. 2002. Alien annual plants and wildfire in desert tortoise habitat: status, ecological effects, and management. Chelonian Conservation and Biology. 4:330-340.

Brooks, M.L.; Klinger, R.C. 2009. Practical considerations for detecting and monitoring plant invasions. 

In: Inderjit (ed.). Management of non-native invasive plant species. Heidelberg, Germany: Springer: 

168-175.

Brooks, M.L.; Lair, B.M. 2009. Ecological effects of vehicular routes in a desert ecosystem. In: Webb, 

R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, E.V.; Miller, D.M. (eds.) The Mojave Desert: ecosystem processes and sustainability. Reno, NV: University of Nevada Press: 168-195.

Brooks, M.L.; Lusk, M. 2008. Fire management and invasive plants: a handbook. Arlington, VA: U.S. 

Department of the Interior, Fish and Wildlife Service, 27 p.

Brooks, M.L.; Matchett, J.R. 2006. Spatial and temporal patterns of wildfires in the Mojave Desert, 1980-

2004. Journal of Arid Environments. 67:148-164.

Brooks, M.L.; Minnich, R.A. 2006. Southeastern Deserts Bioregion. In: Sugihara, N.G.; van Wagtendonk, 

J.W.; Shaffer, K.E.; Fites-Kaufman, J.; Thode, A.E. (eds). Fire in California’s ecosystems. Berkeley, 

CA: University of California Press: 391-414.

Brooks, M.L.; Pyke, D. 2001. Invasive plants and fire in the deserts of North America. In: Galley, K.; Wilson, T. (eds.). Proceedings of the invasive species workshop: The role of fire in the control and spread 

of invasive species; Fire conference 2000: The first national congress on fire ecology, prevention and 

management. Miscell. Publ. No. 11. Tallahassee, FL: Tall Timbers Research Station: 1-14.

Chambers, J.C.; Roundy, B.A.. Blank, R.R.; Meyer, S.E.; Whittaker. A. 2007. What makes Great Basin 

sagebrush ecosystems invasible by Bromus tectorum? Ecological Monographs. 77:117-145.

Courtenay, W.R., Jr.; Deacon, J E. 1983. Fish introductions in the American southwest: a case history of 

Rogers Spring, Nevada. Southwestern Naturalist. 28:221-224.

DeFalco, L.A.; Fernandez, G C.J.; Nowak, R.S. 2007. Variation in the establishment of a non-native annual grass influences competitive interactions with Mojave Desert perennials. Biological Invasions. 

9:293-307.

Denny, R.N. 1974. The impact of uncontrolled dogs on wildlife and livestock. Transactions North AmericanWildlife and Natural Resources Conference. 39:257-291.

Deuser, Curt. 2009. [Personal communication]. May 1. Boulder City, NV: U.S. Department of the Interior, 

National Park Service, Lake Mead National Recreational Area.

Dowell, R.V.; Gilbert, A.; Sorensen, J. 1997. Red imported fire ant found in California. California Plant 

Pest and Disease Report. 16(3-4):50-55.

Dudley, T.L 2009. Invasive plants in Mojave Desert riparian areas. In: Webb, R.H.; Fenstermaker, L.F.; 

Heaton, J.S.; Hughson, D.L.; McDonald, E.V.; Miller, D.M. (eds.). The Mojave Desert: ecosystem processes and sustainability. Reno, NV: University of Nevada Press: 125-155.

Esque, T.C. 1994. Diet and diet selection of the desert tortoise (Gopherus agassizii) in the northeast Mojave Desert. M.S. Thesis. Fort Collins: Colorado State University. 243 p.

Evans, R.D.; Rimer, R.; Sperry, L.; Belnap, J. 2001. Exotic plant invasion alters nitrogen dynamics in an 

arid grassland. Ecological Applications. 11:1301-1310.

Goodsell, J.A.; Kats, L.B. 1999. Effect of introduced mosquitofish on Pacific treefrogs and the role of 

alternate prey. Conservation Biology. 13:921-924.
72 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Gramradt, S.C.; Kats, L.B. 1996. Effect of introduced crayfish and mosquitofish on California newts. 

Conservation Biology. 10:1155-1162.

Grover, C.D.; Dayton, K.C.; Menke, S.B; Holway, D.A. 2008. Effects of aphids on foliar foraging by Argentine ants and the resulting effects on other arthropods. Ecological Entomology. 33:101–106.

Haynes J.L.; Cashner, R.C. 1995. Life history and population dynamics of the western mosquitofish: a 

comparison of natural and introduced populations. Journal of Fish Biology. 46:1026-1041.

Howard, V. 2011. Salvinia molesta. USGS Nonindigenous Aquatic Species Database, Gainseville, FL. Revision Date: 2/12/2008. Online: http://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=941. [2012, 

Oct 29].

Hubbs, C.; Deacon, J.E. 1964. Additional introductions of tropical fishes into southern Nevada. Southwestern Naturalist. 9:249-251.

Jacono, C.C.; Richerson, M.M. 2011. Myriophyllum spicatum. USGS Nonindigenous Aquatic Species 

Database, Gainesville, FL. Revision Date: 10/15/2008. Online: http://nas.er.usgs.gov/queries/factsheet.

aspx?SpeciesID=237 [2012, Oct 29].

Jaeger, J. 2012. [Personal communication]. May 2. Las Vegas, NV: University of Nevada, Las Vegas, 

School of Life Sciences.

Jennings, M.R.; Hayes, M.P. 1994. Decline of native ranid frogs in the desert southwest. In: Brown, P.R.; 

Wright, J.W. (eds.). Herpetology of the North American deserts—Proceedings of a symposium. Special 

Publ. No 5. Southwestern Herpetologists Society: 183-211.

Kelrick, M.A.; MacMahon, J.A. 1985. Nutritional and physical attributes of seed of some common sagebrush steppe plants: some implications for ecological theory and management. Journal of Range Management. 38:56-69.

Lenth, B.; Brennan, M.; Knight, R.L. 2006. The effects of dogs on wildlife communities. Final research 

report submitted to: Boulder County Open Space and Mountain Parks. Fort Collins: Colorado State 

University.

Lowry, D.A. 1978. Domestic dogs as predators on deer. Wildlife Society Bulletin. 6:38-39.

Mahan, B.R.; Gipson, P.S.; Case, R. M. 1978. Characteristics and distribution of coyote X dog hybrids 

collected in Nebraska. American Midland Naturalist. 100:408-415.

Mazzola, M.B.; Chambers, J.C.; Pyke, D.; Schupp, E.W.; Blank, R.R.; Allcock, K.G.; Nowak, R.S. 2010. 

Effects of resource availability and propagule supply on native species recruitment in sagebrush ecosystems invaded by Bromus tectorum. Biological Invasions. doi 10.1007/s10530-010-9846-0.

McClay, W. 2000. Rotenone use in North America (1988-1997). Fisheries. 25:15-21.

Nagy, K.A.; Henen, B.T.; Vyas, D.B. 1998. Nutritional quality of native and introduced food plants of wild 

desert tortoises. Journal of Herpetology. 32:260-267.

Miller, R.F; Knick, S.T.; Pyke, D.A.; Meinke, C.W.; Hanser, S.E.; Wisdom, M.J.; Hild, A.L. 2011. Characteristics of sagebrush habitats and limitations to long-term conservation. In: Knick, S.T.; Connelly, 

J.W. (eds.). Greater sage-grouse: ecology and conservation of a landscape scale species and its habitat. 

Studies in Avian Biology No. 38. Berkeley, CA: University of California Press: 145-184.

National Invasive Species Council. 2001. Meeting the invasive species challenge: National Invasive 

Species Management Plan. Washington, DC; U.S. Department of Agriculture, National Invasive Species Information Center. 80 p. Online: http://www.invasivespeciesinfo.gov/docs/council/mp.pdf. 

[2012, Oct 29].

National Invasive Species Council. 2008. 2008-2012 National invasive species management plan. Washington, DC; U.S. Department of Agriculture, National Invasive Species Information Center. 35 p. Online: http://www.invasivespeciesinfo.gov/council/mp2008.pdf. [2012, Oct 29].

Nico, L.; Fuller, P. 2010. Cyprinella lutrensis. USGS Nonindigenous Aquatic Species Databas. Gainesville, FL. U.S. Department of the Interior, U.S. Geological Survey. Online: http://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=518[2012, Oct 29].

Nico, L.; Fuller, P.; Jacobs, G.; Cannister, M.; Larson, J.; Fusaro, A. 2011. Gambusia affinis. USGS Nonindigenous Aquatic Species Database. Revision Date: 11/21/2011. Gainesville, FL: U.S. Department of the 

Interior, U.S. Geological Survey. Online: http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=846. 

[2012, Oct 29].

Oberg, K.E. 1967. On the principal way of attack of rotenone in fish. Ark. Zool. 18:217-220.

Osterman-Kelm, S.; Atwill, E.R.; Rubin, E.S; Jorgensen, M.C.; Boyce, W.M. 2008. Interactions between 

feral horses and desert bighorn sheep at water. Journal of Mammalogy. 89:459-466.

Porter, S.D.; Van Eimeren, B.; Gilbert, L.E. 1988. Invasion of red imported fire ants (Hymenoptera: 

Formicidae): Microgeography of competitive replacement. Annuals of the Entomological Society of 

America. 81:913-918.

Radosevich, S.; Holt, J.; Ghersa, C. 1997. Weed ecology: implications for management. New York, NY: 

John Wiley and Sons. 589 p.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 73

Richardson, D.M.; Pysek, P.; Rejmanek, M.; Barbour, M.G.; Panetta, F.D.; West, C.J. 2000. Naturalization 

and invasion of alien plants: concepts and definitions. Diversity and Distributions. 6:93-107.

Scoppettonni, G.G. 1993. Interactions between native and nonnative fishes of the upper Muddy River, 

Nevada. Transactions of the American Fisheries Society. 122:599-608.

Suarez A.W.; Holway, D.A.; Case, T.J. 2001. Patterns of spread in biological invasions dominated by 

long-distance jump dispersal: Insights from Argentine ants. Proceedings of the National Academy of 

Sciences. 98:1095–1100.

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/

SNAP-S-R-Strategy-2009r.pdf. [2011, April 6].

U.S. Fish and Wildlife Service. 1994. Desert tortoise (Mojave population) recovery plan. Portland, OR: 

U.S. Department of the Interior, Fish and Wildlife Service. 73 p. Online: http://www.fws.gov/nevada/

desert_tortoise/dt_recovery_plan.html. [2012, Oct 29].

U.S. Fish and Wildlife Service. 1995. Recovery plan for the Virgin River fishes. Denver, CO: U.S. Department of the Interior, Fish and Wildlife Service.. 53 p. Online: http://www.fws.gov/southwest/es/arizona/

Documents/RecoveryPlans/Virgin_River_Fishes_RP.pdf. [2012, Oct 29].

Vinson, S.B. 1997. Invasion of the red imported fire ant (Hymenoptera: Formicidae): spread, biology, and 

impact. American Entomologist. 43:23-39.

Warner, P.J.; Bossard, C.C.; Brooks, M.L.; [and others]. 2003. Criteria for categorizing invasive nonnative plants that threaten wildlands. California Exotic Pest Plant Council and Southwest Vegetation 

Management Association. 
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USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 75

Chapter 5

Fire History, Effects, and Management in 

Southern Nevada

Matthew Brooks, Jeanne Chambers, and Randy McKinley

Introduction

Fire can be both an ecosystem stressor (Chapter 2) and a critical ecosystem process, 

depending on when, where, and under what conditions it occurs on the southern Nevada 

landscape. Fire can also pose hazards to human life and property, particularly in the 

wildland/urban interface (WUI). The challenge faced by land managers is to prevent 

fires from occurring where they are likely to threaten ecosystem integrity or human 

developments, while allowing fires to occur where they will provide ecosystem benefits. The Southern Nevada Agency Partnership (SNAP) Science and Research Strategy 

summarizes this desired outcome with Sub-goal 1.1, which is to manage wildland fire 

to sustain Southern Nevada’s ecosystems (table 1.3; Chapter 1). This chapter provides 

information that will help land managers develop strategies to achieve this goal. It begins with a background section on fire history, spatial and temporal patterns of fire, and 

fire effects for the major ecosystem types of southern Nevada, (table 1.1; Chapter 1). 

Potential fire management actions are then discussed, the overall implications of the 

information to fire management are summarized, and the major knowledge gaps are 

described.

Fire History

Southern Nevada is situated within a broad ecotone between the Central Basin and 

Range of the Cold Desert ecoregion to the north and the Mojave Basin and Range 

of the Warm Desert ecoregion to the south, two regions more commonly recognized 

as the Great Basin and Mojave Desert (Chapter 1). The topography of this region is 

dominated by broad basins separated by isolated mountain ranges that contribute to 

local environmental gradients that translate into highly variable vegetation types and 

fire regimes. The predominant view of fire in this region is focused on the ecosystem 

types that dominate the majority of the landscape, namely Mojave Desert scrub and to 

a lesser extent blackbrush/shadscale (table 1.1; Chapter 1). This view is that fires were 

historically infrequent; all fires are detrimental because they have been historically 

infrequent and native species are not adapted to them, and significant management 

responses are often required to mitigate their negative effects on natural, cultural, and 

recreational resources. Although one or more of these assumptions is likely accurate 

across most of this region, there are some areas that likely do not align with this dogma 

because of their differing fire histories and recovery potential. The probability of fire in 

any ecosystem is a function of sufficient fuel, conducive weather conditions, and sources 

of ignition (van Wagtendonk 2006). These factors vary over the landscape in southern 

Nevada and back through history, so it is erroneous to think that the occurrence of fire 

has been relatively constant across space and time. Understanding the fire history of 
76 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

southern Nevada is essential for evaluating the causes of recent fire trends and placing 

them within the correct evolutionary context to better evaluate their effects, develop 

well justified fire management plans, and manage individual fires appropriately.

Prehistoric Fire Record

The deserts of North America were created during the early Pleistocene (approximately 

2 million year ago) when uplifting mountain ranges established a rainshadow blocking 

storms moving eastward from the Pacific Ocean and northwestward from the Gulf of 

Mexico (Axelrod 1995). In the process, forests and woodlands retreated from lowlands 

and moved into higher elevation refugia. Since the last glacial period at the beginning 

of the Holocene approximately 10,000 years ago, the Mojave Desert and southern Great 

Basin Desert have continuously experienced arid to semi-arid conditions (Van Devender 

1977; Van Devender and Spaulding 1979; Tausch and Nowak 2000; Tausch and others. 

2004). Conditions since then have fluctuated, but generally trended toward increased 

aridity (Van Devender 1977; Van Devender and Spaulding 1979) that has likely caused 

an upslope shift in vegetation formations and their associated fire regimes (McKinley 

and others, in press; Tausch and Nowak 2000; Tausch and others 2004).

Indigenous humans also influenced fire regimes in pre-historic North America 

(Williams 2000), including Paiutes in southern Nevada and Shoshones in eastern 

Nevada (Stewart 1980). Fire was used for hunting game, clearing vegetation, growing 

food, opening pathways of travel, managing pest species, and facilitating the growth 

of vegetation with desirable properties (e.g. basket materials, tobacco, seeds for meal, 

game forage, fuel-breaks). The shift of vegetation formations upslope during the Holocene was likely mirrored by indigenous humans following natural resources necessary 

for survival in the Mojave and Great Basin deserts. In the Mixed Conifer, Piñon and 

Juniper, and Sagebrush Ecosystems of the Mt. Irish area of Lincoln County, fires were 

very frequent from 1550 to 1860 (mean fire return interval 4 years), but then declined 

precipitously between 1861 and 2006 (only two fires in 1883 and 1916) (Biondi and 

others 2011). This transition from frequent to infrequent fire was coincident with EuroAmerican settlement and the displacement of Native Americans in this region during the 

middle 1800s. Accordingly, fire most likely occurred primarily at higher elevations and 

in more mesic riparian areas, both because fuels were more conducive to fire spread and 

ignitions from Native Amreicans were likely more frequent in those areas. In addition, 

current lightning occurrence in southern Nevada is positively correlated with elevation 

due to the orographic effects of terrain on climate (Randerson and others 2004), a physical phenomenon that has likely occurred as long as the mountain ranges of southern 

Nevada have been in existence back through the Holocene and beyond.

With increased aridity, decreased productivity, and decreased human presence over 

prehistoric time, the spatial extent of fire across southern Nevada undoubtedly declined 

and became increasingly isolated within disjunct high elevation areas. A dominance 

shift from perennial grasses to woody non-sprouting shrubs (Spaulding 1990) suggests 

a change in fuelbed characteristics from one that is conducive to fire spread and adapted 

to periodic fire, to one which is less conducive and less resilient to fire (McKinley and 

others, in press; Miller and Wigand 1994). In addition, the change from perennial grasses 

to shrubs suggests a shift of summer rains of the North American monsoon away from 

southern Nevada, and with that shift a decline in the incidence of lightning from summer thunderstorms.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 77

Historic Fire Record

The first accounting of extensive historic fire in southern Nevada was reported by Croft 

(1950) who estimated that 20 percent of the 161,875 ha (400,000 acres) of blackbrush 

(Coloegyne ramossissima) that occurred in the region burned during the late 1930s and 

early 1940s. This time period coincided with a 4-year period of high rainfall and strong 

El Nino-Southern Oscillation (ENSO) signature from 1938-1941, which was one of the 

highest rainfall years on record, eclipsed only by rainfall totals during 1983 and 2005 

(Hereford and others 2006; National Climate Data Center, www.ncdc.noaa.gov). It appears that high rainfall temporarily increased fuel loading and continuity and facilitated 

fire spread. During the mid-century drought from 1942 to 1975 there were relatively 

few fires documented in southern Nevada, followed by a significant increase in fires 

when precipitation began to increase in 1976 (Brooks and others 2007; McKinley and 

others, in press). This has been attributed to low fuel loads and fuelbed continuity and 

infrequent lightning from summer monsoons during the middle decades of the 1900s, 

followed by increases in precipitation and lightning during the latter decades (McKinley 

and others, in press).

Ranchers and U.S. Bureau of Land Management (BLM) staff implemented a program 

of prescribed burning in the late 1930s and into the 1940s to increase forage production for livestock in blackbrush stands of southern Nevada (Croft 1950). Additional 

blackbrush burning likely occurred at least through the 1960s, because a policy review 

during that time by the Range and Forestry Office of BLM in Nevada recommended that 

blackbrush burning continue to increase forage production (Dimock 1960). However, it 

is unlikely that most of these mid-century fires spread extensively considering the low 

productivity of these systems and drought conditions during the middle 1900s.

Current Fire Record

Fire records for recent decades have been derived using point occurrence databases 

publically available for Federal lands in the Mojave Desert (Brooks and Esque 2002; 

Brooks and Matchett 2006; Brooks and Minnich 2006) and other desert regions in North 

America (e.g. Collins and others 2006; Knapp 1997; Schmid and Rogers 1988and others). Although these point occurrence databases include all reported fires, they can also 

contain a high degree of error, up to 30 percent for DOI lands (Brown and others 2002) 

and can therefore be highly misleading. There are also regional sources of fire perimeter 

data that can provide more precise information than that associated with point occurrences (McKinley and others, in press). However, these fire perimeter databases can also 

misrepresent area burned by as much as 18 percent (Kolden and Weisberg 2007) and 

are typically only available for short time intervals within specific geographic areas. In 

contrast, the current fire record results summarized below in this chapter were derived 

using Landsat satellite imagery to precisely document area burned by large fires (≥1,000 

acres) between 1972 and 2007 in Lincoln and Clark Counties (McKinley and others, in 

press). Although these large fires only represent 1-2 percent of the total number of fires 

that occurred during that time interval in southern Nevada, they comprise 93 percent of 

the total area burned.

Approximately one million acres burned in Lincoln and Clark counties as a result of 

116 large fires that occurred during a 36-year period from 1972 through 2007 (McKinley 

and others, in press). A chronology of these fires is graphically portrayed in figure 5.1 

where shades from cool to warm colors represent the chronology of fire occurrence 

beginning with the oldest fires (blue) and ending with the recent fires (red). This figure 

shows that most of the older fires (pre-2005) occurred in Lincoln County, aside from 

a cluster of fires during the 1980s in the Spring Mountains of western Clark County. 
78 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Figure 5.2 illustrates that most of the burned acreage (90%) occurred in areas that had 

not previously burned during the 36-year study period, 8 percent occurred in areas that 

had burned once before, and 2 percent occurred in areas that had burned two or three 

times before during this time period.

The number of fires and area burned from 1972 through 2007 may have been unprecedented in the historic record extending back to the late 1800s (McKinley and others, 

in press). In particular, the 2005 and 2006 fire seasons were extreme events that had 

Figure 5.1—Large fire chronology 1972 through 2007 inclusive (≥1,000 acres). Shades from 

cool to warm colors represent the chronology of fire occurrence beginning with the oldest fires 

(blue) and ending with the recent fires (red) (reprinted with permission from McKinley and others, in press).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 79

a major influence on the fire statistics for both number of fires and total area burned. 

The number of fires and area burned in those 2 years were so statistically anomalous 

that it is appropriate to evaluate trends with and without them included in the analyses. 

When 2005 and 2006 were excluded from the analyses, the number of fires and total 

area burned from 1972 through 2007 actually showed an increase up to the mid-1990s 

followed by a downward trend (fig. 5.3), a pattern that has persisted through 2012 

(Matthew Brooks, personal observation of fire frequency while conducting studies in 

the Mojave Desert). Although the conditions that led to the fires in 2005 and 2006 may 

only occur every century or more (see below), this does not mean large areas will not 

burn in the future.

Figure 5.2—Fire frequency of large fires 1972 through 2007 inclusive (≥1,000 acres) 

(reprinted with permission from McKinley and others, in press).
80 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

These trends must also be considered within the context of the 36-year sampling 

period (1972-2007). Previous studies from the Mojave Desert have reported both 

increasing numbers of fires (1980-1995, Brooks and Esque 2002) and no change in 

number of fires (1980-2004, Brooks and Matchett 2006). The differing conclusions of 

these two previous studies were entirely due to the different timespans of the datasets 

they used. As an extreme example, the conclusions published in Brooks and Matchett 

(2006) may have been very different if the data set included just 1 or 2 additional years 

(2005 and 2006). Thus, fire trends derived from only a few decades of data must be 

evaluated very cautiously, especially in a place like the Mojave Desert where fire occurrence is so episodic.

Temporal and Spatial Patterns of Burning

Evidence presented above from the historic and current fire record suggests that fire 

activity in southern Nevada is primarily associated with the warm (positive) phase of 

the multi-decadal Pacific Decadal Oscillation (PDO) cycle during which perennial fuels 

increase, and secondarily with the El Niño phase of the interannual El Niño-Southern 

Figure 5.3—Patterns over time (1972-2007) for the number of large fires (≥1,000 acres), total area 

burned (log10 acres), mean fire size (log10 acres), and the proportion of burned area classified as 

high severity in Clark and Lincoln counties, Nevada. The shape of the relationship was derived 

from generalized additive models. Dotted lines are 95% confidence bands (modified with permission from McKinley and others, in press).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 81

Oscillation (ENSO) cycle during which fine ephemeral fuels increase. It appears that 

the ENSO effect may not be sufficient alone to promote large fires, and may only kick 

in during the latter part of or soon after a multi-decadal period of high rainfall associated with the PDO (e.g. after 1993, and especially during 2005 and 2006). Although 

intentional burning by humans has at times added significantly to acres burned, these 

fires likely remain small when climatic conditions cause fuelbeds to be sparse.

Non-native annual grasses alter fire regimes worldwide through a process known as 

the grass/fire cycle (D’Antonio and Vitousek 1992; Brooks and others 2004). Species in 

the genera Bromus are specifically associated with changes in the temporal and spatial 

patterns of burning in upland areas of Mojave and Great Basin Deserts (Brooks 1999; 

Brooks and Matchett 2006; Brooks and Pyke 2001; Link and others 2006; Whisenant 

1990). Although these species can undoubtedly alter fire regimes of southern Nevada, 

their influence is ultimately tied to the longer-term PDO and shorter-term ENSO 

cycles. Warm PDO phases are associated with exponential population growth of nonnative annual grasses, such as that documented for Bromus rubens from the late 1970s 

through 1990 in southern Nevada (Hunter 1991). Increasing populations lead to high 

propagule production and dispersal into new areas (Brooks 2009), potentially increasing the regional scope of the grass/fire cycle. The El Niño ENSO phase is associated 

with years of extremely high rainfall that lead to episodic spikes in fuel loads created 

by invasive annual grasses and heightened fire hazards, especially in lower and middle 

elevation shrublands (Brooks and Matchett 2006). The hallmark of the grass/fire cycle 

is a landscape dominated by non-native annual plants, with low abundance of native 

woody species, and short fire return intervals. In southern Nevada, such landscapes are 

currently most common in Lincoln County (fig. 5.2), and fig. 5.4 illustrates how many 

of these landscapes look when burned.

Figure 5.4—A section of the 2005 Southern Nevada Fire Complex in the Tule Desert 

region of Lincoln County, Nevada. This is an area that had burned within the past few 

decades and was dominated by standing dead Bromus spp. biomass at the time of the 

fire (photo credit, Bureau of Land Management, Ely Field Office files).
82 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

One major factor that could decouple fire regimes from the PDO/ENSO cycles is 

related to the potential for the monsoon track to shift farther north and west from its 

current position at the southwest margin of the region (Hereford and others 2006). The 

vast majority of fires that occurred during the past few decades in the Mojave Desert 

have been associated with areas experiencing both high winter rainfall and high summer monsoonal rainfall and lightning, the former boosting fine fuel loads and the latter 

providing ignition sources and extreme wind conditions (J. Tagestad and others, in 

preparation). If the monsoonal track moves further into the Mojave Desert, then fires 

may follow, and if these fires move into areas where fire was historically infrequent 

and conditions are conducive to growth of non-native annual grasses, then a grass/fire 

cycle may emerge in those areas as well. In contrast, if the monsoon moves south and 

eastward, then fires may become less prevalent and the grass/fire cycle may wane as a 

significant land management threat.

Another factor that could affect future fire occurrence is increasing human population. 

More people likely mean more human ignitions. More people also mean more fossil fuel 

combustion that leads to increased rates of regional nitrogen deposition (see Chapter 2). 

Plant productivity, and therefore fuel production, especially non-native herbaceous fuels, 

are primarily influenced by precipitation and soil nitrogen levels (Brooks 2003; Rao and 

Allen 2010). Because elevated CO2 increases water use efficiency of Bromus species, 

it has the potential to exacerbate the problem (Smith and others 2009; Chapter 2).

Alpine and Bristlecone Pine Ecosystems—These ecosystem types are located above 

2,600 m in the Spring Mountains and the Sheep Range. Although lightning is relatively 

frequent in these ecosystems, fuels are sparse and continuity is low and most fires do 

not spread beyond single bristlecone pine (Pinus longaeva) or limber pine (Pinus flexilus) trees (Fryer 2004; Johnson 2001).

Mixed Conifer, Piñon and Juniper, and Sagebrush Ecosystems—These ecosystem 

types are predominantly located in the Spring and Sheep mountain ranges at elevations 

between 1,200 and 3,200 m. Lightning occurs frequently in these ecosystem types. 

These shrublands, woodlands, and forest stands are dominated by sagebrush (Artemisia spp.), chaparral shrubs, juniper (Juniperus spp.), piñon pine, and small stands 

of ponderosa pine, and have fire patterns that are driven mostly by long-term, decadal 

to century-scale PDO patterns of rainfall and perennial fuel accumulation (Brooks and 

Matchett 2006; Littell and others 2009). Continuity and amounts of native perennial 

fuels alone can be sufficient to carry fire under extreme fire weather conditions (i.e. 

high temperatures and wind, and low relatively humidity), and fire is a part of the natural disturbance regime. Years of high rainfall can produce additional herbaceous fuels 

that enhance fuelbeds and potentially further facilitate fire spread, but they also can 

increase live perennial fuel moisture levels that can decrease spread rate. Thus, the net 

effect of high rainfall on fire behavior at high elevations can be hard to predict.

Blackbrush/Shadscale and Mojave Desert Scrub Ecosystems—Fire patterns in 

these low and middle elevation shrublands, dominated by saltbush (Atriplex spp.), creosotebush (Larrea tridentata), and blackbrush, are affected most by short-term, interannual patterns of rainfall and ephemeral herbaceous fuels associated with the ENSO 

cycle (Brooks and Matchett 2006). Fire frequency is higher at the interface with higher 

elevation ecosystem types where fires often start and spread. Continuity and amounts 

of perennial fuels are insufficient alone to carry fire; pulses of herbaceous fuels following periods of high rainfall are necessary to fill the interspaces between perennials 

and allow fire to spread, and fire is not a major part of the natural disturbance regime. 

Fuels created by non-native annual grasses are more persistent than those from native 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 83

forbs, and as such contribute more to fire spread potential (Brooks 1999). Altered fire 

regimes from invasive annual grasses (i.e. the grass/fire cycle) are most prevalent in 

these ecosystem types (Brooks and Matchett 2006).

Riparian and Spring Ecosystems—Fire patterns in riparian zones depend on where 

they occur on the southern Nevada landscape. The major riparian corridors that occur 

along the rivers of southern Nevada are situated at lower elevations within upland areas dominated by Mojave Desert scrub. Pre-historic Holocene and historic conditions 

of perennial grasses and shrubs as an understory beneath canopies of towering cottonwoods supported periodic low to moderate intensity surface fire that spread very rarely 

into the sparse surrounding uplands (Dwire and Kauffman 2003). Thus, fire is part of 

the natural disturbance regime, although at moderately long-return intervals (Petit and 

Naiman 2007). Indigenous humans also used fire during the Holocene to clear riparian 

terraces for agricultural purposes and to promote growth of basketry materials (e.g. 

rushes, reeds, and milkweed). The spread of fires was likely limited by barriers of vegetation gaps, standing water, and narrow bottleneck points along the floodplain where 

gaps occurred in the more consistently dry upland benches. Following the invasion of 

saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia), ladder fuels and 

overall fuel loads increased, resulting in a more frequent and high intensity crown fire 

regime (Busch and Smith 1993; Lovich and others 1998; Busch 1995). In addition, 

the invasion of non-native annual grasses in both the riparian and surrounding uplands 

provides more continuous fuelbeds that likely allow fires to reach greater size now 

than in the past. In contrast, fire patterns in higher elevation riparian zones embedded 

within blackbrush, sagebrush, and mixed conifer uplands are affected more by the fire 

regimes of the surrounding ecosystem types than by the riparian fuels themselves. 

Similarly, patterns of natural fires at isolated springs are controlled by the fire regime 

of the surrounding vegetation. There is also evidence that indigenous humans, and then 

later Anglo settlers, used fire to reduce vegetation cover to facilitate hunting opportunities and enhance water flow rates.

Fire Effects

Fire and Fire Regime Characteristics

Although land management actions focus on individual fires, the ultimate influence 

of fires across landscapes and over time is attributed to fire regimes. The type (ground, 

surface, or crown fire), frequency (i.e., return interval), intensity (heat released), severity (ecological response), size, spatial complexity, and seasonality of fire define the fire 

regime within a given geographic area or vegetation type. Over very long time periods, 

the prevailing fire regime conditions can have a strong influence on the evolution of 

species. When fire regimes are altered (e.g. by plant invasions or land management 

practices) the recovery of the resident species following fire can be compromised and 

landscapes can be converted to new vegetation types that are better adapted to the new 

fire regime (Brooks 2008). Thus, the management of individual fires must be placed 

within the broader context of how they will affect the management of fire regimes.

It must also be understood that all fires are not the same. Unfortunately, the vast 

majority of published studies on fire effects report the effects of “fire” as if it is a 

univariate factor. Multiple aspects of fire behavior, seasonality, and spatial pattern can 

influence the effects of fire. Fire behavior can vary widely based on fuel, weather, and 

ignition characteristic (van Wagtendonk 2006). In addition, rate of spread, residence 

time, flaming zone depth, fuel energy content, fire type (ground, surface, crown), and 
84 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

other factors can influence fire intensity (energy released), which is a primary factor 

associated with fire severity (effects on the environment). The season during which a fire 

occurs can also significantly influence the survivorship of individuals and the responses 

of populations and communities (Fites-Kaufman and others 2006). Fires that occur 

when plants and animals are reproducing are often most damaging because they can 

potentially eliminate recruitment for the year (Fites-Kaufman and others 2006; Shaffer 

and others 2006and others). Survivorship of perennial plants is also lower when they 

are actively growing because below-ground carbohydrate reserves are depleted, whereas 

survivorship is higher when they are dormant because below-ground reserves are at 

their peak (Pyke and others 2010). Survivorship of animals may also be higher when 

they are hibernating or otherwise located below-ground and away from intense heating 

(Shaffer and others 2006). Fires also differ based on their spatial patterns of burning. 

Heterogeneous burns with unburned islands and abundant areas of low fire severity 

provide sources of propagules to recolonize burned areas, thus decreasing recovery 

time to pre-burn conditions. Homogenous complete burns with few unburned islands 

and uniformly moderate to high fire severity are often slower to recover to pre-burn 

conditions unless the resident species are fire adapted. Thus, one should never assume 

similar ecological responses to fire per se, but instead should expect similar responses 

among fires of similar characteristics considering the factors discussed above plus additional site and ecosystem type factors discussed below.

Site Characteristics

The predominant life forms of plants and animals at a site can influence their overall 

responses to fire. Plant life forms with meristem (perennating) tissue located aboveground 

tend to have the highest mortality rates because that life sustaining tissue occurs close 

to the flames and smoldering fuels and is exposed to the highest temperatures during 

fires (Pyke and others 2010). The general exception is when meristems are located far 

aboveground and away from flames with limited ladder fuels to carry fire up into their 

vicinity (e.g. some palm trees). In contrast, plant life forms with meristem tissue or 

dormant seeds located at or below the surface of the mineral soil tend to have the lowest 

mortality rates because they occur where temperatures are lowest during fires (Brooks 

2002). Animal taxa that are more vagile or arboreal can avoid fire-induced mortality 

better that than those that are more sedentary (Shaffer and others 2006). However, susceptibility to mortality among the very young is more a factor of where their nests or 

dens are located, than the vagility of their species. For example, birds that are extremely 

vagile are more adept at avoiding extreme temperatures from fire, but nestlings have 

high mortality rates because they are typically situated within flammable nests located in 

the heart of the fuelbed and combustion zone. Thus, effects of fire on plants and animals 

can vary depending on the types of species. However, the longer term effects of fire on 

subsequent growing conditions or habitat characteristics are generally thought to have 

even greater effects on populations and communities.

The effects of fire can vary greatly depending on the elapsed time since the previous 

fire. Excessively short fire return intervals that do not allow time for individual plants 

to recover or new individuals to establish and reach reproductive maturity can reduce 

the abundance of maladapted species at a site. This is a significant mechanism by which 

vegetation type conversions occur as part of the grass/fire cycle (Brooks 2008). Excessively long fire return intervals that allow the abnormal accumulation of surface and 

ladder fuels can alter fire behavior and similarly reduce the abundance of maladapted 

species.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 85

Relative concern about fire effects within a given area often hinges on the current or 

potential future dominance by invasive non-native plants. These species alone are often 

undesirable from a natural resource management perspective, but when their effects on 

fuelbeds and fire regimes are considered they often become significant fire management 

concerns as well (Brooks 2008).

Other factors such as historical and current land uses and weather patterns (especially 

precipitation) can influence the effects of fire at a particular site. Historically intense land 

use disturbance such as livestock grazing can produce similar effects as antecedent fire, 

including reduced perennial cover, reduced species diversity, and increased dominance 

by invasive plants. Thus, the landscape response to fire in these areas may be similar 

to that associated with short fire return intervals. Similarly, periods of drought before 

burning may reduce a species’ abundance and resource reserves, and drought following burning may hinder its post-fire survival and/or establishment rates, in both cases 

rendering the species less tolerant.

Ecosystem-Specific Effects

Alpine and Bristlecone Pine Ecosystems—Bristlecone pine and limber pine trees 

are thin barked and lack adaptations to fire. These tree species can only survive low 

intensity surface fire or lightning strikes that do not result in complete girdling of the 

cambial tissue (Brooks and Minnich 2006; Fryer 2004; Johnson 2001). Many of these 

long lived trees have multiple scars indicating survival following lightning strikes that 

occurred repeatedly over their 1,000+ year lifespan, but apparently these ignitions did 

not spread to engulf trees and probably did not spread beyond the trees struck. Sparse 

surface fuels result in small fires and low fire intensities that likely had limited effects 

on small woody shrubs and herbaceous species in the understory. As a consequence of 

a warming climate, invasive annual grasses may move upslope and present fine fuel 

management problems in the future, and fire may facilitate this process (table 5.1).

Mixed Conifer Ecosystem—Interior ponderosa pine (Pinus ponderosa var. scopulorum) is one of the most fire-adapted conifer species in North America. Its adaptations 

include open crowns, self-pruning branches, thick bark, thick bud scales, tight needle 

bunches protecting meristems, high foliar moisture, and a deep rooting habit (Howard 

2003). Widely spaced older trees display higher fire survival rates than more densely 

packed and younger trees. White fir (Abies concolor) is a thin barked tree species with 

branches and foliage from top to bottom that make it highly vulnerable to mortality 

from fire. Mountain mahogany (Cercocarpus spp.), Gambel oak (Quercus gambelii), 

manzanita (Arctostaphylos spp.), and snowberry (Symphoricarpos albus) are all elements of the interior chaparral vegetation type often found in the understory of mixed 

conifer sites. All but mountain mahogany are extremely tolerant of fire (Brooks and 

others 2007).

Long intervals without fire allow the accumulation of understory and ladder fuels 

that generally result in higher severity crown fires that can threaten the persistence of 

isolated mixed conifer stands in southern Nevada (table 5.1). High severity events are 

often followed by initial dominance by understory chaparral species that may persist as 

an alternative vegetation type if conditions are no longer conducive to pine establishment. A warming climate may exacerbate this process.
86 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 Table 5.1—Typical fire management concerns associated with site and fire characteristics and guidelines for appropriate fuels management, fires suppression, and Emergency Stabilization and Rehabilitation (ES&R) actions in the major ecosystem types of southern Nevada. Ecosystem type burned Typical fire management concerns Guidelines for appropriate management actions Alpine and Bristlecone pine Fire – Fires that burn more than a few acres and/or com- pletely consume multiple trees. Site – Tree mortality and in- creased down woody fuels. Low tree recruitment post-burn and increased dominance of Bromus spp. could alter fire regime. Fuels – Rarely warranted Suppression – Rarely warranted except to protect small and/or isolated stands if excessive fire spread is likely. ES&R – Rarely warranted unless perhaps to control invasive plants or following excessively large and severe fires. Mixed conifer Fire – High severity crown fire. Long fire return interval that allow excessive fuel accumula- tion. Site – Heavy surface and lad- der fuel loads could lead to high severity crown fire. Wild- land/urban interface (WUI) lim- its fire management options. Fuels – Periodically warranted in the WUI, egress routes, and where surface and ladder fuels have accumulated increasing the risk of large fires. Mechanical treatments may be initially needed, but subsequent treatments should utilize low severity, surface prescribed fire. Follow-up control of invasive plants may be needed during the first few post-treatment years. Suppression – Rarely warranted except in the WUI, egress routes, and where surface and ladder fuels have accumulated increasing the risk of large fires. Low severity surface fire with minimal crowning should be allowed as a natural fire regime component for vegeta- tion management benefits. Follow-up control of invasive plants may be needed during the first few post-fire years. ES&R – May be warranted to stabilize slopes near the WUI or following excessively large and severe fires. Piñon and Juniper Fire – High severity crown fire. Short fire return interval that does not allow re-establish- ment of shrub understory or trees. Site – Dominant invasive annu- als. Short fire return intervals (≤60 years). Fuels – Rarely warranted except in the WUI and egress routes and in shrub-dominated areas exhibiting tree expansion. Prescribed fire may be the more cost-effective over large areas. Follow-up control of invasive plants may be needed during the first few post-fire years. Suppression – Warranted in the WUI, and to prevent large, high severity crown fires, but low severity surface fire in areas of undesir- able tree expansion may be allowed as a natural fire regime component for vegetation management benefits. Follow-up control of inva- sive plants may be needed during the first few post-fire years. ES&R –Warranted to reestablish native plant community characteristics and to control invasive plants if inadequate perennial herba- ceous species and shrubs exist for recovery. Herbicides may allow short-term control but long-term control requires a wider array of management actions, aerial seedings have low to moderate establishment rates. Fire – Large, homogenous fires Site – Dominant invasive annu- als. Short fire return intervals (≤40 years). Fuels – Rarely warranted, except in the WUI and egress routes and perhaps to increase the competitive ability of perennial herbaceous species and prevent invasive annual grass dominance. Prescribed fire rarely warranted except perhaps to create a stand-age mosaic in very old late-successional contiguous stands. Follow-up control of invasive plants may be needed during the first few post-treatment years. Suppression – Warranted in the WUI, and in areas with low abundance of perennial herbaceous species and high risk of conversion to annual invasive grasses. ES&R – May be warranted to reestablish the native community and to control invasive plants if inadequate perennial herbaceous spe- cies and shrubs exist for recovery. Herbicides may allow short-term control but long-term control requires a wider array of management actions, aerial seedings have low to moderate establishment rates.

(continued)
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 87 Blackbrush/ shadscale Fire – Large, homogenous fires. Site – Dominant invasive an- nuals. Short to moderate fire return intervals (≤100 years). Fuels – May be warranted to reduce non-native annual grass fuels, perhaps centered on roads, to facilitate fire suppression. Follow-up treatments may be needed on an annual basis. Suppression – Warranted under most circumstances. Prescribed fire is never warranted except perhaps for experimental purposes. ES&R – May be warranted to reestablish the native community and to control invasive plants if inadequate perennial herbaceous spe- cies and shrubs exist for recovery. Herbicides may allow short-term control of non-native annual grasses, but long-term control requires a wider array of management actions including reestablishment of native perennial species. Aerial seedings have low establishment rates. Livestock closures are necessary post-fire to facilitate recovery of native perennial plants. Mojave desert scrub Fire – High severity, large, ho- mogenous fires Site – dominant invasive an- nuals, short to moderate fire return intervals (≤100 years) Fuels – May be warranted to reduce non-native annual grass fuels, perhaps centered on roads, to facilitate fire suppression. Follow-up treatments may be needed on an annual basis. Suppression – Warranted under most circumstances. Prescribed fire is never warranted except perhaps for experimental purposes. ES&R – May be warranted to reestablish the native community and to control invasive plants if inadequate perennial herbaceous spe- cies and shrubs exist for recovery. Herbicides may allow short-term control but long-term control requires a wider array of management actions including reestablishment of native perennial species. Aerial seedings have low establishment rates. Livestock closures are necessary post-fire to facilitate recovery of native perennial plants. Riparian and Spring Fire – High severity crown, large homogeneous fire. Site – Dominant invasive pe- rennials. Heavy surface and ladder fuel loads could lead to high severity crown fire. Flood disturbance may have larger effects than fire especially in unregulated riverine systems (e.g. Virgin River) Fuels – May be warranted to reduce non-native tamarisk and Russian olive fuels to reduce high severity fire. Prescribed fire may be the most cost-effective way to reduce invasive plan biomass over large areas, but follow-up control of surviving invasive plants will always be needed during the first few post-fire years, potentially followed by native plant revegetation. Suppression – May be warranted in the WUI or where tamarisk and native vegetation are intermixed, otherwise low to moderate se- verity fire may be allowed where native fuels predominate as a natural fire regime component for vegetation management benefits, or moderate severity fire may be allowed where tamarisk dominates to remove above-ground biomass as a prelude to other tamarisk con- trol actions such as herbicide treatments followed by native plant revegetation. ES&R – May be warranted to control tamarisk, herbicides may allow short-term control but long-term control requires a wider array of management actions including native plant revegetation which may be accomplished by seedings or outplantings. Table 5.1—(Continued). Ecosystem type burned Typical fire management concerns Guidelines for appropriate management actions
88 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Piñon and Juniper Ecosystems—Single-leaf piñon (P. monophylla), Utah juniper 

(Juniperus osteosperma), Rocky Mountain juniper (Juniperus scopulorum), and western juniper (Juniperus occidentalis) are relatively thin barked and contain ladder fuels 

that facilitate consumption of their entire canopies, so they have low tolerance of fire 

(Brooks and Minnich 2006). However, stands can re-establish within about a century. 

Understory vegetation, such as interior chaparral, at higher elevations is very tolerant 

of fire that occurs at moderate return intervals. Sagebrush is intolerant of fire and rabbitbrush (Chrysothamnus spp.) is fire tolerant, but sagebrush communities can reestablish given longer fire return intervals (25-50 years) and relatively small fire size.

Excessively long intervals between fires may lead to canopy closure, seedbank 

depletion, fuel accumulation, and high fire severity, all of which reduce piñon-juniper 

resilience to fire (Allen and others 2008; Miller and others 2005, 2008) (table 5.1). If 

invasive annual grasses are present, they have the potential to dominate post-fire landscapes leading to short intervals (~2-5 years) between fires that do not allow time for 

trees to establish and grow to maturity.

Sagebrush Ecosystem—The sagebrush ecosystem is dominated by several different 

shrub species that are typically killed by fire, including big sagebrush (Artemisia tridentata tridentata, A. tridentata wyomingensis and A. tridentata vaseyana), low sagebrush (A. arbuscula), Bigelow sagebrush (A. bigelovii), and black sagebrush (A. nova). 

Other species such as rabbitbrush, snakeweed (Gutierrezia sarothrae), spiny hopsage 

(Grayia spinosa) and cliffrose (Purshia neomexicana) can resprout if only partially 

burned, and perennial grass species including wheatgrass (Agropyron spp.), bluegrass 

(Poa spp.), and needlegrass (Achnatherum spp.) usually survive topkilling.

High abundance of invasive annual grasses may lead to short fire return intervals 

that do not allow sufficient regeneration times for native sagebrush species to persist 

(table 5.1). These conditions also may lead to large homogenous fires that hinder seed 

dispersal of native perennial species back into burned areas and result in intense competition of the invaders with native seedlings for available resources.

Blackbrush/Shadscale Ecosystem—Blackbrush is the dominant shrub species in areas with shallow limestone-derived soils, and this species is easily killed and very slow 

to re-establish following fire (Brooks and others 2007). Shadscale (Atriplex confertifolia) and budsage (Artemisia spinescens) dominate on heavy, rocky soils and also are 

killed by fire. Other subdominant shrubs species include cliffrose, Mormon tea (Ephedra spp.), snakeweed, wolfberry (Lycium spp.), and spiny hopsage and all can resprout 

to varying degrees.

Similar to sagebrush ecosystems, high abundance of invasive annual grasses may 

lead to fire return intervals that that are shorter than the regeneration times of native 

blackbrush species (table 5.1). Invasive annual grass dominance may also lead to large 

homogenous fires that hinder seed dispersal of native perennial species back into burned 

areas and result in competition of the invaders with native seedlings for available resources. Although perennial plant cover may approach unburned conditions within the 

first four post-fire decades, species composition typically does not (Abella 2009; Brooks 

and others, in prep.; Engel and Abella 2011).

Mojave Desert Scrub Ecosystem—Creosotebush is the dominant species in upland 

areas and saltbush species are dominant in alkaline soils of lowland basin areas. Bajadas, the most common landform, are dominated by creosote bush and white bursage 

(Ambrosia dumosa); subdominants include desert thorn (Lycium andersonii), bladder 

sage (Salazaria mexicana), indigo bush (Psorothamnus fremontii), blackbrush, brittlebush (Encelia farinosa), and burro bush (Hymenoclea salsola). Most of these species 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 89

have the capacity to survive fire if more than half of their aboveground biomass is left 

unburned (Brooks and Minnich 2006). Yucca species such as Joshua tree (Yucca brevifolia) and Mojave yucca (Yucca schidigera) often survive burning, but the Joshua tree 

often dies within the first few years after fire due to drought and herbivory stress on 

resprouts (DeFalco and others 2010).

Similar to sagebrush and blackbrush ecosystems, high abundance of invasive annual 

grasses may lead to excessively short fire return intervals that do not allow native Mojave desert scrub species to reestablish (Brooks 2011) (table 5.1). Although perennial 

plant cover may approach unburned conditions within the first four post-fire decades, 

species composition typically does not (Abella 2009; Brooks and others, in prep.; Engel 

and Abella 2011).

Riparian and Spring Ecosystems—Historical fire coupled with periodic flooding has 

resulted in riparian plant species adaptations that confer some degree of tolerance to 

fire. The invasion of saltcedar, Russian olive and invasive annuals have increased fuel 

loads, created ladder fuels where little previously existed, and resulted in the potential 

for larger, more intense, and more frequent fires than occurred historically (Dwire and 

Kaufman 2003) (table 5.1). Although some native riparian species may not survive 

this altered fire regime (e.g. cottonwood trees), others are clonal and are capable of 

surviving fire and resprouting (e.g., willows). However, the altered fire regime can 

also be accompanied by vigorous post-fire resprouting and seedling establishment of 

non-natives creating an intense competitive environment that can suppress native species (Dudley and Brooks 2006). Thus, the net effects on natives can be significant even 

though they may be generally tolerant of fire and other disturbances.

The degree to which fire may have affected the evolution of plant species in the vicinity of springs is related to the fire regime of the surrounding vegetation type. Current 

species assemblages may also have been affected by historical fire use by indigenous 

humans. In addition, some spring sites are dominated by non-native saltcedar, which 

can increase its dominance following fire if it is not actively managed.

Management Actions

Pre-Fire Fuels Management

Livestock grazing can reduce cover of perennial vegetation in the Mojave Desert (Brooks 

and Berry 2006), which may have led to reduced fuel continuity and landscape-scale 

flammability of fuelbeds in mid to upper elevation ecosystem types such as blackbrush/

shadscale, sagebrush, and piñon and juniper after grazing began in the late 1800s (Brooks 

and Minnich 2006). Intensive grazing associated with livestock watering sites also can 

be associated with reduced cover of red brome (Bromus rubens) (Brooks and others 

2006), which is the primary fine fuel that carries fire in the Mojave Desert (Brooks 1999; 

Brooks and Minnich 2006). Although livestock grazing has been shown to reduce flame 

lengths and fire spread rates in the Great Basin (Diamond and others 2009), it may only 

be a significant factor in early successional vegetation stands dominated by herbaceous 

species (Launchbaugh and others 2008). In addition, the intensity of grazing required 

to significantly alter fire behavior may actually facilitate the long-term dominance of 

non-native grasses that are often one of the most significant fuel management concern 

in the Mojave and Great Basin Deserts (Brooks and others 2007; Knick and Connelly 

2011; Wisdom and others 2005). Moreover, extensive grazing over many decades on 

predominantly BLM lands in Lincoln County, Nevada, is coincident with the largest 

expanses of burned landscapes in the entire Mojave Desert (Brooks and Matchett 2006). 
90 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

In contrast, nearby lands within the Desert National Wildlife Refuge to the west of these 

BLM lands have been protected from livestock grazing since the refuge was created in 

the 1930s and do not contain evidence of widespread fires (Brooks and others 2007).

Following the 2005 Mojave Desert fires, there was serious discussion about using 

herbicides to manage invasive annual fuels along the margins of dirt and paved roads to 

create fuelbreaks and reduce the window of opportunity for fires to spread and become 

large (e.g. Brooks and others 2005) (table 5.1), however it has rarely been implemented 

in part because its efficacy has yet to be evaluated in southern Nevada. Grass-specific 

herbicide used in small plot experiments has been effective at controlling the non-native 

Mediterranean split grass (Schismus spp.) promoting post-fire establishment of less 

flammable native forb species in the northwestern Sonoran Desert (Steers and Allen 

2010). Even if herbicides are effective in the short-term, they would need to be applied 

at least every few years as a part of a regular maintenance program to maintain fuelbreaks. If this is done, then these corridors of managed fuels can be used to facilitate 

fire suppression efforts and potentially reduce the frequency of fire starts from vehicles 

travelling along roads that parallel treated areas. Mechanical thinning of fuels is a viable 

management option at very localized scales, due to relatively high cost and potential for 

undesirable side-effects. For example, narrow (e.g. <10 m wide) managed fuel zones 

along the margins of roads may be appropriate to minimize anthropogenic ignitions 

in sagebrush, blackbrush/shadscale, and Mojave Desert scrub ecosystems (table 5.1). 

Mechanical thinning of understory fuels in old mixed conifer stands may be necessary 

prior to the reintroduction of low to moderate intensity surface fires. This same approach 

of understory thinning followed by low to moderate intensity fire can be used in areas 

exhibiting piñon and juniper expansion into areas where the presence of these trees is 

not desirable. If fuel beds are already conducive to low to moderate intensity fire, then 

fire alone should be the preferred alternative.

It should be noted that fuelbreaks, thinnings, or any other type of fuels reduction 

project can also have negative effects, such as facilitating the spread of invasive plants 

(Merriam and others 2006). Accordingly, the cost and ecological effects associated with 

the creation and maintenance of managed fuel zones should always be weighed against 

their efficacy in slowing or stopping fires, the additional costs and efficacy of suppression efforts where fuelbreaks are not present, and the ecological effects of increased 

burned areas where fires attain larger size due to the absence of managed fuel zones.

Fire Suppression

Clearly, the most effective way to protect the majority of the low to mid elevation 

shrubland ecosystem types of southern Nevada from fire damage is to prevent fires from 

starting and/or spreading into large areas. This requires aggressive fire suppression efforts that may include aerial water and retardant drops and off-road travel by suppression 

equipment (e.g., engines, dozers). The use of these tactics should not be taken lightly, 

because phosphate-based retardants may promote dominance by invasive annual plants 

(Besaw and others 2011; Brooks and Lusk 2008) and off-road travel, especially the use 

of dozers, can damage both natural and cultural resources. Thus, the potential negative 

effects of aggressive fire suppression must be weighed against the potential negative 

effects of fires spreading to cover more area and the ability to mitigate negative suppression effects immediately following fires.

In contrast, wildland fire use may be the preferred alternative rather than fire suppression at higher elevation and tree dominated ecosystems in southern Nevada (table 5.1). 

Fire spread potential is minimal in the alpine and bristlecone pine ecosystem type, but 

if these conditions change in the future (e.g. due to climate change or plant invasions) 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 91

then fire suppression may be necessary. Periodic low to moderate intensity fire is a 

desirable natural ecosystem process in the mixed confer ecosystem type, and to a lesser 

degree in the piñon and juniper and sagebrush ecosystem types. Fire suppression in these 

types should only be limited to what is required to protect the wildland-urban interface 

(WUI) and/or to limit the spread of fire into excessively large fires that could threaten 

the persistence of relatively small isolated vegetation stands.

Post-Fire Emergency Stabilization and Rehabilitation

Aerial seeding is often used to increase the recovery potential of native vegetation 

and decrease the dominance of invasive annual plants on post-fire landscapes in southern Nevada. Although very few studies exist from the Mojave Desert, numerous studies have been published regarding post-fire seeding in the Intermountain West. These 

studies indicate that establishment success of seeding projects depends on precipitation 

(Wirth and Pyke 2009) and that very high seeding rates may be required at the lower 

end of the precipitation spectrum (Thompson and others 2006). They also suggest that 

successful seeding can lead to lower invasive species abundance (Evans and Young 

1978; Goodrich and Rooks 1999; Thompson and others 2006; Wirth and Pyke 2009), 

although unsuccessful seeding efforts may actually increase invasive plant abundance 

(Ratzlaff and Anderson 1995). Studies near completion from the Mojave Desert provide only scant evidence of establishment success following aerial seeding of post-fire 

landscapes in southern Nevada (Brooks and others. in prep.). These studies also indicate 

that, in general, perennial seedlings only appear in measureable numbers where both 

rainfall is high and density of invasive annual plants is low. Thus, seedings alone may 

not be the correct tool to control invasive annual plant populations in areas that they 

already dominate. Another study near completion reports that establishment of seeded 

species can be improved where mechanical pitting is done using hand tools and seeds 

are broadcast by personnel on the ground (DeFalco and others, in prep.). In general, 

aerial seedings have very low establishment rates in southern Nevada and Emergency 

Stabilization and Rehabilitation (ES&R) resources may be better applied in other ways 

(table 5.l).

Temporary closures for livestock grazing are also implemented to provide native 

perennial vegetation a chance to recover following fires. These closures typically last 

only a few years, and it is unclear if they are beneficial. They also appear difficult to 

enforce, as livestock are often observed within closure areas (Matthew Brooks, personal 

observation of post-fire landscapes during the winter following the 2005 fire season, 

Lincoln County, Nevada). Survival of residual native plants may be enhanced by protection from post-fire grazing, especially in blackbrush/shadscale and Mojave Desert scrub 

ecosystems where species generally have low capacity for post-fire recovery (table 5.1).

Knowledge Gaps

Understanding Fire Histories

A better understanding of fire histories of southern Nevada ecosystem types can be 

used to develop more effective management plans for these areas. Specific studies targeting key ecosystem types and locations are needed to test current hypotheses regarding 

assumed historic fire frequencies. These include dendrochronology studies of the mixed 

conifer zone in the Spring Mountains, and soil stratigraphy studies using charcoal lenses 

as proxies for fire events within watersheds dominated by single ecosystem types.
92 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Climate and Fire Size and Frequency

Routine evaluations of the relationship of climate to fire size and frequency and how 

this relationship might change with climate warming are needed to develop effective fire 

management strategies. Precise descriptions of spatial and temporal patterns of burning 

only span a few decades of comprehensive records (e.g., agency reports and satellite 

imagery). Conclusions about fire trends can vary widely depending upon which time 

interval one evaluates within the current record. Re-evaluation of these data should be 

done at regular intervals (e.g., 5 year) to test the robustness of the current hypotheses 

regarding short-term ENSO and longer-term PDO effects on fire regimes.

Fire Effects on Plant Species and Vegetation Types

The effects of fire on plant species and vegetation types must be more thoroughly 

understood before predictive models can be useful to management. Within each ecosystem type the various effects of fire, fire regime, and local site characteristics need to be 

investigated further. This will require intensive data from numerous fires, and possibly 

the use of experimental fires. Even less information is available regarding the effects 

of fire on animals, but because so many sensitive species are associated with particular 

ecosystem types, a full understanding of fire effects on animals can only be realized 

after a more complete understanding of vegetation responses.

Post-Fire Management

Additional information is needed regarding appropriate management actions after 

fire. It is well established that aerial seedings of post-fire landscapes have very low 

establishment rates. However, much less is understood about other management actions 

designed to reestablish native vegetation. Also, little is known about the effects of postfire grazing. For example, how does the duration and intensity of post-fire grazing by 

livestock affect vegetation resilience to fire and expansion of invasive annual grasses? 

How effective is livestock grazing at managing fuels created by invasive annual plants?

Fire Suppression Impacts

Considering that fire suppression may be the most effective fire management tool in 

low to mid elevation ecosystem types, there is a need to better understand the relative 

impact, both negative and positive, of aggressive fire suppression tactics (e.g. retardant 

drops and off-road travel) versus allowing fires to spread and burn more areas.

Semi-Arid Ecosystem Response to Wildfire

Because tree infilling and growth are ongoing processes in higher elevation conifer 

and piñon and juniper ecosystems, information is needed on the response of these semiarid ecosystems to wildfire and fire and fuels treatments. Information also is needed 

on how fire and fuels treatments can be used for restoring and maintaining landscape 

heterogeneity of these diverse ecosystems.

Management Implications

Important take-home messages for land managers are that (1) the effect of an 

individual fire event should be evaluated within the context of the ecosystem type in 

which it occurs, the characteristics of the fire, and characteristics of the site; (2) fire 

suppression is the most cost effective way to manage fires across most of southern 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 93

Nevada, except in a few ecosystem types where fire is part of the natural disturbance 

regime and wildland fire use should be an option to achieve management objectives; 

and (3) the current range of post-fire mitigation tools used are either ineffective or their 

effectiveness is poorly documented. Like all aspects of land management, fire management must ultimately be placed in the broader context of all the other factors associated 

with managing landscapes in southern Nevada. In some cases decisions may need to 

be made regarding where to allocate limited resources, and in other cases conflicting 

objectives may need to be resolved between fire management and those focused on 

other management topics (especially natural and cultural resources). The information 

contained in this chapter should help all parties better understand issues associated with 

fire management.

References

Abella, S.R. 2008. Fire history and forest structural change in the Spring Mountains. Faculty Publications (SEPA). Paper 377. Online: http://digitalcommons.library.unlv.edu/sea_fac_articles/377. [2012, 

Oct 29]

Abella, S.R. 2009. Post-fire plant recovery in the Mojave and Sonoran Deserts of North America. Journal 

of Arid Environments. 73:699-707.

Allen, E.A.; Chambers, J.C.; Nowak, R.S. 2008. Effects of a spring prescribed burn on the soil seed bank 

in sagebrush steppe exhibiting pinyon-juniper expansion. Western North American Naturalist. 68:265-

277.

Axelrod, D.I. 1995. Outline history of California vegetation. In: Barbour, M.G.; Major, J. (eds.). Terrestrial vegetation of California. California Native Plant Society, Special Publication Number 9: 139-193.

Besaw, L.M.; Thelan, G.C.; Sutherland, S.; Metlen, K.; Callaway, R.M. 2011 Disturbance, resource pulses 

and invasion: short-term shifts in competitive effects, not growth response favour exotic annuals. Journal of Applied Ecology. 48:998-1006.

Biondi, F.; Jamieson, L.P.; Strachan, S.; Sibold, J. 2011. Dendroecological testing of the pyroclimatic 

hypothesis in the central Great Basin, Nevada, USA. Ecosphere. 21:1-20.

Brooks, M.L 1999. Alien annual grasses and fire in the Mojave Desert. Madroño. 46:13-19.

Brooks, M.L. 2002. Peak fire temperatures and effects on annual plants in the Mojave Desert. Ecological 

Applications. 12:1088-1102.

Brooks, M.L. 2003. Effects of increased soil nitrogen on the dominance of alien annual plants in the Mojave Desert. Journal of Applied Ecology. 40:344-353.

Brooks, M.L. 2008. Plant invasions and fire regimes. In: Zouhar, K.; Kapler Smith, J.; Sutherland, S.; 

Brooks, M.L. (eds.). Wildland Fire in ecosystems: Fire and nonnative invasive plants. RMRS-GTR42-volume 6. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 33-46.

Brooks, M.L. 2009. Spatial and temporal distribution of non-native plants in upland areas of the Mojave 

Desert. In: Webb, R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, E.V.; Miller, D.M. 

(eds.). The Mojave Desert: Ecosystem processes and sustainability. Reno, NV: University of Nevada 

Press: 101-124.

Brooks. M.L. 2011. Effects of high fire frequency in creosotebush scrub vegetation of the Mojave Desert. 

International Journal of Wildland Fire. http://dx.doi.org/10.1071/WF10140.

Brooks, M.L.; Berry, K.H. 2006. Dominance and environmental correlates of alien annual plants in the 

Mojave Desert. Journal of Arid Environments. 67:100-124.

Brooks, M.L.; D’Antonio, C.M.; Richardson, D.M.; Grace, J.B.; Keeley, J.E.; DiTomaso, J.M.; Hobbs, 

R.J.; Pellant, M.; Pyke, D. 2004. Effects of invasive alien plants on fire regimes. BioScience. 54:677-

688.

Brooks, M.L.; DeFalco, L.; Esque, T. 2005. Consultation with USGS on the Southern Nevada Complex 

BAER Plan. Letter to Erv Gasser, Burned Area Emergency Response Team Leader, 2005 Southern 

Nevada Complex, 11 August.Unpublished data on file at: AGENCY, CITY, STATE. 4 p.

Brooks, M.L.; Esque, T.C. 2002. Alien annual plants and wildfire in desert tortoise habitat: status, ecological effects, and management. Chelonian Conservation and Biology. 4:330-340.

Brooks, M.L.; Esque, T.C.; Duck, T. 2007. Fuels and fire regimes in creosotebush, blackbrush, and interior 

chaparral shrublands. In: Hood, S.; Miller, M. (eds.). Fire ecology and management of the major ecosystems of southern Utah. RMRS-GTR-202. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station: 97-110.
94 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Brooks, M.L.; Lusk, M. 2008. Fire management and invasive plants: a Handbook. United States Fish and 

Wildlife Service, Arlington, VA. 27 p.

Brooks, M.L.; Matchett, J.R. 2006. Spatial and temporal patterns of wildfires in the Mojave Desert. 1980-

2004. Journal of Arid Environments. 67:148-164.

Brooks, M.L.; Minnich, R.A. 2006. Southeastern deserts bioregion. In: Sugihara, N.G.; van Wagtendonk, 

J.W.; Shaffer, K.E.; Fites-Kaufman, J.; Thode, A.E. (eds.). Fire in California’s ecosystems. Berkeley, 

CA: The University of California Press: 391-414.

Brooks, M.L.; Pyke, D. 2001. Invasive plants and fire in the deserts of North America. In: Galley, K.; Wilson, T. (eds.). Proceedings of the invasive species workshop: The role of fire in the control and spread 

of invasive species. fire conference 2000: The First National Congress on Fire Ecology, Prevention and 

Management. Miscel. Publ. No. 11. Tallahassee, FL: Tall Timbers Research Station: 1-14.

Brown T.J.; Hall, B.L.; Mohrle, C.R.; Reinbold, H.J. 2002 Coarse assessment of Federal wildland fire occurrence data. Report for the National Wildfire Coordinating Group. Applications Report 02-04. Desert 

Research Institute, Division of Atmospheric Sciences, Climate, Ecosystems and Fire. 31 p.

Busch, D.E. 1995. Effects of fire on southwestern riparian plant community structure. Southwestern Naturalist. 40:259-267.

Busch, D.E.; Smith, S. 1993. Effects of fire on water and salinity relations of riparian woody taxa. Oecologia. 94:186-194.

Collins, B.M.; Omi, P.N.; Chapman, P.L. 2006. Regional relationships between climate and wildfireburned area in the interior west, USA. Canadian Journal of Forest Research. 36:699-709.

Croft, A.R. 1950. Inspection of black brush burn, May 12, 1950. Memorandum to the unpublished report, 

Bureau of Land Management, State Supervisor for Nevada, 6 p. plus photographs. Unpublished report 

on file at: U.S. Department of the Interior, Bureau of Land Management, Caliente, NV.

D’Antonio, C.M.; Vitousek, P.M. 1992. Biological invasions by exotic grasses, the grass/fire cycle, and 

global change. Annual Review of Ecology and Systematics. 3:63–87.

DeFalco, L.A.; Esque, T.C.; Scoles-Sciulla, S.J.; Rodgers, J. 2010. Desert wildfire and severe drought 

diminish survivorship of the long-lived Joshua tree (Yucca brevifolia: Agavaceae). American Journal of 

Botany. 97(2):243-250.

Diamond J.M; Call, C.A.; Devoe, N. 2009. Effects of targeted cattle grazing on fire behavior of cheatgrass-dominated rangeland in the northern Great Basin, USA. International Journal of Wildland Fire. 

18:944–950.

Dimock, D.E. 1960. Report on blackbrush burn observations, April 18-20, 1960. Memorandum to the 

Bureau of Land Management, State Supervisor for Nevada. 6 p. Unpublished report on file at: U.S. 

Department of the Interior, Bureau of Land Management, Caliente, NV.

Dudley, T.; Brooks, M.L. 2006. Saltcedar invasions can change riparian fire regimes. In: Sugihara, N.G.; 

van Wagtendonk, J.W.; Fites-Kaufman, J.; Shaffer, K.E.; Thode, A.E. (eds.). Fire in California’s ecosystems. Berkeley, CA: University of California Press: 409 pp.

Dwire, K.A.; Kauffman, J.B. 2003. Fire and riparian ecosystems in landscapes of the western USA. Forest 

Ecology and Management. 178:61-74.

Engel, C.E.; Abella, S.R. 2011. Vegetation recovery in a desert landscape after wildfires: influences of 

community type, time since fire and contingency effects. Journal of Applied Ecology. 48:1401–1410.

Evans, R.A.; Young, J.A. 1978. Effectiveness of rehabilitation practices following wildfire in a degraded 

big sagebrush-downy brome community. Journal of Range Management. 31:185-188.

Fites-Kauffman, J.; Bradley, A.F.; Merrill, A.G. 2006. Fire and plant interactions. In: Sugihara, N.G.; van 

Wagtendonk, J.W.; Fites-Kaufman, J.; Shaffer, K.E.; Thode, A.E. (eds.). Fire in California’s ecosystems. Berkeley, CA: University of California Press: 94-117.

Fryer, J.L. 2004. Pinus longaeva. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Online: http://www.fs.fed.us/database/feis/ [ 2011, December 28].

Goodrich, S.; Rooks, D. 1999. Control of weeds at a pinyon-juniper site by seeding grasses. In: Monsen, 

S.B.; Stevens, R. (compilers). Proceedings: ecology and management of pinyon-juniper communities 

in the Interior West. Proceeding RMRS-P-9. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Experiment Station: 403-407.

Hereford, R.; Webb, R.H.; Longpré, C.I. 2006. Precipitation history and ecosystem response to multidecadal precipitation variability in the Mojave Desert region, 1893-2001. Journal of Arid Environments. 67:13-34.

Howard, Janet L. 2003. Pinus ponderosa var. scopulorum. In: Fire Effects Information System, [Online]. 

U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Online: http://www.fs.fed.us/database/feis/ [2011, December 28].
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 95

Johnson, Kathleen A. 2001. Pinus flexilis. In: Fire Effects Information System, [Online]. U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). 

Online: http://www.fs.fed.us/database/feis/ [2011, December 28].

Hunter, R. 1991. Bromus invasions on the Nevada Test Site: present status of B. rubens and B. tectorum 

with notes on their relationship to disturbance and altitude. Great Basin Naturalist. 51:176–182.

Knapp, P.A. 1997. Spatial characteristics of regional wildfire frequencies in intermountain west grassdominated communities. Professional Geographer. 49:39-51.

Knick, S.T.; Connelly, S.T. 2011. Greater sage-grouse – ecology and conservation of a landscape species 

and its habitats. Studies in Avian Biology, No. 38. Berkely, CA: Univeristy of California Press. 646 p.

Kolden, C.A.; Weisberg, P.J. 2007. Assessing accuracy of manually-mapped wildfire perimeters in topographically dissected areas. Fire Ecology. 3:22-31.

Launchbaugh, K.; Brammer, B.; Brooks, M.L.; and others. 2008, Interactions among livestock grazing, 

vegetation type, and fire behavior in the Murphy Wildland Fire Complex in Idaho and Nevada, July 

2007. U.S. Geological Survey Open-File Report 2008-1214. 42 p.

Link, S.O.; Keeler, C.W.; Hill, R.W.; Hagen, E. 2006. Bromus tectorum cover mapping and fire risk. International Journal of Wildland Fire .15:113-119.

Littell, J.S.; McKenzie, D.; Peterson, D.L.; Westerling, A.L. 2009. Climate and wildfire area burned in the 

western U.S. ecoprovinces, 1916-2003. Ecological Applications. 19:1003-1021.

Lovich, J.E.; de Gouvenain, R.C. 1998. Saltcedar invasion in desert wetlands of the southwestern United 

States: ecological and political implications. In: Kelly, M.; Wagner, E.; Warner, P. (eds.). Proceedings 

California Exotic Pest Council, Vol. 4: 1998. October 2-4, Ontario, CA: California Exotic Pest Council: 

45-55.

McKinley, R.A.; Brooks, M.L.; Klinger, R.C. [In press]. Fire History of Clark and Lincoln Counties in 

Southern Nevada. Open File Report, Sioux Falls, SD: U.S. Geological Survey. 62 p.

Merriam, K.E.; Keeley, J.E., Beyers, J.L. 2006. Fuel breaks affect nonnative species abundance in Californian plant communities. Ecological Applications. 16:515–527.

Miller, R.F.; Bates, J.D.; Svejcar, T.J.; Pierson, F.; Eddleman, L.E. 2005. Ecology, biology, and management of western juniper. Tech. Bull. 152. Corvallis, OR: Oregon State University Agricultural Experiment Station 80 p.

Miller, R.F.; Tausch, R.J.; McArthur, D.E.; Johnson, D.D.; Sanderson, S.C. 2008. Age structure and expansion of pinyon-juniper woodlands: a regional perspective in the Intermountain West. RMRS-RP-69. 

Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 

15 p.

Miller, R.F.; Wigand, P.E. 1994. Holocene changes in semiarid pinyon-Juniper woodlands. BioScience. 

4:465-474.

Petit, N.E.; Naiman, R.J. 2007. Fire in the riparian zone: characteristics and ecological consequences. 

Ecosystems. 10:673-687.

Pyke, D.A.; Brooks, M.L.; D’Antonio, C.M. 2010. Fire as a restoration tool: A decision framework for 

predicting the control or enhancement of plants using fire. Restoration Ecology. 18:274-284.

Randerson, D.; Soule, D.A.; Sanders, J.B. 2004. Investigation of lightning flashes as function of terrain 

elevation. Proceedings of the 18th International Lightning Detection Conference; 6-11 June 2004; Helsinki, Finland. Ref. No. 26. 3 p.

Rao, L.E.; Allen, E.B. 2010. Combined effects of precipitation and nitrogen deposition on native and 

invasive winter annual production in California deserts. Oecologia. 162: 1035–1046

Ratzlaff, T.D.; Anderson, J.E. 1995. Vegetal recovery following wildfire in seeded and unseeded sagebrush steppe. Journal of Range Management. 48:386-391.

Schmid, M.K.; Rogers, G.F. 1988. Trends in fire occurrence in the Arizona upland subdivision of the Sonoran Desert, 1955 to 1983. Southwestern Naturalist. 33:437–444.

Shaffer K.E.; Laudenslayer, W.F., Jr. 2006. Fire and animal interactions. In: Sugihara, N.G.; van Wagtendonk, J.W.; Fites-Kaufman, J.; Shaffer, K.E.; Thode, A.E. (eds.). Fire in California’s ecosystems. 

Berkeley, CA: University of California Press: 118-146.

Smith, S.D.; Charlet, T.N.; Fenstermaker, L.F.; Newingham, B.A. 2009. Effects of global change on Mojave Desert ecosystems. . In: Webb, R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, 

E.V; Miller, D.M. (eds.). The Mojave Desert: Ecosystem processes and sustainability. Reno, NV: University of Nevada Press: 31-56.

Spaulding, W.G. 1990. Vegetational and climatic development of the Mojave Desert: The last glacial 

maximum to the present. In: Betancourt, J.L.; van Devender, T.R.; Martin, P.S. (eds.). Packrat Middens: 

the last 40,000 years of biotic change. Tucson, AZ: The University of Arizona Press: 166-199.

Steers, R.J.; Allen, E.B. 2010. Post-fire control of invasive plants promotes native succession in a burned 

desert shrubland. Restoration Ecology. 18:334-343.
96 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Stewart, O.C. 1980. Forgotten Fires: Native Amreicans and the Transient Wilderness. Norman OK: University of Oklahoma Press. 364 pp.

Tagestad, J.; Brooks, M.; Cullinan, V.; Downs, J.; McKinley, R. [In preparation]. Precipitation regime 

classification for the Mojave Desert: Implications for fire occurrence.

Tausch, R.J.; Nowak, C.L. 2000. Influences of Holocene climate and vegetation changes on present and 

future community dynamics. Journal of Arid Land Studies. 10S:5-8.

Tausch, R.J.; Nowak, C.L.; Mensing, S.A. 2004. Climate change and associated vegetation dynamics 

during the Holocene: The paleoecological record. In: Chambers, J.C.; Miller, J.R. (eds.). Great Basin 

riparian ecosystems: Ecology, management, and restoration. Washington, DC: Island Press: 24-48.

Thompson, T.W.; Roundy, B.A.; McArthur, E.D.; Jessop, B.D.; Waldron, B.; Davis, J.N. 2006. Fire rehabilitation using native and introduced species: a landscape trial. Rangeland Ecology and Management. 

59:237-248.

Van Devender, T.R. 1977. Holocene woodlands in the Southwestern deserts. Science. 198:189-192.

Van Devender, T.R.; Spaulding, W.G. 1979. Development of vegetation and climate in the Southwestern 

United States. Science. 204:701-710.

van Wagtendonk 2006. Fire as a physical process. In: Sugihara, N.G.; van Wagtendonk, J.W.; FitesKaufman, J.; Shaffer, K.E.; Thode, A.E. (eds.). Fire in California’s Ecosystems. Berkeley, CA: University of California Press: 38-57.

Whisenant, S.G. 1990. Changing fire frequencies on Idaho’s snake river plains: ecological and management implications. In: McArthur, E.D.; Romney, E.M.; Smith, S.D; Tueller, P.T. (eds.). Proceedings—

symposium on cheatgrass invasion, shrub die-off, and other aspects of shrub biology and management; 

5-7 April 1989; Las Vegas, NV. Gen. Tech. Rep. INT-276. Ogden, UT: U.S. Department of Agriculture, 

Forest Service, Intermountain Research Station: 4-7.

Williams, G.W. 2000. Introduction to aboriginal fire use in North America. Fire Management Today. 

60(3):8-12.

Wirth, T.A.; Pyke, D.A. 2009. Final report for emergency stabilization and rehabilitation treatment monitoring of the Keeney Pass, Cow Hollow, Double Mountain, and Farewell Bend fires. U.S. Geological 

Survey Open-File Report 2009-1152. 62 p.

Wisdom, M. J.; Rowland, M.M.; Suring, L.H. 2005. Habitat threats in the sagebrush ecosystem: methods 

of regional assessment and applications in the Great Basin. Lawrence, KS: Alliance Communication 

Group. 301 p.
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Chapter 6

Species of Conservation Concern and 

Environmental Stressors: Local, Regional, and 

Global Effects

Steven M. Ostoja, Matthew L. Brooks, 

Jeanne C. Chambers, and Burton Pendleton 

Introduction

Species conservation has traditionally been based on individual species within the 

context of their requisite habitat, which is generally defined as the communities and 

ecosystems deemed necessary for their persistence. Conservation decisions are hampered by the fact that environmental stressors that potentially threaten the persistence 

of species can operate at organizational levels larger than the habitat or home range 

of a focal species. Resource managers must therefore simultaneously consider local, 

regional, and/or global scale stressors for effective conservation and management of 

species of concern. 

The wide ranging effects associated with global stressors such as climate change 

may exceed or exacerbate the effects of local or regional stressors. Although resource 

managers may only be able to directly affect local and regional stressors, they still 

need to understand the direct and interactive effects of global stressors and ultimately 

how they affect the lands they manage. Conservation of species in southern Nevada is 

further complicated by the fact that the region includes one of the largest and fastest 

growing urban centers in North America. To accomplish the goal of species conservation, resource managers must identify actionable management options that mitigate the 

effects of local and regional stressors in the context of the effects of global stressors that 

are beyond their control. 

Species conservation is typically focused on a subset of species often referred to as 

species of conservation concern that have either demonstrated considerable decline or 

are naturally rare or have limited distributions. Stressors can directly and indirectly 

impact species in a variety of ways and through a diversity of mechanisms. Some 

stressors have been more intense in the past (e.g., livestock grazing) whereas others are 

only now emerging as new stressors (e.g., solar energy development, climate change). 

The primary stressors affecting southern Nevada ecosystems are listed in table 2.1 and 

reviewed in detail in Chapter 2. This chapter addresses Sub-goal 1.4 in the SNAP Science Research Strategy which is to sustain and enhance southern Nevada’s biotic communities to preserve biodiversity and maintain viable populations (table 1.3; Turner and 

others 2009). We provide numerous examples of how stressors affect the range and/or 

habitat of select species of conservation concern. It is important to note that the species 

or groups of species discussed in this chapter by no means represent a comprehensive 

treatment of all species of conservation concern listed in table 1.2 (Chapter 1). Rather, 

several species where chosen as examples for each southern Nevada ecosystem type 

to illustrate how stressors and linkages among them can affect species of conservation 

concern, keeping in mind that many of the species considered here are found in more 
98 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

than one ecosystem type. In addition, the stressors that may impact a species in one 

ecosystem may not be those that affect it in another ecosystem and different species in 

the same ecosystem may not be affected by the same suite of stressors. Finally, at the 

start of each ecosystem section we summarize key resource concerns, species used as 

examples, key stressors, and potential synergistic effects of those stressors relative to 

the species examples.

Alpine and Bristlecone Pine Ecosystems

Key resource concerns General lack of understanding of basic ecology of 

species, need for assisted migration 

Species examples Rare, covered (i.e., under regional resource management plans) and/or endemic plants

Local and regional stressors Recreation, invasive species, nitrogen deposition, 

habitat modification, disease, altered fire regime

Global stressors Climate change

Synergistic effects Climatic induced susceptibility to nitrogen deposition, stochastic disturbance/recreation and invasive 

species, climate change altering local feedback 

systems (pollinators, herbivory, fire regimes)

The alpine ecosystem occurs at sites generally above 3,500 m in the Spring Mountains 

where alpine fell-fields and exposed dry rocky soils occur. Alpine meadows can also be 

found in swales where soil moisture accumulates in fine textured soils. We also include 

in this section the bristlecone pine ecosystem, which occurs on dry rocky slopes above 

the mixed conifer (2,600 m) and below the alpine ecosystems in the Spring and Sheep 

Mountain ranges. At its upper ecotone, bristlecone pine occurs as open woodlands transitioning into alpine fell-fields, whereas at its lower ecotones bristlecone pine is intermixed 

with other tree species as it transitions into the mixed conifer ecosystem. These alpine and 

bristlecone pine ecosystems occur as sky islands, where species occupy sites that occur 

in relative isolation amidst the vast lower elevation desert landscape. The geographic 

isolation among sites and the unique biophysical setting and environmental extremes 

of these ecosystems have led to the evolution of unique plant and animal assemblages 

and numerous endemic species, as is evident in the Spring Mountains (Clokey 1951). 

Several species of covered, rare, and/or endemics plant species occur within the alpine 

and bristlecone pine ecosystems of southern Nevada. 

Alpine and bristlecone pine ecosystems are susceptible to various stressors and disturbances because of their relative isolation and extreme elevation. Species inhabiting 

these ecosystems have few options to negotiate associated stressors, especially those 

that operate at global and regional scales (e.g., climate change and atmospheric nitrogen 

deposition). Locally, recreation (e.g., snow skiing developments, rock climbing), invasive 

species (e.g., dandelion), associated stochastic disturbance events (e.g., avalanches), and 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 99

altered fire regimes can affect the species that occur here. The limited amount of available habitat in these ecosystems limits the degree to which species, especially plants, 

can respond to disturbance or stressors.

The effects of climate change and associated global stressors on alpine ecosystems 

in particular have been associated with increased species richness at mountain peaks as 

populations of lower elevation species move upslope (Pauli and others 1996). Subsequent increases in the numbers of potentially competing species may threaten resident 

alpine species. Climate change can lead to changes in snow duration, depth, and extent, 

which may differentially produce substantial changes in the carbon and nitrogen soil 

dynamics of alpine ecosystems (Williams and others 1998). Climate change can further 

affect the type, timing, and amount of precipitation, which is especially detrimental to 

species living in alpine and other ecosystems (Chapter 2). Warming climate conditions 

leading to longer growing seasons may also result in the upslope migration of mixed 

conifer species; the associated increase in understory fuels may alter fire regimes and 

threaten the persistence of bristlecone pines and other white pine species (Chapter 5).

Alpine and bristlecone pine ecosystems are also very susceptible to atmospheric 

nitrogen deposition, which is a broad scale regional disturbance that can alter naturally 

low rates of primary productivity and soil microbial activity (Chapter 2). Although nitrogen is a key nutrient for plants, high rates of nitrogen deposition from atmospheric 

pollutants have been linked to ecosystem stresses in plants including increased rates of 

herbivory, pathogen susceptibility, and reduced frost and drought tolerance (Bowman 

and Steltzer 1998). Nitrogen deposition has also been shown to promote dominance of 

invasive annual plants in the Mojave Desert (Brooks 2003), which could promote the 

establishment of altered fire regimes (Brooks and Pyke 2001). Nitrogen deposition is a 

consequence of urbanization and industrialization and, given the proximity of the alpine 

ecosystems to the greater Las Vegas area, its potential ecological effects are significant.

Because of difficulty in access and the relative isolation of the sky-island ecosystem, 

direct disturbance from human activity is rare. However, recreational use, including 

hiking, camping, and activities associated with rock climbing, can lead to soil disturbance and compaction and erosion, and these activities have increased during recent 

decades with human population increases in the greater Las Vegas region. In addition, 

recreational activities may facilitate the introduction of non-native plant species (DRI 

2008) by both facilitating dispersal and causing disturbances that can facilitate weed 

establishment rates. Invasive annual grasses moving upslope could pose a particular 

threat to bristlecone pines from altered fire regimes (Chapter 5).

Alpine and bristlecone pine ecosystems are essentially high elevation deserts, with 

limited water availability and extremely short growing seasons. Collectively, the stressors that act on this ecosystem can have dire effects on species of conservation concern, 

potentially affecting key habitat requirements for naturally rare and/or endemic species. 

Few management options exist for regional managers to negotiate reductions to global 

climate change, or similar widespread regional stressors such as nitrogen deposition. 

However, actions focused on minimizing impacts from recreation and/or invasive species and altered fire regimes can be important for species of conservation concern that 

inhabit these ecosystems.
100 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Mixed Conifer Ecosystem

Key resource concerns General lack of understanding of basic ecology of 

species, increased fire and invasive species risk

Species examples Endemic butterflies

Local and regional stressors Fire suppression, habitat modification/fragmentation, 

invasive species, vegetation management, recreation 

and unregulated grazers

Global stressors Climate change

Synergistic effects Fuels thinning operations and invasive species

The mixed conifer ecosystem occurs in the Spring and Sheep Mountains from 1,200 m 

to 3,200 m in southern Nevada. This ecosystem consists of three unique types: (1) white 

fir forests, (2) ponderosa pine forests, and (3) ponderosa pine/mountain shrub community 

(see Chapter 7). Unlike adjacent ecosystems at lower elevations, mixed conifer forests 

receive more precipitation, have longer growing seasons, and experience milder summertime temperatures, all of which provide the necessary conditions to support diverse 

groups of plants and animals. 

The mixed conifer system is affected by a suite of local and regional stressors including fire and fuels management activities, recreation, and urban and water development. 

Historical fire suppression has promoted fuel accumulation, which can lead to high 

intensity fires that burn large areas and compromise habitat integrity (Battaglia and 

Shepperd 2007). These stressors have individually and synergistically compromised 

the stability and persistence of species of conservation concern in the region, and this 

is especially evident in the Spring Mountains. The effect of climate change on episodic 

and stochastic weather events coupled with long-term effects associated with years of 

fire suppression, and more recently invasive species and recreation, combine to impact 

the persistence of butterflies endemic to the Spring Mountains (USFWS 2011a). 

Eight species of endemic butterflies occur in the Spring Mountains and are managed by 

the United States Forest Service (USFS) in cooperation with the United States Fish and 

Wildlife Service (USFWS) under a Conservation Agreement between the two agencies. 

Four of the eight species have been identified as conservation priorities including the 

Mt. Charleston blue butterfly (Plebejus shasta charlestonensis), Morand’s checkerspot 

(Euphydryas anicia morandi), Spring Mountains acastus checkerspot (Chlosyne acastus 

robusta), and Spring Mountains dark blue butterfly (Euphilotes ancilla purpura). These 

four species were identified as a priority in the Conservation Agreement because of the 

limited number of locations where the species are currently known to occur. In 2006, 

these species were added to the Forest Service Regional (R4) Forester’s Sensitive Species List, and they are currently among the species of conservation concern in southern 

Nevada (table 1.2; Chapter 1).

The Mt. Charleston blue butterfly, one of seven unique subspecies of the wider 

ranging Shasta blue butterfly (Plebejus shasta), was petitioned for listing as an endangered 

species in 2005. The habitat for the Mt. Charleston blue butterfly is characterized as flat 

ridgelines above 2,500 m occupied by its host plant species. Primary among these host 

plants is Torrey’s milkvetch (Astragalus calycosus var. calycosus), a small, low-growing 

perennial and herbaceous legume that grows in open areas between 1,500 and 3,300 m 

in subalpine, bristlecone, and mixed-conifer communities in the Spring Mountains 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 101

(Weiss and others 1997). On March 8, 2011, the USFWS announced that listing the 

species is warranted, but precluded by higher priority actions; therefore they added it 

to the list of candidate species. If it rises higher on the priority list, the USFWS will 

develop a proposed rule to list this subspecies and make any determination on critical 

habitat during development of the proposed listing rule (USFWS 2011a).

Climate change is among the factors hypothesized to be responsible for the decline of 

the Mt. Charleston blue butterfly. Extreme climate events potentially linked to climate 

change can adversely affect butterflies with small restricted populations (Gilpin and 

Soulé 1986; Shaffer and others 2001). The Mt. Charleston blue is thought to be susceptible to random environmental and climatic events, specifically, extreme precipitation 

and drought events (Murphy and others 1990). The timing and number of emergent 

individuals that reproduce depend on a combination of environmental conditions; the 

result can mean the difference between a successful and an unsuccessful year for the 

species in question. Madsen and Figdor (2007) reported a nearly 30 percent increase in 

storm frequency associated with extreme precipitation in the past 6 decades in Nevada. 

Such extreme weather events directly impact the life cycle of the subspecies, and also 

indirectly impact the subspecies as mediated through host plant dynamics. The IPCC 

(2001) predicts that altered regional patterns of temperature and precipitation as a result 

of global climate change will continue. These altered climate patterns could increase 

the potential for extreme precipitation events and drought throughout the range of the 

Mt. Charleston blue, which may intensify the threats this species may be experiencing.

Various forms of habitat modification, including years of fire suppression, and introductions of non-native invasive species, are linked to the declines in species of conservation concern in the mixed conifer ecosystem (Weiss and others 1988). Historically, 

low-severity fires typically burned through Ponderosa pine stands within the range of 

the Mt Charleston blue and may have allowed for a more open mixed conifer forest 

characterized by a more abundant and diverse understory. Fire suppression has led to 

altered community successional patterns, which has altered host plant dynamics, altered 

butterfly movement patterns and reduced solar insolation (Wiess and others 1997). Additionally, the closing of the forest canopy may have compromised the metapopulation 

processes including colonization and recolonization dynamics. Shrub and forb in-filling 

as well as increased dominance of invasive grasses may out-compete and potentially 

decrease the abundance and quality of host plant resources for this butterfly species. 

The mixed conifer ecosystem may also be affected by various forms of recreational 

use, including hiking, rock climbing, and skiing. The Spring Mountains are home to the 

Las Vegas Ski and Snowboard Resort (LVSSR) that operates under a USFS special use 

permit. It is difficult to assess the degree to which the resort affects the endemic butterflies within the Spring Mountains. It is also possible that the active management for 

ski runs and potential expansion, including thinning of trees and shrubs and seeding of 

non-native species for erosion control, may indirectly impact the butterfly by preventing host plants from reestablishing in disturbed areas. Such disturbances are different 

from naturally created forest gaps and may not promote host plant establishment. In 

summary the effects of such disturbance features and events on host plant establishment 

are unknown and require further investigation.

In 2009, the USFS initiated the Spring Mountains National Recreation Area Hazardous 

Fuels Reduction Project to reduce accumulated forest fuel and lower fire risk by providing fuel breaks along human-use corridors, on the edges of private property, and at other 

human use areas such as campgrounds. Treatments varied widely depending on specific 

site conditions, but generally included use of heavy equipment and mastication treatments. 

These operations require investigation because they may directly impact butterfly population dynamics and habitat if individuals or host plant patches are killed or destroyed. 
102 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

The mixed conifer ecosystem is the focus of a diverse and varied set of management 

programs including vegetation and fuels management, rare species conservation, nonnative species management, endemic butterfly research, and more. Increased pressure 

from urbanization and recreation will continue to challenge resource managers with 

balancing permitted human activities with protecting ecosystem integrity. 

Piñon and Juniper Ecosystem

Key resource concerns Range expansion and stand in-fill, larger and higher 

severity fires, non-native species, disease

Species examples Piñon jay, gray vireo, gray flycatcher, desert bighorn 

sheep

Local and regional stressors Fire, invasive species, nitrogen deposition, vegetation management and unregulated grazers

Global stressors Climate change (e.g., extended drought, longer fire 

seasons and periods of severe fire weather), carbon 

dioxide enrichment

Synergistic effects Conversion to annual grasses and complete loss 

of habitat, extended drought and insect outbreaks, 

grazing and brown headed cowbird parasitism, 

woodland expansion and increased bighorn sheep 

predation rates

The piñon-juniper woodlands occur between 1,500 and 2,500 m, below the mixed 

conifer ecosystem, and are often intermixed or adjacent to the sagebrush ecosystem. 

At the upper elevation ecotones the dominate species include single-leaf piñon (Pinus 

monophylla), Gambel oak (Quercus gambelii), mountain mahogany (Cercocarpus spp.) 

and sagebrush (Artemisia spp.), whereas at lower ecotones important species include 

Utah juniper (Juniperus osteospera), Rocky Mountain juniper (J. scopulorum), western Juniper (J. occidentalis), rabbitbrush (Chrysothamnus) and sagebrush. While this 

ecosystem type makes up about 12 percent of the state, it is less well represented in 

southern Nevada. 

The expansion of piñon-juniper woodlands has been widely documented across the 

southwestern United States (Miller and others 2008), and this is thought to be largely 

due to reduced frequency of fire (Bauer and Weisberg 2009). Reports indicate that over 

the past 150 years piñon-juniper woodlands have expanded into other ecosystem types 

(e.g., sagebrush) and have also experienced increased plant density (i.e., in-filling), 

which has resulted in reduced dominance or the complete loss of understory plant species (Bauer and Weisberg 2009; Miller and others 2008). Miller and others (2008) found 

that at sites in the Great Basin, the area occupied by piñon and or juniper has increased 

125 to 625 percent since 1860. The woodland expansion is greater at mesic sites and 

in-filling rates are greater at lower elevations (Weisberg and others 2007). The landscape 

scale shifts are primarily thought to be due to climate change, altered fire regimes, and 

livestock grazing (Romme and others 2009a,b). These dynamics may promote insect 

pressure leading to mortality, fire risk, and non-native plant invasions. Conversion to 

piñon-juniper woodland from other critical ecosystem types (e.g., sagebrush) promotes 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 103

an increased risk of large-scale and higher severity fires, which impact wildlife within 

the piñon-juniper ecosystem. At lower elevations, fire may ultimately result in invasive 

annual grass dominance.

More recently, massive piñon pine die-offs have been documented across the West. 

Breshears and others (2005) found that from 40 to 80 percent of piñon (Pinus edulis) 

trees died between 2002 and 2003 at sites in Arizona, Colorado, New Mexico, and Utah, 

which may be related to climatic shifts and interactions with forest pathogens (Breshears 

and others 2009). Periodic droughts have promoted reductions in canopy cover, thereby 

resetting the successional clock in these systems (see Clifford 2011). Extended drought 

is a significant factor in insect outbreaks that can kill large stands of trees (Breshears 

and others 2005). 

Within the piñon-juniper woodland, species including the piñon jay (Gymnorhinus 

cyanocephalus), gray vireo (Vireo vicinior), and gray flycatcher (Empidonax wrightii) 

are experiencing notable population reductions (Sauer and others 2008). Stand in-filling 

and piñon pine die-off have translated to decreased bird species’ abundances in this 

ecosystem (Sauer and others 2008). The piñon jay caches piñon seeds, on which it relies 

throughout the year, in more open transitional stands near sagebrush and other more open 

habitat. However, shifts in community composition and die-off have resulted in lower 

piñon seed crops. The large expanses of closed-canopy stands without a satisfactory 

understory component are not suitable for piñon jays. According to ongoing telemetry 

studies being conducted by the Great Basin Bird Observatory, piñon jays prefer mixed 

age, early to mid-successional stands with a structurally diverse ecotone. 

Gray vireos use mature or mixed-age piñon-juniper woodlands with scattered trees 

and open canopies, especially where juniper is more abundant (Goguen and others 2005). 

The gray vireo may be negatively impacted by stand in-fill due to altered fire regimes, 

reduction of shrub cover due to livestock grazing, increased abundance of invasive plants, 

and brown-headed cowbird (Molothrus ater) parasitism (Goguen and Mathews 2001). 

For example, Goguen and Mathews (1998) found that livestock grazing can indirectly 

affect the nesting success of some songbird species by increasing cow bird abundance, 

although data specific to southern Nevada is lacking. The gray flycatcher uses a diversity 

of habitats in Southern Nevada but has a preference for the piñon-juniper ecosystem in 

the Mojave portion of its distribution (Sterling 1999). Gray flycatchers use moderately 

open piñon-juniper/sagebrush transitional habitats and therefore have the potential to 

be negatively impacted by stand in-fill.

The desert bighorn sheep (Ovis canadensis nelsoni) occurs on sparsely vegetated 

steep slopes, canyons, and washes within multiple ecosystem types in southern Nevada, 

including piñon and juniper woodlands. Especially important habitat includes treeless or 

rocky areas that provide escape routes from predators. Desert bighorn sheep and other 

subspecies have experienced major population declines from the 1850s to the early 20th

century (Buechner 1960). The desert bighorn is less studied than other subspecies, but 

reports suggest that numerous factors have contributed to population declines including disease, low reproductive output, habitat loss/fragmentation and degradation and 

predation (Buechner 1960; Gutiérrez-Espeleta and others 2000). 

Disease is among the most important factors that has led to the decline of the desert 

bighorn sheep (USFWS 2000a), especially diseases contracted from domesticated cattle 

and sheep (Gildart 1999; Jessup 1985). Increased human effects, including habitat loss 

and degradation, have also impacted the desert bighorn sheep (DeForge 1981; Hick and 

Elder 1979). Such impacts include increased noise, lighting, and increased human and 

pet presence in sheep habitat. The increased presence of humans and pets promotes an 

increase in some predators including coyotes, especially along the wilderness/urban 
104 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

interface (Ditchkoff and others 2006). Desert bighorn have also been shown to avoid 

areas where feral horses are present, potentially altering their foraging and watering 

preferences (Ostermann-Kelm and others 2008). Climate variability can also lead to poor 

diet quality for desert bighorn sheep, a pattern especially important at lower elevations 

such as occur in Mojave Desert scrub (Epps 2004). 

Increased woodland expansion, especially increased cover near watering sites, may 

also be facilitating increased predation rates by mountain lions (Puma concolor) on desert 

bighorn sheep. This same phenomenon is thought to be occurring with the Sierra Nevada 

Bighorn (Ovis canadensis sierra) populations (R. Klinger, personal communication). 

Predation by other species, including coyotes (Canis latrans) and bobcats (lynx rufus), 

may also reduce lamb recruitment, although the effects of these predators are not well 

known (Wehausen 2005). 

Resource managers should consider using fire, vegetation management actions (thinning techniques), invasive species management, and restrictions on recreation activities 

when managing this ecosystem (see Crow and van Riper 2010). Dynamics brought upon 

by a changing climate, including drought and associated interactions with insects or 

other pathogens, will continue to challenge local resource managers. 

Sagebrush Ecosystem

Key resource concerns General habitat loss and degradation, grass-fire 

cycle, woodland encroachment

Species examples Sage thrasher, sage sparrow, burrowing owl

Local and regional stressors Fire, invasive species, nitrogen enrichment, OHV 

use, energy development

Global stressors Climate change (i.e., extended drought), carbon 

dioxide enrichment

Synergistic effects Grazing, annual grass invasion and fire regime shifts; 

climate change and woodland encroachment

Sagebrush ecosystems are less well represented in southern Nevada compared to the 

rest of the state. In southern Nevada the sagebrush ecosystem can be found in the Spring, 

Sheep, and Virgin Mountains at elevations between 1,500 to 2,800 m (RECON 2000). 

The loosely applied term sagebrush ecosystem is used to describe ecological systems 

where members of the genus Artemisia are the dominant species. In southern Nevada 

this includes big sagebrush (A. tridentata), low sagebrush (A. arbuscula), Bigelow 

sagebrush (A. bigelovii), silver sagebrush (A. cana), and black sagebrush (A. nova). The 

specific species association depends on elevation, topography, soil type, and degree of 

aridity. 

Sagebrush ecosystems represent a contentious place marker among ranchers and conservationists across the Intermountain West. It has been argued that decades of improper 

land management have led to deterioration of this ecosystem type. It is thought that 

overgrazing, among other causes, has contributed to the reduction of associated species 

thereby promoting the invasion and dominance of invasive annual grasses, including 

cheatgrass (Bromus tectorum) and red brome (B. madritensis) (DiTomaso 2000). With 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 105

the expanding dominance of invasive annuals grasses, fine fuels have become ubiquitous, and the potential for fire to ignite and rapidly spread is increased. Once burned, 

the area can become dominated by invasive grasses that effectively out-compete native 

species. This then allows for a reduction in the fire return interval from about 50 to 

200 years to only several years. This is a well-established dynamic called the grass-fire 

cycle, which has rapidly transformed countless hectares of landscape to invasive annual 

grass dominance (Brooks and others 2004; D’Antonio and Vitousek 1992). Sagebrush 

is not well adapted to fire and is only able to regenerate from seed post fire, which may 

take years to decades. With the onset of the grass-fire cycle, natural regeneration of the 

native dominated communities is nearly impossible and active restoration efforts are 

not widely successful. Mojave scrub and blackbrush communities, other ecosystems 

described in this chapter, are also degraded by this grass-fire cycle dynamic. 

To further complicate matters, climate change from carbon dioxide enrichment has 

been shown to increase productivity and biomass accumulation as well as alter the carbon 

to nitrogen ratio and digestibility of Bromus spp., potentially enhancing the competitive abilities of these non-native invaders (Smith and others 1987) and increasing the 

fuel loads (Ziska and others 2005). Sagebrush communities are also under threat from 

piñon-juniper expansion. Moreover, energy development, urban development and offhighway vehicle (OHV) recreation also place pressure on this ecosystem, which may 

be further exacerbated by future changes in climate (change in precipitation timing and 

type, melt off, and temperature shifts). 

The ecological impacts associated with sagebrush habitat deterioration, or loss to 

annual grassland type conversion, have been widely documented in the Intermountain 

West. The deterioration alters soil morphology (Norton 2004), soil biota (Belnap and 

others 2005), native plant biodiversity (Humphrey and Schupp 2001), as well as diversity 

of invertebrates (Ostoja and others 2009), small mammals (Ostoja and Schupp 2009), 

reptiles (Newbold 2005), and birds (Knick and others 2003; Knick and Rotenberry 2002; 

Paige and Ritter 1999). However, the evaluation of specific mechanisms for shifts of 

wildlife species or communities have received less attention (but see Rieder and others 

2010). 

At the same time, the upper elevation sagebrush ecotones are experiencing increased 

juniper dominance, which may also compromise the integrity of the ecosystem for 

specific wildlife populations or guilds (see piñon-juniper section above). In fact, much 

of what is mapped by the USFS as the sagebrush ecosystem in the Spring Mountains 

National Recreation Area has a substantial component of juniper trees (Steven Ostoja, 

personal observation of plant community composition in the Spring Mountains, June, 

2009). 

In southern Nevada, bird species of conservation concern in sagebrush habitat include 

the sage thrasher (Oreoscoptes montanus), sage sparrow (Amphispiza belli), burrowing owl (Athene cunicularia), and others (see www.gbbo.org). Each of these species is 

negatively affected by habitat degradation and loss caused by urban, agricultural, energy, 

or other development. Sage thrashers use sagebrush habitat in southern Nevada during 

winter and migration periods; they prefer large expanses of sagebrush or shrub habitat, 

avoiding areas with junipers even when at low densities (Noson and others 2006). The 

burrowing owl is declining throughout much of its former range and is recognized as 

a National Bird of Conservation Concern by the U.S. Fish and Wildlife Service (Klute 

and others 2003). The owl is a yearlong resident throughout most of Clark County, but 

is only a summer and spring resident in adjacent southern Nevada counties. Increased 
106 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

development and associated effects (e.g., roads) promotes human disturbance to breeding colonies of owls (Poulin and others 1993). Moreover, because they are a ground 

nesting owl, domestic and feral dogs also have the potential to do great harm to their 

populations. The sage sparrow relies on large expanses of southern Nevada sagebrush 

and shrubland habitat during winter and migration periods. The sage sparrow is reported 

to be sensitive to cheatgrass invasion because of the reduction of shrub cover and loss 

of sparsely vegetated inter-shrub area that it requires for foraging. Research investigating the effects of grazing on sagebrush birds has shown mixed results (Page and others 

1978; Saab and others 1995). 

Invasive brome grasses, woodland expansion, and human activities will likely continue to threaten the sagebrush ecosystem in southern Nevada. Without question, these 

dynamics are closely linked to global stressors like climate change and pose a significant 

management challenge to land managers. The degree to which increased brome grass 

invasion is due to local disturbance versus increasing concentrations of carbon dioxide, 

nitrogen deposition, and climate mediated events is unclear. Climate models with projections of species range expansion may aid managers when considering management 

actions for species of conservation concern in this ecosystem type. At the same time, 

because so little of the sagebrush ecosystem naturally occurs in the region, conservation 

of what remains is important in the development of land management plans.

Blackbrush and Shadscale Ecosystems

Key resource concerns General habitat loss and degradation, grass-fire cycle

Species examples Blackbrush

Local and regional stressors Fire, invasive species, nitrogen enrichment, OHV 

use, energy development

Global stressors Climate change (precipitation patterns), carbon 

dioxide enrichment

Synergistic effects Unknown

Blackbrush ecosystems are woody evergreen shrublands dominated by blackbrush 

(Coleogyne ramosissima) and are primarily found on thermic and shallow limestonederived soils between 1,200 and 1,800 m in elevation (Pendleton and others 1995). 

Some blackbrush stands also occur on more mesic, deeper, and sandier soils, although 

that is not the norm in the Mojave Desert (Brooks and Matchett 2003; Matthew Brooks, 

personal observation of blackbrush community substrates throughout the Mojave Desert 

during the 1990s and 2000s). Shadscale (Atriplex confertifolia) can be dominant within 

the same elevation range on heavy, rocky soils (Brooks and others 2007). Associated 

species include Mormon tea (Ephedra spp.), wolfberry (Lycium spp.), hopsage (Grayia 

spinosa), and various species of grasses (Brooks and others 2007). The distribution of the 

ecosystem type is influenced by moisture, temperature, and soil types within the elevation range. Recent genetic analyses suggest that blackbrush is divided into two unique 

metapopulations, one centered in the Mojave Desert and the second on the Colorado 

Plateau (Richardson and Meyer 2012). Although we include both the blackbrush and 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 107

the shadscale ecosystems in this section due to their similar ecological ranges, we focus 

on the dynamics and species composition associated with blackbrush due to the limited 

information available on shadscale.

Blackbrush/shadescale ecosystems are used as winter forage by deer and bighorn 

sheep (Bowns and West 1976) and habitat for numerous species of birds and small 

mammals (Brown and Smith 2000). In addition, there are 11 covered species that occur 

in the blackbrush ecosystem of Clark County, eight of which are reptiles and three of 

which are vascular plants. Here, we limit our discussion to blackbrush because it has 

been reduced to remnant patches or is in a highly degraded state throughout southern 

Nevada. The blackbrush ecosystem is one of the most flammable ecosystems in the 

Mojave Desert. Fires burn plants to ground level and destroy soil seedbanks (Brooks 

and Draper 2006; Brooks and others 2007). Because natural recruitment is low for all 

plants in this ecosystem, it may take centuries for natural recovery to occur following 

fire (Minnich 2003; Webb and others 1987). Disturbances, including grazing and recreation, allow the establishment of invasive species including Bromus spp. (see sagebrush 

section in this chapter). Once Bromus spp. is established, the grass-fire cycle is initiated 

and conversion of the area to non-native annual grasses is likely. 

Fire, invasive species, grazing, development and recreation are among the greatest 

stressors to this ecosystem type. Grazing appears to have lasting effects on blackbrush 

shrub cover, soil crusts, and associated perennial plant cover (Jeffries and Klopatek 

1987). Blackbrush ecosystems in healthy ecological condition were likely more extensive prior to European contact (see Brooks and others 2007). Large areas of blackbrush 

were burned into the mid-1900s to increase livestock forage production and are currently 

dominated by early seral species. Only sporadic re-colonization by blackbrush has 

occurred, and that has been focused on the more mesic end of this species’ ecological 

range (M. Brooks, unpublished data). Recreational use, including foot, bike, horseback 

riding, and OHV use, can cause soil compaction and limit plant recruitment, which may 

facilitate habitat fragmentation. Habitat fragmentation may be especially problematic 

near rural and urban development. 

Other potential stressors that threaten blackbrush and the integrity of the ecosystem 

include the application of pesticides, climate change, increased carbon dioxide in the 

atmosphere, and fire ants (Solenopsis spp.). It is possible that the use of pesticides near 

rural areas may harm burrowing insects (e.g., ants) and small vertebrates (e.g., lizards 

and small mammals), thereby affecting patterns of plant recruitment and growth. Additionally, climate change may affect soil moisture and associated warming temperatures 

may affect associated species of conservation concern in this ecosystem. Rising carbon 

dioxide concentrations in the air have been linked to increased productivity of nonnative annual grasses (Ziska and others 2005). Native ant species burrowing activities 

are important to this ecosystem, and, may be negatively affected by non-native fire ants. 

Fire ants may also reduce survivorship of native mammals and ground-nesting birds 

(Lessard and others 2009; Smith and others 2004). 

As suggested for the sagebrush ecosystem, focusing on protecting the remaining 

remnant patches of the blackbrush/shadscale ecosystem would be of greatest benefit. 

Because natural regeneration is so limited, especially for blackbrush, it is feared that 

this ecosystem could disappear without intense restoration management efforts (Jones 

2011). Restoration efforts to reestablish blackbrush in the Mojave Desert have had 

limited success due to seed and seedling predation and low germination rates under hot 

and dry conditions. 
108 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Mojave Desert Scrub Ecosystem

Key resource concerns General habitat loss, fragmentation and degradation

Species examples Bajadas: desert tortoise; Sand dunes: three-corner 

milkvetch and white marginated penstemon; Gypsum soils: sticky ringstem, Las Vegas bearpoppy, 

and Las Vegas buckwheat

Local and regional stressors Fire, invasive species, nitrogen enrichment, OHV 

use, energy development, habitat loss/fragmentation, 

feral dog/cat predation, grazing, mineral extraction 

and dumping

Global stressors Climate change (precipitation patterns), carbon 

dioxide enrichment

Synergistic effects Land development, recreation, and invasive species

The Mojave Desert scrub ecosystem is characterized by widely and regularly spaced 

shrubs up to 3 m tall, and occurs on well-drained soils on slopes, fans, and valley bottoms below 1,200 m (Shoenherr 1992). Several subtypes are considered within this 

ecosystem type, including bajadas (also called alluvial fans), sand dunes, and gypsum 

soil. 

Bajadas

Bajadas are the most common landform in southern Nevada and are dominated by 

creosote bush (Larrea tridentata) and white bursage (Ambrosia dumosa), with other 

sub-dominant species including desert thorn (Lycium andersonii), bladder sage (Salazaria mexicana), indigo bush (Psorothamnus fremontii), blackbrush, brittlebush (Encelia 

farinosa), and burro bush (Hymenoclea salsola). This is the primary ecosystem type 

surrounding the major cities of southern Nevada and through which most of the major 

highways pass (fig. 1.2; Chapter 1), placing it within the wildland urban interface. Increased urbanization promotes human activities that have placed this ecosystem type 

and the iconic species it supports, including the desert tortoise (Gopherus agassizii) and 

the burrowing owl, at increased risk. 

Federally listed as threatened under the Endangered Species Act, the Mojave population of the desert tortoise can be found in regions throughout the Mojave and Colorado 

Deserts north and west of the Colorado River in Utah, Arizona, southern Nevada, and 

California. The desert tortoise frequents creosote bush dominated Mojave Desert scrub 

vegetation, and other low elevation vegetation types, including saltbrush (Atriplex spp.), 

and to a lesser extent blackbrush ecosystems (Bury and others 1994). As of 2007, the 

estimated desert tortoise population density in the northeast Mojave Desert was 1.7 individuals/km2, the lowest of all six recovery units (USFWS 2011b). 

Recreational human activities such as target shooting and off road driving are known 

to directly kill or injure desert tortoises (Ladehoff and others 1990). For example, about 

10 percent of shell remains from a tortoise study plot near Littlefield, Arizona, were 

found to have bullet holes (www.federalregister.gov). These occurrences are obviously 

more common at locations near urban areas where human activity is more frequent. 

People also collect tortoises for pets, food, and various commercial trades, which further 

compromises tortoise populations (Grover and DeFalco 1995). 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 109

Livestock grazing has been implicated in the decline of desert tortoise populations 

(Berry 1986). Avery and Neibergs (1997) noted that for most vegetation metrics considered, grazed sites were similar to ungrazed sites, although they did find that bulk density 

and penetration resistance of soils were greater at grazed sites. Cattle may compete 

with desert tortoises for forage, especially after winters of above average rainfall when 

abundant ephemeral resources are available (P. Medic, personal communication). Direct 

effects of cattle can include rubbing and nudging of tortoises; indirect effects include 

trampling of actively used burrows and destruction of shading vegetation around actively 

used burrows (Ladehoff and others 1990). 

OHV use and livestock grazing have been implicated in concomitant reductions in 

native vegetation and increases in invasive species (Brooks and Pyke 2001; Lovich and 

Bainbridge 1999). Tortoise resource availability and quality may be locally compromised 

where invasive species densities have increased. Where vegetation cover has been reduced, tortoise habitat quality also is reduced, because fewer sites to shelter from the 

sun are available to them (USFWS 2008, 2011b).

Tortoises are also subject to diseases that affect populations. Upper respiratory tract 

disease (URTD) and a shell disease occur in the species. URTD occurs more commonly 

in wild populations near cities where captive animals may have infected those populations (USFWS 2008, 2011b). Habitat degradation, poor nutrition and drought are likely 

involved in increasing the susceptibility of individual animals to URTD (Jacobson and 

others 1991). The USFWS suggests that reducing the human-related spread of URTD 

and improving habitat conditions may be effective management tools for controlling 

URTD in wild populations (USFWS 2008, 2011b). 

The common raven (Corvus corax) is a predator of the tortoise. The raven is associated with human subsidized food resources throughout the Mojave Desert (Kristan and 

Boarman 2007). Consequently, common ravens have been implicated as contributors 

to the decline of the desert tortoise (Kristan and others 2004) through direct predation 

on hatchlings and juveniles (USFWS 2011b). Predation pressure on tortoises can be 

especially important in drought years (Esque and others 2010).

Climate change may affect the desert tortoise through changes associated with animal 

metabolism and water relations that could shift population demography (see Henen 

and others 1998). Other effects of climate change may come indirectly, with changes 

in vegetation patterns or increased dominance of invasive species. These, too, may 

further compromise tortoise habitat. The USFWS (2011b) desert tortoise recovery plan 

estimates that $159 million, plus additional costs that cannot be estimated, is needed in 

order for the species to become self-sustaining into the future. 

Sand Dunes

Sand dunes form with the combination of a sand source and windy conditions. In 

the Mojave Desert scrub ecosystem, sand dunes are common to playas, remnant lakes, 

and xeric bottomland basins. Sand dunes are home to highly specialized species that are 

adapted to living in harsh environmental conditions with limiting resources and water. 

The model animal of sand dunes may be the desert kangaroo rat (Dipodomys deserti), 

whose fossorial nocturnal nature and fine-tuned biology allows it to escape predators, 

survive without free water, and recover stored food caches when resources dwindle. 

Also present in dune systems are several plant species of conservation concern that are 

receiving some attention (are ‘covered’) under the Clark County Multiple Species Habitat 

Conservation Plan (MSHCP): three-corner milkvetch (Astragalus geyeri var. triquetrus) 

and white margined beardtongue (Penstemon albomarginatus). Three-corner milkvetch 

is a small ephemeral annual forb that occurs on open, deep sandy soil or dunes that are 
110 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

generally stabilized by vegetation or gravel veneer (Morefield 2001). Reports indicate that 

difficulty in managing the species comes from general lack of knowledge regarding the 

species ecology and population dynamics (RECON 2000). White-margined beardtongue 

is a small herbaceous perennial forb with a long taproot requiring fine, deep, alluvial 

sand within the Mojave Desert scrub ecosystem. This species prefers sand dunes at the 

base of hills and mountains in wind-blown sand dune areas but is also found in deep 

loose sand in washes (Button 1991; Scogin 1989). 

Significant threats to the aforementioned species are posed by human activities, 

including the use of OHVs and multiple use trails that impact habitat and directly kill 

individual plants (RECON 2000). Energy development and associated urban expansion also threaten species directly and indirectly through habitat loss (Anderson 2001). 

Many trails and roads created for energy development directly affect individuals and 

populations. Once the trails or roads are on the landscape, they become available to the 

general public, support access to the desert landscape and allow increased, repeated use 

by various recreation groups. Established white-margined beardtongue individuals may 

survive isolated or infrequent OHV disturbance because the plant can re-sprout from the 

tap root if the above ground portions are damaged (Scogin 1989). However, sustained 

and repeated disturbance is much more likely to kill individual plants, and can have 

a significant impact on populations of both species. Domestic livestock grazing and 

activities associated with feral animals have the potential to result in significant habitat 

destruction as well (RECON 2000). Activities associated with water management, including diversion and ground water pumping, can make natural water unavailable and 

also potentially threaten the species. 

Gypsum Soils

This ecosystem supports various gypsum soil community types. Gypsum is a soft 

sulfate mineral, and gypsum soils occur on more than 100 million ha on Earth (Verheye 

and Boyadgiev 1997). Gypsum soils are restricted to arid and semi-arid climates where 

low precipitation prevents gypsum from leaching (Parsons 1976). The physical and 

chemical properties common to gypsum soils are stressful to most plants. At the same 

time, these soils support a conspicuous and diverse set of endemic and rare plants in arid 

and semi-arid regions, and southern Nevada is no exception. The Las Vegas bearpoppy 

(Arctomecon californica) is endemic to gypsum soils in the eastern Mojave Desert and 

a MSHCP covered species. It has a patchy distribution across low “badland” hills, and 

is sometimes found on ridges and benches. Larger populations occur in Las Vegas Valley and on gypsum soils associated with the Colorado River drainage (RECON 2000). 

Another MSHCP covered species is sticky ringstem (Anulocaulis leisolenus), which 

also occurs on gypsum derived soils, primarily in the Frenchman Mountain area east 

of Las Vegas and further east to the Muddy Mountains and Gold Butte (RECON 2000). 

Sticky ringstem often co-occurs with the Las Vegas bearpoppy (RECON 2000). The Las 

Vegas buckwheat (Eriogonum corymbosum var. nilesii) is also restricted to gypsum-rich 

soils in Clark and Lincoln counties. 

Once widespread and abundant, the Las Vegas bearpoppy has experienced population 

extirpations throughout southern Nevada (RECON 2000). The Las Vegas bearpoppy’s 

decline is attributed to land development, general habitat degradation, highway construction and backcountry road development, and OHV use (ADGF 2000). Habitat loss and 

fragmentation due to urbanization are also cited as contributing to population losses and 

declines (RECON 2000). These direct effects on the populations have also translated to 

associated higher order effects, and reports indicate that pollinators have declined due 

to habitat fragmentation (NNHP 2001). Sticky ringstem habitat has been modified and 

degraded due to urbanization, development including mining, recreational activities, 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 111

and trampling by ungulates (RECON 2000). Increased recreational use could result 

in mortality of individual plants as well as loss or disturbance to cryptogamic crusts 

(RECON 2000). Many of the historical populations of the Las Vegas buckwheat were 

lost to development as the greater Las Vegas area expanded. Extant populations are 

experiencing threats from habitat loss, invasive species, and climate change (USFWS 

2010) and it is currently a candidate for Federal protection. 

Mojave scrub is the most extensive habitat type in the region, and because of its 

prevalence at the wildland-urban interface it will be subject to increased local, regional, 

and global threats. Management efforts that concentrate on maintaining natural shrub 

densities, soil crusts, and healthy native vegetation where widespread intensive disturbance has been minimal would be most beneficial.

Desert (Mojave Lowland) Riparian Ecosystem

Key resource concerns Tamarisk invasion, biological control beetle 

Species examples Yellow billed cuckoo, southwestern willow flycatcher

Local and regional stressors Invasive species, fire, grazing, water diversion and 

extraction

Global stressors Climate change (precipitation patterns and runoff)

Synergistic effects Beetle induced vegetation/habitat changes and 

selective herbivory by unregulated grazers

In southern Nevada, this ecosystem occurs at elevations below 1,200 m and includes 

the Virgin, Muddy, and Colorado Rivers and Las Vegas Wash as well as adjacent systems 

(RECON 2000). Desert riparian and associated aquatic ecosystems are influenced by 

precipitation, topography, and geology (Poff and others 1997). Additionally, the intensity, 

timing, and frequency of flood events have an important role in shaping and maintaining this ecosystem type. Historically, Mojave riparian ecosystems were dominated by 

Fremont cottonwood (Populus fremontii), Goodding’s willow (Salix gooddingii), and 

various species of shrub willows (Salix spp.). In higher elevations velvet ash (Fraxinus 

velutina) was an important species. Other riparian plants include honey mesquite (Prosopis glandulosa) and a variety of native herbaceous species. Mojave riparian ecosystems 

contribute disproportionally to local and regional species richness despite the relatively 

small area they occupy compared to other ecosystems in the region (Naiman and others 

1993). 

All rivers in the Mojave Desert in Nevada have been altered through surface water 

diversions, channelization, and dams, thereby resulting in compromised biological and 

hydrogeomorphic conditions and a loss of system structure and function. The biophysical 

characteristics (periodic scour, flooding, and sediment deposition) necessary to support 

riparian plant species and patterns of heterogeneity no longer exist for river systems in 

southern Nevada (Busch and Smith 1995). Consequently, much of the riparian vegetation is now dominated by invasive species, especially tamarisk, which is also called 

saltcedar (Tamarix spp.) (Shafroth and others 2005). 

This ecosystem type is one of the most degraded and imperiled systems in the region. Stressors to this ecosystem include global effects of climate change; regional and 

local effects of fire, recreation, water manipulation projects; and the aforementioned 

effects of invasive species (e.g., Tamarisk, and aquatic – see Chapter 3). Climate change 

effects, especially resulting in changes in flow regimes linked to precipitation (timing 
112 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

and quantity), and increased evapotranspiration may further impact this ecosystem. It is 

expected that climate change will result in a warmer, drier climate, and reduced surface 

water across the range of species of conservation concern (i.e., yellow-billed cuckoo 

(Coccyzus americanus) and southwestern willow flycatcher (Empidonax traillii subsp. 

extimus)). However, various regional and local stressors individually and synergistically 

may prove to have a greater influence on species of conservation concern. 

Tamarisk is highly competitive with native species and in most cases is the dominant 

species where it occurs. The effect of Tamarisk dominance on wildlife habitat has been 

considered most commonly for birds (van Riper and others 2008), and generally indicates that moderate levels of Tamarisk provide better habitat than sites that are Tamarisk 

monocultures. Although reports have stated that Tamarisk is the preferred habitat for 

flycatchers (Davis and others 2011) it should be cautioned that previously published 

reports on this subject (van Riper and others 2008) do not reach the same conclusion. 

Efforts to control Tamarisk have been widely implemented and include the use of 

chemicals, mechanical methods, and fire. Most recently, land managers have released a 

biological control agent, the northern Tamarisk beetle (Diorhabda carinulata), which is 

native to Eurasia. In 2006, the northern Tamarisk beetle was released near St. George, 

Utah, and has subsequently expanded along reaches of the Virgin River. During the summer of 2011 the beetles became established within Tamarisk stands farther downstream 

along the Virgin River, and it may reach Lake Mead National Recreation Area (NRA) 

by 2012 or 2013. Based on patterns of defoliation along the Colorado River near Moab, 

Utah, the beetles will require multiple generations to cause substantial impact or even 

death to localized patches of Tamarisk stands at Lake Mead NRA However, the effect 

of the beetle on wildlife is unknown (Bateman and others 2010). Efforts are in place to 

evaluate the long-term effects of the northern Tamarisk beetle on wildlife and associated 

habitat quality (Bateman and others 2010; also see Bateman and Ostoja 2012). 

Although, the effects of introduced biological control species on wildlife groups have 

received little consideration (but see Pearson and Callaway 2005, 2006, 2008), two 

potential outcomes seem plausible. First, the beetle may provide increased resources 

for insectivorous and omnivorous species, thereby conferring advantage for wildlife 

able to capitalize on these increased prey numbers (Pearson and Callaway 2005, 2006, 

2008). However, beetle-caused defoliation and eventual death of Tamarisk trees may 

negatively affect birds by reducing breeding and nesting habitat. For example, defoliation may change the conditions surrounding a nest, which may lead to reductions in nest 

success due to loss of cover and increased predation associated with the microclimate 

of the nest. How the flycatcher and the cuckoo respond to this dynamic is unknown, 

but is of keen interest to ecologists and managers working in the area (see Bateman and 

others 2010). 

Even with widespread type conversions, this ecosystem continues to support a 

diversity of organisms including fish, invertebrates, reptiles, amphibians, birds, and 

mammals (Bateman and Ostoja 2012). This ecosystem is also home to numerous species of conservation concern including the Federally endangered southwestern willow 

flycatcher and yellow-billed cuckoo. These are two species that are also covered in the 

Clark Country MSHCP (Clark County 2000). 

The southwestern willow flycatcher is a small insect eating neotropical bird that uses 

riparian habitat for feeding, sheltering and cover while breeding, migrating, and dispersing (Paxton and others 2007). It was Federally listed in 1995 due to its small population 

size, historical and recent population declines, and habitat threats. The yellow-billed 

cuckoo is a medium sized bird that breeds in large blocks of riparian habitat (Johnson 

and others 2008). Nevada has listed the species as critically imperiled due to extreme 

rarity, imminent threats, and/or biological factors (Morefield 2011).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 113

In Clark County, Nevada the yellow-billed cuckoo’s decline has been linked to the 

reduction and degradation of riparian habitat, river channelization, livestock grazing, 

and use of pesticides, non-native species (Tamarisk), recreation, and brown-headed 

cowbird parasitism (Clark County 2000). Nevada has listed the species as a State Rank 

S1 Nevada State Protected, which means that the species is protected in Nevada and is 

considered critically imperiled due to extreme rarity, imminent threats, and/or biological 

factors.

Other local stressors that influence the habitat conditions for the flycatcher and 

cuckoo include grazing and recreation. Unregulated grazing along riparian systems can 

compromise ecological integrity where animals occur in sufficient numbers. Livestock 

that freely roam along arid riparian ecosystems can introduce a great deal of disturbance 

including reductions in stream bank stability and erosion. Loss of stream bank quality 

can lead to increased bank deterioration and reductions in habitat for wildlife. In addition, livestock can shift the competitive balance among co-occurring plant species 

via selective herbivory. Grazing animals can selectively remove desirable plants such 

as germinating cottonwood (Populus sp.) and willows, thereby decreasing native plant 

regeneration, and thereby indirectly facilitating co-occurring less palatable weedy plants. 

The effort to remove Tamarisk will be undermined if unregulated grazers selectively 

remove regenerating native vegetation, thereby facilitating increases in secondary weed 

populations. These types of synergistic effects are certainly difficult to predict but merit 

consideration and attention. 

Best management practices for conservation of this ecosystem include protecting and 

potentially enhancing large to medium patches of habitat for species of conservation 

concern, with the goal of maintaining a heterogeneous habitat complex of open, mixed 

species and with a varied age canopy, shrub thickets, flowering shrubs, and forbs with 

ample floodplain and wetland sites intermixed. Protection of old growth trees and sites 

that have minimal invasive species dominance could also be given priority. Conservation 

would be enhanced if grazing and OHV use could be kept at levels whereby sites are not 

permanently impacted and bare soil is not exposed in large patches. Restoration of sites 

where Tamarisk has been controlled or burned could also be a priority, especially where 

these sites are adjacent to nearby native patches and where the effect of grazing or OHV 

use is absent to minimal. Evaluation of biocontrol effects on vegetation trajectories and 

wildlife habitat would be useful to support future land management decisions. 

Spring Ecosystems

Key resource concerns Habitat loss/deterioration, unregulated grazers

Species examples Relict leopard frog

Local and regional stressors Diversion/ground water pumping, land/water development, unregulated grazers, non-native aquatic 

species, recreation, disease (Chytrid fungus)

Global stressors Climate change (precipitation patterns)

Synergistic effects Water/urban/agricultural development & habitat 

isolation; small population size/isolation and disease 

susceptibility
114 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Aquatic springs are biophysically diverse ecosystems due to differences in water 

chemistry, slope, substrate type, persistence, morphology, and size. Springs are most 

influenced by the type of aquifer, flow rate, landscape position, and local biology. There 

are two main types of springs, perennial and intermittent. Perennial springs are typically 

found at sites where deep aquifer ground water reaches the surface. Intermittent springs 

are typically fed by shallow ground water from localized precipitation. Most springs in 

Clark County are intermittent and less than 200 are persistent (Sada 2000). They vary 

in size, are biophysically diverse, and can be found from 250 m to 3300 m elevation in 

all landscape settings. The basic environmental and biological characteristics of several 

hundred larger springs within Clark County have been inventoried (Sada 2000; Sada 

and Nachlinger 1996, 1998). 

Springs are inhabited by many spring-obligate species including invertebrates and 

vertebrates, some of which may be found only in one spring with highly limited distributions (see LaRivers 1949, 1950, 1962). This ecosystem type also provides habitat 

for 14 MHSCP-covered species including the relict leopard frog (Rana onca), which 

is a candidate for Federal listing under the protection of the Endangered Species Act. 

The relict leopard frog is a small sized spotted frog with an adult body length of 1 3⁄4 to 

3 1⁄4 inches (Jennings 1988, 1993). Typical habitat includes permanent small streams, 

springs, and spring-fed wetlands (Jennings 1988). The species prefers relatively open 

shorelines where dense vegetation does not dominate. Once thought to be extinct, the 

relict leopard frog is known to occur at fewer than 10 unique sites (Jaeger and others 

2001). The loss of relict leopard frog populations occurred concurrently with the loss or 

alteration of aquatic habitat due to spring drainage and water development for agricultural 

and urban applications (Jennings and Hayes 1994). Other notable high-profile species 

endemic to this ecosystem type not considered here include various species of desert 

fishes, for example dace (Rhinichthys spp.) and pupfishes (Cyprinodontidae spp.). 

Spring ecosystems are highly sensitive to environmental disturbances. Because water 

resources are especially prized in arid ecosystems, natural spring systems are used for 

livestock, recreation, agriculture, and various domestic purposes (Sada and Vinyard 

2002). Springs also are indirectly impacted by regional groundwater withdrawal pumping and water diversions. Most springs have been invaded by non-native aquatic and 

terrestrial species that can affect ecosystem properties (Chapter 3). Invasive species 

include invertebrates, bullfrogs (Rana catesbeiana), crayfish, turtles (e.g., red-eared 

slider (Trachemys scripta ssp. elegans)), introduced aquarium species (e.g., mosquito 

fish (Gambusia sp.)), cichlids and other predatory fishes, as well as plants (e.g., Tamarisk 

species, fan palms). Introduced cichlids are voracious predators and may consume eggs 

and tadpoles (Romin 1997). Introduced bullfrogs, another fierce predator, are known 

to eliminate native leopard frogs in the western United States through competition and 

predation (Hayes and Jennings 1986).

Non-native and unregulated ungulates have been shown to negatively affect spring 

and associated aquatic habitat by trampling vegetation and soils, and concomitantly 

causing water quality impacts. Cattle using water sources can draw down smaller water 

bodies, leaving amphibian egg masses exposed. This leads to desiccation of the eggs, 

which can increase fungal infections (USFWS 2000b). Cattle can also directly kill egg 

masses and maturing and adult animals (USFWS 2000b). Loss of streamside vegetation 

due to cattle grazing can reduce habitat for insects and small mammals (USFWS 2001), 

which are important dietary components for aquatic species (Cordone and Kelley 1961), 

including the relict leopard frog. Feral burros also have been implicated in the reduction 

of frog population numbers due to overgrazing of shoreline vegetation, trampling, and 

urination and defecation in the water (CBD 2002; Jaeger and Barnes 2001). It should 

be noted, however, that frogs benefit from open water habitat, which may be increased 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 115

by cattle or other ungulate grazing. Three recent population extinctions occurred when 

emergent vegetation encroached into pools following the removal of livestock (RLFWG 

2001). At still another two sites, after livestock grazing stopped frog populations were 

reported to stabilize (CBD 2002; Jaeger and Barnes 2010). Management actions require 

a detailed understanding of the interactions of the variety of influences on habitat condition. Monitoring is also important, so that managers know if the actions taken are leading 

to the desired conservation outcome. It is important to note that burros and horses rely 

on predictable water sources when present within any ecosystem type and sustained 

trampling and grazing at the water sources can have a variety of negative effects. 

Chytridiomycosis is an infectious disease of amphibians caused by the fungus Batrachochytrium dendrobatidis (“Bd” or chytrid fungus; Berger and others 1998). The 

extraordinary virulence of chytrid fungus has caused the decline or extinction of hundreds 

of amphibian species around the world during the last several decades (Skerratt and 

others 2007) and hundreds more are considered at risk as chytrid fungus spreads into 

new areas. Chytrid fungus damages the mouthparts of tadpoles, then damages keratin 

in the skin of metamorphosed frogs, eventually killing them. Spores of chytrid fungus 

are ubiquitous in soil, but the aquatic spores infecting frogs is relatively new to science 

(Berger and others 1998). In 1998, chytrid fungus was found in numerous Arizona 

amphibians (RLFWG 2001). Reports suggest that chytrid fungus is most virulent at 

temperatures ≤23 °C and its pathogenicity and virulence decline significantly at ≥27 °C 

(Piotrowski and others 2004). It appears that thermal springs provide important habitat 

where frogs can persist despite the presence of chytrid fungus. Luckily, the relict leopard 

frog only occurs naturally in thermal springs that all have source temperatures >30 °C 

(Jaeger and Haley 2011). 

While attention was given to a single species in this section, other notable species exist 

in this and associated riparian ecosystems. These include various species of pupfishes 

and daces as well as invertebrates and plants. The habitats that support these species 

are highly imperiled due to direct effects of historical and ongoing manipulation or 

destruction, and their conservation will be an ongoing challenge to resource managers. 

While not discussed in this section, the effects of climate change are likely to intensify 

the local and regional stressors. Management of the springs ecosystem is particularly 

difficult because of its critical dependence on already limited water availability. 

Knowledge Gaps and Research Guidance

The overview of research on species of conservation concern provided in this chapter 

is not a complete review of all species and research topics, but it is a good representation of the nature of single species research in southern Nevada. One of the hallmarks 

of this body of research is that very little is known about the relative threats posed to, 

or the mitigation actions needed to protect virtually all species of concern except perhaps the desert tortoise. Too often research jumps immediately to mitigation strategies, 

without first determining what specific factors pose the greatest threats and are the most 

important to mitigate. In addition, the evaluation of potential threats typically focuses 

on the usual anthropogenic suspects (e.g., OHVs, livestock grazing, invasive species, 

and climate change) without first carefully considering which factors are most likely to 

pose the greatest threats. Finally, fundamental science associated with the life history 

characteristics and habitat requirements of species typically receives the least attention, 

even though these topics are where research programs could most benefit conservation 

programs. In the section below, we provide a case study that illustrates how a research 

program was organized in a hierarchical and thoughtful way, in order to provide maximum cost-efficiency and ultimate utility in the management of species of conservation 

concern.
116 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Research Strategy Case Study: Endemic Butterflies of the Spring 

Mountains

The Spring Mountains are home to numerous endemic species, including eight butterfly taxa, as discussed previously. Four of these species have very limited distributions 

and there is concern that their populations may be declining. One of these species, the 

Mt. Charleston blue butterfly, is currently a Candidate species for listing by the USFWS. 

Very little is known about the autecology and habitat requirements of these eight butterfly species. Conservation of these species can be based on a comprehensive research 

framework such as the one proposed below. Although this framework is specific to the 

endemic butterflies of the Spring Mountains, it provides a good example of what is 

required to fully inform land managers about species of conservation concern.

Initially, it is critical to understand the life cycles and the key habitat, threats, and 

restoration factors associated with each life history stage for each butterfly species. 

Detailed information is needed regarding overwintering stages, larval development, 

pupation, and adult behavior including oviposition, roosting, basking, and mating. For all 

of these stages, habitat preferences and related phenologies (the specific seasonal timing 

of life history events) must be understood, as well as potential threats and mitigating 

restoration factors (fig. 6.1). This kind of natural history information has been critical 

in other studies of the population persistence of butterflies (e.g., New and others 1995; 

Weiss and others 1988). 

The next step is to describe the species’ population structure and dynamics, including identification of the highest priority populations that are critical to the persistence 

of each butterfly. Butterflies occur in relatively discrete patches or populations across 

the landscape (fig. 6.2). The degree to which patches of occupied habitat are or are not 

connected by dispersal is of primary importance for the management of rare species 

(Hanski and Thomas 1994). From a conservation perspective, it is also important to 

know if all patches have equal probabilities of going extinct or being recolonized following extinction (as is assumed in a classic metapopulation). In reality, all patches do 

not have equal probabilities of persistence through time; instead, some locations act as 

demographic sources (providing migrants that move to other locations) while others 

act as sinks (receiving immigrants that act to maintain local populations that would 

otherwise not persist) (Boughton 1999). 

Figure 6.1—Conceptual model illustrating how habitat factors (H), threats 

(T), and/or restoration activities (R) could impact a butterfly or invertebrate 

species, and their relationships with critical habitat factors at the adult (A), 

egg (E), larval (L), and pupa (P) life history stages at the within-patch scale.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 117

The third step is to describe the structural and floristic composition of the habitat for 

each species, including habitat used during each season as well as for dispersal. Attempts 

to characterize habitat for butterflies and other species can often be hampered by preexisting biases regarding “suitable conditions” for a particular species. For butterflies, 

presence of larval host plants and nectar resources is often assumed to be sufficient to 

define requisite habitat, but that assumption can be erroneous. There is a pressing need 

to understand the net habitat requirements (across life history stages) for focal butterfly 

species, and in particular how to distinguish between suitable and unsuitable habitat 

(fig 6.3). Specifically, there is a need to characterize suitable habitat (both within and 

among patches) associated with population persistence. In some cases natural enemies 

may be an important habitat consideration, because mortality from natural enemies can 

Figure 6.3—A habitat dynamics model illustrating the transition of habitat from suitable to 

unsuitable (or vice versa) depending on the influence of threats and/or restoration factors 

(the list of habitat characteristics here is illustrative, not exhaustive). 

Figure 6.2—A conceptual model showing how threats and restoration can 

affect among (habitat) patch dispersal. Patches are represented by life cycle 

diagrams for adults (A), eggs (E), larva (L) and pupa (P), and dispersal among 

patches is shown as dotted lines being potentially impacted by both threats 

(TD) and restoration (RD).
118 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

be a significant factor that is frequently ignored in butterfly conservation plans (Bergman 

1999). Precise knowledge of habitat requirements is needed to inform a range of management decisions including where and how to initiate restoration efforts, where to allocate 

resources when it comes to mitigating certain threats, and where to attempt reintroductions of butterflies should that become necessary. Knowledge of habitat requirements 

can also direct management efforts by identifying species most at risk through habitat 

destruction or degradation. This is especially important in the Spring Mountains where 

vegetation management activities (i.e. fuels reduction/thinning operations) could have 

an impact/threat on the habitat condition of these species and could easily be modified.

As only a final step, habitat restoration and mitigation actions should be evaluated. 

Ecological restoration is accomplished by the redirection of natural populations, communities, wildlife habitat, or other ecosystem processes toward trajectories deemed more 

desirable (Jordan and others 1987). These trajectories can be defined in many ways, but 

are often focused on promoting specific habitat features known to be critical to a species, 

which is the focus of conservation planning (e.g., the Spring Mountains endemic butterflies). The development of relevant restoration treatments to achieve desired outcomes 

requires an understanding of the essential habitat features of the focal species, and the 

ecological processes necessary to increase the abundance and/or quality of these habitat 

features. Accordingly, it is not prudent to initiate and/or implement restoration activities until such information is available. In fact, many restoration attempts have failed, 

and resources have been wasted, because of insufficient knowledge regarding species’ 

autecology (Montalvo and others 1997; Pullin 1996). In brief, it is critical to know 

what is damaged and what one should be repairing before repair attempts are initiated. 

However in the short-term it may be prudent to eliminate stressor impacts to reduce 

the potential threat so the species is able to persist even when the desired information 

to make a completely informed decision is unavailable. 

Management Implications

Historically, actions such as limiting grazing or closing OHV trails have been some 

of the primary tools used by land managers in southern Nevada to reduce anthropogenic 

impacts to species of conservation concern. However, managers are increasingly faced 

with broader and more complex issues that cannot be effectively addressed by regionally 

or locally based management actions. For example, few if any options exist for local 

resource managers to directly combat effects associated with climate change or nitrogen 

deposition, even though they are responsible for ensuring the protection of the species 

directly or indirectly affected by such stressors. Research that can help disentangle local or regional effects from global effects would be especially useful for conservation 

planning and management of species of conservation concern. Additionally this would 

help focus management toward factors where there are actionable options. 

References

Anderson, J.L. 2001. The white-margined penstemon (Penstemon albomarginatus Jones), a rare Mohave 

Desert species, and the Hualapai Mountains land exchange in Mohave County, Arizona. In: Maschinski, J.; Holter, L., tech. (eds.). Southwestern rare and endangered plants: Proceedings of the Third 

Conference; 2000 September 25-28; Flagstaff, AZ. Proceedings RMRS-P-23. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station: 27-37.

Arizona Department of Game and Fish. 2000. Heritage data management system: plant abstract for Arctomecon californica DRAFT. Arizona Game and Fish. Arizona Game and Fish Department. 4 p. Online: 

http://www.azgfd.gov/w_c/edits/documents/Arctcali.d.pdf [2012, Oct 29].
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 119

Avery, H.W.; Neibergs, A. 1997. Effects of cattle grazing on the desert tortoise, Gopherus agassizii: nutritional and behavioral interactions. In: Van Abbema, J. (ed.). Proceedings: Conservation, restoration, 

and management of tortoises and turtles—An international conference; July 1993; State University of 

New York, Purchase. New York: New York Turtle and Tortoise Society: 13-20.

Bateman, H.L.; Dudley, T.L.; Bean, D.W.; Ostoja, S.M.; Hultine, K.R.; Kuehn, M.J. 2010. A river system 

to watch: documenting the effects of saltcedar (Tamarix spp.) biocontrol in the Virgin River Valley. 

Ecological Restoration. 28:405-410.

Bateman, H.L.; Ostoja, S.M. 2012. Invasive woody plants affect the composition of native lizard and 

small mammal communities in riparian woodlands. Animal Conservation. 15:294-304.

Battaglia, M.A.; Shepperd, W.D. 2007. Ponderosa pine, mixed conifer, and spruce-fir forests. In: S.M. 

Hood and M. Miller (eds.). Fire Ecology and Management of the Major Ecosystems of Southern Utah. 

Gen. Tech. Rep. RMRS-GTR-202, Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station: 7-37.

Bauer, J.M.; Weisberg, P.J. 2009. Fire history of a central Nevada piñon-juniper woodland. Canadian 

Journal of Forest Research-Revue Canadienne De Recherche Forestiere. 39:1589-1599.

Belnap, J.; Phillips S.L.; Sherrod S.K.; Moldenke, A. 2005. Soil biota can change after exotic plant invasion: does this affect ecosystem processes? Ecology. 86:3007-3017.

Berger, L.; Speare, R.; Daszak, P.; Green, D.E.; Cunningham, A.A.; Goggin, C.L.; Slocombe, R.; Ragan, 

M.A.; Hyatt, A.D.; McDonald, K.R.; Hines, H.B.; Lips, K.R.; Marantelli, G.; and Parkes, H. 1998. 

Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests 

of Australia and Central America. Proceedings of the National Academy of Sciences. 95:9031-9036.

Bergman, K. 1999. Habitat utilization by Lopinga achine (Nymphalidae: Satyrinae) larvae and ovipositing females: implications for conservation. Biological Conservation. 88:69-74.

Berry, K.H. 1986. Desert tortoise (Gopherus agassizii) research in California, 1976-1985. Herpetologica. 

42: 62-67.

Boughton, D.A. 1999. Empirical evidence for complex source-sink dynamics with alternative states in a 

butterfly metapopulation. Ecology. 80:2727-2739.

Bowman W.D.; Steltzer, H. 1998. Positive feedbacks to anthropogenic nitrogen deposition in Rocky 

Mountain alpine tundra. Ambio. 27:514-517. 

Bowns, J.E.; West, N.E. 1976. Blackbrush (Coleogyne ramosissima Torr.) on southern Utah rangelands. 

Research Report. Logan, UT: Utah State University, Department of Range Science, Utah Agricultural 

Experiment Station. 27 p.

Breshears, D.D.; Myers, O.B.; Meyer, C.W.; Barnes, F.J.; Zou, C.B.; Allen, C.D.; McDowell, N.G.; Pockman, W.T. 2009. Tree die-off in response to global change-type drought: mortality insights from a 

decade of plant water potential measurements. Frontiers in Ecology and the Environment. 7:185-189.

Breshears, D.D.; Cobb, N.S.; Rich, P.M.; Price, K.P.; Allen, C.D.; Balice, R.G.; Romme, W.H.; Kastens, 

J.H.; Floyd, M.L.; Belnap, J.; Anderson, J. J.; Myers, O. B.; Meyer C.W. 2005. Regional vegetation dieoff in response to global-change-type drought. Proceedings of the National Academy of Sciences of the 

United States of America. 102: 15144-15148.

Brooks, Matthew. 2012. Photographic comparisons of burned landscapes of southern Nevada between the 

1940s and 2000s. Unpublished photographic database on file at: U.S. Department of the Interior, U.S. 

Geological Survey, Western Ecological Research Center, Yosemite Field Station. Oakhurst, CA.

Brooks, M.L. 2003. Effects of increased soil nitrogen on the dominance of alien annual plants in

the Mojave Desert. Journal of Applied Ecology. 40:344-353.

Brooks, M.L.; D’Antonio, C.M.; Richardson, D.M.; Grace, J.B.; Keeley, J.E.; DiTomaso, J.M.; Hobbs, R.J.; 

Pellant, M.; Pyke, D. 2004. Effects of invasive alien plants on fire regimes. BioScience. 54:677-688.

Brooks, M.L.; Pyke, D. 2001. Invasive plants and fire in the deserts of North America. In: Galley, K.; Wilson, T. (eds.). Proceedings of the invasive species workshop: The role of fire in the control and spread 

of invasive species. Fire conference 2000: The First National Congress on Fire Ecology, Prevention and 

Management. Miscell. Publ. No. 11. Tallahassee, FL: Tall Timbers Research Station: 1-14.

Brooks, M.L.; Matchett J.R. 2003. Plant community patterns in unburned and burned blackbrush (Coleogyne ramosissima) shrublands in the Mojave Desert. Western North American Naturalist. 63:283-298.

Brooks, M.L.; Esque T.C.; Duck T. 2007. Fuels and fire regimes in creosote bush, blackbrush, and interior chaparral shrublands. In: Hood, S.; Miller, M. (eds.). Fire ecology and management of the major 

ecosystems of southern Utah. Gen. Tech. Rep. RMRS-GTR-202. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station: 97-110.

Brooks, M.L.; Draper J.V. 2006. Fire effects on seedbanks and vegetation in the eastern Mojave Desert: 

implications for postfire management. Proceedings of the Third International Fire Ecology and Management Congress; 13-17 November 2006; San Diego, CA. 3 p. Online: http://www.nps.gov/moja/

naturescience/upload/Fire%20congress%202006_brooks%20and%20draper_extended%20abstract.

pdf [2012, Oct 29]. 
120 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Brown, J.K.; Smith J.K., [eds.]. 2000. Wildland fire in ecosystems: effects of fire on flora. Gen. Tech Rep. 

RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station. 257 p.

Buechner, H.K. 1960. The bighorn sheep in the United States: its past, present, and future. Wildlife Monograph 4. Wildlife Society. 174 p.

Bury, R.B.; Esque T.C.; DeFalco L.A.; Medica P.A. 1994. Distribution, habitat use, and protection of 

the desert tortoise in the eastern Mojave Desert In: Bury, R.B.; Germano, D.J (eds.). Biology of North 

American tortoises. National Biological Survey, Fish and Wildlife Research 13: 57-72. Online: http://

www.fort.usgs.gov/Products/Publications/2724/2724.pdf. [2012, Oct 29].

Busch, D.E.; Smith, S.D. 1995. Mechanisms associated with decline of woody species in riparian ecosystems of the southwestern U.S. Ecological Monographs. 65:347-370.

Button, C. 1991. Our unique Arizona flora: White-margined beard-tongue. Arizona Native Plant Society 

newsletter. 15(1): 5. 

Center for Biological Diversity (CBD). 2002. Petition to list the relict leopard frog (Rana onca) as an 

endangered species under the endangered species act. Report presented to the secretary of the interior. 

Online: http://www.biologicaldiversity.org/species/amphibians/relict_leopard_frog/pdfs/petition.pdf. 

[2012, Nov 5]. 

Clark County (CC MSHCP). 2000. Clark County Multi-Species Habitat Conservation Plan. [Online]. 

Available: www.clarkcountynv.gov/Depts/dcp/Documents/.../LENAFINAL.pdf. [2012, Oct 29].

Clark County Department of Comprehensive Planning and U.S. Fish and Wildlife Service, Relict Leopard 

Frog Working Group (RLFWG). 2001. Rana onca: rangewide conservation assessment and strategy. 

Working Draft 12-31-01. U. S. Fish and Wildlife Service, Arizona Department of Game & Fish, Utah 

Department of Natural Resources, Nevada Department of Wildlife, National Park Service, Bureau of 

Reclamation, Bureau of Land Management, Las Vegas Valley Water District.

Clifford, M.J.; Cobb, N.S.; Buenemann, M. 2011. Long-term tree cover dynamics in a piñon-juniper 

woodland: climate-change-type drought resets successional clock. Ecosystems. 14:949-962.

Clokey, I.W. 1951. Flora of the Charleston Mountains, Clark County, Nevada. Berkeley, CA: University 

of California Press. 274 p.

Cordone, A.J.; Kelley, D.W. 1961. The influence of inorganic sediment on the aquatic life of streams. 

California Fish and Game. 47:189-228.

Crow, C.; van Riper, III. C. 2010. Avian community responses to mechanical thinning of a piñon-juniper 

woodland: specialist sensitivity to tree reduction. Natural Areas Journal. 30:191-201.

D’Antonio, C.M.; Vitousek, P.M. 1992. Biological invasions by exotic grasses, the grass/fire cycle, and 

global change. Annual Review of Ecology and Systematics 23: 63-87.

Davis, M.A.; Chew, M.K.; Hobbs, R.J.; Lugo, A.E.; Ewel, J.J.; Vermeij, G.J.; Brown, J.H.; Rosenzweig, 

M.L.; Gardener, M.R.; Carroll, S.P.; Thompson, K.; Pickett, S.T.; Stromberg, J.C.; Del Tredici, P.; Suding, K.N.; Ehrenfeld, J.G.; Grime, J.P.; Mascaro, J.; Briggs, J.C. 2011. Don’t judge species on their 

origins. Nature. 474:153-154.

DeForge, J.A. 1981. Stress: changing environments and the effects on bighorn sheep. Desert Bighorn 

Council Transactions. 25: 15-16.

Desert Research Institute. 2008. Task 7: First iteration conceptual models for 11 MSHCP ecosystems. Annual Report. Project 2005-DRI-574A-P. Reno, NV: Desert Research Institute.

DiTomaso, J.M. 2000. Invasive weeds in rangelands: species, impacts, and management. Weed Science. 

48:255-265.

Ditchkoff, S.S.; Saalfeld, S.T.; Gibson C.J. 2006. Animal behavior in urban ecosystems: modifications due 

to human-induced stress. Urban Ecosystems. 9:5-12.

Epps, C.W. 2004. Population processes in a changing climate: extinction, dispersal, and metapopulation dynamics of desert bighorn sheep in California. Ph.D. dissertation, Berkely, CA: University of California. 135 p.

Esque, T.A.; Nussear, K.E.; Drake, K.K.; Walde, A.D.; Berry, K.H.; Averill-Murray, R.C.; Woodman, A.P.; 

Boarman, W.I.; Medica, P.A.; Mack, J.; Heaton, J.S. 2010. Effects of subsidized predators, resource 

variability and human population density on desert tortoise populations in the Mojave Desert, USA. 

Endangered Species Research. 12:167-177. 

Gildart, R.C. 1999. Mountain Monarchs: Bighorn Sheep. Minnetonka, MN: North World Press. 144 p.

Gilpin, M.E.; Soulé, M.E. 1986. Minimum viable populations: processes of species extinction. In Soulé, 

M.E. (ed.). Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer & 

Associates: 19-34.

Goguen, C.B.; Mathews, N.E. 1998. Songbird community composition and nesting success in grazed and 

ungrazed piñon-juniper woodlands. Journal of Wildlife Management. 62: 474-484.

Goguen, C.B.; Mathews, M.E. 2001. Brown –headed cowbird behavior and movements in relation to 

livestock grazing. Ecological Applications. 11:1533-1544. 

Goguen, C.B.; Curson, D.R.; Mathews, M.E. 2005. Breeding ecology of the gray flycatcher in piñonjuniper woodlands in New Mexico. Western Birds. 36:286-295. 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 121

Grover, M.C.; DeFalco, L.A. 1995 Desert tortoise (Gopherus agassizii): status-of-knowledge outline with 

references. Gen. Tech. Rep. INT-GTR-316. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 140 p.

Gutiérrez-Espeleta, G.A.; Kalinowski, S T.; Boyce, W.M.; Hedrick P.W. 2000. Genetic variation and population structure in desert bighorn sheep: implications for conservation. Conservation Genetics. 1:3-15.

Hanski, I.; Thomas, C.D. 1994. Metapopulation dynamics and conservation: a spatially explicit model 

applied to butterflies. Biological Conservation. 68:167-180.

Hayes, M.P.; Jennings, M.R. 1986. Decline of ranid frog species in western North America: are bullfrogs 

(Rana catesbeiana) responsible? Journal of Herpetology. 20:490-509.

Henen, B.T.; Peterson, C.C.; Wallis, I.R.; Nagy, K.A.; Berry K.H. 1998. Effects of climatic variation on 

field metabolism and water relations of desert tortoises. Oecologia. 117:365-373. 

Humphrey, L.D.; Schupp, E.W. 2001. Seed banks of Bromus tectorum dominated communities in the 

Great Basin. Western North American Naturalist. 61: 85-92.

IPCC (Intergovernmental Panel on Climate Change). 2001 Third assessment report: climate change. Online: http://www.grida.no/publications/other/ipcc_tar/. [2012, Nov 6]. 

Jacobson, E.R.; Gaskin, J.M.; Brown, M.B.; Harris, R.K.; Gardiner, C.H.; Lapointe, J.L.; Adams, H.P.; 

Reggiardo, C. 1991. Chronic upper respiratory tract disease of free ranging desert tortoises (Xerobates 

agassizii) Journal of Wildlife Diseases. 27:296-316.

Jaeger, J.R.; Barnes J.G. 2010. Relict leopard frog monitoring and management (Rana onca). Final Report 

to Lake Mead National Recreation Area, National Park Service. Online: http://www.clarkcountynv.

gov/Depts/dcp/Documents/Library/dcp%20reports/2010/Relict%20Leopard%20Frog%20Management%20NPS%20476%20Nov%202010.pdf. [2012, Oct 30].

Jaeger, J.R.; Haley, R. 2011. Rana onca monitoring and management. Abstract. Laughlin NV: Colorado 

River terrestrial and riparian meeting. 

Jaeger, J.R.; Riddle, B.R.; Jennings, R.D.; Bradford, D.F. 2001. Rediscovering Rana onca: evidence for 

phylogenetically distinct leopard frogs from the border region of Nevada, Utah, and Arizona. Copeia. 

2001:339-354.

Jeffries, D.L.; Klopatek, J.M. 1987. Effects of grazing on the vegetation of the blackbrush association. 

Journal of Range Management. 40:390-392.

Jennings, M.R. 1988. Rana onca Cope, relict leopard frog. Catalogue of American amphibians and reptiles. 417.1-417.2. Salt Lake City UT: Society for the Study of Amphibians and Reptiles. 

Jennings, M.R.; Hayes, M.P. 1994. Decline of native ranid frogs in the desert southwest. In: Brown, P.R.; 

Wright, J.W. (eds.). Herpetology of the North American deserts. Special Publ. No 5. Southwestern 

Herpetologists Society: 183-211.

Jennings, R.D. 1993. Rediscovery of Rana onca in southern Nevada and taxonomic reevaluation of some 

Southwest leopard frogs. Abstract. Annual Meeting of American Society of Ichthyologists and Herpetologists; May 1993; Austin, TX: 178.

Jessup, D.A. 1985. Diseases of domestic livestock which threaten bighorn sheep populations. Desert Bighorn Council Transactions. 29: 29-33.

Johnson, M.J.; Durst S.L.; Calvo, C.M.; Stewart, L.; Sogge, M.K.; Bland, G.; Arundel, T. 2008. Yellowbilled Cuckoo distribution, abundance, and habitat use along the lower Colorado River and its tributaries, 2007 Annual Report. Open-File Report 2008-1177. U.S. Geological Survey. 274 p.

Jones, L.C. 2011. Ecology and restoration of blackbrush (Coleogyne ramosissima) in the Mojave Desert. Abstract. Annual Meeting of American Society of Ichthyologists and Herpetologists; May 1993; Austin, TX. 

Klinger, Robert C. 2013. [Personal communication]. February 12. Oakhurst CA: U.S. Department of the 

Interior, U.S. Geological Survey, Western Ecological Research Center, Yosemite Field Station.

Klute, D.S.; Ayers, L.W.; Green, M.T.; Howe, W.H.; Jones, S.L.; Shaffer, J.A.; Shefield, S.R.; Zimmerman, T.S. 2003. Status assessment and conservation plan for the Western Burrowing Owl in the United 

States. Biol. Tech. Publ. USFWS/BTP-R6001-2003.Washington, DC: U.S. Department of the Interior, 

Fish and Wildlife Service. 

Knick, S.T.; Rotenberry, J.T. 2002. Effects of habitat fragmentation on passerine birds breeding in Intermountain shrub steppe. Studies in Avian Biology. 25:130-140.

Knick, S.T.; Dobkin, D.S.; Rotenberry, J.T.; Schroeder, M.A.; Vander Haegen, M.; Van Riper, III. C. 2003. 

Teetering on the edge or too late? Conservation and research issues for avifauna of sagebrush habitats. 

The Condor. 105:611-634.

Kristan, W.B.; Boarman, W.I. 2007. Effects of anthropogenic developments on common raven nesting 

biology in the west Mojave Desert. Ecological Applications. 17:1703-1713.

Kristan, W.B.; Boarman, W.I.; Crayon, J.J. 2004. Diet composition of common ravens across the urbanwildland interface of the West Mojave Desert. Wildlife Society Bulletin. 32:244-253.

Ladehoff, N.M.; Johnson, T.B.; Palmer B.K.; Schwalbe, C.R. 1990. Bibliography of published and unpublished references pertinent to management and conservation of the Desert Tortoise in Arizona. Phoenix, 

AZ: Arizona Game and Fish Department.
122 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

LaRivers, I. 1949. A new species of Microcylleopus from Nevada (Coleoptera: Dryopidae). Entomological News. 60:205-209.

LaRivers, I. 1950. A new naucorid genus and species from Nevada (Hemiptera: Naucroidae). The PanPacific Entomologist. 26:19-21.

LaRivers, I. 1962. Fishes and Fisheries of Nevada. Carson City, NV: Nevada State Fish and Wildlife 

Commission. 

Lessard, J.; Fordyce, J.A.; Gotelli, N.J.; Sanders, N.J. 2009. Invasive ants alter the phylogenetic structure 

of ant communities. Ecology. 90:2664-2669. 

Lovich, J.E.; Bainbridge, D. 1999. Anthropogenic degradation of the southern California desert ecosystem 

and prospects for natural recovery and restoration. Environmental Management. 24: 309-326.

Madsen, T.; Figdor, E. 2007. When it rains it pours: global warming and rising frequency of extreme precipitation in the U.S. Environment America. 47 p. Online: http://www.environmentamerica.org/sites/

environment/files/reports/When-It-Rains-It-Pours----US---WEB.pdf. [2012, Nov 5].

Medica, Phil. 2012. [Personal communication]. April 9. email: U.S. Department of the Interior, U.S. Geological Survey, Western Ecological Research Center, Las Vegas Field Station.

Miller, R.F.; Tausch, R.J.; McArthur, E.D.; Johnson, D.D.; Sanderson, S.C. 2008. Age structure and 

expansion of pinon-juniper woodlands: a regional perspective in the Intermountain West. Res. Pap. 

RMRS-RP-69. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain 

Research Station. 15 p.

Minnich, R.A. 2003. Fire and dynamics of temperate desert woodlands in Joshua Tree National 

Park. Report submitted to the National Park Service, Joshua Tree National Park. Contract number 

P8337000034/0001. 32 p.

Montalvo, A.M.; Williams, S.L.; Rice, K.J.; Buchmann, S.L.; Cory, C.; Handel, S.N.; Nabhan, G.P.; Primack, R.; Robichaux, R.H. 1997. Restoration biology: a population biology perspective. Restoration 

Ecology. 5:277-290.

Morefield, J.D. (editor). 2001. Nevada Rare Plant Atlas. Carson City: Nevada Natural Heritage Program, 

compiled for the U.S. Department of Interior, Fish and Wildlife Service, Portland, Oregon and Reno, 

Nevada. Online: http://heritage.nv.gov/atlas/atlastxt.pdf. [2012, Nov 4].

Murphy, D.D.; Freas, K.E.; Weiss, S.B. 1990. An environment-metapopulation approach to population 

viability analysis. Conservation Biology. 4:41-50.

Naiman, R.J.; Decamps, H.; Pollock, M. 1993. The role of riparian corridors in maintaining regional biodiversity. Ecological Applications. 3:209-212.

New, T.R.; Pyle, R.M.; Thomas, J.A.; Thomas, C.D.; Hammond, P.C. 1995. Butterfly conservation management. Annual Review of Entomology. 40:57-83.

Newbold, T.A.S. 2005. Desert horned lizard (Phrynosoma platyrhinos) locomotor performance: the influence of cheatgrass (Bromus tectorum). Southwestern Naturalist. 50:17-23.

Norton, J.B.; Monaco, T.A.; Norton, J.M; Johnson, D.A.; Jones, T.A. 2004. Soil morphology and organic 

matter dynamics under cheatgrass and sagebrush-steppe plant communities. Journal of Arid Environments. 57:445-466.

Noson, A.C.; Schmitz, R.A.; Miller, R.F. 2006. Influence of fire and juniper encroachment on birds in 

high-elevation sagebrush steppe. Western North American Naturalist. 66: 343-353.

Ostermann-Kelm, S.; Atwill, E.R.; Rubin, E.S.; Jorgensen, M.C.; Boyce, W.M. 2008. Interactions between feral horses and desert bighorn sheep at water. Journal of Mammalogy. 89:459-466.

Ostoja, S.M.; Schupp, E.W. 2009. Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communities. Diversity and Distributions. 15 863-870.

Ostoja, S.M.; Schupp, E.W.; Sivy, K. 2009. Ant assemblages in intact big sagebrush and converted cheatgrass-dominated habitats in Tooele County, Utah. Western North American Naturalist. 69:223-234.

Page, J.L.; Dodd, N.L.; Osborne, T.O.; Carson, J.A. 1978. The influence of livestock grazing on non-game 

wildlife. Cal-Neva Wildlife 1978: 159-173.

Paige, C.; Ritter, S.A. 1999. Birds in a sagebrush sea: managing sagebrush habitats for bird communities. 

Partners in Flight Western Working Group, Boise, ID. 47 p. Online: http://www.partnersinflight.org/

wwg/sagebrush.pdf. [2012, Oct 29]. 

Parsons, R.F. 1976. Gypsophily in plants. A review. American Midland Naturalist. 96:1-20.

Pauli, H.; Gottfried, M.; Grabherr, G. 1996. Effects of climate change on mountain ecosystems – upward 

shifting of alpine plants. World Resource Review. 8:382-390. 

Paxton, E.H.; Sogge, M.K.; Durst, S.L.; Theimer, T.C.; Hatten, J.R. 2007. The ecology of the southwestern willow flycatcher in central Arizona—a 10-year synthesis report. Open-File Report 2007-1381. 

U.S. Geological Survey. 143 p.

Pearson, D.E.; Callaway, R.M. 2005. Indirect nontarget effects of host-specific biological control agents: 

implications for biological control. Biological Control. 35:288-298. 

Pearson, D.E.; Callaway R.M. 2006. Biological control agents elevate hantavirus by subsidizing deer 

mouse populations. Ecology Letters. 9:443-450.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 123

Pearson, D.E.; Callaway, R.M. 2008. Weed-biocontrol insects reduce native-plant recruitment through 

second-order apparent competition. Ecological Applications. 18:1489-1500.

Pendleton, B.K.; Meyer, S.E.; Pendleton, R.L. 1995. Blackbrush biology: after three years of a long term 

study. In: Roundy, B.A.; McArthur, E.D.; Haley, J.S.; Mann, D.K. (comps). Proceedings: Wildland 

Shrub and Arid Land Restoration Symposium, 1993 October 19-21, Las Vegas, NV. Gen. Tech. Rep. 

INT-GTR-315. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research 

Station: 223-227. 

Piotrowski, J.S.; Annis, S.L. Longcore, J.E. 2004. Physiology of Batrachochytrium dendrobatidis, a chytrid pathogen of amphibians. Mycologia. 96:9-15

Poff, N.L.; Allan, J.D.; Bain, M.B.; Karr, J.R.; Prestegaard, K.L.; Richter, B.D.; Sparks, R.E.; Stromberg, 

J.C. 1997. The natural flow regime: a paradigm for river conservation and restoration. Bioscience. 

47:769-784.

Poulin, Ray, L. Danielle Todd, E. A. Haug, B. A. Millsap and M. S. Martell. 2011. Burrowing Owl (Athene 

cunicularia). In: Poole, A. (ed.). The Birds of North America Ithaca, NY: Cornell Lab of Ornithology. 

Online: http://bna.birds.cornell.edu/bna/species/061. [2012, Oct 30]. 

Pullin, A.S. 1996. Restoration of butterfly populations in Britain. Restoration Ecology. 4:71–80.

RECON (Regional Environmental Consultants, Inc.). 2000. Final Clark County Nevada multiple species 

habitat conservation plan and environmental impact statement. Prepared for Clark County Administrative Services. Las Vegas, NV. 550 p. plus appendices.

Rieder, J.P.; Newbold, T.A.S.; Ostoja, S.M. 2010. Structural changes in vegetation coincident with annual grass 

invasion negatively impacts sprint velocity of small vertebrates. Biological Invasions. 12:2429-2439.

Richardson, B.A.; Meyer, S.E. 2012. Paleoclimate effects and geographic barriers shape regional population genetic structure of blackbrush (Coleogyne ramosissima: Rosaceae). Botany. 10:293-299.

Romin, S. 1997. The relicts that persist in Nevada. Bajada. 5: 11.

Romme, W.H.; Floyd, L.; Hanna, D. 2009a. The forests of southwestern Colorado and Northwestern New 

Mexico: How the past and present inform our choices for the future. Highlands Section, southwestern 

Colorado & northwestern New Mexico. Fort Collins, CO: Colorado Sate University, Colorado Forest 

Restoration Institute. 16 p. Online: http://warnercnr.colostate.edu/docs/frs/cfri/SCColoradoShort.pdf. 

[2012, Nov 4]. 

Romme, W.; Allen, C.D.; Bailey, J.D.; Baker, W.L.; Bestelmeyer, B.T.; Brown, P.M.; Eisenhart, K.S.; 

Floyd, L.; Huffmand, D.W.; Jacobs, B.F.; Miller, R.F.; Muldavin, E.H.; Swetnam, T.W.; Tausch, R.J.; 

Weisberg, P.J. 2009b. Historical and modern disturbance regimes, stand structures, and landscape dynamics in pinon-juniper vegetation of the western United States. Rangeland Ecology and Management. 

62:203-222.

Saab, V.A.; Bock, C.E.; Rich, T.D.; Dobkin, D.S. 1995. Livestock grazing effects in western North America. In: Martin, T.E.; Finch, D.M. (eds.). Ecology and management of neotropical migratory birds. New 

York, NY: Oxford University Press: 311-353.

Sada, D.W. 2000. Geologically persistent springs in southern Nevada and southeastern California as indicated by aquatic macroinvertebrate assemblages. Unpublished report to U.S. Environmental Protection 

Agency, Office of Research and Development, Las Vegas, NV.

Sada, D.W.; Vinyard, G.L. 2002. Anthropogenic changes in historical biogeography of Great Basin aquatic biota. In: Hershler, R.; Madsen, D.B.; Currey, D. (eds.). Great Basin aquatic systems history. Smithsonian Contributions to the Earth Sciences No. 33. pp. 277-295.

Sada, D.W.; Nachlinger, J.L. 1996. Spring Mountains Ecosystem: Vulnerability of Spring-fed Aquatic and 

Riparian Systems to Biodiversity Loss. Unpublished report to U.S. Fish and Wildlife Service, Reno, NV.

Sada, D.W.; Nachlinger, J.L. 1998. Spring Mountains ecosystem: vulnerability of spring-fed aquatic and 

riparian systems to biodiversity loss: Part II, springs surveyed in 1997. Unpublished report to U.S. Bureau of Land Management, Las Vegas, NV.

Sauer, J.R.; Hines, J.E.; Fallon, J. 2008. The North American breeding bird survey, results and analysis 

1966 - 2007. Version 5.15.2008. Laurel, MD: USGS Patuxent Wildlife Research Center. Online: http://

www.mbr-pwrc.usgs.gov/bbs/bbs.html. [2012, Oct 30]. 

Scogin, R. 1989. Studies of Penstemon albomarginatus in California. Report for Rancho Santa Ana Botanic Garden, Claremont, CA.

Shaffer S.L.; Bartlein, P.J.; Thompson, R.S. 2001 Potential changes in the distributions of western north 

America tree and shrub taxa under future climate scenarios. Ecosystems. 4:200-215. 

Shafroth, P.B.; Cleverly, J.R.; Dudley, T.L.; van Riper, III C.; Stuart, J.N. 2005. Control of Tamarix in the 

western United States: implications for water salvage, wildlife use, and riparian restoration. Environmental Management. 35:231–246.

Shoenherr, A.A. 1992. A Natural History of California. Berkeley, CA: University of California Press. 772 p.

Skerratt, L.F.; Berger, L.; Speare, R.; Cashins, S.; McDonald, K.R.; Phillott, A.D.; Hines, H.B.; Kenyon, 

N. 2007. Spread of chytridiomycosis has caused the rapid global decline and extinction of frogs. EcoHealth. 4:125-134. 
124 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Smith, S.D.; Strain, B.R.; Sharkey, T.D. 1987. Effects of CO2 enrichment on four Great Basin grasses. 

Functional Ecology. 1:139-143.

Smith, J.E.; Taylor, S.J.; Whelan, C.J.; Denight, M.L.; Stake, M.M. 2004. Behavioral interaction between 

fire ants and vertebrate nest predators at two black-capped vireo nests. Wilson Bulletin. 116: 163-166. 

Sterling, J.C. 1999. Gray Flycatcher (Empidonax wrightii). In: Poole, A., (ed.). The Birds of North America Ithaca, NY: Cornell Lab of Ornithology. Online: http://bna.birds.cornell.edu/bna/species/061. [2012, 

Oct 30]. 

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/

SNAP-S-R-Strategy-2009r.pdf. [2011, April 6].

United States Fish and Wildlife Service (USFWS). 2000a. Recovery plan for bighorn sheep of the Peninsular Ranges, California. Portland, OR: U.S. Department of the Interior, Fish and Wildlife Service, 

Region 1. 251 p.

United States Fish and Wildlife Service (USFWS). 2000b. Recovery plan for the California red-legged 

frog (Rana aurora draytonii). Portland, OR: U.S. Department of the Interior, Fish and Wildlife Service, Region 1. Online: http://www.fws.gov/arcata/es/amphibians/crlf/documents/020528.pdf. [2012, 

Oct 30]

United States Fish and Wildlife Service (USFWS). 2001. Relict leopard frog (Rana onca) historical synopsis. Unpublished summary. Albuquerque, NM : U.S. Department of the Interior, Fish and Wildlife 

Service, Region 2. 

United States Fish and Wildlife Service (USFWS). 2008. Draft revised recovery plan for the Mojave 

population of the desert tortoise (Gopherus agassizii). Sacramento, CA: U.S. Department of the Interior, Fish and Wildlife Service, Region 8, Pacific Southwest Region. 209 p. 

United States Fish and Wildlife Service (USFWS). 2010. March 2010 update of 2004 Table of known occurrences of Eriogonum corymbosum var. nilesii, Las Vegas Buckwheat, in the Las Vegas Valley, Clark 

County, Nevada. Unpublished table. Las Vegas, NV: U.S. Fish and Wildlife Service, Southern Nevada 

Field Office. 1 p.

United States Fish and Wildlife Service (USFWS) 2011a. Endangered and threatened wildlife and plants; 

12-month finding on a petition to list the Mt. Charleston Blue Butterfly as endangered or threatened. 

FWS-R8-ES-2010; MO 92210-0-0008. 76 FR 12667.

United States Fish and Wildlife Service (USFWS) 2011b. Revised recovery plan for the Mojave population of the Desert Tortoise (Gopherus agassizii). Sacramento, CA: U.S. Department of the Interior, Fish 

and Wildlife Service, Region 8, Pacific Southwest Region.. 246 p. Online: http://www.fws.gov/nevada/

desert_tortoise/documents/recovery_plan/RRP%20for%20the%20Mojave%20Desert%20Tortoise%20

-%20May%202011.pdf. [2012, Oct 30].

van Riper, III. C.; Paxton, K.L.; O’Brien, C.; Shafroth, P.B.; McGrath, L.J. 2008. Rethinking avian response to Tamarix on the lower Colorado River: A threshold hypothesis. Restoration Ecology. 16:155-

167.

Verheye W.H.; Boyadgiev, T.G. 1997. Evaluating the land use potential of gypsiferous soils from field 

pedogenic characteristics. Soil Use and Management. 13:97-103.

Webb, R.H.; Steiger, J.W.; Turner, R.M. 1987. Dynamics of Mojave Desert assemblages in the Panamint 

Mountains, California. Ecology. 68:478-490.

Weisberg, P.J.; Lingua E.; Pillai, R.B. 2007. Spatial Patterns of piñon and juniper woodland expansion in 

central Nevada. Rangeland Ecology and Management. 60:115-124.

Weiss, S.B.; Weiss, A.D.; Murphy, D.D.; Austin, G.T. 1997. Final report on endemic butterflies of the 

Spring Mountains. Stanford University/Nevada State Museum. Unpublished report prepared for U.S. 

Fish and Wildlife Service, Reno, NV.

Weiss, S.B.; Murphy, D.D.; White, R.R. 1988. Sun, slope, and butterflies: topographic determinants of 

habitat quality for Euphydryas editha. Ecology. 69:1486-1496.

Wehausen, J.D. 2005. Nutrient predictability, birthing seasons, and lamb recruitment for desert bighorn 

sheep. Granite Mountain Symposium 1.

Williams, M.W.; Brooks, P.D.; Seastedt, T. 1998. Nitrogen and carbon soil dynamics in response to climate change in a high-elevation ecosystem in the Rocky Mountains, U.S.A. Arctic and Alpine Research. 30:26-30.

Ziska; L.H.; Reeves; J.B.; Blank, B. 2005. The impact of recent increases in atmospheric CO2 on biomass 

production and vegetative retention of cheatgrass (Bromus tectorum): implications for fire disturbance. 

Global Change Biology. 11:1325-1332.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 125

Chapter 7

Maintaining and Restoring Sustainable 

Ecosystems in Southern Nevada

Jeanne C. Chambers, Burton K. Pendleton, Donald W. Sada, 

Steven M. Ostoja, and Matthew L. Brooks

Introduction

Managers in southern Nevada are challenged with determining appropriate goals 

and objectives and developing viable approaches for maintaining and restoring 

sustainable ecosystems in a time of rapid socio-ecological and environmental change. 

Sustainable or “healthy” ecosystems supply clean air, water and habitat for a diverse 

array of plants and animals. As described in Chapter 1, sustainable ecosystems retain 

characteristic processes like hydrologic flux and storage, geomorphic processes, biogeochemical cycling and storage, biological activity and productivity, and population 

regeneration and reproduction over the normal cycle of disturbance events (modified 

from Chapin and others 1996 and Christensen and others 1996). Ecological restoration 

of stressed or disturbed ecosystems is an integral part of managing for sustainable ecosystems. The Society for Ecological Restoration International (SERI) defines ecological restoration as the process of assisting the recovery of an ecosystem that has been 

degraded, damaged, or destroyed (SERI 2004).

Many of southern Nevada’s ecosystems are being subjected to anthropogenic 

stressors that span global, regional, and local scales (Chapter 2), and are crossing ecological thresholds to new alternative states (Chapter 4 and Chapter 5). These alternative 

states often represent novel communities with disturbance regimes that differ significantly from historic conditions. Past management and restoration goals often focused 

on returning ecosystems to pre-disturbance conditions (Harris and others 2006). This 

approach assumes stable or equilibrium conditions and ignores changes in ecosystem 

processes due to land uses, increases in CO2 concentrations, and climate change. A more 

realistic approach is to base management and restoration goals on the current potential 

of an ecosystem to support a given set of ecological conditions, and on the likelihood 

of future change due to a warming climate (Harris and others 2006). This approach 

requires understanding ecosystem resilience to anthropogenic disturbance and climate 

change, the alternative states that exist for ecosystems, and the factors that result in 

threshold crossings (Bestelmeyer and others 2009; Hobbs and Harris 2001; Stringham 

and others 2003; Whisenant 1999). It also requires the ability to predict how climate is 

likely to influence ecosystems in the future (Harris and others 2006).

This chapter addresses the restoration aspects of Sub-goal 1.3 in the SNAP Science 

Research Strategy which is to restore and sustain proper function of southern Nevada’s 

watersheds and landscapes (table 1.3; Turner and others 2009). The effects of global, 

regional and local stresses on southern Nevada ecosystems are presented in Chapter 2. 

Here, we discuss appropriate objectives and develop guidelines for maintaining and 

restoring southern Nevada ecosystems. We then discuss the differences in ecological 

resilience to stress and disturbance and resistance to invasive species in southern Nevada 
126 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

ecosystems and describe restoration and management approaches for the different ecosystem types. We conclude with knowledge gaps and management implications.

Resistance and Resilience of Southern 

Nevada Ecosystems

The overarching objective for restoration and management of southern Nevada ecosystems is to maintain and restore sustainable ecosystems that are resilient to stress and 

disturbance and resistant to invasion. Resilience is defined as the capacity of an ecosystem 

to regain its fundamental structure, processes, and functioning (or recover) when subjected to stressors or disturbances like drought, livestock grazing, or wildfire (e.g., Allen 

and others 2005; Holling 1973; Walker and others 1999). In this context, resilience is a 

function of the underlying ecosystem attributes and processes that determine ecosystem 

recovery. Resistance is the capacity of an ecosystem to retain its fundamental structure, 

processes, and functioning (or remain largely unchanged) despite stresses, disturbances 

or invasive species. Resistance to invasion is a function of the biotic and abiotic factors 

and ecological processes in an ecosystem that limit the establishment and population 

growth of an invading species (D’Antonio and Thomsen 2004). The abiotic and biotic 

attributes and ecosystem processes that determine resilience to stressors and resistance 

to invasion can be illustrated with a simple conceptual model (fig. 7.1). Environmental 

characteristics as defined by climate, topography, and soils determine the abiotic and 

biotic attributes and processes of an ecosystem. In turn, the abiotic and biotic attributes 

and processes provide feedbacks to one another and determine the inherent potential of 

an ecosystem to support a given set of ecological conditions and plant species. Over time, 

climate, disturbance and stressors affect the abiotic and biotic attributes and processes 

and determine the current ecological conditions of the system. The current ecological 

conditions, as influenced by the legacy of past disturbances and stressors, determine 

resilience to disturbance and resistance to invaders at any point in time.

Figure 7.1—The environmental variables and site conditions that influenced resilience to 

disturbance and resistance to invasion. Disturbances can decrease ecological site conditions and negatively affect resilience and resistance.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 127

Southern Nevada ecosystems differ in ecological resistance and resilience because 

of strong elevation/climate gradients and large differences in their environmental characteristics (Chapter 1). The Clark County Multiple Species Habitat Conservation Plan 

(MSHCP) categorizes 11 ecosystems based on elevation and soil moisture (fig. 7.2). In 

general, temperature regimes and effective precipitation are the primary drivers of ecological processes and determine overall resource availability and ecosystem productivity. 

The resilience of southern Nevada ecosystems to stresses typically increases along these 

environmental/productivity gradients (Brooks and Chambers 2011). These gradients 

also determine the likelihood that climate conditions are suitable for establishment of 

non-native grasses and other invaders (e.g., Chambers and others 2007; Condon and 

others 2011). Ecosystems influenced by elevated water tables and high levels of soil 

moisture are in a separate category, as environmental conditions can vary considerably 

among these ecosystems. Factors like soil and water chemistry are important drivers of 

ecosystem processes for these ecosystems.

Figure 7.2—A conceptual model that categorizes 11 ecosystems of the 

Clark County MSHCP along two environmental gradients: elevation and 

soil moisture. This model is based on general knowledge of environmental 

gradients of ecosystems. The shape, size, and relative position of the ellipses and circles are hypothetical (from Desert Research Institute 2008). 
128 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Restoration Considerations for Southern 

Nevada Ecosystems

Restoration and management priorities and activities differ significantly among 

southern Nevada ecosystems because of large variation in their resilience and resistance. Overarching strategies are protection, prevention, and restoration (table 7.1). 

Passive restoration to eliminate or minimize stress is a component of protection and 

prevention; active restoration is a component of prevention and restoration. Guidelines 

for the restoration and management of the diverse ecosystems in southern Nevada can 

be developed based on an understanding of their relative resilience and resistance, the 

dominant stressors that affect them, and the actions most appropriate to maintain and 

restore them (table 7.2).

Table 7.1—An approach for categorizing management activities in southern Nevada ecosystems 

based on protection, prevention and restoration (modified from D’Antonio and Chambers 

2006; Brooks and Chambers 2011).

Protection 

Focus Ecosystems with low resilience and/or resistance, ecosystems of high conservation concern, and ecosystems at risk of crossing ecological thresholds to 

new alternative states. 

Objectives Eliminate or minimize current and future stressors. 

Activities Closure or active control of recreational use and burro and cattle grazing to allow natural regeneration; fire suppression in Mojave Desert scrub, blackbrush 

and lower elevation sagebrush and piñon and juniper ecosystems to prevent 

an invasive annual grass-fire cycle; control of placement and development of 

road and utility corridors, urban expansion, and solar energy projects to minimize fragmentation and surface disturbance.

Prevention

Focus Ecosystems with inherently higher resilience and/or resistance that are in 

moderate to high ecological condition. 

Objectives Maintain or increase resilience and resistance of areas with declining ecological conditions. 

Activities Vegetation management to decrease risk of high severity fires, maintain understory composition, and prevent invasion; mechanical vegetation management treatments to decrease decadent or over-dense shrubs and increase 

perennial herbaceous vegetation.

Restoration

Focus Ecosystems known to respond favorably to restoration treatments and ecosystems of conservation concern. 

Objectives Increase resilience and resistance of ecosystems by revegetating or rehabilitating areas disturbed by fire, recreational activities, road and utility corridors, 

urban expansion, solar energy projects, and other surface disturbances. Provide assisted migration for species being displaced by climate change.

Activities Soil surface stabilization to curtail dust; seedbed preparation to mitigate soil 

physical and chemical disturbance and provide favorable conditions for plant 

establishment; transplanting or seeding native species adapted to the local 

environment and climate warming. 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 129

Table 7.2—Resilience and resistance characteristics of the major ecosystem types in southern Nevada and guidelines for 

appropriate management actions. 

Ecosystem Resilience and resistance Guidelines for appropriate management actions

Alpine and 

Bristlecone 

pine

Resilience – Very low to low. Extreme temperatures, short growing seasons, slow growth, and low 

establishment rates. Low capacity to adapt/migrate with climate 

warming.

Resistance – Moderate to high. 

Few annual species are adapted 

to extreme environment; resistance may decrease as climate 

warms. 

Protection – Primary emphasis. Minimize stress from recreational 

activities, including firewood gathering. Monitor changes in temperature and precipitation and in species distributions and community 

composition. 

Prevention – Rarely warranted except to suppress fires with potential to spread. 

Restoration – Rarely warranted except for assisted migration of 

trees or revegetation of areas with die-off. Information on species 

environmental and establishment requirements is required.

Mixed conifer Resilience – Moderate to high. 

Relatively high precipitation, long 

growing seasons, and moderate 

growth and establishment rates. 

Potential to migrate upslope with 

climate warming.

Resistance – Moderate to low. 

Multiple non-native invaders 

adapted to environmental conditions; competition with invaders 

from established native plants can 

be high.

Protection – Control inappropriate recreational activities and overgrazing; detect and eradicate invasive species.

Prevention – Warranted to decrease fuel loads, restore understory 

composition, and decrease invasion. Potential for Wildland Fire Use 

and prescribed fire where risk of large or high severity fire is low 

and fire spread can be controlled, and for tree thinning followed by 

surface fire or pile burning in WUI and areas with higher fuel loads. 

However, more information is needed on the responses of southern 

Nevada ecosystems.

Restoration – Warranted following surface disturbance or in areas 

with insufficient fire tolerant understory species for site recovery 

after fire. Seed burial (drilling) or transplanting natives adapted to 

local site conditions and climate warming preferred.

Piñon and 

Juniper

Resilience – Moderate. Moderate precipitation, long growing 

seasons, moderate to slow growth 

and establishment. Potential for 

die-off at lower elevations with climate warming.

Resistance – Low. Many nonnative invaders adapted to environmental conditions; competition 

from established shrubs and 

herbaceous species dependent 

on site productivity and ecological 

condition.

Protection- Control inappropriate recreational activities and overgrazing; detect and eradicate invasive species; suppress fires at 

lower elevations and that threaten ecosystem integrity.

Prevention-Warranted to decrease fuel loads, restore understory 

composition, and decrease invasion. Focus is on mesic sites in early to intermediate stages of tree expansion, and in moderate to high 

ecological condition. Potential for Wildland Fire Use and prescribed 

fire on productive sites at high elevation; mechanical treatments 

more appropriate on sites with low productivity. 

Restoration – Warranted following surface disturbance and in areas 

with insufficient fire tolerant understory species for site recovery 

after fire. Seed burial (drilling) or transplanting natives adapted to 

local site conditions and climate warming preferred.

Sagebrush Resilience – Moderate to low. 

Types at higher elevations and 

with deeper soils have moderate 

resilience; types at lower elevations and on shallow soils have 

low resilience.

Resistance – Moderate to low. 

Types at higher elevations are 

more resistant to annuals invaders than those at lower elevations. 

Resistance generally decreases 

as site productivity or herbaceous 

perennial species and ecological 

condition decreases. 

Protection–Control inappropriate recreational activities and overgrazing, detect and eradicate invasive species, suppress fires at 

lower elevations and that threaten ecosystem integrity.

Prevention– Warranted to restore or maintain sagebrush types, and 

increase understory species and resistance to invaders. Focus is 

on resilient and resistant sites. Potential for Wildland Fire Use and 

prescribed fire to control tree expansion, and shrub mowing and 

selective herbicides to decrease competition from overstory sagebrush. Information on ecosystem response is needed.

Restoration – Warranted following surface disturbance and in areas 

with insufficient fire tolerant understory species for site recovery 

after fire. Seed burial (drilling) or transplanting natives adapted to 

local site conditions and climate warming preferred. Livestock closures required post-restoration to facilitate recovery.

(continued)
130 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Blackbrush Resilience – Low to very low. 

Low precipitation, moderately high 

temperatures, episodic recruitment. Potential to migrate upslope 

with climate warming.

Resistance – Low to very low. 

Environmental conditions conducive to establishment of invasive 

annual bromes. Low competition 

from native species due to low 

productivity. 

Protection – Primary emphasis. Suppress fires, actively control 

cattle and burro grazing and inappropriate recreational activities, 

detect and eradicate new invaders.

Prevention – Not warranted under most circumstances.

Restoration – Warranted following surface disturbance and in areas 

with insufficient fire tolerant understory species for site recovery 

after fire. Seed burial (drilling) or transplanting natives adapted to 

local site conditions and climate warming preferred. Livestock closures required after fire and restoration activities to facilitate recovery of native perennial plants.

Mojave 

Desert scrub

Resilience – Very low. Extreme 

environmental conditions, episodic recruitment, slow ecosystem 

recovery.

Resistance– Low. Environmental 

conditions of more mesic systems 

conducive to establishment of annual grasses; few species adapted to most extreme conditions. 

Low competition from natives due 

to low productivity. 

Protection – Primary emphasis. Suppress fires, actively control inappropriate recreational activities and overgrazing by cattle, horses 

and burros, detect and eradicate new invaders.

Prevention – Not warranted under most circumstances.

Restoration – Warranted following surface disturbance and in areas 

with insufficient fire tolerant understory species for site recovery 

after fire. Seed burial (drilling) or transplanting natives adapted to 

local site conditions and climate warming preferred. Livestock closures required after fire and restoration to facilitate recovery of native perennial plants.

Riparian and 

Spring

Resilience –Low to moderately 

high. High water availability but 

high water temperatures, harsh 

water chemistry, and scouring 

floods. Water availability likely to 

decrease with climate warming.

Resistance – Low. Many invasive 

species in a variety of taxa adapted to high availability of water. 

Protection– Maintain or increase current water allocations and in 

stream flows, actively control inappropriate land uses, recreational 

activities and overgrazing, detect and eradicate new invaders.

Prevention–Warranted to reduce non-native tamarisk and Russian 

olive and to manage fuels. Biocontrol, prescribed fire, mechanical 

treatments, or herbicides can be used, but restoration of native species must follow. 

Restoration– Warranted to maintain river and stream channels 

by manipulating flow regimes, and to restore or create habitat for 

native species of concern. Methods include manipulating water 

depths, velocities and temperatures to meet requirements for species establishment and persistence, and revegetating with native 

species adapted to the site conditions.

Consideration of the predicted effects of climate change on the different ecosystems 

and the implications for management will be needed to maintain and restore southern 

Nevada ecosystems. Climate change models predict high rates of temperature increase for 

desert ecosystems like the Mojave (Loarie and others 2009). By 2100, climate change is 

likely to result in the disappearance of some existing climate conditions, the appearance 

of some novel climate conditions, and the formation of new communities with no past 

or present analogs (Williams and Jackson 2007). Bioclimatic envelope models predict 

shifts in the distributions of keystone species like creosote bush (Larrea tridentata) 

(Rehfeldt and others 2006) and Joshua tree (Yucca brevifolia) (Cole and others 2011), 

and of invasive species like cheatgrass (Bradley and others 2009). Due to the rapid rate 

of change, many species may require assisted migration, and “transformative” restoration 

may be needed in areas that no longer have the climate conditions necessary to support 

the current set of species (Harris and others 2006; Bradley and others 2009).

Table 7.2—(Continued). 

Ecosystem Resilience and resistance Guidelines for appropriate management actions
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 131

Alpine Ecosystem

Alpine ecosystems occur on the Spring Mountains above 3,500 m. They are comprised 

of alpine fell-fields on exposed rocky, dry soils, and alpine meadows that occur in swales 

where soil moisture is higher and sand and silt soils accumulate (Clokey 1951). They 

have generally low resilience to disturbance and low productivity due to short growing 

seasons, temperature extremes, and slow growth rates (Chambers 1995). Few invasive 

species are adapted to the extreme environmental conditions. Because alpine species 

have slow growth and low establishment rates, the potential for adapting to a warming 

climate is low; because of their locations at the top of mountain ranges, the capacity to 

migrate also is low.

Modeling of species-environment relationships and potential changes in plant species 

distributions with a 3 °C increase in temperature for the White Mountains, California, 

indicated that species distributions would shift upwards and decrease in extent but that 

specific outcomes would depend on species affinities for various soil types (Van de Ven 

and others 2007). For a similar temperature increase in Great Basin alpine ecosystems, 

predicted extinction rates were 44% for mammals, 23% for butterflies, and 17% for 

plants (Murphy and Weiss 1992).

Restoration and management goals for alpine ecosystems in southern Nevada necessarily focus on protection due to their low resilience (table 7.2). Human activities are 

generally low, but stress from recreational activities should be minimized. A key aspect 

of managing these ecosystems is monitoring the rate and magnitude of change in the 

abiotic environment (temperature and precipitation) and in species distributions and community composition (Desert Research Institute 2008). North-facing slopes and certain 

soil types may serve as refugia for many native species (Van de Ven and others 2007), 

but these relationships are not well understood. Species loss in these fragile ecosystems 

from rapid warming may require assisted migration in the form of revegetation with 

species from lower elevation zones. Methods for restoring high elevation ecosystems 

are well-researched and include revegetation with seeds and transplants (Chambers 

1997; Urbanska and Chambers 2002). Specific approaches for assisted migration, such 

as methods for species selection and matching species to newly available sites, have 

yet to be investigated.

Bristlecone Pine Ecosystem

The bristlecone pine ecosystem occurs in the Spring and Sheep Mountains at elevations of 2,700 m to 3,500 m on exposed, dry, rocky slopes and ridges in the subalpine 

zone (Pase and Brown 1982). This ecosystem is comprised of evergreen conifer forest 

dominated by widely spaced Great Basin bristlecone pine (Pinus longaeva) that 

frequently forms pure stands from the tree line down to its contact with limber pine 

(P. flexilis). Associated shrub species include dwarf juniper (Juniperus communis), 

Clokey mountain sage (Salvia dorrii var. clokeyi), and sagebrush (Artemisia spp.), but 

dense bristlecone pine forests often have low understory species richness and productivity (RECON 2000).

Similar to alpine ecosystems, cold temperatures, intense sunlight, low soil nutrients, 

a short growing season, and lengthy periods of snow cover result in low productivity 

and low ecosystem resilience (Holtmeier and Broll 2007). Recruitment is episodic 

and depends on local topography, soil types, short-term weather patterns and longer 

term climate, and, for bristlecone pines, seed predation/caching by rodents and birds. 

Recent research shows tree-ring growth in bristlecone pine within the region over the 

last century that is unmatched in millennia (3,700 yrs) indicating environmental 

changes that are probably linked to increases in temperature (Salzera and others 2009). 
132 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

An advance of treeline has been documented for mountain ranges that have already 

exhibited temperature increases, and is predicted for other ranges as the climate warms 

(Grace and others 2002). Although seedling establishment of bristlecone pine may increase 

with warmer temperatures, the species may become more susceptible to pathogens and 

disease. White pine blister rust (Cronartium ribicola) was recently reported in Rocky 

Mountain bristlecone pine (P. aristata) (Blodgett and Sullivan 2004), and Great Basin 

bristlecone pine is a potential host for white pine blister rust (Kliejunas and Adams 

2003). Mountain pine beetle (Dendroctonus ponderosae) may reproduce more rapidly 

due to climate warming and cause greater damage to bristlecone pines. Currently, fires 

are caused by lightning and are small and infrequent. Higher fuel loads due to warmer 

weather and increased tree growth plus deadwood caused by bark beetles may increase 

fire frequency (Desert Research Institute 2008).

As for alpine ecosystems, restoration and management goals for bristlecone pine ecosystems in southern Nevada focus on protection (table 7.2). Human activities primarily 

involve recreational use and firewood gathering for campfires, which can damage trees 

and initiate fires. These types of uses should be discouraged. Management should include 

monitoring the rate and magnitude of change in the abiotic environment (temperature 

and precipitation) and in species distributions and community composition (Desert 

Research Institute 2008). Understanding the population dynamics of bristlecone pine 

(recruitment and mortality) is essential for determining if assisted migration of the trees 

or revegetation of areas with high mortality is required. Understanding the environmental 

and establishment requirements of both the trees and associated species is necessary to 

determine appropriate revegetation methods.

Mixed Conifer Ecosystems

The mixed conifer ecosystem is comprised of three tree and shrub dominated communities that occur at 1,200 m and 3,200 m in elevation (RECON 2000): the white fir, 

ponderosa pine, and ponderosa pine/mountain shrub communities. The white fir community occurs in the Spring and Sheep Mountains on north and east-facing slopes at 

elevations between 2,200 and 3,200 m and is dominated by white fir (Abies concolor). 

Other tree species include bristlecone pine (P. longaeva) and limber pine (P. flexilis) at 

higher elevations, and ponderosa pine (P. ponderosa) at lower elevations. The ponderosa 

pine community covers the largest area of any conifer forest in southern Nevada, ranges 

from 1,200 m to 2,700 m in elevation, and is dominated by ponderosa pine. Associated 

tree species include white fir, bristlecone pine, limber pine, singleleaf piñon (P. monophylla), Utah juniper (Juniperus osteosperma), and mountain mahogany (Cercocarpus 

spp.). The ponderosa pine/mountain shrub community has less ponderosa pine and is 

co-dominated by mountain shrubs, like oak (Quercus gambelii), mountain mahogany, 

snowberry (Symphoricarpos albus), and manzanita (Arctostaphylos spp.). Relatively 

high precipitation, mild temperatures, and long growing seasons result in moderately 

high ecological resilience in the mixed conifer ecosystem. Multiple non-native invaders 

are adapted to these communities decreasing ecological resistance.

Interactions among climate, fire, and pine bark beetles strongly affect the structure 

and composition of mixed conifer ecosystems. Overall growth rates in southern Nevada 

mixed conifer ecosystems are low, reflect those in other southwest ecosystems, and 

are strongly influenced by drought (Biondi and others 2011). In general, trees respond 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 133

positively to winter-spring precipitation and negatively to spring-summer temperature 

(Biondi and others 2011). Recruitment is associated with moist and fire-free periods, 

while die-off is related to droughts lasting more than 10 years (Brown and Wu 2005). 

The likelihood of pine bark beetle outbreaks is increased by higher temperatures and 

forest homogeneity, and trees are most susceptible to beetles when drought stressed or 

after fire (Raffa and others 2008). As the climate warms, increases in pine bark beetle 

outbreaks and die-offs are likely for trees growing at the margin of their ecological 

tolerances. Upslope movement of tree populations will require favorable conditions for 

tree recruitment and lack of widespread fire.

Increases in tree densities and fuel loads and reductions in plant species diversity 

have occurred in many southwest mixed conifer forests due to factors like favorable 

climate for tree recruitment, overgrazing, and fire suppression (Allen and others 2002). 

Fuel loads and fire risk are increasing in some mixed conifer communities in southern 

Nevada (Abella and others 2011). Fire regimes and fire return intervals depend on the 

aridity and topographic characteristics of the site. Fire regimes vary from high frequency, 

low severity to mixed severity (Biondi and others 2011; Jamieson 2008; Kilpatrick 

2009; Kitchen 2010). On an arid site (Mt. Irish), the fire return interval for fires that 

scarred at least 10% of recorder trees was 66 years (Biondi and others 2011). On a mesic 

site (Clover Mountains), comparable fire return intervals ranged from 17 to 34 years 

(Kilpatrick 2009). Many stands in the ponderosa pine community have limited extent 

and are characterized by old age trees, especially on drier mountain ranges (fig. 7.3). 

Understory species composition affects resilience to both fire and fuel treatments due 

to effects on tree regeneration, fire behavior and soil erosion (Allen and others 2002). 

Many of the understory shrubs in the ponderosa pine/mountain shrub community are fire 

tolerant and promote recovery after fire (fig. 7.3). Perennial herbaceous species increase 

resistance to annual grasses in all community types (Chambers and others 2007).

Restoration and management goals for mixed conifer ecosystems include protection 

and restoration, but emphasize prevention (table7.2). Most campgrounds and recreational 

activities occur in this type. Allen and others (2002) list 16 broad principles for restoring 

southwestern ponderosa pine ecosystems including preventing or minimizing crown 

fire, restoring or maintaining understory composition, and preventing invasion by nonnative species. The focus is on resilient and resistant stands with climatic conditions and 

understory species that will ensure recovery. Considerable information exists on specific 

fire and fuels treatments for managing ponderosa pine and mixed confer ecosystems 

(Brown and others 2000). In a ponderosa pine community in Grand Canyon National 

Park, wildland fire use decreased fuel loads, reduced duff layers, and increased species 

richness of annual and biennial forbs (Laughlin and others 2004). Tree thinning coupled 

with understory burning decreased the risk of crown fire and increased stand resilience, 

but tree kill and understory response depended on climate and pre-treatment ecological conditions in other southwest ponderosa pine ecosystems (Fule and others 2005; 

Moore and others 2006). Because of the aridity and small extent of many of southern 

Nevada’s mixed conifer ecosystems, and the number of species of conservation concern, 

the emphasis should be on use of thinning, and mechanical treatments until additional 

information is available on responses to fire treatments. Information also is needed on 

restoring landscape heterogeneity and the effects of climate change.
134 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Figure 7.3—(A) An arid ponderosa pine community on the Sheep 

Range with a sparse understory of sagebrush. Many of these communities are of limited extent and are characterized by old aged trees. 

Historic fire return intervals were long and preventative management 

to control fuels needs to be exercised with caution. (B) A ponderosa 

pine/mountain shrub community on the Spring Mountains after a 

wildfire. This community is characterized by shrub species that resprout after fire and promote site recovery. Preventative management 

should focus on preventing crown fires and maintaining the understory 

(photos by Patti Novak-Echenique). 

A

B
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 135

Piñon and Juniper Ecosystem

The piñon and juniper ecosystem occurs from 1,500 m to 2,500 m in the Spring, Sheep, 

Virgin, and McCullough Mountains (RECON 2000). Sagebrush co-exists with piñon and 

juniper at all elevations. At higher elevations, singleleaf piñon dominates, but co-occurs with 

other coniferous trees and shrubs like Gambel’s oak (Quercus gambelii) and mountain mahogany (Cercocarpus spp.). At lower elevations, Utah juniper (J. osteosperma) dominates and 

Rocky Mountain juniper (J. scopulorum), western juniper (J. occidentalis), rabbitbrush 

(Chrysothamnus spp.) and blackbrush (Coleogyne ramosissima) are minor components. 

Singleleaf piñon and Utah juniper co-dominate at middle elevations. Relatively high precipitation, mild temperatures, and long growing seasons result in moderate resilience, but 

local conditions influence disturbance and treatment outcomes. Many non-native invaders 

are adapted to these communities and ecological resistance is low.

Piñon and juniper ecosystem in the southwestern United States respond to the high 

variation in precipitation with major pulses of woody plant establishment and mortality 

(Swetnam and Betancourt 1998). Water stress can trigger rapid and extensive dieback 

(Breshears and others 2005). Broadscale tree mortality can shift ecotones between 

vegetation types, alter regional distributions of overstory and understory vegetation, 

and change disturbance processes such as fire and erosion (Allen and others 2010). 

Drought-associated water stress also can increase susceptibility of trees to insects and 

other pathogens (Breshears and others 2005). The piñon ips beetle (Ips confusus) occurs 

in southern Nevada and is a species that can undergo broadscale outbreaks following 

high temperatures and drought (Breshears and others 2005).

Piñon and juniper expansion and infilling are occurring in southern Nevada shrublands due to a variety of factors including climate change, increased CO2 concentrations, 

overgrazing, and fire suppression (fig. 7.4; Abella and others 2011; Miller and others 

2008). The increase in trees has the potential to significantly increase fuel loads. Fire 

frequency, size, and severity in piñon and juniper ecosystems are strongly influenced 

by fuel loads and climate. Recent fire history studies in central Nevada and Mesa Verdi 

National Park, Colorado, indicate that historical fire regimes were characterized by 

small, infrequent and high severity fires, and that stand replacing fires occurred about 

every 200 to 400+ years (Bauer and Weisberg 2009; Floyd and others 2004; Romme 

and others 2009). Fires occurred with higher frequency during droughts and on more 

mesic sites (Bauer and Weisberg 2009).

Restoration and management goals in piñon and juniper ecosystems include protection and restoration, but emphasize prevention (table 7.2). Restoration goals include 

preventing or minimizing crown fire, restoring or maintaining shrubs and perennial 

herbaceous species in the understory, and preventing invasion by non-native species. 

The focus is on resilient and resistant ecosystems with sufficient perennial herbaceous 

species and shrubs for recovery. Resilient piñon and juniper ecosystems are typically 

on more mesic sites, in the early to intermediate stage of tree expansion (i.e., phase I to 

phase II woodlands; sensu Miller and others 2005), and in moderate to high ecological 

condition (fig. 7.4). Both prescribed fire and mechanical treatments, like shredding 

and cutting and leaving the trees, are used to reduce fuel loads and increase resilience 

in these ecosystems (Miller and others 2005; Monsen and others 2004; Pyke 2011). 

Mechanical treatments are typically of lower severity than prescribed fire and are used 

on sites with more severe environmental conditions and with a high risk of fire-tolerant 

invaders like cheatgrass. Because of the aridity of many of southern Nevada’s piñon and 

juniper ecosystems, and the number of species of conservation concern, the emphasis 

should be on thinning and mechanical treatments until additional information is available on responses to fire treatments. Information also is needed on restoring landscape 

heterogeneity and the effects of climate change.
136 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Figure 7.4— (A) Piñon expansion into 

a mountain big sagebrush ecological 

site type on the Desert National Wildlife 

Refuge. Preventative management to 

maintain the understory sagebrush 

community using mechanical tree removal, Wildland Fire Use or prescribed 

fire can be considered on sites with 

favorable climatic conditions and sufficient perennial herbaceous species 

and shrubs for recovery. (B) Old age 

piñon on a black sagebrush ecological site on the Desert National Wildlife 

Refuge. Protective management of old 

age stands located on harsh ecological 

sites should be considered. (C) A dense 

piñon stand on the Spring Mountains. 

Preventative management using mechanical treatments to decrease fire 

risk should be considered in WUI areas. 

Due to tree competition and understory 

depletion, restoration will be required 

following fire (photos by Patti NovakEchenique).

A

B

C
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 137

Sagebrush Ecosystem

The sagebrush ecosystem typically ranges in elevation from 1,500 m to 2,800 m in the 

Spring, Sheep, and Virgin Mountains (RECON 2000). In southern Nevada, sagebrush 

species include big sagebrush (A. tridentata), low sagebrush (A. arbuscula), Bigelow 

sagebrush (A. bigelovii), silver sagebrush (A. cana), and black sagebrush (A. nova). The 

dominant sagebrush communities differ in response to local topography, soil type, and 

water availability. Big sagebrush community types can occur as relatively, large, open, 

and discontinuous stands, but often occur with trees species (piñon pine, junipers, ponderosa pine, mountain mahogany) and other shrubs (bitterbrush, rabbitbrush, snakeweed 

[Gutierrezia sarothrae], blackbrush, shadscale [Atriplex confertifolia], and spiny hopsage 

[Grayia spinosa]) (fig. 7.4) (Clokey 1951). Ecological resilience is a function of local 

site conditions and the community type. Higher elevation types with greater precipitation and productivity like A. tridentata ssp. vaseyana have moderately high resilience 

while lower elevation and less productive types like A. tridentata ssp. wyomingensis

and A. nova have lower resilience (Brooks and Chambers 2011). Resistance decreases 

as elevation and productivity decrease (Chambers and others 2007).

Risks to sagebrush ecosystems include overgrazing, land use change, piñon and juniper expansion, invasion of non-native plants, and altered fire regimes (Wisdom and 

others 2005). Climate change poses a substantial additional risk. Sagebrush species 

are likely to respond to climate warming by moving northward or upslope in response 

to shifts in frost lines (Neilson and others 2005). Risk analyses of sagebrush types in 

southern Nevada that assessed the interactive effects of land use conversion, land use 

(roads, agriculture, etc.), and cheatgrass invasion indicated that sagebrush communities 

in southern Nevada were at greater risk of losing suitable habitat due to climate change 

than due to disturbance (Bradley 2010).

In southwestern and arid ecoregions, precipitation in seasons prior to the fire season is 

more highly associated with burn area than warmer temperatures or drought the year of 

fire due to the importance of fine fuel production (e.g., invasive annual grasses) (Littell 

and others 2009). However, increasing aridity may result in a decrease in area burned 

due to a reduction in fine fuels.

Restoration and management goals and methods vary for these diverse ecosystems due 

to differences in resilience and resistance (table 7.2). In general, the focus of restoration 

is on maintaining and restoring a desirable proportion of sagebrush types, increasing the 

abundance of perennial understory species that promote resilience, and increasing resistance to invasive species. Strategies for sagebrush types with inherently low resilience 

and resistance focus on protection and include eliminating stressors like inappropriate 

recreation, overgrazing, and fire. Prevention can be an effective strategy for sagebrush 

types with higher resilience and resistance. Wildland Fire Use and prescribed fire have 

been used in higher elevation types exhibiting tree expansion (fig. 7.4A), but additional 

information on fire effects are needed for southern Nevada ecosystems. Mowing and 

selective herbicides have been used to increase perennial herbaceous species by reducing 

competition from decadent or over-dense sagebrush. Restoring sagebrush ecosystems that 

have crossed ecological thresholds to invasive grass dominance is expensive, difficult, 

and of lower priority. Although methods exist for protection, prevention, and restoration 

of mesic sagebrush ecosystems (e.g., D’Antonio and others 2009; Monsen and others 

2004; Pyke 2011), we still lack the necessary tools to manage and restore more arid 

sagebrush ecosystems. Sagebrush ecosystems are highly susceptible to climate change 

and we know little about assisted migration or transformative restoration.
138 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Blackbrush Ecosystem

The blackbrush ecosystem occurs at elevations between 1,250 and 1,800 m in the 

transition zone between the Mojave Desert and Great Basin (RECON 2000). At upper 

elevations it integrates into the Utah juniper community, while at lower elevations it 

transitions into the creosote-bursage community. It is the dominant shrub in the understory of most Joshua tree communities. Shrubs associated with blackbrush include 

spiny hopsage, mormon tea, shadscale, desert thorn, and snakeweed. The blackbrush 

ecosystem has very little resilience to disturbance due to low effective precipitation, 

moderately high temperatures and episodic recruitment of blackbrush (Bowns 1973). 

Resistance to invasion by annual grasses, especially red brome (Bromus madritensis

ssp. rubens), is extremely low because the environmental conditions that characterize 

this ecosystem are ideally suited to its establishment and reproduction.

Risks to the blackbrush ecosystem include overgrazing by cattle and burros, offhighway vehicle (OHV) and recreational activities, annual grass invasion, and altered 

fire regimes. Historically, the blackbrush ecosystem experienced small localized fires 

and recovery occurred within a few decades (Brooks and Matchett 2006). However, due 

to invasion by exotic annual grasses and an increase in fine fuel loads and fuel continuity, 

extensive areas of the blackbrush ecosystem have burned within the last decade (Chapter 

4 and Chapter 5). Blackbrush is not fire-adapted and is incapable of resprouting following 

fire. Consequently, parts of this ecosystem are being converted to annual grass dominance 

and are susceptible to repeated burns (Brooks and others 2007).

In the blackbrush ecosystem, the focus of restoration and management is on protection 

coupled with restoration (table7.2). Protection of this ecosystem includes suppressing 

large fires and actively controlling overgrazing by wild horses, burros, and cattle. The 

characteristics of this ecosystem vary considerably over environmental/productivity 

gradients (fig. 7.5). Lower elevation blackbrush communities are characterized by 

thermic soils and often contain a minor component of creosote bush. Revegetation is difficult due to low spring and early summer moisture, increasing CO2, and 

higher nighttime winter temperatures (Jones 2011; Zitzer 2009). The distribution of 

the creosote-bursage community is limited by nighttime winter temperatures (Webb 

and Bowers 1993) and is expected to move up-slope with climate change. Thus, at 

lower elevations within the blackbrush ecosystem, early seral shrubs from the creosote 

and bursage community may be better candidates for restoration than species from the 

blackbrush community. Higher elevation and more mesic blackbrush communities are 

characterized by mesic soils, and species from the blackbrush community are the best 

choice for seed mixes.

Considerable information exists on the establishment requirements of blackbrush including seed dispersal and longevity in the soil (Auger 2005; Zitzer 2009), seed dormancy, 

germination, and survival (Meyer and Pendleton 2005; Pendleton 2008; Pendleton and 

Meyer 2004), and the importance of mycorrhizae and biological soil crusts (Pendleton 

and others 1999). Blackbrush typically establishes under nurse plants, and establishment 

success of blackbrush may be increased by including other species with high seedling 

establishment in the seed mix (Abella and Newton 2009). Transplanting seedlings of 

blackbrush and the other dominant shrubs in the community into shrub islands that can 

serve as future seed sources also should be considered but several years of supplemental 

water may be required (Pendleton 2008; Winkel and others 1995). Blackbrush seldom 

produces large crops of seeds, but the seeds that are produced exhibit long-term viability 

(Pendleton and others, in press). This indicates that seeds can be harvested during mast 

years and stored until needed. Additional information is needed on relationships among 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 139

climate, soil characteristics, and establishment of the species in both creosote/bursage 

and blackbrush communities if assisted migration and transformative restoration is to 

succeed.

Mojave Desert Scrub Ecosystem

Mojave Desert scrub occurs at elevations below 1,220 m and is the most widespread 

ecosystem in southern Nevada (~73% of Clark County) (RECON 2000). This type is 

characterized by three community types: Mojave Desert mixed scrub, mesquite/catclaw, 

and salt desert shrub.

Figure 7.5—(A) A more arid blackbrush ecological site on thermic 

soils that exhibits low productivity and has a minor component of 

creosotebush (photo by Patti Novak-Echenique). (B) A more mesic blackbrush ecological site on mesic soils with slightly higher 

productivity. Note the presence of juniper (photo by Matt Brooks). 

Protective management should be emphasized on both site types. 

Due to ongoing climate change, restoration of the thermic site should 

include early seral species from the Mojave Desert scrub type. 

A

B
140 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Mojave Desert mixed scrub—Mojave Desert mixed scrub is unique because it includes a wide variety of distinctive soil types and plant communities often intermix. 

Bajadas, the most common landform, are dominated by creosote bush and white bursage (Ambrosia dumosa); subdominants include desert thorn (Lycium andersonii), 

shadscale, spiny hopsage, ratany (Krameria erecta), bladder sage (Salazaria mexicana), indigo bush (Psorothamnus fremontii), blackbrush, brittlebush (Encelia farinosa), and burro bush (Hymenoclea salsola) (RECON 2000). Sand dunes, gypsum soils, 

cliff/rock outcrops, and steep slopes occur as isolated patches that support Joshua tree, 

prickly pear cactus (Opuntia spp.), yucca (Yucca spp.), cholla (Cylindropuntia spp.), 

and hedgehog cactus (Echinocereus spp.).

Mojave Desert mixed scrub communities have low ecological resilience and have 

exhibited little resistance to invasive species (Brooks and Chambers 2011). Most longlived Mojave Desert scrub species are poorly adapted to disturbances that remove 

aboveground biomass or kill plants, although most short-lived early seral species increase in abundance following disturbance. Reproduction of long-lived species depends 

on appropriate environmental conditions for either clonal regeneration and/or seedling 

establishment and is episodic (Webb and others 2009). The life history strategies of these 

species coupled with the harsh environment significantly increases the complexity of 

restoration.

Mojave Desert mixed scrub is subject to most of the stressors listed in Chapter 2, 

including urbanization, energy development, invasive species and the resulting increase 

in fire frequency, unregulated recreation, and OHV activity. Climate change further 

strains this ecosystem. The distribution of many Mojave Desert scrub species is limited 

by cold temperatures (Pockman and Sperry 1997; Webb and Bowers 1993), and climate 

models predict that Mojave Desert scrub species will move northward and upslope as 

temperatures continue to warm. One model predicts that northern Nevada and southern 

Idaho may have climates suitable for creosotebush by 2060 (Rehfelt and others 2006).

Invasion of non-native annual grasses (Bromus madritensis ssp. rubens and Schismus 

barbatus) and some forbs (e.g., Brassica spp.) has significantly increased fine fuel loads 

in Mojave Desert scrub vegetation and is resulting in unprecedented fires (Chapters 4 

and 5). Years with high precipitation are associated with high fuel loads and large-scale 

fires (Brooks and Minnich 2006). Many woody desert species are fire intolerant and 

do not readily recover after fire; this results in progressive conversion to annual grass 

dominance, and an annual-grass fire cycle characterized by repeated fires (Brooks 2011).

Due to inherently low resilience and resistance of Mojave Desert scrub communities, 

restoration and management must focus on protection and restoration (table 7.2). In these 

ecosystems, protection includes eliminating or reducing stressors such as fire, dispersed 

recreational activities, OHV use, and overgrazing by wild horses, burros, and cattle. 

New utility-scale, alternative energy sites should be placed to minimize fragmentation 

and species loss.

The state-of-knowledge for restoring Mojave Desert scrub was recently summarized 

by Abella and Newton (2009), Webb and others (2009), and Weigand and Rogers (2009). 

Restoration activities should address the presence of invasive species, a potential increase in fire frequency, and current and projected climate conditions. Creosotebush, 

the dominant shrub, exhibits limited resprouting after disturbances that do not kill the 

plant; other shrubs like white bursage reestablish over time. Also, there has been some 

success with seeding and transplanting Mojave Desert scrub species when appropriate 

methods are used (Bainbridge 2007). Full recovery is slow and depends on an absence 

of repeated fire (Engel and Abella 2011). Similar to the blackbrush ecosystem, Mojave 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 141

Figure 7.6—(A) An arid creosotebush 

ecological site with relatively low productivity (photo by Matt Brooks). (B) A 

slightly less arid creosotebush ecological site. (C) A severely disturbed site on 

Camp Ibis military base after 50 years 

of recovery (photos B and C by Patti 

Novak-Echenique). Protective management should be emphasized on both site 

types. Due to ongoing climate change, 

restoration of the less arid site should 

include species from the more arid type.

Desert mixed scrub communities are wide-ranging and occur over broad environmental 

gradients that influence resilience and restoration approaches (fig. 7.6). Some species in 

hotter and drier sites within Mojave Desert mixed scrub communities may be at or past 

thresholds of persistence due to the novel mix of stressors that include invasive species, 

warmer winters, and hot and potentially dryer summers. Recent increases in nighttime 

temperatures due to climate change have relaxed the biogeographical constraints on 

many desert species, and they can now establish at locations that were previously too 

cold (Kelly and Goulden 2008; Loarie and others 2009; Tylianakis and others 2008). 

Thus, restoration strategies for degraded sites at higher elevations should consider including species that are projected to migrate to these areas. Information is needed on 

A

B

C
142 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

the environmental tolerances of these species and their establishment requirements over 

the range of predicted climates.

Salt desert scrub community—The salt desert scrub ecosystem forms a mosaic within the Mojave Desert mixed scrub and blackbrush ecosystems. It is found between 800 

and 1,800 m, and is associated with playas, basins, and poorly drained depressions 

with silty loam soils. The primary shrubs of the salt desert scrub community are shadscale, desert holly (Atriplex hymenelytra), Bailey’s greasewood (Sarcobatus baileyi), 

desert thorn, Torrey saltbush, (Atriplex torreyi), winterfat (Krascheninnikovia lanata), 

bursage, fourwing saltbush (Atriplex canescens), mormon tea, horsebrush (Tetradymia 

canescens), and snakeweed (RECON 2000). Other shrubs include greasewood (Sarcobatus vermiculatus), blackbrush, iodine bush (Allenrolfea occidentalis), and creosotebush. This lower-elevation and very dry ecosystem has very low ecological resilience, 

but may have slightly higher resistance to invasive species than Mojave Desert mixed 

scrub due to low moisture availability. Salt desert scrub in the Great Basin is more 

resilient than in southern Nevada due to higher rainfall and cooler temperatures in the 

Great Basin.

Risks to the salt desert shrub ecosystem include utility-scale renewable energy development (particularly in playas), urbanization, burro and cattle grazing, recreational and 

OHV activity and accompanying dust production, invasive annual grasses, and associated increases in fire frequency. Urbanization is a primary concern as this ecosystem 

has the highest percentage loss to urban land development of all major ecosystems in 

the SNAP area (Chapter 2). Large areas of salt desert scrub have been lost to urban 

development in Green Valley/Henderson and in northwest Las Vegas. Climate change 

will cause additional stress.

Restoration and management priorities for this ecosystem are similar to those for 

Mojave Desert mixed scrub: control of recreational activities, including OHV use; 

careful selection of sites for alternative energy facilities; and maintenance of appropriate populations of burros. Limited information is available on restoration of salt desert 

shrub species, although seeding of Atriplex has had some success (Abella and Newton 

2009). Maintaining this ecosystem in southern Nevada will require identifying those 

locations where it still occurs and prioritizing its protection in land use plans. Specific 

elements should include preventing fragmentation by maintaining minimum patch sizes.

Mesquite/catclaw community—The mesquite/catclaw community is a small component (~1%) within Mojave Desert scrub. It is comprised of screwbean mesquite 

(Prosopis pubescens), honey mesquite (P. glandulosa), and catclaw acacia (Acacia 

greggii) and occurs in patches (1 ha to >1,000 ha) where perennial groundwater is not 

more than 10 m from the surface. The greatest extent of the mesquite/catclaw community in southern Nevada was found previously in the Las Vegas Valley. Most of this 

community type now has been lost due to urbanization, OHV use, climate change and 

exotic species (Desert Research Institute 2008). Maintaining this community in southern Nevada will require identifying the locations where it still occurs and prioritizing 

its protection in land use plans to ensure that minimum patch sizes are maintained and 

fragmentation is prevented.

Riparian/Aquatic Ecosystems

In southern Nevada, the desert riparian/aquatic ecosystem occurs primarily along the 

Colorado River, Las Vegas Wash, and Virgin and Muddy Rivers at elevations below 

600 m (RECON 2000). Water is perennial in the Colorado River, Las Vegas Wash, and 

Muddy River, but is intermittent in the Virgin River. In perennial reaches, the aquatic 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 143

community includes fish and aquatic macroinvertebrates. The riparian community is 

characterized by woody, deciduous, and emergent obligatory and facultative wetland 

vegetation. Native woody vegetation includes Fremont cottonwood (Populus fremontii), 

black cottonwood (Populustrichocarpa), sandbar willow (Salix exigua), Goodding willow (S. gooddingii), velvet ash (Fraxinus velutina), desert willow (Chilopsis linearis), 

and honey mesquite. Woody vegetation along intermittent reaches is relatively sparse 

and consists mostly of desert willow and acacia (Acacia spp.). Due to high productivity 

and water availability, this ecosystem provides essential cover, water, food, and breeding 

sites for several endangered species and many other species of conservation concern. 

However, seasonally high water temperatures, harsh water chemistry, high turbidity, 

scouring floods, and sandy substrates result in moderate to low resilience. These systems 

exhibit low resistance to woody invaders like tamarisk (Tamarix spp.) and Russian olive 

(Elaeagnus angustifolia).

Riparian/aquatic ecosystems are some of the most degraded in southern Nevada 

(Desert Research Institute 2008). Stressors include altered flow regimes resulting from 

dams and diversions, impoundments, and channelization; invasive species and altered 

fire regimes; woodcutting; burro, wild horse, and cattle grazing; agricultural clearing; 

and urban and ex-urban development. The rapid rate of temperature increase and higher 

drought severity index predicted to occur with climate change (Loarie and others 2009) 

will likely result in decreased water availability for riparian/aquatic ecosystems.

Protection, prevention, and restoration are all important activities in these ecosystems 

(table 7.2). Surface water, groundwater, and sediment dynamics coupled with water and 

soil chemistry determine the composition and abundance of both aquatic organisms 

and plant species in these arid riparian/aquatic ecosystems (Anderson and others 2004; 

Briggs 1996). Specific activities are determined by the characteristics of the system and 

are usually conducted to maintain or improve channel and flow characteristics and to 

restore or create habitat for one or more species of concern. Protection is a cross-cutting 

activity that involves minimizing disturbance and sediment and chemical inputs from 

the diversity of stressors that affect these ecosystems. Prevention aimed at controlling 

invasive species also is a cross-cutting activity. Removal of woody invaders, including tamarisk and Russian olive, using biocontrol agents, like the saltcedar leaf beetle 

(Diorhabda elongata), herbicides, or cutting is widespread, but follow-up restoration 

activities and habitat trade-offs require careful consideration (Shafroth and others 2005; 

Shanahan and others 2011).

In the Lower Colorado River Basin, the Multi-Species Conservation Program focuses 

on four ecosystem types: cottonwood/willow, honey mesquite, marsh, or backwater. 

Active restoration/habitat creation involves assessing the physical, chemical, and biological conditions necessary for establishment and maintenance of species of concern 

(amphibians and native fish populations) and manipulating flow regimes to obtain the 

desired characteristics (Scoppettone and others 2005). This can include improving spring 

and stream connectivity, and restoring pools, riffles, and the natural substrate. The site 

is then revegetated with native plants adapted to the new conditions. In actively eroding 

systems like Las Vegas Wash, which has municipal and industrial wastewater inputs, 

erosion control, environmental monitoring, and wetlands restoration and enhancement 

are implemented to reduce erosion and address water-quality concerns (RECON 2000). 

Because of the importance of upstream activities and disturbances on downstream flows, 

sediment regimes and water quality, increased emphasis is being placed on large-scale 

watershed planning and regional collaboration (e.g., U.S. Army Corp of Engineers 2008).
144 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Springs Ecosystems

Springs occur from approximately 250 m to 3,300 m elevation in all landscape settings 

(e.g., mountains, gullies, valley floors, hillside, etc.) in southern Nevada. The MSHCP 

reported 506 springs in Clark County. However, an inventory of the basic environmental 

and biological characteristics of most large springs (Sada and Nachlinger 1996, 1998) 

indicates that Clark County springs dry frequently and that less than 200 persistent 

springs occur in the county. The geology, climate, topographic position, aquifer size, and 

flow path of the water determine the hydrologic characteristics of springs. In turn, the 

hydrologic characteristics of springs structure spring environments and the biotic communities that they support (Sada and Herbst 1999, 2006; Sada and others 2001, 2000). In 

southern Nevada, springs are generally supported by mountain block, local, or regional 

aquifers with different environmental and biological characteristics (Knochenmus and 

others 2007; Mifflin 1968).

Springs in mountainous recharge areas are supported by mountain block aquifers. 

These springs are generally small and are perched, that is, they discharge water that 

flows along an impermeable layer near the soil surface. They are typically cold (<10 °C) 

with low chemical concentrations (specific conductivity <500 μmhos) and neutral pH 

(6.0 to 8.0). Harsh conditions in these springs are mostly attributed to natural factors 

such as periodic drying (seasonal or during droughts), scouring floods, and fire. Thus, 

they are characterized by moderately low resilience. Disturbances are mostly due to 

trampling and overgrazing by wild horses, burros, elk, and cattle, and recreational use. 

These springs are minimally affected by groundwater removal, but may be susceptible 

to drier conditions with climate warming due to low flows.

Local aquifers support springs that are often around the margins of valleys at lower 

elevations. These aquifers are generally larger than mountain block aquifers, and 

springs fed by local aquifers are more persistent, less affected by drought, and dry 

infrequently. Most local springs are cool (10 to <25 °C), their chemical concentrations 

are low (specific conductance <1000 μmhos), and their pH is generally neutral (6.0 to 

8.0). These springs are characterized by moderately high resilience. However, most of 

these springs have been altered by livestock trampling, annual grass fires, diversions, 

and/or recreation. These systems also may be impacted by groundwater withdrawal, 

and decreased groundwater recharge due to climate change.

Springs that are supported by regional aquifers are generally large compared to mountain block aquifer and local aquifer springs. Regional aquifers extend through several 

topographic basins and encompass thousands of square kilometers. Most importantly, 

they are persistent over long periods of time (tens of thousands of years) and are minimally affected by drought conditions. Regional springs are warm (25 to 40 °C), their 

chemical concentrations are relatively benign (specific conductance of generally 500 

to 1,000 μmhos, but may be as high as 1,500 μmhos), and their pH is generally neutral 

(near 7.4). These springs are minimally affected by natural events because they are large 

and located on valley floors where scouring floods are uncommon; thus, these springs 

also have moderately high natural resilience. However, most regional springs have 

been affected by past agricultural practices (pesticides, removal of vegetation, grazing 

by burros and cattle, ground water pumping, and surface diversions) and continue to 

be affected by altered flows, recreation, and grazing by horses, burros, and cattle.

As for riparian/aquatic ecosystems, restoration and management strategies for spring 

ecosystems must be based on their topographic setting, hydrologic characteristics, and 

macroinvertebrate and vegetation communities (Sada and Herbst 1999, 2006; Sada and 

others 2000, 2001). In addition, benthic macroinvertebrate and riparian communities of 

Mojave Desert and Great Basin springs generally differentiate along a physiochemical 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 145

stress gradient where highly stressed springs support depleted communities composed 

of animals and plants that are more tolerant of harsh physicochemical environments than 

springs with less stressful environments (Fleishman and others 2006; Sada and others 

2005). Protection of these systems requires maintaining sufficient water availability to 

support the existing aquatic organisms and riparian vegetation by reducing or minimizing 

ground water withdrawal and surface diversions. Protection also includes minimizing 

or eliminating stress due to grazing and trampling by cattle and burros and recreation. 

Prevention can be used to control invasive woody and herbaceous species. Restoration can be used to restore spring hydrology by eliminating diversions and vegetation 

communities by revegetation with the appropriate native species. For spring systems 

supported by regional aquifers with existing or potential stream channels, modification 

of flows can be used to create stream channels with the necessary water depths, velocities, and temperatures to support native species of concern, like the Amargosa pupfish 

(Scoppettone and others 2005).

Knowledge Gaps

Cross-cutting information needs include a better understanding of the factors that 

determine resilience and resistance in southern Nevada’s diverse ecosystems and of the 

interacting effects of the region’s stressors. Knowledge of the environmental conditions 

required for establishment and persistence of native plant species and methods for their 

restoration is also needed. Information needs specific to the region’s stressors include 

climate change, land use, invasive species, and fire.

Climate Change. More accurate predictions of changes in both temperature and precipitation; ecosystem specific information on the effects of climate change on species 

distributions, disturbance regimes and recovery processes.

Land Use. Knowledge of the distribution and extent of current and future land uses 

and their effects on current and future ecosystem resilience; information on the minimum patch sizes and degree of fragmentation that ecosystems can tolerate; information 

on the amount and effect of N deposition on native ecosystems and annual invaders; 

land use planning tools to ensure land use is consistent with maintaining and restoring 

ecosystems.

Invasive Species. Increased knowledge of feedbacks to invasion from regional 

stressors like increased CO2, altered fire regimes, and overgrazing; knowledge of the 

environmental conditions required for establishment and persistence of invasive plants 

and of their capacities to adapt and migrate in a warming environment; methods for 

controlling invaders and restoring natives that are consistent with ecosystem restoration and maintenance.

Fire. Increased knowledge of fire effects on annual species invasion and ecosystem 

recovery for the different ecological sites that characterize Mojave Desert scrub and 

blackbrush ecosystems; increased knowledge of the interacting effects of effective precipitation, ecosystem productivity, and understory species composition on fire return 

intervals for southern Nevada mixed conifer and piñon and juniper ecosystems; fire 

and fire surrogate tools for mixed conifer, piñon and juniper and sagebrush ecosystems.
146 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Management Implications

Protection is a critical component of restoring and maintaining southern Nevada ecosystems due to the arid environment and numerous stressors. Preventative management is 

a viable option only in more mesic or higher elevation ecosystems that do not comprise 

much of the total land area. Restoration is challenging in all ecosystems. Maintaining 

sustainable ecosystems will require a greater focus on assessing ecological condition, 

prioritizing restoration and management activities, and selecting the most appropriate 

treatments. Monitoring and adaptive management will be essential.

Assessment and Prioritization

An integrated and consistent assessment of southern Nevada ecosystems and their 

relative resilience and resistance can be used to categorize and prioritize management 

and restoration activities. Addressing the widespread stressors affecting these ecosystems 

and providing habitat for species of concern requires a broad scale approach that crosses 

administrative boundaries. Most management plans now encompass landscapes with 

multiple project areas and are developed in consultation with partner agencies. Several 

tools already exist for developing landscape-scale and cross-boundary assessments. Soil 

surveys exist for most of southern Nevada including spring systems and lands managed by the BLM, most of Desert National Wildlife Refuge, and Lake Mead (USDA 

NRCS 2012). Soils characteristics, along with climate and topography determine the 

potential to support a given ecological site type (fig. 7.1). Draft ecological site descriptions (ESDs) exist for most of the region that has soils surveys (contact NRCS Nevada 

State Office, http://www.nv.nrcs.usda.gov/contact/). Soil types and ESDs can be used 

in a GIS environment as the basis for evaluating the relative resilience and resistance 

of the ecosystems in the region, and the degree to which current ecological conditions 

deviate from potential conditions. Recent research has developed geospatial tools for 

identifying critical habitat for species of concern in the Great Basin that could be used 

in southern Nevada (Meinke and others 2009). Methods also have been developed to 

examine linkages among adjacent ESDs and the interacting effects of landforms and 

disturbances (Bestelmeyer and others 2011).

The utility of this approach can be illustrated for the blackbrush ecosystem. ESDs 

are part of a land classification system that describes the potential of a set of climate, 

topographic, and soil characteristics and natural disturbances to support a dynamic set 

of plant communities (Bestelmeyer and others 2009; Stringham and others 2003). ESDs 

use state (a relatively stable set of plant communities that are resilient to disturbance) 

and transition (the drivers of change among alternative states) to describe the range in 

variation of plant communities (Stringham and others 2003). The reference state often 

includes several plant communities that differ in dominant plant species relative to 

time since disturbance. Alternative states describe new sets of communities that 

are separated by largely irreversible transitions (thresholds) and that may persist 

over time. A generalized state and transition model is presented for the blackbrush 

ecosystem (fig. 7.7). Different ecological sites occur within the blackbrush ecosystems 

that are differentiated by relative aridity (thermic vs. mesic soils). Alternative states and 

transitions differ for the two ecological site types and this has important implications in 

a warming environment.

Restoration and Management Approaches

Once an area has been prioritized for active restoration and/or management, a series 

of logical steps can be used to develop the restoration plan. These include identifying 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 147

Figure 7.7—Hypothetical state and transition model for the thermic and mesic blackbrush ecological site types that considers potential transitions with a warming climate. 

The thermic state is more arid and has a minor component of creosotebush and 

bursage. For both reference states, disturbances that reduce blackbrush increases 

grass abundance; time and/or grazing increases shrub abundance. Grazing, stressors 

and climate conditions that favor invaders can result in transition to an invaded state. 

Time and or grazing results in greater abundance of annual grasses; drought and soil 

and seed pathogens that target annual grasses result in higher shrub abundance. 

Return to the reference state requires protection and climate conditions that favor 

natives. Fire can convert the invaded state to an annual grass and forb state and 

result in repeated fire. A warming climate may disfavor annual invaders and favor a 

creosote dominated state.
148 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

landscape priorities and ecological sites, determining the current state of the site, selecting the appropriate action(s), and determining post-treatment management. A general 

approach that asks questions to identify the information required in each step is provided 

in table 7.3. These questions can be modified to include the specific information needed 

for restoration of different ecosystem types.

Table 7.3—General guidelines for conducting a restoration project in southern Nevada (modified from 

Miller and others 2007; Pyke 2011; Tausch and others 2009).

Steps in the process Questions to be addressed

I. Identify landscape priorities 1. Where are priority sites for protection, prevention and

 and ecological sites restoration? Consider the landscape context.

 2. What are the topographic characteristics and soils of 

the site? Verify soils mapped to the location and collect information on soil texture, depth and basic chemistry (pH, calcium carbonate, etc.)

 3. How will topographic characteristics and soils affect 

vegetation establishment and erosion? Evaluate erosion risk based on topography and soil characteristics. 

 4. What is the potential native plant community for the 

site? Match soil components to their correlated ESD. 

This provides a list of potential species for the site.

II. Determine current state 5. Is the site still within the reference state of the state

 of the site and transition model for this ecological site?

III. Select appropriate action 6. How far does the site deviate from the reference 

state? 

 7. Do sufficient perennial shrubs and herbaceous species exist to facilitate recovery? No action is needed.

 8. Are invasive species a minor component? Protection 

or preventative management may prevent conversion. 

 9. Do invasive species dominate the site while native 

life forms are missing or severely under represented? 

Active restoration is required to restore habitat.

 10. Are species from drier or warmer ecological sites 

present? Restoration with species from the drier or 

warmer site should be considered. 

 11. Have soils or other aspects of the physical environment been altered? The site may have crossed a 

threshold and represent a new ecological site type 

requiring new site-specific restoration approaches.

IV. Determine post-treatment 12. How long should the site be protected before

 management land uses begin? In general, sites 

 with lower resilience and resistance should be 

protected for longer periods. 

 13. How will monitoring be performed? Restoration effectiveness monitoring includes a complete set of measurements, analyses, and a report.

 14. Are adjustments to the restoration approach needed? 

Adaptive management is applied to future projects by 

compiling information based on consistent findings 

from multiple locations.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 149

Monitoring Activities

Monitoring programs designed to track ecosystem changes in response to both 

stressors and management actions can be used to increase understanding of ecosystem resilience and resistance and to realign restoration and management approaches 

and implement adaptive management (Chapter 1). Information is increasing on likely 

changes in southern Nevada ecosystems with additional stress and climate warming, 

but a large degree of uncertainty still exits. Strategic placement of monitoring sites and 

repeated measurements of key abiotic (precipitation, temperature, evaporation) and 

biotic (dominant native and exotic species) variables and ecological conditions can be 

used to decrease uncertainty and increase the effectiveness of management decisions. 

Monitoring also can be used to track changes in regional and local stressors over time 

like the level of nitrogen deposition and the intensity of wild horse and burro grazing. 

Monitoring sites should span the environmental/productivity gradients and ecosystem 

types that occur in southern Nevada. In addition, the following areas of high priority 

should be monitored:

1. ecosystem types of small extent under development pressure like mesquite/

catclaw and salt desert shrub;

2. ecosystems that support numerous species of conservation concern like springs 

and riparian areas;

3. ecotones between ecosystem types where changes in response to climate are 

expected to be largest (Loehle 2000; Stohlgren and others 2000);

4. ecological sites with different climatic conditions and soils that are exhibiting 

invasion and repeated fires; and

5. ecological sites with different climatic conditions and soils that are exhibiting 

tree expansion and increased fire risk.

Monitoring the response of ecosystems to management actions and active restoration 

also is of high priority as it provides information on treatment effectiveness that can be 

used to adjust methodologies.

Monitoring activities are most beneficial when consistent approaches are used 

among and within agencies to collect, analyze, and report monitoring data. Common 

databases can be used by agency partners to record and share monitoring data, like the 

Land Treatment Digital Library (USGS 2010), to facilitate this process. A restoration 

geodatabase was recently developed by southern Nevada agencies to facilitate the collection and sharing of data from each agency. This geodatabase includes an inventory 

and assessment of upland ecological disturbances, recommended restoration methods, 

documentation of restoration treatments, and monitoring of restored sites. Once this 

database is implemented, analysis of the data will help to identify trends and largescale problems that can be addressed by the interagency restoration team, as well as 

to evaluate effectiveness of restoration treatments, determine the best techniques, and 

make adjustments on the ground as needed.

Protocols have been developed to guide field staff in data collection and decision 

making for the restoration of road disturbances (DeFalco and Scoles-Sciulla 2011). 

According to these protocols, implementation monitoring should be conducted for up 

to 2 years following restoration to evaluate effectiveness of restoration treatments, and 

ecological monitoring should occur approximately every 5 years to determine how 

ecosystem functions are recovering. Monitoring includes photo documentation and 

measuring plants (including non-natives), erosion features, soils (compaction, stability), 

and biological soil crusts.
150 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

References

Abella, S.R.; Engel, E.C.; Lund, C.L.; Spencer, J.E. 2009. Early post-fire plant establishment on a Mojave 

Desert burn. Madrono. 56:137-148.

Abella, S.R.; Hurja, J.C. ; Merkler, D.J. ; Denton, C.W. ; Brewer, D.G. 2011. Overstory-understory relationships along forest type and environmental gradients in the Spring Mountains of southern Nevada, 

USA. Folia Geobotanica. doi. a0.1007/sl2224-011-9108-7.

Abella, S.R; Newton, A.C. 2009. A systematic review of species performance and treatment effectiveness 

for revegetation in the Mojave Desert, USA. In: Fernandez-Bernal, A.; De La Rosa, M. A. Arid environments and wind erosion. Hauppauge, NY: Nova Science Publishers, Inc: 45-74.

Allen, C.D.; Savage, M.; Falk, D.A.; Suckling, K.F.; Swetnam, T.W.; Shulke, T.; Stacey, P.B.; Morgan, P.; 

Hoffman, M.; Klinger, J.T. 2002. Ecological restoration of southwestern ponderosa pine ecosystems: a 

broad perspective. Ecological Applications. 12:1418-1433.

Allen, C.D.; Macalady, A.; Chenchouni, H.; Bachelet, D. and others. 2010. A global overview of drought 

and heat-induced tree mortality reveals emerging climate change risks for forests. Forest Ecology and 

Management. 259:660–684.

Allen, C.R.; Gunderson, L; Johnson, A.R. 2005. The use of discontinuities and functional groups to assess 

relative resilience in complex systems. Ecosystems. 8:958-966.

Anderson, Michelle D. 2001. Coleogyne ramosissima. In: Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Online: http://www.fs.fed.us/database/feis/ [2011, July 27].

Anderson, B.W.; Russell, P.E.; Ohmart, R.D. 2004. Riparian revegetation: an account of two decades of 

experience in the arid southwest. Blythe, CA: Avvar Books. 268 p.

Auger, J. 2005. Effects of resource availability and food preferences on population dynamics and behavior 

of Ord’s kangaroo rats (Dipodomys ordii). Reno, NV: University of Nevada Press. 150 p. Dissertation.

Bainbridge, D.A. 2007. A guide for desert and dryland restoration. Washington, DC: Island Press. 391 p.

Bauer, J.M.; Weisberg, P.M. 2009. Fire history in a central Nevada pinyon-juniper woodland. Canadian 

Journal of Forest Research. 39:1589-1599.

Bestelmeyer, B.T; Tugel, A.J.; Peacock, G.L., Jr.; Robinett, D.G.; Shaver, P.L.; Brown, J.L.; Herrick, J.E.; 

Sanchez, H.; Havstad, K.M. 2009. State-and-transition models for heterogeneous landscapes: a strategy 

for development and application. Range Ecology and Management. 62:1-15.

Bestelmeyer, B.T.; Goolsby, D.P.; Archer, S.R. 2011. Spatial perspectives in state-and-transition models: 

a missing link to land management? Journal of Applied Ecology. 48: 746-757. 

Biondi, F.; Jamieson, L.P.; Strachan, S.; Sibold, J. 2011. Dendrochronology testing of the pyroclimatic 

hypothesis in the central Great Basin, Nevada, USA. Ecosphere. 2:1-20.

Blodgett, J.T.; Sullivan, K.F. 2004. First report of white pine blister rust on Rocky Mountain bristlecone 

pine. Plant Disease. 88: 311.

Bowns, J.E. 1973. An autecological study of blackbrush (Coleogyne ramosissima Torr.) in southwestern 

Utah. Logan, UT: Utah State University. 115 p. Dissertation.

Bradley, B.A. 2010. Assessing ecosystem threats from global and regional change: hierarchical modeling 

of risk to sagebrush ecosystems from climate change, land use and invasive species in Nevada, USA. 

Ecography. 33:198-208.

Bradley, B.A.; Oppenheimer, M.; Wilcove, D.S. 2009. Climate change and plant invasions: restoration 

opportunities ahead? Global Change Biology. 15:1511-1521.

Breshears, D.D.; Cobb, N.S.; Rich, P.M.; Price, K.P.; Allen, C.D.; Balice, R.G.; Romme, W.H.; Kastens, 

J.H.; Floyd, M.L.; Belnap, J.; Anderson, J.J.; Myers, O.B.; Meyer. C.W. 2005. Regional vegetation 

die-off in response to global-change-type drought. Proceedings of the National Academy of Science. 

102:15144-15148.

Briggs, M. K. 1996. Riparian ecosystem restoration in arid lands: strategies and references. Tucson, AZ: 

University of Arizona Press. 159 p.

Brooks. M.L. 2011. Effects of high fire frequency in creosotebush scrub vegetation of the Mojave Desert. 

International Journal of Wildland Fire. Online: http://dx.doi.org/10.1071/WF10140.

Brooks, M.L.; Chambers, J.C. 2011. Resistance to invasion and resilience to fire in desert shrublands of 

North America. Rangeland Ecology and Management. 64:431-438.

Brooks, M.L.; Esque, T.C.; Duck, T. 2007. Chapter 6: Creosotebush, blackbrush, and interior chaparral 

shrublands. In: Hood, S.M.; Miller, M. (eds.). Fire ecology and management of the major ecosystems 

of southern Utah. Gen. Tech. Rep. RMRS-GTR-202. Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Research Station: 97-110.

Brooks, M.L.; Matchett, J.R. 2006. Spatial and temporal patterns of wildfire in the Mojave Desert, 1980-

2004. Journal of Arid Environments. 67:148-164.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 151

Brooks, M.L.; Minnich, R.A. 2006. Fire in the southeastern Desert Bioregion. In: Sugihara, M.G.; van 

Wagendonk, J.W.; Fites-Kaufman, J.; Shaffer, K.E.; Thode, A.E. (eds.). Fire in California ecosystems. 

Berkeley, CA: University of California Press: 391-414.

Brown, James K.; Smith, Jane Kapler. 2000. Wildland fire in ecosystems: effects of fire on flora. Gen. 

Tech. Rep. RMRS-GTR-42 Vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 257 p.

Brown, P.; Wu, R. 2005. Climate and disturbance forcing of episodic tree recruitment in a southwestern 

ponderosa pine landscape. Ecology. 86:3030-3038.

Chambers, J.C. 1995. Disturbance, life history strategies, and seed fates in alpine herbfield communities. 

American Journal of Botany. 82:421-433.

Chambers, J.C. 1997. Restoration of alpine ecosystems in the United States. In: Urbanska, K.; Webb, 

N. (eds.). Restoration ecology and sustainable development. Cambridge, UK: Cambridge University 

Press: 161-187.

Chambers, J.C.; Roundy, B.A.; Blank, R.R.; Meyer, S.E; Whittaker, A. 2007. What makes Great Basin 

sagebrush ecosystems invasible by Bromus tectorum? Ecological Monographs. 77:117-145.

Chapin, F.S., III.; Torn, S.E.; Tateno, M. 1996. Principles of ecosystem sustainability. The American Naturalist. 148:1016-1037.

Christensen, N.L.; Bartuska, A.M.; Brown, J.H.; Carpenter, S.; D’Antonio, C.; Francis, R.; Franklin, J.F.; 

MacMahon, J.A.; Noss, R.F.; Parsons, D.J.; Peterson, C.H.; Turner, M.G.; Woodmansee, R.G. 1996. 

The report of the Ecological Society of America Committee on the scientific basis for ecosystem management. Ecological Applications. 6:665-691.

Clokey, I.W. 1951. Flora of the Charleston Mountains, Clark County, Nevada. Berkeley, CA: University 

of California Press. 274 p.

Cole, K.L.; Ironside, K.; Eischeid, J.; Garfin, G.; Duffy, P.B.; Toney, C. 2011. Past and ongoing shifts in 

Joshua tree distribution support future modeled range contraction. Ecological Applications. 21:137–

149.

Condon, L; Weisberg, P.L.; Chambers, J.C. 2011. Abiotic and biotic influences on Bromus tectorum invasion and Artemisia tridentata recovery after fire. International Journal of Wildland Fire. 20:1-8.

D’Antonio, C.; Chambers, J.C. 2006. Using ecological theory to manage or restore ecosystems affected by 

invasive plant species. In: Falk, D.; Palmer, M.; Zedler, J. (eds.). Foundations of Restoration Ecology. 

Covelo, CA: Island Press: 260-279.

D’Antonio, C.M.; Chambers, J.C.; Loh, R.; Tunison, J.T. 2009. Applying ecological concepts to the management of widespread grass invasions. In: Inderjit, R.L. (ed.). Ecological invasions and restoration. 

Netherlands: Springer: 123-149.

D’Antonio, C.M.; Thomsen, M. 2004. Ecological resistance in theory and practice. Weed Technology. 

18:1572-1577.

Defalco, L.A.; Scoles-Sciulla, S.J. 2011. Protocol for documenting disturbances, prioritizing restoration, 

and evaluating restoration effectiveness for vehicle disturbances in Mojave Desert uplands. Unpublished report compiled for Southern Nevada Restoration Team partners, Las Vegas, NV.

Desert Research Institute. 2008. Task 7: First iteration conceptual models for 11 MSHCP ecosystems. Annual Report. Project 2005-DRI-574A-P. Reno, NV, Desert Research Institute.

Engel, C.E.; Abella, S.R. 2011. Vegetation recovery in a desert landscape after wildfires: influence of 

community type, time since fire and contingency effects. Journal of Applied Ecology. 48:1401-1410.

Fleishmann, E.; Murphy, D.D.; Sada, D.W. 2006. Effects of environmental heterogeneity and disturbance 

on the native and non-native flora of desert springs. Biological Invasions. 8:1091-1101.

Floyd, M.L.; Hanna, D.D.; Romme, W.H. 2004. Historical and recent fire regimens in piñon-juniper 

woodlands on Mesa Verde, Colorado, USA. Forest Ecology and Management. 198:269-289.

Fule, P.Z.; Laughlin, D.C.; Covington, W.W. 2005. Pine-oak forest dynamics five years after ecological 

restoration treatments, Arizona, USA. Forest Ecology and Management. 218:129-145.

Grace, J.; Berninger, F.; Nagy, L. 2002. Impacts of climate change on tree line. Annals of Botany. 90:537-

544.

Harris, J.A.; Hobbs, R.J.; Higgs, E.; Aronson. J. 2006. Ecological restoration and global climate change. 

Restoration Ecology. 14:170-176.

Hobbs, R. J.; Harris, J.A. 2001. Restoration ecology: repairing the earth’s damaged ecosystems in the new 

millennium. Restoration Ecology. 9:239-246.

Holling, C.S. 1973. Resilience and stability in ecological systems. Annual Review of Ecology and Systematics. 4:1-23.

Holtmeier, F.; Broll, G. 2007. Treeline advance: driving processes and adverse factors. Landscape. 1: 

1-33. doi: 10.3097/LO.200701.

Jamieson, L.P. 2008. Fire history of a pinyon/juniper-ponderosa pine ecosystem in the Intermountain 

West. Reno, NV: University of Nevada. 86 p. Thesis.
152 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Jones, L.C. 2011. Ecology and restoration of blackbrush (Coleogyne ramoissima) in the Mojave Desert. 

Abstracts of the 96th annual meeting of the Ecological Society of America; August 7-12, 2011; Austin, 

TX. Online: http://esameetings.allenpress.com/2011/webprogram/Paper32306.html. [2012, Oct 29]

Kelly, A.E.; Goulden, M.L. 2008. Rapid shifts in plant distribution with recent climate change. Proceedings of the National Academy of Sciences. 105:11823-11826.

Kilpatrick, M. 2009. A tree-ring based fire history of the Clover Mountains, Lincoln County, Nevada. 

Reno, NV: University of Nevada. 108 p. Thesis.

Kitchen, S.G. 2010. Historic fire regimes of eastern Great Basin (USA) mountains reconstructed from tree 

rings. Provo, UT: Brigham Young University. 166 p. Dissertation.

Kliejunas, J.; Adams, D. 2003. White pine blister rust in California. Tree Notes No. 27. California Department Of Forestry and Fire Protection. 4 p. Online: http://ceres.ca.gov/foreststeward/pdf/treenote27.pdf. 

[2012, Oct 29]

Knochenmus, L.; Wilson, J.; Laczniak, R.; Sweetkind, D.; Thomas, J.; Justet, L.; Hershey, R. 2007. 

Ground-water conditions. In: Welch, A.; Bright, D. (eds.). Water resources of the Basin and Range 

carbonate aquifer system in White Pine County, Nevada, and adjacent areas in Nevada and Utah. OpenFile Report 2007-1156. U.S. Department of the Interior, U.S. Geological Survey: 58-61.

Laughlin, D.C.; Bakker, J.D.; Stoddard, M.T.; Daniels, M.L.; Springer, J.D.; Gildar, C.N.; Green, A.M.; 

Covington, W.W. 2004. Toward reference conditions: wildfire effects on flora in an old-growth ponderosa pine forest. Forest Ecology and Management. 199:137-152.

Littell, J.S.; McKenzie, D; Peterson, D.L.; Westerling, A.L. 2009. Climate and wildfire area burned in the 

western U.S. ecoprovinces, 1916-2003. Ecological Applications. 19:1003-1021.

Loarie, S.R.; Duffy, P.B.; Hamilton, H.; Asner, G.P.; Field, C.B.; Ackerly, D.D. 2009. The velocity of 

climate change. Nature. 462:1052-1055.

Loehle, C. 2000. Forest ecotone response to climate change: sensitivity to temperature response functional 

forms. Canadian Journal of Forest Research. 30:1362-1645.

Meinke, C.W.; Knick, S.T.; Pyke, D.A. 2009. A spatial model to prioritize sagebrush landscapes in the 

Intermountain West (U.S.A.) for restoration. Restoration Ecology. 17:652-659.

Meyer, S.E.; Pendleton, B.K. 2005. Factors affecting seed germination and seedling establishment of a 

long-lived desert shrub (Coleogyne ramosissima: Rosaceae). Plant Ecology. 178:171-187.

Mifflin, M.D. 1968. Delineation of ground-water flow systems in Nevada. Technical Report Series H-W: 

Hydrology and water resources publication No. 4. Reno, NV: Desert Research Institute, University of 

Nevada System. 103 p.

Miller, R.F.; Bates, J.D.; Svejcar, T.J.; Pierson, F.B.; Eddleman, L.E. 2005. Biology, ecology, and management of western juniper. Tech. Bull. 152. Corvallis, OR: Oregon State University, Agricultural Experiment Station. 77 p.

Miller, R.F.; Bates, J.D.; Svejcar, T.J.; Pierson, F.B.; Eddleman, L.E. 2007. Western juniper field guide: 

asking the right questions to select appropriate management actions. Circular 1321. Reston, VA: U.S. 

Department of the Interior, Geological Survey.

Miller, Richard F.; Tausch, Robin J.; McArthur, E. Durant; Johnson, Dustin D.; Sanderson, Stewart C. 

2008. Age structure and expansion of piñon-juniper woodlands: a regional perspective in the Intermountain West. Res. Pap. RMRS-RP-69. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station. 15 p.

Monsen, Stephen B.; Stevens, Richard; Shaw, Nancy L., comps. 2004. Restoring western ranges and 

wildlands. Gen. Tech. Rep. RMRS-GTR-1136-vol-1, 2, and 3. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 294 + index.

Moore, M.M.; Casey, C.A.; Bakker, J.D.; Springer, J.D.; Fule, P.Z.; Covington, W.W.; Laughlin, D.C. 

2006. Herbaceous vegetation responses (1992-2004) to restoration treatments in a ponderosa pine forest. Rangeland Ecology and Management. 59:135-144.

Murphy, D.D.; Weiss, S.B. 1992. The effects of climate change on biological diversity in western North 

America: species losses and mechanisms. In: Peters, R.; Lovejoy, T. (eds.). Global warming and biodiversity. New Haven, CT: Yale University Press: 355-368.

Nielson, R.P.; Lenihan, J.M.; Bachelet, D.; Drapek, R.J. 2005. Climate change implications for sagebrush 

ecosystems. Transactions, 70th North American wildlife and natural resources conference; March 16-

19, 2005. Arlington, VA: Wildlife Management Institution Publications Department: 145-159.

Pase, C.P.; Brown, D.E. 1982. Rocky Mountain (petran) and madrean montane coniferous forests. In: 

Brown, D.E., (ed.). Biotic communities of the American Southwest-United States and Mexico. Desert 

Plants. 4(1/4):43-48.

Pendleton, B.K. 2008. Coleogyne ramosissima Torr. In: Bonner, F.T.; Karrfalt, R.P. (eds.). The woody 

plant seed manual. Agriculture handbook 727. Washington, DC: U.S. Department of Agriculture, Forest 

Service: 422-425.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 153

Pendleton, B.K.; Meyer, S.E. 2004. Habitat-correlated variation in blackbrush (Coleogyne ramosissima: 

Rosaceae) seed germination response. Journal of Arid Environments. 59:229-243.

Pendleton, R.L.; Pendleton, B.K.; Howard, G.L. 1999. Effects of microbiotic soil crust organisms and mycorrhizal fungi on seedling growth of blackbrush (Coleogyne ramosissima). CERL Tech. Rep. 99/108. 

U.S. Army Corps of Engineers, Engineer Research and Development Center. 26 p.

Pendleton, R.L.; Pendleton, B.K.; Meyer, S.E.; Carlson, S.; Morrison, E. 2012. Viability of blackbrush 

(Coleogyne ramosissima Torr. [Rosaceae]) seed following long-term storage. Native Plant Journal. 

13:5-13.

Pockman, W.T.; Sperry, J. S. 1997. Freezing induced xylem cavitation and the northern limit of Larrea 

tridentata. Oecologia. 109:19-27.

Pyke, D.A. 2011. Restoring and rehabilitating sagebrush habitats. In: Knick, S.T.; Connelly, J.W. (eds.). 

Greater sage-grouse: ecology and conservation of a landscape species and its habitats. Studies in Avian 

Biology. Berkeley, CA: University of California Press: 531-548.

Raffa, K.F.; Aukema, B.H.; Bentz, B. J.; Carroll, A.L.; Hicke, J.A.; Turner, M.G.; Romme, W.H. 2008. 

Cross-scale drivers of natural disturbances prone to anthropogenic amplification: the dynamics of bark 

beetle eruptions. Bioscience. 58:501-517.

RECON (Regional Environmental Consultants, Inc.). 2000. Final Clark County Nevada multiple species 

habitat conservation plan and environmental impact statement. Prepared for Clark County Administrative Services. 550 p. plus appendices.

Rehfeldt, G.E.; Crookston, N.L.; Warwell, M.V.; Evans, J.S. 2006. Empirical analyses of plant-climate 

relationships for the western United States. International Journal of Plant Science. 167:1123-1150.

Romme, W.H.; Allen, C.D.; Bailey, J.D.; Baker, W.L.; Bestelmeyer, B.T.; Brown, P.M.; Eisenhardt, K.S.; 

Floyd, M.L.; Huffman, D.W.; Jacobs, B.F.; Miller, R.F.; Muldavin, E.H.; Swetnam, T.W.; Tausch, R.J.; 

Weisberg, P.J. 2009. Historical and modern disturbance regimes, stand structures, and landscape dynamics in piñon-juniper vegetation of the western United States. Rangeland Ecology and Management. 

62:203-222.

Sada, D.W.; Herbst, D.B. 1999. Habitat use by rare aquatic macroinvertebrates in spring brooks of the upper Muddy River, Nevada. Unpublished report to The Nature Conservancy, Southern Nevada Projects 

Office, Las Vegas, NV.

Sada, D.W.; Herbst, D.B. 2006. Ecology of aquatic macroinvertebrates in Travertine and Nevares Springs, 

Death Valley National Park, California, with an examination of diversion effects on their abundance and 

community structure. Unpublished report to U.S. National Park Service, Death Valley National Park.

Sada, D.W.; Fleishman, E.; Murphy, D.D. 2005. Associations among spring-dependent aquatic assemblages and environmental and land use gradients in a Mojave Desert mountain range. Diversity and 

Distributions. 11:91-99.

Sada, D.W.; Herbst, D.B.; Smith, F.J. 2000. A survey of springs on Ruby Lake National Wildlife Refuge 

(Elko and White Pine Counties, Nevada) and the influence of habitat alteration on the structure of 

aquatic invertebrate communities. Unpublished report to U.S. Fish and Wildlife Service, Ruby Lake 

National Wildlife Refuge, NV.

Sada, D.W.; Nachlinger, J.L. 1996. Spring Mountains Ecosystem: Vulnerability of spring-fed aquatic and 

riparian systems to biodiversity loss. Unpublished Report to the U.S. Fish and Wildlife Service, Las 

Vegas, NV.

Sada, D.W.; Nachlinger, J.L. 1998. Spring Mountains ecosystem: vulnerability of spring-fed aquatic and 

riparian systems to biodiversity loss: Part II, Springs Surveyed in 1997. Unpublished Report to the U.S. 

Bureau of Land Management, Las Vegas, NV.

Sada, D.W.; Williams, J.E.; Silvey, J.C.; Halford, A.; Ramakka, J.; Summers, P.; Lewis, L. 2001. Riparian 

area management: a guide to managing, restoring, and conserving springs in the western United States. 

Tech. Ref. 1737-17. Denver, CO: Department of the Interior, Bureau of Land Management. BLM/ST/

ST-01/001+1737.

Salzera, M.W.; Hughes, M.K.; Bunn, A.G.; Kipfmueller, K.F. 2009. Recent unprecedented tree-ring 

growth in bristlecone pine at the highest elevations and possible causes. Proceedings of the National 

Academy of Science. 106:20,348–20,353.

Scoppettone, G.G.; Rissler, P.H.; Gourley, C.; Martinez, C. 2005. Habitat restoration as a means of controlling non-native fish in a Mojave Desert oasis. Restoration Ecology. 13:247-256.

Shafroth, P.B; Cleverly, J.R.; Dudley, T.L.; Taylor, J.P.; Van Riper III, C.; Weeks, E.R.; Stuart, J.N. 2005. 

Control of Tamarix in the Western United States: implications for water Salvage, wildlife use, and riparian restoration. Environmental Management. 35:231-246.

Shanahan, S.A.; Nelson, S.M.; Van Dooremolen, D.M.; Eckberg, J.R. 2011. Restoring habitat for riparian 

birds in the lower Colorado River watershed: an example from Las Vegas, Wash, NV. Journal of Arid 

Environments. 75:1182-1190.
154 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Society for Ecological Restoration International Science and Policy Working Group [SERI]. 2004. The 

SERI Primer on Ecological Restoration. Version 2. Online: www.ser.org and www.ser.org/pdf/primer3.

pdf . [2012, April 9].

Stohlgren, T.J.; Owen, A.J.; Lee, M. 2000. Monitoring shifts in plant diversity in response to climate 

change: a method for landscapes. Biodiversity and Conservation. 9:165-186.

Stringham, T.K.; Krueger, W.C.; Shaver, P.L. 2003. State and transition modeling: an ecological process 

approach. Journal of Range Management. 56:106–113.

Swetnam, R.W.; Betancourt, J.L. 1998. Mesoscale disturbance and ecological response to decadal climate 

variability in the American southwest. Journal of Climate. 11:3128-3147.

Tausch, R.J.; Miller, R.R.; Roundy, B.A.; Chambers, J.C. 2009. Piñon and juniper field guide: asking the 

right questions to select appropriate management actions. U.S. Geological Survey Circular 1335. 94 p. 

Online: http://pubs.usgs.gov/circ/1335/. [2012, April 9].

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M;, Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy. Southern Nevada Agency Partnership. Online: http://snap.gov/upload/SNAP-S-RStrategy-2009r.pdf. [2011, April 6].

Tylianakis, J.M.; Didham, R.K.; Bascompte, J.; Wardel, D.A. 2008. Global change and species interactions in terrestrial ecosystems. Ecology Letters. 11:1351-1263.

Urbanska, K.M.; Chambers, J.C. 2002. High-elevation ecosystems. In: Perrow, M.R; Davies, A.J. (eds.). 

Handbook of restoration ecology. Cambridge, UK: Cambridge University Press. 2: 376-400.

U.S. Army Corp of Engineers. 2008. Virgin River Watershed – Utah, Arizona and Nevada. Comprehensive watershed analysis. Final Report. August, 2008. Online: http://planning.usace.army.mil/toolbox/

library/misc/virginriverwatershed.pdf. [2012, Aug 15]

USDA Natural Resources Conservation Service. 2012. Web soil survey. Online: http://websoilsurvey.nrcs.

usda.gov/app/WebSoilSurvey.aspx. [2012, April 9].

U.S. Geological Survey (USGS). 2010. Land Treatment Digital Database. Online: http://greatbasin.

wr.usgs.gov/ltdl/Default.aspx. [2012, April 9].

Van de Ven, C.M.; Weiss, S.B.; Ernst, W.G. 2007. Plant species distributions under present conditions and 

forecasted for warmer climates in an arid mountain range. Earth Interactions. 11:1-33.

Walker B.H; Kinzig A.; Langridge J. 1999. Plant attribute diversity, resilience, and ecosystem function: 

the nature and significance of dominant and minor species. Ecosystems. 2:1–20.

Webb, R.H; Bowers, J.E. 1993. Changes in frost frequency and desert vegetation assemblages in Grand 

Canyon, Arizona. In: Redmond, K.T.; Tharps, V.L. (eds.). Proceedings of the ninth annual Pacific Climate (PACLIM) workshop; April 21-24; 1992. Tech. Rep. No. 3. California Department of Water Resources, Interagency Ecological Studies Program: 71-82.

Webb, R.H.; Defalco, L.A.; Esque, T.C.; Medica, P.A. 2009. A review of selected long-term ecological 

studies of the Mojave Desert ecosystem. In: Webb, R.H.; Fenstermaker, L.F.; Heaton, J.S.; Hughson, 

D.L.; McDonald, E.V.; Miller, D.M. (eds.). The Mojave Desert. Las Vegas, NV: University of Nevada 

Press: 429-456.

Weigand, J.; Rodgers, J. 2009. Active restoration for the Mojave Desert. In: Webb, R.H.; Fenstermaker, 

L.F.; Heaton, J.S.; Hughson, D.L.; McDonald, E.V.; Miller, D.M. (eds.). The Mojave Desert. Las Vegas, 

NV: University of Nevada Press: 378-409.

Whisenant, S.G. 1999. Repairing damaged wildlands – a process-oriented, landscape-scale approach. 

Cambridge, UK: Cambridge University Press. 312 p.

Williams, J.J.; Jackson, S.T. 2007. Novel climates, no-analog communities, and ecological surprises. 

Frontiers in Ecology and the Environment. 5:475-482.

Winkel,V.K.; Ostler, W.K.; Gabbert, W.D.; Lyon, G.L. 1995. The effects of seedbed preparation, irrigation 

and water harvesting on seedling emergence at the Nevada Test Site. In: Roundy, B.A.; MacArthur, 

E.D.; Haley, J.S.; Mann, D.K., (comps.). 1995. Proceedings, wildland shrub and arid land restoration 

symposium; October 19-21; Las Vegas, NV. Gen. Tech. Rep. INT-GTR-315. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 135-141.

Wisdom, M.J.; Rowland, M.M.; Suring, L.H. (eds.). 2005. Habitat threats in the sagebrush ecosystem: 

methods of regional assessment and applications in the Great Basin. Lawrence, KS: Alliance Communications Group, Allen Press. 301 p.

Zitzer, S.F.; 2009. Recruitment of native and non-native annual and perennial plant species following 

wildfire in a blackbrush (Coleogyne ramosisima) community in south central Nevada. Poster Session 

67-113. Abstracts of the 94th annual meeting of the Ecological Society of America. August 2-7, 2009. 

Albuquerque, NM. Online: http://eco.confex.com/eco/2009/techprogram/P19214.HTM. [2012, July 

22].
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Chapter 8

Human Interactions With the Environment 

Through Time in Southern Nevada

Carol Raish

Introduction

Southern Nevada is rich in irreplaceable cultural resources that include archeological remains, historic sites, cultural landscapes, and other areas of significance to Native Americans and other cultural groups. The Southern Nevada Agency Partnership 

(SNAP) seeks to provide for responsible use of Southern Nevada’s lands in a manner 

that preserves heritage resources and promotes an understanding of human interaction 

with the landscape. This chapter addresses Sub-goal 2.1 in the SNAP Science Research 

Strategy which is to develop an understanding of human interactions with the environment through time (table 1.3; Turner and others 2009). A review of human occupation 

in the region as derived from southern Nevada’s cultural resources is presented with a 

focus on the following questions.

1. Did humans use varying environmental zones through time and how were these 

zones used?

2. What influences did humans have on the landscape through history?

3. Did changes in the environment influence human use and occupation of the 

landscape over time?

4. Did human interaction with other groups influence the environment or resource 

utilization? and

5. Did resource use vary through time?

The depth with which these questions can be discussed is dependent on the nature and 

extent of archeological survey coverage of the region (fig. 8.1) and the nature of the 

resources themselves. Gaps in knowledge and implications for regional management 

are reviewed in final sections of this chapter.

The area shows wide-ranging use of resources and environmental zones over time. 

The focus of this overview is on the time periods primarily informed by archeological 

sources, from roughly 11,950 BP (10,000 BC) to 100 BP (AD 1850). This time period 

encompasses the end of the Pleistocene/beginning of the Holocene until occupation by 

Euro-Americans. There is evidence, although scant, of human occupation of southern 

Nevada at the end of the Pleistocene. Groups producing these remains are viewed as 

nomadic hunters and scavengers of large fauna, who also undoubtedly utilized both 

small game and plant resources (Harper and others 2006). The Early Holocene represents a broad spectrum of adaptations to changing climatic conditions that were affecting Holocene plant and animal resources (Ezzo and Majewski 1996). The beginnings 

of agriculture, with continued important exploitation of wild resources and seasonal 

movement, are indicated prior to 2350 BP (400 BC) and increase in intensity until ca. 

750/650 BP (AD 1200/1300). With the decline of agriculture as a major subsistence 

practice in the area around 750/650 BP (AD 1200/1300), archeological remains reflect 
156 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Figure 8.1—Map of southern Nevada archeological survey coverage.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 157

a return to a more nomadic foraging way of life that was supplemented by smaller-scale 

agriculture (Ahlstrom and Roberts 2012; Altschul and Fairley 1989; Ezzo and Majewski 

1996). This more mobile adaptation is associated with the Southern Paiute, who were 

residents of the region at European contact and who occupy southern Nevada today.

Focal Area

The area under study is mainly centered in southern Nevada’s Clark County but lands 

in Lincoln and Nye Counties also are included, as well as a small portion of Mohave 

County, Arizona (fig. 1.1). The geographic focus includes areas surrounding Lake Mead, 

the Muddy and Virgin Rivers, and the Las Vegas Valley. It extends west to Sloan Canyon National Conservation Area, the Spring Mountains National Recreation Area, and 

Ash Meadows National Wildlife Refuge. Physiographic features important for human 

occupation in and surrounding the location include the Muddy and Virgin Mountains, 

Moapa and Virgin Valleys, the Valley of Fire, the Muddy and Virgin Rivers, the Las 

Vegas Valley, and the Spring Mountains (figs. 8.2 and 8.3). These lands encompass nine 

distinct ecosystem types and support multiple species of management concern (tables 

1.1 and 1.2).

Culture History and Chronology

A variety of terms have been used to describe the cultural chronology of the region. 

Ezzo and Majewski (1996) list some of the more important designations and their associated time periods. We do not present all prior chronological schemes here, but correlate 

each sequence with the most common previously used names for the time period. In 

addition, different chronological schemes are currently used for the lands surrounding 

the Moapa and Virgin River Valleys, the Las Vegas Valley, and the Ash Meadows area 

of the Northern Mojave. These differences are based both in research history and in 

material culture variations. Thus, each of these geographic areas is discussed separately 

with the appropriate chronological terms (tables 8.1 and 8.2).

Paleo-Archaic 11,950-7,450 BP (10,000-5500 BC)

For this period and for the Middle and Late Archaic periods, the Las Vegas Valley and 

Northern Mojave area are included in the discussion owing to a similar chronological 

sequence (Ahlstrom and Roberts 2008; Roberts and Ahlstrom 2007). Diagnostic artifact 

overlap between the Paleo-Indian and Early Archaic has led Great Basin archeologists to 

designate the period Paleo-Archaic, as used here (Grayson 1993; Warren and Crabtree 

1986). This period encompasses the end of the Pleistocene epoch and the first several 

thousand years of the Holocene (Harper and others 2006). It includes the earliest known 

human occupations in southern Nevada and also is referred to as the Lake Mojave period 

(Ezzo and Majewski 1996).

There has been considerable paleoenvironmental research in southern Nevada and 

the Great Basin that is relevant to this time period. These studies have derived data from 

packrat middens and from paleohydrological research on spring deposits and pluvial lake 

basins. Information from this research indicates that climatic changes from a moister, 

temperate regime to current climatic conditions began around 13,950 BP (roughly 

12,000 BC) with deglaciation of the mountains within the area. A continuing trend 

toward aridity and drying of pluvial lakes is indicative of southern Nevada’s climate in 

the Holocene, with an increase in succulents in lower environments and a movement 

of woodlands to higher elevations (Ezzo 1996).
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Figure 8.2—Map of the Moapa and Virgin Valleys.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 159

Figure 8.3—Map of the Las Vegas Valley.
160 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

The majority of knowledge concerning the Paleo-Archaic comes from projectile 

points that are often found as isolated occurrences and that provide little information 

about lifeways in the Great Basin during this time. Evidence of occupation in southern 

Nevada itself is scant. Two artifact traditions are distinguished in the area during the 

period: fluted points, such as Clovis, and stemmed points, such as Lake Mojave (Grayson 

1993; Harper and others 2006).

Table 8.1—Chronological sequence for the Moapa and Virgin River Valleys (adapted from Ahlstrom and 

Roberts 20121; Ezzo 19952; Harper and others 20063; Lyneis 20124). Question marks indicate 

uncertain date range.

Period Subperiod Date range Source

Paleo-Archaic 11,950-7450 BP (10,000-5500 BC) 3

Paleo-Indian 11,450-10,950 BP (9500-9000 BC) 2, 3

Early Archaic 11,150-7450 BP (9200-5500 BC 3

Archaic Middle Archaic 7450-4950 BP (5500-3000 BC) 3

Late Archaic 4950-2350 (?) BP (3000-400 (?) BC) 3

Late Archaic/Early

Agricultural 2350 (?)-1450 BP (400 (?) BC-AD 500) 3

Virgin Branch 1600-750/650 BP (AD 350-1200/1300) 1, 3, 4

Moapa phase 1600-1400 BP (AD 350-550) 3

Muddy River phase 1400-1200 BP (AD 550-750) 3

Lost City phase 1200-800 BP (AD 750-1150) 3

Mesa House phase 800-750/650 BP (AD 1150-1200/1300) 1, 3, 4

Late Prehistoric and 

Protohistoric 750/650-150 BP (AD 1200/1300-1800) 3, 4

Historical 150-0 BP (AD 1800-1950)3

Table 8.2—Chronological sequence for the Las Vegas Valley (adapted from Roberts 

and Ahlstrom 2007).

Period Subperiod Date range

Paleo-Archaic 11,450-7450 BP (9500-5500 BC)

Paleo-Indian 11,450-10,950 BP (9500-9000 BC)

Early Archaic 11,150-7450 BP (9200-5500 BC) 

Archaic Middle 7,450-4950 BP (5500-3000 BC)

Late 4950-1450 BP (3000 BC-AD 500)

Terminal Late 1949-1450 BP (AD 1-500)

Ceramic Early 1450-950 BP (AD 500-1000)

Middle 950-450 BP (AD 1000-1500)

Late 450-100 BP (AD 1500-1850)

Historical Early 450-100 BP (AD 1500-1850)

Late 100-50 BP (AD 1850-1900) 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 161

 Clovis points are representative of the Paleo-Indian occupation found across the 

Americas. The points were used with the thrusting spear or atlatl (spear-thrower) and 

are generally considered to indicate the activities of nomadic groups that subsisted by 

hunting and scavenging Pleistocene megafauna, represented by mammoth, camel, horse, 

and bison. Paleo-Indian sites include camps, kill and butchering locations, and isolated 

projectile points (Cordell 1997; Harper and others 2006; Roth 1993). Clovis points are 

rare in the study area and are usually found in restricted contexts confined to lowland 

valleys and lake shores. No Clovis points have been found directly associated with 

Pleistocene megafauna in southern Nevada, nor have they been found in stratified, welldated contexts (Roth 2012). The distribution of sites with these fluted points indicates 

that Paleo-Indian use of the area was sporadic but patterned, suggesting small-scale 

hunting expeditions into the area by highly mobile groups following game corridors, 

such as washes and valleys (Jones and Edwards 1994; Roth 2012).

The Great Basin Stemmed point series was defined at Pleistocene Lake Mojave, 

California (60 to 70 miles south of Ash Meadows National Wildlife Refuge), with sites 

having Lake Mojave projectile points and Silver Lake projectile points, as well as artifacts referred to as crescents (Grayson 1993; Warren and Crabtree 1986). The culture 

dates to between 11,150 and 7,450 BP (roughly 9200 to 5500 BC), which overlaps 

both the Paleo-Indian and Early Archaic periods. Stemmed points were first identified 

in lakeshore environments leading researchers to focus on marsh or lacustrine locales 

and subsistence resources. However, more recent work has identified stemmed points 

in a variety of other environments leading to the view that the makers of these points 

used additional plant and animal resources from various locations (Harper and others 

2006; Roth 2012). In general, Paleo-Archaic sites do not contain identifiable features 

or ground stone, indicating an emphasis on hunting and gathering plant resources that 

did not require heavy grinding or parching (Roth 2012). The scarcity of Paleo-Archaic 

sites in southern Nevada and elsewhere undoubtedly reflects the depth at which these 

sites may be buried, the lack of intact, exposed surfaces, the nature and mobility of the 

subsistence adaptation, and the fact that Paleo-Archaic sites may not be recognized 

without diagnostic projectile points (Cordell 1997).

Middle Archaic 7450-4950 BP (5500-3000 BC)

The Archaic Period represents a broad spectrum adaptation to Holocene animal 

and plant resources that derived from environmental conditions similar to those of the 

present. The Archaic in North America seems to represent localized cultural traditions 

that developed out of Paleo-Indian traditions. Tools came to be more diverse as groups 

adapted to the mosaic of environments resulting from the climate transition from the 

Pleistocene to the Holocene. Movement between ecological zones for resource procurement undoubtedly occurred (Ezzo and Majewski 1996; Fowler and Madsen 1986). 

The Middle Archaic adaptation centers on generalized foraging and a broad spectrum 

economy (Basgall 2000). Middle Archaic sites are generally small with sparse artifact 

assemblages indicating short-term use by small, mobile groups (Lyneis 1982). During 

these times, plant procurement and processing tools, storage cists, and snares and traps 

for small game came into use. Artifacts of the Middle and Late Archaic include large, 

diagnostic projectile points attached to darts for use with the atlatl; thus, the Middle 

Archaic is also referred to as the Pinto period after the Pinto point (Ezzo and Majewski 

1995; Warren and Crabtree 1986).

Middle Archaic sites and components are known from the Tule Springs area, the 

Eglington Escarpment, along Duck Creek, and at the Corn Creek Dunes site in the 

Las Vegas Valley. Pinto points also are reported from lithic scatter sites in the Moapa 

area (Ezzo and Majewski 1996). Middle Archaic sites also are known from the Ash 
162 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Meadows area in the Amargosa Valley, a relatively lush valley with a variety of wild 

resources including marsh resources, mesquite beans, and piñon nuts (Roth 2012). Site 

types include isolated projectile points; rockshelters; larger artifact scatters presumably 

representing re-use over a long period of time; lithic scatters; and fire-cracked rock 

generally considered indicative of roasting pits.

Pinto period sites in southern Nevada seem to be located near water sources such 

as drainages and remnant pluvial lakes. Unusually arid conditions are thought to have 

driven the settlement pattern (Ezzo and Majewski 1996). The toolkit contains items for 

hunting and processing game as well as milling implements indicating some reliance on 

plant food sources requiring processing. Milling stones and mortars increase throughout 

the Archaic. Sites with features and ground stone are much more common than during 

the Paleo-Archaic, suggesting a shift toward increased processing activities. These sites 

are widespread and occur in multiple ecological zones, showing the growing importance 

of plant foods (Lyneis 1982; Roth 2012). Sites with features and ground stone in the 

piñon-juniper zone indicate piñon use during this period (Roth 2012).

Late Archaic 4950-2350 BP (?) (3000-400 BC ?)

The question marks in the date range indicate that the date range is uncertain. The 

Late Archaic, or Gypsum period (table 8.1), is discussed as having a climatic shift toward 

greater precipitation and an increased diversity of plant resources available to southern 

Nevada groups. Thus, the period shows a continuing, increased emphasis on both plant 

and hard-seed processing and a greater occurrence of milling implements on Gypsum 

sites (Ezzo and Majewski 1996). Mortars and pestles indicate mesquite bean processing. 

Greater use of valley floors also may indicate a growing importance of mesquite in the 

diet, although it was not a staple resource until later periods (Roth 2012). Piñon was 

still exploited in the uplands, and one site in the Gold Butte area of the eastern portion 

of the project area also has agave roasting pits indicating the use of agave during the 

period. In addition, hunting of both large mammals (such as big horn sheep) and small 

mammals appears to have played an important role in resource procurement during the 

period (Harper and others 2006).

Gypsum Cave, the type site for the Gypsum Point, is located east of the northeastern 

edge of the Las Vegas Valley (Ezzo and Majewski 1995; Harrington 193; Roberts and 

Ahlstrom 2007) and has Late Archaic radiocarbon dates. Gypsum period components 

also occur in the Corn Creek Dunes area, along Duck Creek, in the southeastern corner 

of the Las Vegas Valley (Brooks and others 1975), in the Ash Meadows region, the 

Yucca Mountain/Forty Mile Wash area and around the Muddy and Virgin Rivers (Roth 

2012). Late Archaic sites include caves, rockshelters, campsites, roasting pits, hearths, 

and scatters of flaked and ground stone. Site locations indicate that groups continued a 

mobile strategy seasonally exploiting ecological zones from a wide range of elevations 

and landforms (Ezzo and Majewski 1996; Roth 2012). The Gypsum period is also the 

time when long-distance trade goods, such as marine shell from California, appeared in 

the region (Lyneis 1982). Ceremonial sites appear during the time period indicated by 

caves used for ritual purposes, rock art, and specialized artifacts such as intentionally 

broken and painted dart fragments. Split twig figurines occur in the region (Fowler and 

others 1973; Roth 2012).

Sites of the Middle and Late Archaic can be difficult to identify because the generally small, mobile groups who produced them tended to leave a scanty and dispersed 

occupation record. In addition, and similar to Paleo-Archaic archeological remains, 

identification is also difficult if no diagnostic projectile points are present. Thus, many 

Archaic sites may be misclassified (Lyneis 1982). These problems apply most particularly to surface lithic scatters identified during archeological surveys.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 163

Late Archaic/Early Agricultural 2350 (?)-1450 BP 

(400 (?) BC-AD 500)

The question marks in the date range indicate that the date range is uncertain. From 

this point on, Las Vegas Valley and Mojave Desert research use a different chronological scheme and are discussed separately in following sections. The Early Agricultural 

encompasses the Lowland Virgin Moapa phase 1600-1400 BP (AD 350-550), which 

corresponds to the Basketmatker II (BM II) and the first half of the BM III in the Pecos Classification used on the Colorado Plateau and in the Four Corners area. These 

time periods represent the beginning of the Virgin Branch Ancestral Puebloan [(Virgin 

Anasazi), referred to as the Western Virgin Puebloan archaeological culture by Ahlstrom 

and Roberts (2012)]. This occupation is located in portions of northern Arizona, southwestern Utah, and southern Nevada (Ezzo and Majewski 1996). The Lowland Virgin 

area (Lyneis 1995) lies at the western edge of the Virgin Branch occupation, comprising the Virgin and Muddy River Valleys and surrounding areas. On the east, the Virgin 

Branch is bordered by the Kayenta Ancestral Puebloan. On the north, west, and south 

mobile groups bordered the region (Ezzo and Majewski 1996).

The Early Agricultural and earlier portions of the Moapa phase, like BM II, lack 

ceramics and retain use of the atlatl as reflected by larger, corner and side-notched dart 

points (Lyneis 1995). Pit structures and rockshelters with semi-subterranean storage 

cists are associated with BM II and the Early Agricultural in the area. Pit structures are 

found in groupings of one to five with interior hearths and clay floors. These groupings 

generally lack separate storage features, which may suggest seasonal or temporary use 

(Clark 1984; Ezzo and Majewski 1996; Lyneis 1995; Shutler 1961). There is substantial 

evidence of maize farming during the period with materials coming from the Upper and 

Lower Moapa Valleys and from the uplands east of the Virgin River Valley. This evidence 

is derived from radiocarbon dates obtained directly from maize samples indicating the 

presence of maize horticulture by the AD 200s and possibly in the AD 100s. Remains 

of beans and cucurbits (squash/pumpkin/gourd) are also present (Ahlstrom and Roberts 

2012).

Studies indicate mobility in the Moapa phase with small groups probably occupying 

sites on a temporary and/or seasonal basis. Access to both upland resources and farm 

land in the valleys is shown by site locations. This indicates a weaker commitment to 

agriculture than in later times (Myhrer 1986). Wild plant species maintained an important 

role in subsistence as did hunted game (Lyneis 1995).

Muddy River Phase 1400-1200 BP (AD 550-750)

The Muddy River phase corresponds roughly to the latter portions of BM III with many 

of the same diagnostic attributes. Grayware ceramics, the bow and arrow, two-handed 

manos, and basin and slab metates (grinding implements) appear in the archeological 

record during this time period. Small, stemmed and notched points suggest use of the 

bow and arrow (Lyneis 1995; Shutler 1961).

Both pit structures and Basketmaker components have been identified from this 

period. Fourteen pit structures from four different sites in the Upper and Lower Moapa 

Valley were excavated by Harrington and associates (Shutler 1961). Also, 17 sites were 

found to contain Basketmaker components in the Moapa Valley, indicating that sites 

tended to be evenly distributed throughout the valley (Clark 1984). The excavated pit 

structures varied in size with some designated as habitations, while other, smaller ones 

are considered to be storage structures. The information obtained from these studies 

indicates that pit structures usually occurred in small groups of five or fewer as in the 

previous phase, had plastered floors, and were generally circular in shape with some 
164 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

having hearths (Ahlstrom and Roberts 2012; Ezzo and Majewski 1996). Two pit structures excavated on Black Dog Mesa in the Upper Moapa Valley date to the BM III and 

possibly the later Pueblo I Lost City Phase (Ahlstrom and Roberts 2012). Both structures 

provided botanical evidence for the cultivation of maize and cucurbits, as well as the 

use of amaranth and tansy mustard.

Pit structures were located on mesas above the valley and on low knolls in the valley, suggesting that farming of the valley floor agricultural land was becoming more 

important (Shutler 1961). The observation that sites were evenly distributed throughout 

the valley (although the best agricultural land is in the lower portion of the valley) indicates that foraging and use of a wide range of ecological zones remained important 

during the phase (Clark 1984). Upland resources such as agave were used throughout the 

period (Ahlstrom and Roberts 2012). The settlement pattern and resource use were not 

significantly different from that of the previous phase. Interaction with other groups is 

demonstrated by ceramics presumably imported from areas to the east (Lyneis 1992b).

Lost City Phase 1200-800 BP (AD 750-1150)

The Virgin Branch Lost City phase corresponds to Pueblo I-II of the Pecos classification. During this phase the Virgin Branch population peaked and expanded into the 

Las Vegas Valley. Settlements became larger and surface structures appeared during the 

later portions of the phase (Harper and others 2006; Lyneis 1995). The technological 

changes of the prior phase continued with increased ceramic variation in both imported 

and locally produced varieties. Increases in ceramics and ground stone milling implements demonstrate an increasing emphasis on agriculture (Myhrer 1989).

Habitation sites tended to be located on low knolls on the valley floor in proximity 

to agricultural land, with a greater concentration in the lower part of the Moapa Valley 

than in the Muddy River phase. This locational preference is considered to be another 

indicator of the growing importance of agriculture (Clark 1984); although upland resources, such as agave, were used throughout the period (Ahlstrom and Roberts 2012). 

Irrigation in the form of small diversion dams along the slow-flowing, spring-fed Muddy 

River is inferred during these times (Ezzo and Majewski 1996; Lyneis 1995; Shutler 

1961).

Pit structures, with associated storage cists or above-ground masonry storage rooms, 

were used for habitation during the early portion of the phase (Lyneis 1995). The storage 

cists are often arranged end-to-end in an arc, sometimes attached to the pit structure 

itself (Lyneis 1995). During the later portion of the phase, surface living rooms were 

generally placed within a curving alignment of storage rooms that defined a courtyard 

space shared by small groups of one or a few families.

A well-known site of the period that is located on the Muddy River in the Lower 

Moapa Valley is Main Ridge. The site is unusual because of its large size and capacity 

to house up to 100 people in a series of courtyard groups, which are as closely placed as 

the topography allows. Subsistence remains from the site indicate cultivation of maize, 

squash, and beans and exploitation of a variety of wild plants such as cattails, prickly 

pear cactus, amaranth, saltbush, goosefoot, tansy mustard, and grasses. Faunal remains 

included those of desert bighorn, rabbits and hares, birds, and desert tortoise (Harry 

2008; Harry and Watson 2010). Ceramics date the site to a relatively brief period around 

900 BP (AD 1050) (Lyneis 1992b). Main Ridge is described as being ideally suited for 

interaction with settlements along the Lower Virgin River and to the east. Non-local 

goods indicate interactions with other groups and include ceramics from the Kayenta 

and northern San Juan areas, as well as beads and shell ornaments from the south and 

west (Lyneis 1992b).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 165

Mesa House Phase 800-750/650 BP (AD 1150-1200/1300)*

Population in the Lowland Virgin area declined and the extent of occupation decreased during the Mesa House phase, which corresponds to Early PIII in the Pecos 

Classification (*More recent information by Lyneis (2012) discussed in Ahlstrom and 

Roberts (2012) has extended PIII in the area to AD 1300). By the end of this phase, the 

Virgin Branch cultural tradition was no longer apparent in southern Nevada (Harper 

and others 2006). Material culture during the phase was similar to that produced during 

the previous Lost City phase, especially in terms of flaked and ground stone tools. The 

difference between artifacts of the phases centers on ceramics with the presence of new 

types of decorated wares originating in the upper Virgin area and the Kayenta area to 

the east. Both turquoise and salt were mined and possibly traded (Ezzo and Majewski 

1996; Shutler 1961). Maize, squash, and beans were cultivated and a variety of wild 

plants were exploited including those from upland areas. An increase in the number of 

projectile points during the Mesa House phase led Hayden (1930) to suggest increasing 

warfare during the time period.

Known sites are located in the Lower Moapa Valley and are situated on mesas or other 

landforms above the valley floor, which suggests a defensive location (Lyneis 1996). 

These include Mesa House, Three Mile Ruin, and Adam 2. Rooms are primarily surface 

habitation and storage structures that almost completely enclose a courtyard. Sites are 

considered to be larger than simple households but still relatively small. For example, 

of 33 structures in Mesa House’s formal layout, only three to five are habitation rooms 

(Lyneis 1986, 1995, 1996; Shutler 1961). The available research indicates that kivas 

(religious/ceremonial structures) are not present in Lowland Virgin Branch occupations 

(Lyneis 1995).

Ezzo and Majewski (1996) discuss various views on the end of the Virgin Branch or 

“abandonment” in the area. Warfare with other groups moving into the region (Shutler 

1961), climatic deterioration in the form of severe drought (Larson and Michaelson 

1990), and collapse of Ancestral Puebloan society at the end of PII with a breakdown 

of links with Mexico are briefly presented. Lyneis’s discussion of the topic (1992a,b, 

1995, 1996) is most convincing with consideration of climatic and environmental 

change, demography, changes in trade networks, and assimilation or competition with 

the Paiute. She argues that none of the models alone is sufficient to explain the end of the 

Virgin Branch in the area stating that “just as for other parts of the northern Southwest, 

understanding the processes of abandonment and the fate of the populations remains a 

major challenge” (Lyneis 1995: 235).

Las Vegas Valley—Terminal Late Archaic 1949-1450 BP (AD 1-500), 

Ceramic Period 1450-100 BP (AD 500-1850)

North Mojave—Late Archaic to 1450 BP (AD 500), Late PrehistoricCeramic 1450-150 BP (AD 500-1800)

Terminal Late Archaic—The Terminal Late Archaic in the Las Vegas Valley encompasses the period during which pit structures, agriculture, and the bow and arrow came 

into use in the area, with the introduction of ceramics at the beginning of the following 

time period. Evidence of farming in the southeastern corner of the Las Vegas Valley on 

the bank of Las Vegas Wash has radiocarbon dated contexts that produced maize pollen 

or charred kernels. The earliest of the date ranges in this area are from 2050-1700 BP 

(100 BC-AD 250) and from 2300-2000 BP (350-50 BC) (Ahlstrom and Roberts 2012).
166 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

In the Mojave the bow and arrow appear between 1650-1450 BP (AD 300-500) 

(Ahlstrom 2005) with the appearance of ceramics several centuries later. Sites and 

components from the Las Vegas Valley include a campsite and a pit structure at the 

Clark County Wetlands Park in Las Vegas Wash. The site is consistent with those from 

the Muddy River in demonstrating use of pit structures and the bow and arrow prior to 

ceramics (Roberts and Ahlstrom 2007).

Ceramic Period—The Early Ceramic (1450-950 BP, AD 500-1000) corresponds to the 

following sequences: Patayan I, Basketmaker III and Pueblo I, and the Muddy River 

and early Lost City phases in the Moapa and Virgin Valleys. It also corresponds to the 

early portion of the Late Prehistoric-Ceramic in the Mojave sequence. Sites from this 

time period include pit structures, rock shelters, roasting pits, storage features, rock 

rings, hearths, and artifact scatters located throughout the Las Vegas Valley. Maize was 

grown during the period and wild plant foods, such as mesquite pods, hedgehog cactus 

fruit, and chenopods, remained important (Ahlstrom and Roberts 2012).

The earlier portion of the Ceramic period in the Valley features Rose Spring arrow 

points and prehistoric Puebloan grayware, while the later portion has Cottonwood Triangular and Desert Side-notched points with Paiute and some Tizon brownwares. In 

earlier times (pre-750 BP, AD 1200), these sites show more intensive, longer term use 

and are considered to be habitations; later sites reflect less intensive, shorter term use 

and are designated campsites (Roberts and Ahlstrom 2007). During the early portion of 

the Late Prehistoric, Ceramic from 1450-750 BP (AD 500-1200) in the Mojave Desert 

projectile point assemblages contain corner-notched Rose Spring and un-notched Cottonwood Triangular points, along with milling stones, manos, and mortars and pestles 

(Ahlstrom and Roberts 2008; Warren and Crabtree 1986).

Grayware pottery, primarily Virgin Branch, occurs more frequently on sites in central 

and northern portions of the Valley from Las Vegas Springs north. Buff and brownwares (Patayan, Paiute brownware, and Tizon Brown) are more prevalent on sites in 

the southern portion of the Las Vegas Valley. These differences suggest contacts with 

Patayan groups to the south along the Lower Colorado River as indicated at sites in 

the Duck Creek and Lower Las Vegas Wash areas. Patayan archeological remains are 

associated with ancestral Yuman-speaking groups, who live along the Lower Colorado 

today (Roberts and Ahlstrom 2007).

Sites with a predominance of grayware indicate contacts with Virgin Branch peoples 

to the northeast in the Moapa Valley. These contacts demonstrate routes of travel between the areas (Roberts and Ahlstrom 2007). Various sites have mixed assemblages of 

Patayan, Virgin Branch, and Paiute brownware pottery, indicating repeated short-term 

movement into the Las Vegas Valley by different groups (Seymour 1997). Conversely, 

the Las Vegas Valley could have had a resident population that established contacts 

with both Virgin Branch groups to the northeast in the Moapa and Virgin River Valleys 

and with groups to the south along the Colorado River (Roberts and Ahlstrom 2007). 

At the Corn Creek Dunes site in northern Las Vegas Valley both Great Basin Brown 

Ware and Pueblo utility ware (grayware) were made locally (Lyneis 2011). There is 

still considerable discussion and uncertainty about the cultural affiliation of some sites 

in the Valley and discussion over whether indigenous populations adopted or acquired 

outside technology or whether migrant populations moved into the area.

The ceramic data seemingly show that outside contacts in the Early Ceramic period 

were with the Virgin Branch area and those in the Middle and Late periods were with 

the Patayan area to the south along the Lower Colorado River. In the Middle Ceramic, 

Paiute pottery appeared in the Valley. However, there is considerable debate about the 

entrance of the Paiute into the valley, as well as the cultural affiliation of sites, which 

is discussed in a following section.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 167

In the Northern Mojave during the early Late Prehistoric-Ceramic there is evidence 

of contact with Virgin Branch populations in the form of pottery that has been found 

across southern Nevada and into southeastern California (Warren and Crabtree 1986). 

These pottery sherds could represent trade or the presence of Puebloan groups foraging 

in the area (Warren and Crabtree 1986).

The Middle Ceramic (950-450 BP, AD 1000-1500) in the Las Vegas Valley roughly 

matches the Patayan II period and Pueblo II and III. In the Virgin Branch sequence 

the Middle Ceramic corresponds with the late Lost City and Mesa House phases up to 

abandonment by the Virgin Branch at roughly 750/650 BP (AD 1200/1300). The Middle 

Ceramic also corresponds to the Late Prehistoric-Ceramic from 750-450 BP (AD 1200-

1500) in the Mojave sequence. Both Ancestral Puebloan and Patayan ceramic types often 

occur with equal representation on sites of this time period perhaps indicating ties to 

both groups (Roberts and Ahlstrom 2007). In the later part of the period, after the end 

of the Virgin Branch occupation of the Lowland Virgin area, Patayan and Paiute pottery 

become more prevalent.

Most Middle Ceramic sites are located in well-watered locales, such as near springs, 

and consist of pit structures, rockshelters, roasting pits, and hearths. Two apparent 

multi-room pueblo structures are located at the Big Spring Site toward the center of the 

Las Vegas Valley. Sites of the period indicate the use of both wild and domesticated 

resources including maize, cucurbits (squash/pumpkin/gourd), yucca fruits and pods, 

hedgehog cactus, and Chenopodium or Amaranthus seeds. There is substantial evidence 

for the consumption of desert tortoise (Roberts and Ahlstrom 2007). Defining artifact 

characteristics of this period in the Mojave area include continuing use of Cottonwood 

Triangular points with the addition of Desert Side-notched points by around 750 BP 

(AD 1200).

With the later pre-European contact periods, sequences and archeological information converge in the Las Vegas Valley, the Muddy and Virgin River Valleys, and Ash 

Meadows National Wildlife Refuge area in the Northern Mojave. In the Las Vegas Valley, the Late Ceramic corresponds to the Patayan III period. However, the frequency of 

Patayan types actually declines as the frequency of Southern Paiute Brownware rises 

(Roberts and Ahlstrom 2007). After the abandonment of the region by the Virgin Branch 

Puebloan groups, archeological remains indicate a return to a more mobile foraging way 

of life with a subsistence base of hunting and gathering supplemented by small-scale 

agriculture (Ezzo and Majewski 1996). Late Ceramic sites comprise rockshelters, roasting 

mounds, and open shelters. These sites have evidence of the use of both domesticated 

and wild resources such as agave, mesquite seeds, prickly pear cactus seeds, domestic 

squash seeds, coyote melon, and desert tortoise (Roberts and Ahlstrom 2007).

The Northern Mojave produces evidence for occupation during the post 750 BP (AD 

1200) times of the Late Prehistoric-Ceramic in the form of both projectile points and 

pottery. The Ash Meadows area crosses the territories of the Western Shoshone and 

the Southern Paiute in the 1800s (Livingston and Nials 1990). Evidence demonstrates 

a nomadic foraging lifeway with horticulture in small fields near well-watered areas 

(Ahlstrom and Roberts 2008; Livingston and Nials 1990).

The entry of the Southern Paiute into southern Nevada is a topic of continuing interest 

that has been reviewed and debated by a number of researchers. Aikens and Witherspoon 

(1982) and Goss (1977) argue that the group arrived in Southern Nevada in the Early or 

Middle Archaic based on linguistics, settlement patterning, and persistence of certain 

projectile points through time. Lyneis (1982, 1994) and Warren and Crabtree (1986) 

argue that they arrived no earlier than 950 BP (AD 1000) and possibly not until after 

abandonment by the Virgin Branch Ancestral Puebloan based on the view that Virgin 

Branch and Southern Paiute material culture items do not co-occur and that where items 
168 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

from both groups are present, the Southern Paiute artifacts overlie those of the Virgin 

Branch (Ezzo and Majeweskis 1996). Southern Paiute sites in the region are difficult to 

identify with respect to time period because of a lack of chronological control, leading 

to uncertainty concerning their attribution to the prehistoric, protohistoric, or historic 

periods (Ezzo and Majewski 1996).

Protohistoric and Historic Periods ca. 350-120 BP, ca. 120 BP to 

present (ca. AD 1600-1830, ca. AD 1830 to present)

The general emphasis of this review is on the primarily pre-European contact periods 

in southern Nevada that are informed by archeological materials. Thus, the following 

periods of initial contact with Europeans (Protohistoric) and later Euro-American settlement (Historic) are presented in less detail. At the time of European contact, regional 

residents were the Southern Paiute Tribe, as well as the Chemehuevi Tribe (included 

with the Paiute). The Southern Paiute Tribe is made up of independent bands, or groups. 

Each band has its own government. The Southern Paiute Tribe was located in the more 

southerly portions of the area and the Western Shoshone in the more westerly section 

(Euler 1966; Kelly and Fowler 1986; Steward 1938). The Mojave and Hualapai Tribes 

were located to the south and southeast. There was considerable interaction among these 

groups as they moved in and out of Southern Nevada (Ruppert 1976). Information on 

the Southern Paiute (Nuwuvi) is the focus of this discussion.

Southern Paiute habitation structures known archaeologically and ethnographically 

consisted of wickiups (a conical frame of branches covered with layers of bark, grass, 

or brush) in winter and brush shelters in summer (Inter-Tribal Council of Nevada 1976). 

Material culture comprised a wide range of basketry forms for storage, transport, resourcegathering, and cooking, as well as ceramics in some groups (Fowler and Dawson1986; 

Fowler and Fowler 1981; Kelly 1964; Stewart 1942). Baskets were apparently favored 

over the heavier pottery owing to the nomadic Paiute lifestyle. Other items of material 

culture included the bow and arrow, nets, woven items, grinding implements, and flint 

knives, with trade items such as shells and cloth (Euler 1966).

The Southern Paiute subsistence base emphasized hunting, foraging, and farming in 

the valley bottoms. They used many plants and animals ranging from insects and small 

mammals to deer and mountain sheep. Wild plant foods were prickly pear, yucca, piñon 

nuts, grass seeds, agave, acorns, wild grapes, and roots. These wild plant foods, primarily gathered by the women, were the dietary mainstay, with mesquite beans and pods of 

considerable importance. Men were the hunters. Maize, beans, squash, sunflower, and 

amaranth were farmed (Kelly 1964; Ruppert 1976).

Resources were generally obtained in a seasonally transhumant round (seasonal 

movement to gather resources), which varied from group to group and habitat to habitat. 

Farming was normally not intensive; older people often cared for the fields while the 

remainder of the group gathered resources in other locations (Ezzo and Majewski 1996; 

Inter-Tribal Council of Nevada 1976; Kelly and Fowler 1986). Most sources agree that 

the nuclear family was the primary unit of social organization for the Southern Paiute 

with aggregation and dispersal of larger and smaller groups throughout the year (Euler 

1966; Kelly 1964; Steward 1938). As Euro-Americans increased in numbers in the 

region, the Native Americans were forced to congregate in bigger groups to survive 

(Inter-Tribal Council of Nevada 1976).

The first reported direct European contacts were with the Spanish in the late 1700s 

with the expeditions of Garcés and of Domínguez and Escalante, who were attempt-
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 169

ing to establish a route between Santa Fe, New Mexico, and Monterey, California. 

Although the expedition did not succeed in reaching its goal because of the onset of 

winter, part of their route became a portion of the Old Spanish Trail, that consisted of 

previously existing trails used for raiding and trading (Harper and others 2006).

After the explorers, trappers, and traders extended their operations into the area, an 

active slave trade began that lasted from the late 1700s to the mid-1850s. Captives, 

often Southern Paiute, were transported along the Old Spanish Trail between California 

and New Mexico. Prior enemies of the Southern Paiute, such as the Ute and Navajo, 

conducted slave raids in the region as they went between Spanish, and later, Mexican 

settlements. These raids seriously impacted the people of the Moapa and Las Vegas Valleys forcing them away from favorable agricultural lands, depopulating some Southern 

Paiute bands, and increasing their hostility and fear of travelers and other outsiders 

(Euler 1966; Harper and others 2006; Kelly and Fowler 1986). Slave raiding continued 

in the region until the mid-1850s when steps taken by the Mormons and the territorial 

legislature ended the trade (Harper and others 2006; Kelly and Fowler 1986).

Mormon (Church of Jesus Christ of Latter-day Saints) influence in the general region 

began with their entry into Utah in 1847 and continues today. Mormon activity and 

settlement in southern Nevada have been well documented by Sterner and Ezzo (1996) 

drawing on information from the Church Educational System (LDS 1993). Thus, the 

Mormon Era will not be discussed in detail in this overview other than to note briefly 

the impact of permanent Mormon settlements on the Southern Paiute.

During the 1850s, the Old Spanish Trail became the Mormon Road, which brought 

settlers and other travelers to the area (Harper and others 2006). Increased EuroAmerican settlement displaced the Southern Paiute from long-used agricultural, foraging, and hunting lands, which became depleted by livestock grazing and larger farming 

operations. Interactions with Mormon settlers increased so that by the 1870s the majority 

of Southern Paiute had direct contact with Euro-Americans, with some settling near 

Mormon communities (Kelly and Fowler 1986).

Expansion of Euro-American settlement led to increasing hostilities. In 1873, an executive order was issued setting aside 3,900 square miles (10,101 square kilometers) to 

form the Moapa River Reservation. The reservation was expanded in 1874 then sharply 

reduced to 1.5 square miles (2.4 square kilometers) in 1875 to accommodate complaints 

from white settlers within the reservation lands. In 1982, the reservation was increased 

to its present size of 112 square miles (180 square kilometers) after a petition to congress 

from the Moapa Band of the Paiute (Ezzo and Majewski 1996; Inter-Tribal Council of 

Nevada 1976).

In 1951, the Southern Paiute filed a claim with the Indian Claims Commission, which 

was resolved in 1965 with a monetary settlement (Inter-Tribal Council of Nevada 

1976). Portions of the money from the settlement were invested in improvements to 

the reservation’s business enterprises. In 2011, there were 287 enrolled Tribal members 

with approximately 180 members living on the reservation. The total population was 

estimated at 425 residents (http://www.xeri.com/Moapa/moapa.htm). The Southern 

Paiute have persevered over the years in the face of many obstacles and hardships associated with Euro-American occupation and settlement of the area and are actively 

working to preserve their heritage in publications detailing their history and culture 

(Alley 1986; Ezzo and Majewski 1996).
170 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Knowledge Gaps and Management Implications

Knowledge gaps concerning southern Nevada’s past, as derived from the archeological 

record, result from several sources. Chief among them are the extent of archeological 

survey coverage (the most common means of identifying cultural resources) and the 

nature of archeological survey itself. Approximately 783,756 acres (317,174.8 hectares) 

or 7 percent of the lands under consideration have been surveyed for archeological resources (de Dufour, personal communication; fig.8.1). Thus, a large portion of the area 

has received no coverage. Because Federal agencies are required to assess the effects 

of their ground-disturbing activities on cultural resources1, much of this survey coverage is on Federal lands, which may bias the time period, nature, and types of remains 

found. Managers must always take these regulations into consideration when planning 

ground-disturbing projects.

Because of the sparse nature of archeological survey coverage, basic inventories 

of cultural resources are needed. In particular, inventories that are not associated with 

planned development projects are desirable to expand surveyed lands and address gaps 

in coverage. Complete coverage of the public lands in the study area is not a realistic 

goal because SNAP offices manage over 7 million acres. That is a huge area to meet 

the “complete survey” expectation, which would require over 500 man-years to survey 

with 30-meter transects at 2-miles per hour (Ronning, personal communication 2012a). 

In addition, cultural resource recording standards, as well as the sites themselves, will 

continue to change over time. A more realistic goal for regional-scale inventory would 

be to expand and improve the sample of lands that have been examined and sites that 

have been located and recorded. Landscapes could provide context for apportioning the 

available survey effort, which should be partially based on measuring the redundancy in 

information collected on cultural resources from particular environmental zones. Because 

cultural resources represent finite, non-renewable resources that must be protected for 

the future, an important goal of inventory is to provide baseline information for measuring changes in the condition of sites through time (Lancaster and others 2006).

In addition to the basic need for greater survey coverage, several studies have identified both specific and more general information gaps and have provided recommendations for addressing them. A major recommendation from the working group on the 

Information and State-of-the-Science Summary developed for the Ecosystem Health 

Assessment of Southern Nevada Project (Lancaster and others 2006) was to prepare a 

new Historic Context for the region that would provide current information on cultural 

groups and chronologies, occupational sequences, settlement patterns, and resource use 

through time. Such a Historic Context would structure and promote research important 

to southern Nevada agencies (Lancaster and others 2006). This document has been 

prepared in draft form, and is used in this review (Roberts and Ahlstrom 2012a).

Other general recommendations from the working group include compiling regionwide data sets featuring both survey and excavation data. This data base would also 

include layers suitable for GIS with information on plant communities, springs, surface 

geology, soils, and other pertinent resource information reflective of the close association 

between archeological sites and their environmental surroundings. It is planned that the 

Nevada Cultural Resource Inventory System (NVCRIS) will meet this function. This 

1 Section 106 of the National Historic Preservation Act of 1966 (NHPA) requires Federal agencies to take into account the effects of their undertakings on historic properties, and afford the 

Advisory Council on Historic Preservation (ACHP) a reasonable opportunity to comment. The 

historic preservation review process mandated by Section 106 is outlined in regulations issued 

by ACHP. Revised regulations, “Protection of Historic Properties” (36 CFR Part 800), became 

effective January 11, 2001.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 171

project is managed by the Nevada State Historic Preservation Office (SHPO), which is 

in the process of compiling the data from the Cultural Resource Management (CRM) 

records. The work is funded by the Preserve America project with money provided 

by the Southern Nevada Public Land Management Act (SNPLMA) project (Ronning, 

personal communication 2012b). The working group also recommended producing 

“finder’s guides” to identify locations of existing collections of materials and records 

to assist researchers in locating available information on the region’s cultural resources. 

Another suggestion was to foster interdisciplinary studies of past environments and 

encourage interaction among archeologists, paleoenvironmentalists, and those who 

analyze biological specimens from archeological contexts (Lancaster and others 2006).

More detailed discussions of needed research are found in the draft Prehistoric Context for Southern Nevada (Roberts and Ahlstrom 2012a). The Context presents research 

themes focusing on chronology, settlement patterns/systems, subsistence, technology, 

contacts and exchange, the magico-religious realm, and archeological cultures and ethnicity (Roberts and others 2012). Each topic is discussed by time period—Paleoarchaic 

and Archaic, Puebloan, and Post-Puebloan—with data requirements presented for each 

theme by time period.

In another chapter, Roberts and Ahlstrom (2012b) review various data gaps in southern 

Nevada archeology and suggest detailed data recovery and analytic methods to obtain 

the maximum information possible. They review a broad range of research questions 

including effects of climate changes, identification of non-diagnostic lithic scatters, and 

the need for greater emphasis on subsistence studies in the core Virgin Branch area, 

etc. The authors also recommend methods for survey, testing, and excavation, including backhoe trenching, where appropriate, to identify buried features. In order to locate 

deeply buried Paleo-Indian and Archaic sites during intensive surveys, examination of the 

geomorphological characteristics of the study areas before fieldwork begins to explore 

the possibility of completely buried sites is suggested (Eckerle and others 2011). They 

also suggest more extensive test excavations when there is a potential for intact buried 

deposits (Wintch 2011). Taking advantage of analytic techniques such as radiocarbon 

dating of perishables like baskets and sandals and recovering DNA samples from agave 

quids and coprolites (fossilized feces) is discussed. Such techniques can be applied to 

both recently discovered and curated items (Roberts and Ahlstrom 2012b).

The most common data recovery technique on Federal lands is still the archeological 

survey. By their nature, archeological surveys locate surface remains, although additional information may lie buried beneath the surface. Cultural resource sites may be 

missed because they are difficult to identify from the surface. Sites from the earlier time 

periods in particular, such as Paleo-Indian, Middle Archaic, and Late Archaic, can be 

difficult to find because there are fewer of them, they are generally smaller, and may 

be buried more deeply. The commonly found surface lithic scatters, often produced by 

nomadic hunting and foraging groups but also produced by more sedentary peoples, can 

be notoriously difficult to date or assign to a particular cultural group if no diagnostic 

projectile points or potsherds are present. Managers in the area must take the limitations 

of archeological surveys into consideration when planning ground-disturbing projects 

to ensure that all sites are protected and free from damage as required, or that potential 

damage is mitigated by data recovery as mandated under the Federal regulations of 

Section 1061.

Interpretive scenarios must also take into account the ongoing possibility that discovery of previously unknown resources will alter time lines and chronological schemes. 

The previously discussed recommendations made in the Draft Prehistoric Context for 

Southern Nevada (Roberts and Ahlstrom 2012a) address these issues and make recommendations to assist managers in dealing with the difficulties inherent in interpreting 

the archeological record.
172 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

References

Ahlstrom, R.V.N. (ed.). 2005. Desert oasis: the prehistory of Clark County Wetlands Park, Henderson, 

Nevada. HRA Papers in Archaeology No. 4. Las Vegas, NV: HRA, Inc., Conservation Archaeology. 428 

p. Online: http://hraarchaeology.com/reports.html [2012, Nov 14].

Ahlstrom, R.V.N.; Roberts, H. 2008. Prehistoric culture history. In: Lyon, J.D.; Roberts, H.; Ahlstrom, 

R.V.N.; Harper, C.; Eskenazi, S.; Davide, R.; Fowler, C.; von Till Warren, E. (preparers). Shared place: 

an Archaeological survey of the Ash Meadows National Wildlife Refuge, Nye County, Nevada. HRA 

Archaeological Report No. 07-24. Las Vegas, NV: HRA, Inc., Conservation Archaeology. 396 p.

Ahlstrom, R.V.N.; Roberts, H. 2012. Puebloan Period (A.D. 200-1300). In: Roberts, H.; Ahlstrom, R.V.N. 

(eds.). A Prehistoric Context for Southern Nevada (draft). Las Vegas, NV: HRA, Inc., Conservation 

Archaeology and Carson City, NV: Gnomon Inc.: 115-164.

Aikens, C.M.; Witherspoon, Y.T. 1982. Great Basin and Numic prehistory: linguistics, archaeology, and 

environment. Unpublished paper on file at: Department of Anthropological Studies, University of Nevada, Las Vegas, NV.

Alley, J.R., Jr. 1986. Tribal historical projects. In: D’Azevedo, W.L. (ed.). Great Basin. Handbook of 

North American Indians. Washington, DC: Smithsonian Institution Press: 601-607. Vol. 11.

Altschul, J.H.; Fairley, H.C. 1989. Man, models, and management: an overview of the archaeology of the 

Arizona Strip and its cultural resources. Washington, DC: U.S. Department of the Interior, Bureau of 

Land Management. 396 p.

Basgall, M.E. 2000. The structure of archaeological landscapes in the north-central Mojave Desert. In: 

Schneider, J.S.; Yohe, R.M., II; Gardner, J.K. (eds.). Archaeological passages, a Volume in honor of 

Claude Nelson Warren. Publication in Archaeology Number 1. Hemet, CA: Western Center for Archaeology and Paleontology: 123-138.

Brooks, R.H.; Larson, D.O.; Olson, K.; King, J.; King, G.; Leavitt, R.; Anderson, P. 1975. Prehistoric and 

historic research along the Navajo-McCullough transmission line right-of-way. Nevada Archaeological 

Survey Report No. 4-2-1. Las Vegas, NV: University of Nevada Press.

Church of Jesus Christ of Latter-day Saints. 1993. Church history in the fullness of time: the history of the 

Church of Jesus Christ of Latter-day Saints. Salt Lake City, UT: Church of Jesus Christ of Latter-day 

Saints, Church Educational System. 661 p.

Clark, J.W. 1984. Prehistoric settlement in the Moapa Valley. Anthropological Papers No. 19. Carson City, 

NV: Nevada State Museum. 136 p.

Cordell, L. 1997. Archaeology of the Southwest. 2nd ed. San Diego, CA: Academic Press. 522 p.

de Dufour, K. 2011. [E-mail to Carol Raish]. March 01. 1 leaf. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; 

RMRS-4853 files. 1

Eckerle, W.; Finley, J.; Hanna, R.R. 2011. Data collection strategies for assessing artifact zone spatial and 

associational integrity on sand occupational substrates. In: Seddon, M.; Roberts, H.; Ahlstrom, R.V.N. 

(eds.). Archaeology in 3D: Deciphering buried sites in the western U.S. Washington, DC: SAA Press: 

167-182.

Euler, R.C. 1966. Southern Paiute ethnohistory. Glen Canyon Series No. 28. Anthropological Papers 

No.78. Salt Lake City, UT: University of Utah Press. 187 p.

Ezzo, J.A. 1995. A class I cultural resources survey for the Southern Nevada Water Authority treatment 

and transmission facility, Clark County, Nevada. Technical Series No. 55. Tucson, AZ: Statistical Research Incorporated, SRI Press. 276 p.

Ezzo, J.A., (ed.). 1996. A class I cultural resources survey of the Moapa and Virgin Valleys, Clark County, 

Nevada. Technical Series No. 58, Tucson, AZ: Statistical Research Incorporated, SRI Press. 209 p.

Ezzo, J.A.; Majewski, T. 1995. Prehistory, protohistory, and ethnography. In: Ezzo, J.A. (ed.). A Class I 

cultural resources survey for the Southern Nevada Water Authority Treatment and Transmission Facility, Clark County, Nevada. Technical Series No. 55, Tucson, AZ: Statistical Research Incorporated, SRI 

Press: 35-74.

Ezzo, J.A.; Majewski, T. 1996. The cultural resources of the project area: prehistory, protohistory, and 

ethnography. In: Ezzo, J.A. (ed.). A Class I Cultural Resources Survey of the Moapa and Virgin Valleys, 

Clark County, Nevada. Technical Series No. 58, Tucson, AZ: Statistical Research Incorporated, SRI 

Press: 35-77.

Fowler, C.S.; Dawson, L.E. 1986. Ethnographic basketry. In: D’Azevedo, W.L. (ed.). Great Basin. handbook of North American Indians. Vol. 11. Washington, DC: Smithsonian Institution Press: 705-737.

Fowler, C.S.; Fowler, D.D. 1981. The Southern Paiute: AD 1400-1776. In: Wilcox, D.R.; Masse, W.B. 

(eds.). The Protohistoric Period in the North American Southwest. Anthropological Research Papers 

No. 24. Tempe, AZ: Arizona State University Press. 445 p. plus 10 plates.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 173

Fowler, D.D.; Madsen, D.B. 1986. Prehistory of the Southeastern area. In: D’Azevedo, W.L. (ed.). Great 

Basin. Handbook of North American Indians. Vol. 11. Washington, DC: Smithsonian Institution Press: 

173-182.

Fowler, D.D.; Madsen, D.B.; Hattori, M. 1973. Prehistory of southeastern Nevada. Reno, NV: Desert 

Research Institute Publication in the Social Sciences No. 6.

Goss, J.A. 1977. Linguistic tools for the Great Basin prehistorian. In: Fowler, D.D. (ed.). Models and 

Great Basin Prehistory: a Symposium. Publications in the Social Sciences No. 12. Reno, NV: Desert 

Research Institute: 49-70.

Grayson, D.K.1993. The desert’s past: a natural prehistory of the Great Basin. Washington, DC: Smithsonian Institution Press. 356 p.

Harrington, M.R. 1933. Gypsum Cave, Nevada. Southwest Museum Papers No. 4. Los Angeles, CA: 

Southwest Museum.

Harry, K.G. 2008. Main Ridge 2006 research project: condition assessments, test excavations, and data 

analyses for the UNLV Fall 2006 Field School. Prepared for the Lake Mead National Recreation Area. 

Las Vegas, NV: Department of Anthropology and Ethnic Studies and the Public Lands Institute, University of Nevada Las Vegas.

Harry, K.G.; Watson, J.T. 2010. The archaeology of Pueblo Grande: past and current research within Nevada’s “Lost City.” Kiva. 78(4): 403-424.

Harper, C.; Ahlstrom, R.V.N.; Eskenazi, S. 2006. Introduction. In: Harper, C. (ed.). A room with a view: 

data recovery of an early historical rockshelter site located in the Upper Moapa Valley, Clark County, 

Nevada. HRA Papers in Archaeology No. 5. Las Vegas, NV: HRA, Inc., Conservation Archaeology: 

1-14.

Hayden, I. 1930. Mesa House. Southwest Museum Papers. 4(2): 26-92.

Haynes, C.V. 1969. The earliest Americans. Science. 166: 709-715.

Inter-Tribal Council of Nevada. 1976. Nuwuvi: a Southern Paiute History. Salt Lake City, UT: University 

of Utah Printing Service. 177 p.

Jones, R.C.; Edwards, S.R. 1994. A Clovis Point on the Nevada Test Site. Nevada Archaeologist. 16: 18-23.

Kelly, I.T. 1964. Southern Paiute ethnography. Glen Canyon Series No. 21. Anthropological Papers No.69. 

Salt Lake City, UT: University of Utah.

Kelly, I.T.; Fowler, C.S. 1986. Southern Paiute. In: D’Azevedo, W.L. (ed.). Great Basin. Handbook of 

North American Indians. Vol. 11. Washington, DC: Smithsonian Institution Press: 368-397.

Lancaster, J.; Mouat, D.; Buck, P. (eds.). 2006. Information needs and state-of-the-science summary developed for the Ecosystem Health Assessment for Southern Nevada Project. Report on First Workshop—May 3-4, 2006. Reno, NV: Desert Research Institute. 31 p.

Larson, D.O.; Michaelson, J. 1990. Impacts of climatic variability and population growth on Virgin 

Branch Anasazi cultural developments. American Antiquity. 55: 227-249.

Livingston, S.D.; Nials, F.L. 1990. Archaeological and paleoenvironmental investigations in the Ash 

Meadows National Wildlife Refuge, Nye County, Nevada. Quaternary Sciences Center Technical Report No. 70, Las Vegas, NV: Desert Research Institute. 212 p.

Lyneis, M.M. 1982. Prehistoric southern Nevada study units. In: An archaeological element for the Nevada Historic Preservation Plan. Submitted to Nevada Division of Historic Preservation and Archaeology, Carson City, Nevada. Las Vegas, NV: University of Nevada: 161-206.

Lyneis, M.M. 1986. Residual archaeology of the Main Ridge Locality, Pueblo Grande de Nevada. Western 

Anasazi Reports. 3: 183-259.

Lyneis, M.M. 1992a. Social complexity among the Virgin Anasazi. Kiva. 57: 197-212.

Lyneis, M.M. 1992b. The Main Ridge Community at Lost City: Virgin Anasazi architecture, ceramics, and 

burials. University of Utah Anthropological Papers No. 117, Salt Lake City, UT: University of Utah. 

96 p.

Lyneis, M.M. 1994. East and onto the plateaus? An archaeological examination of the Numic expansion 

in Southern Nevada, Northern Arizona, and Southern Utah. In: Madsen, D.B.; Rhode, D. (eds.). Across 

the West: Human population movement and the expansion of the Numa. Salt Lake City, UT: University 

of Utah Press: 141-149.

Lyneis, M.M. 1995. The Virgin Anasazi, far western Puebloans. Journal of World Prehistory. 9 (2): 199-

241.

Lyneis, M.M. 1996. Pueblo II-Pueblo III change in southwestern Utah, the Arizona Strip, and southern 

Nevada. In: Adler, M.A. (ed.). The Prehistoric Pueblo World, AD 1150-1350. Tucson, AZ: University 

of Arizona Press: 11-28.

Lyneis, M.M. 2011. Ceramics. In: Roberts, H.; Lyon, J. (eds.). Archaeological Excavations at the Corn 

Creek National Register Site, Desert National Wildlife Refuge, Clark County, Nevada. Archaeological 

Report No. 08-22. Las Vegas, NV: HRA, Inc. Conservation Archaeology: 156-184.
174 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Lyneis, M.M. 2012. Appendix D. In: Roberts, H.; Ahlstrom, R.V.N. (eds.). A prehistoric context for southern Nevada (draft). Las Vegas, NV: HRA, Inc., Conservation Archaeology and Carson City, NV: Gnomon Inc.: D 1-20.

Madsen, D.B.1986. Prehistoric ceramics. In: D’Azevedo, W.L. (ed.). Great Basin. Handbook of North 

American Indians. Vol. 11. Washington, DC: Smithsonian Institution Press: 206-214.

Myhrer, K. 1986. Evidence for an increasing dependence on agriculture during the Virgin Anasazi occupation in the Moapa Valley. Las Vegas, NV: University of Nevada. Thesis.

Myhrer, K. 1989. Basketmaker and Puebloan occupation at the Steve Perkins site, Moapa Valley, southern 

Nevada. Unpublished draft report on file at: Museum of Natural History, University of Nevada, Las 

Vegas, NV.

Roberts, H.; Ahlstrom, R.V.N. 2007. Native Americans in southern Nevada before 1492. In: Roberts, 

H.; von Till Warren, E.; Eskenazi, S. (preparers). Coyote named this place Pakonapanti: Corn Creek 

National Register Archaeological District, Desert National Wildlife Refuge, Clark County, Nevada. Las 

Vegas, NV: HRA, Inc., Conservation Archaeology. 27-47. Online: http://hraarchaeology.com/reports.

html [2012, Nov 14].

Roberts, H.; Ahlstrom, R.V.N. (eds.). 2012a. A prehistoric context for southern Nevada (draft). Las Vegas, 

NV: HRA, Inc. Conservation Archaeology and Carson City, NV: Gnomon Inc. 364 p.

Roberts, H.; Ahlstrom, R.V.N. 2012b. Recommendations. In: Roberts, H.; Ahlstrom, R.V.N. (eds.). A prehistoric context for southern Nevada (draft). Las Vegas, NV: HRA, Inc., Conservation Archaeology and 

Carson City, NV: Gnomon Inc.: 293-300.

Roberts, H.; Ahlstrom, R.V.N.; Roth, B. 2012. Prehistoric research themes for southern Nevada. In: Roberts, H.; Ahlstrom, R.V.N. (eds.). A prehistoric context for southern Nevada (draft). Las Vegas, NV: 

HRA, Inc., Conservation Archaeology and Carson City, NV: Gnomon Inc.: 277-292.

Roberts, H.; von Till Warren, E.; Eskenazi, S. (preparers). 2007. Coyote named this place Pakonapanti: 

Corn Creek National Register Archaeological District, Desert National Wildlife Refuge, Clark County, 

Nevada. Las Vegas, NV: HRA, Inc., Conservation Archaeology. 187 p. Online: http://hraarchaeology.

com/reports.html [2012, Nov 14].

Ronning, C. 2012a. Personal communication. [Comment on manuscript]. July 9. Manuscript on file at: 

U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 files.

Ronning. C. 2012b. SNAP review team. May 9. On file at: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 files.

Roth, B. 1993. A Clovis Point from east central Arizona. Kiva. 58: 495-499.

Roth, B. 2012. Paleoindian and Archaic Periods. In: Roberts, H.; Ahlstrom, R.V.N. (eds.). A prehistoric 

context for southern Nevada (draft). Las Vegas, NV: HRA, Inc., Conservation Archaeology and Carson 

City, NV: Gnomon Inc. 364 p.

Ruppert, D.E. 1976. Lake Mead National Recreation Area: an ethnographic overview. Tucson, AZ: U.S. 

Department of the Interior, National Park Service, Western Archeological Center. 90 p.

Seymour, G.R. 1997. A reevaluation of Lower Colorado Buff Ware ceramics; redefining the Patayan in 

southern Nevada. Las Vegas, NV: University of Nevada. Thesis.

Shutler, R., Jr. 1961. Lost City: Pueblo Grande de Nevada. Anthropological Papers No. 5. Carson City, 

NV: Nevada State Museum, Department of Anthropology. 85 p.

Sterner, M.A.; Ezzo, J.A. 1996. Religion, ranching, and railroads: the history of the Muddy and Virgin 

River Valleys. In: Ezzo, J.A. (ed.). A Class I cultural resources survey of the Moapa and Virgin Valleys, 

Clark County, Nevada. Technical Series No. 58. Boulder City, NV: Statistical Research Incorporated, 

SRI Press: 79-130.

Steward, J.H. 1938. Basin-plateau aboriginal sociopolitical groups. Bureau of American Ethnology Bulletin No. 120, Washington, DC: Smithsonian Institution Press. 355 p.

Stewart, O.C. 1942. Culture element distributions, XVIII: Ute—Southern Paiute. University of California 

Anthropological Records. 6(4): 231-356.

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/

SNAP-S-R-Strategy-2009r.pdf. [2011, April 6].

Warren, C.N.; Crabtree, R.H. 1986. Prehistory of the Southwestern area. In: D’Azevedo, W.L. (ed.). Great 

Basin. Handbook of North American Indians. Vol.11.Washington, DC: Smithsonian Institution Press: 

183-193.

Wintch, K.L. 2011. The importance of testing to cultural resource management. In: Seddon, M.; Roberts, 

H.; Ahlstrom, R.V.N. (eds.). Archaeology in 3D: Deciphering buried sites in the western U.S. Washington, DC: SAA Press: 183-194.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 175

Chapter 9

Preserving Heritage Resources Through 

Responsible Use of Southern Nevada’s Lands

Carol B. Raish

Introduction

Southern Nevada’s cultural resources (heritage resources) include archeological 

remains, sacred sites, historic sites, and cultural landscapes of significance to Native 

Americans and many other groups. Locating, maintaining, and protecting these special 

places are part of the mandate of Nevada’s Federal and state agencies. This chapter addresses Sub-goal 2.2 in the SNAP Science Research Strategy, which is to preserve these 

resources through responsible use of southern Nevada’s lands (table 1.3; Turner and 

others 2009). It explores non-destructive means of identifying, recording, and protecting cultural resources. Cultural resources at risk, risk factors, and needed measures to 

protect them are discussed, with a focus on non-destructive preservation and protection 

measures. Selected methods of non-destructive identification, recording, and analysis 

of sub-surface remains are also reviewed. 

Cultural Resources at Risk

Nevada is one of the fastest growing states in the country. According to the 2010 U.S. 

Census, the population grew by 35 percent since 2000 and by 66 percent the previous 

decade. Nevada is the only state that has maintained a growth rate of 25 percent or greater 

for the last three decades (www.census.gov/prod/cen2010/briefs/c2010br-01.pdf). In 

southern Nevada, the population of Clark County (1,951,269) grew by 42 percent from 

2000 to 2010. In-migration from other states has contributed strongly to these growth 

patterns, with newcomers often having little knowledge of the role and importance of 

the state’s history. These population growth trends have considerable influence on how 

the state preserves its past (NVSHPO 2004, 2012).

Agency reports identify both natural and human-caused threats to heritage sites (USDI 

BLM 2000: 5-7):

	 •	 Increasing visitation,

	 •	 Increasing use of public lands for permitted projects,

	 •	 Insufficient staffing and funding for cultural resource programs and law

enforcement,

	 •	 Looting and vandalism, and

	 •	 Urban sprawl and development.

Urban growth and development in and surrounding southern Nevada cities impact the 

heritage resources in the area. Development can lead to resource destruction as construction increases and homes and businesses are built on previously undeveloped lands. In 

addition, urban growth has increased recreation pressure on public lands. According to 

the Nevada Comprehensive Preservation Plan (NCPP) (NVSHPO 2004, 2012), increased 
176 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

pressure on resources from urban growth, recreation, and the use of all-terrain vehicles 

(ATVs) has resulted in increased vandalism and illegal looting (collecting artifacts and/

or excavating on an archeological site without a permit) on previously remote and inaccessible sites.

As one senior Bureau of Land Management (BLM) official noted: “BLM has complete 

regulatory ability to control the impacts on cultural resources of its permit applicants; 

however the greatest threat to cultural resources today is coming from the rapid increase 

in recreational access, with essentially no regulatory control, or enforcement capacity 

in place to deal with growing impacts” (Jarvis 2006: 7). Another official indicated that 

increasing visitation to public lands is resulting in both intentional and unintentional 

damage from collection, vandalism, and surface disturbance. “Remote areas, once protected by their distance from populated areas, are now within easy reach of the hardy 

and well-equipped hiker, off-highway vehicle user, and urban and suburban resident” 

(Jarvis 2006: 27).

Adding to the problem is the fact that law enforcement officers and cultural resource 

staff are unable to monitor activity on all the archeological and historical sites across 

the vast landholdings of the Federal agencies. A report describing Federal agency site 

protection efforts (Swain 2007) describes the approximate ratio of acres per agency law 

enforcement officer. The figures are for the BLM, U.S. Forest Service (FS), National 

Park Service (NPS), and U.S. Fish and Wildlife Service (FWS). While this ratio varies within subunits of the agencies, it serves to indicate the degree of police presence 

on the public lands. Each of the four agencies employs professional cultural resources 

management staff and Law Enforcement Officers (LEOs). These professionals have 

a wide range of tasks, which ultimately result in a relatively small percentage of time 

in the field visiting or monitoring archeological sites. The BLM and FS manage about 

455,000,000 acres (184,131,967.22 hectares) between them but have only one LEO 

per 1,000,000 acres (404,685.64 hectares). The NPS manages ca. 84,000,000 acres 

(33,993,593.95 hectares) with one LEO for every 56,000 acres (22,662.40 hectares) 

and the FWS has 93,000,000 acres (37,635,764.73 hectares) with one LEO for every 

104,000 acres (42,087.31 hectares; Swain 2007). 

Although the exact level of enforcement that would be needed to reduce looting 

and vandalism across the Federal landscape is uncertain, a project from Joshua Tree 

National Park, located in the Mojave Desert to the east of Los Angeles, sheds light 

on the topic. During 1993, the park received special archeological protection funding 

for the systematic monitoring of cultural sites. A long-term volunteer with extensive 

knowledge of the park and its archeological sites was hired to conduct the monitoring. 

The site monitor spent each workday visiting archeological sites and documenting their 

condition. He visited sites near front country campgrounds as well as sites 5 or more 

miles from the nearest road. After 1993, the Park received no additional funds for site 

monitoring (Swain 2007).

From 1985 to 2005, excluding 1992 and 1993, an average of 9.6 looting incidents 

per year was documented. By contrast, in 1992 and 1993, the average number of 

documented incidents per year was 101. Over 200 Archaeological Resources Protection Act (ARPA) violations were documented during 1993 alone. The data from 

Joshua Tree National Park tend to show that only a very small percentage of the 

looting activity on the public lands is actually discovered and documented during 

any given year (Swain 2007). Intensive monitoring can lead to a much higher discovery rate, with presumed positive impacts for site protection. The visibility of 

regular monitoring and LEO presence also can serve as a deterrent to looting and 

vandalism (McAllister, personal communication 2012).
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“Threats to archaeological and historical sites (are not) confined to looting and 

vandalism, as recreational activities, urban sprawl, overuse and natural erosion are 

increasingly taking their toll on our Nation’s irreplaceable treasures” (USDI BLM 

2000: 4). Historic structures, both in the cores of urban areas and in rural areas with 

severely declining populations are also at risk from destruction by development and lack 

of funding for maintenance and restoration. Some structures also have been destroyed 

by arson (NVSHPO 2004, 2012).

Cultural Resource Protection 

Measures and Organizations

Federal agencies in southern Nevada use and recommend a number of measures to 

assist in protecting heritage resources (Jarvis 2006: 27-28). Chief among them are the 

following:

	 •	 Public education and outreach programs.

	 •	 Cultural resource site monitoring.

	 •	 Law enforcement for cultural resources.

Public Education and Outreach

Public education and outreach efforts range from preparing sites and structures to 

receive visitors with trails, signage, and other protection measures such as fencing, to 

active public involvement programs like Passport in Time operated by the FS (USDA 

FS 2011). Rapidly increasing recreational access requires public education concerning the importance and fragility of archeological and historic sites. Cultural resource 

professionals express enthusiasm for the positive effects of their education programs 

on recreational users, believing that education will reduce potential negative impacts 

of increasing visitation to public lands. Many feel most of the inadvertent damage to 

resources could be averted by various current education programs. There is the belief 

that when the public is made aware of the fragility and uniqueness of these resources, 

they will be careful not to damage them (Jarvis 2006). Some of the most successful 

programs involve public participation, like Passport in Time, but they reach a more 

limited audience. Brochures and information kiosks can also be effective teaching tools 

by reaching a wider audience. They are especially effective when they are attractive, 

current, and appropriately placed near the resource in question.

BLM uses two non-profit partners—Tread Lightly, Inc. and the Leave No Trace Center 

for Outdoor Ethics, Inc.—to educate visitors concerning proper treatment of cultural 

resources, as well as the public lands in general (Jarvis 2006). However, many southern 

Nevada BLM managers think that there is insufficient funding to support education 

programs and direct protections like closing roads and trails, building enclosures and 

fences with gates, and other physical barriers to prevent site damage (Jarvis 2006).

Several agencies have long-running, successful, national public involvement programs. These include Passport in Time Program (USDA FS 2011), Adventures in the 

Past, which includes Project Archaeology (USDI BLM 2011), and a relatively new 

Geotourism Partnership project (USDI FWS 2008). The National Park Service (NPS) 

has a long history of both cultural and environmental education efforts. As examples of 

these efforts, the U.S. Forest Service, Passport in Time Program (PIT) pairs professional 

agency archeologists and historians with volunteers on national forests throughout the 

country. PIT projects include archeological survey, excavation, rock art recording and 

restoration, archival research, oral history gathering, and many others (USDA FS 2011).
178 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Project Archaeology, a part of Adventures in the Past, is a national education program 

for teachers of upper elementary and mid-school students that trains the teachers and 

provides curriculum materials for teaching the students to value and care for their archeological and historic heritage (USDI BLM 2011). These education programs attract 

a substantial number of volunteers and are very favorably received. Several agencies 

also have participated in the Preserve America Grant program administered by the NPS 

(Advisory Council on Historic Preservation), which provides matching grants to support preservation efforts through heritage tourism, education, and historic preservation 

planning. However, the Preserve America Grants were not funded for 2011 and funding 

for 2012 is uncertain (USDI NPS 2011a).

A Nevada-specific program, Preserve Nevada, is a non-profit organization dedicated 

to preservation of the state’s cultural, historic, and archeological heritage. The Board 

of Directors is selected from different parts of the state and is designed to bring the 

perspective of a committed and experienced group of preservationists to the task of 

meeting the special needs of Nevada’s resources. Preserve Nevada works with the Public 

History program at the University of Nevada, Las Vegas, and provides the opportunity 

for graduate students to gain experience and training by working closely with the Board 

of Directors on many of the organization’s projects. The students meet with National 

Trust leaders, represent the organization at a variety of functions, and work with both 

state and local governments on planning and development issues. This work provides 

the students with experience and contacts for their future careers in preservation. The 

Preserve Nevada project builds bridges between the community and the university, 

between education and advocacy, and between methods and practices, training a new 

generation of preservation professionals (NVSHPO 2011).

It should be noted that the Nevada Comprehensive Preservation Plan (NCPP) (NVSHPO 

2004) also recommends the use of college interns to assist the Nevada State Historic 

Preservation Office (NVSHPO) and Federal staffs in archeological, architectural, and 

historic surveys and in preparing National Register nominations.

Other examples of creative outreach and education programs come from Lake Mead 

National Recreation Area, which has an active education and interpretive program featuring 

educational programs, field trips, and volunteer experiences. Education programs include 

not only cultural resource activities but also activities from other science programs for 

students and teachers. There is a Hispanic outreach program and a Hispanic community 

partnership program involving all the SNAP agencies, such as the BLM, FS, FWS, and, 

of course, NPS. There are also Professional Development Education opportunities that 

have been developed by the SNAP Education Staff for teachers. Some specific examples 

of historic and cultural programs for students include “Hiking Through History” focusing on Hoover Dam and the U.S. Government Railroad and “Puzzle Pieces of the Past” 

focusing on archeological sites and artifacts (Rowland, personal communication 2012). 

The NPS Submerged Resources Center in Denver has worked at Lake Mead in cooperation with the Woods Hole Oceanographic Institution filming underwater archeological 

sites in the lake. These include an airplane that crashed into the lake and infrastructure 

related to the construction of Hoover Dam. These are used in a program to teach children 

not only about the submerged archeology of the lake but also about other issues related 

to the lake such as water monitoring and problems with the invasive quagga mussel 

(Seeb, personal communication 2012).

Cultural Resource Site Monitoring

Monitoring the condition of heritage resources is an important part of agency responsibilities to their lands. Unfortunately, there is rarely sufficient staff to undertake 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 179

comprehensive site monitoring on a realistic scale and time frame, as mentioned previously (Swain 2007); volunteers are often used to meet this need. In its comprehensive 

plan, the NVSHPO recommended establishment of a site stewardship program to accommodate the public’s desire to become involved in historic preservation activities and 

to take into consideration the small size of state and Federal heritage and preservation 

staffs and budgets (NVSHPO 2004). 

In 2004, the Southern Nevada Agency Partnership (SNAP) Interagency Cultural 

Site Stewardship Team created the SNAP Cultural Site Stewardship Program (CSSP). 

Partners in the SNAP CSSP include NPS, BLM, FWS, FS, and U.S. Bureau of Reclamation (USBR), Nevada Department of Cultural Affairs (NDCA), Lost City Museum 

(LCM), and Nevada State Historic Preservation Office. The program is managed under a 

cooperative agreement with the University of Nevada-Las Vegas, Public Lands Institute 

(UNLV-PLI). The UNLV-PLI Program Manager provides a variety of services including 

recruitment of volunteer site stewards, standardized training, reporting of monitoring 

results to the appropriate Federal agency, and public outreach. The program is composed 

of volunteers who serve as site stewards to monitor at-risk sites for natural or man-made 

damage, which is reported to the responsible land manager (USDI NPS 2007).

The volunteer site stewards participate in training sessions and monitor their assigned 

sites at least four times per year. To date, over 540 volunteer site stewards have been 

trained. They have donated over 16,100 volunteer hours and driven over 212,000 miles. 

Stewards have reported over 645 significant impacts that have resulted in criminal investigations, and have informed management actions including closing of unapproved 

roads, development of a Road Designation Plan, and removal of graffiti from rock art 

sites. The program has been very successful and has received several awards including 

the 2007 U.S. Department of the Interior Cooperative Conservation Award, Certificate 

of Commendation from Senator Harry Reid, and the Preserve America Steward Award 

from First Lady Michelle Obama in 2010 (Phillips 2011).

Effective site monitoring should include frequent site inspections that are apparent 

to site visitors and are undertaken by well-trained and enthusiastic volunteers, who are 

adequately supervised by agency staff (Livingston and others 2005). As discussed in 

the Sloan Canyon Plan (Livingston and others 2005), since agencies depend upon volunteers to accomplish the monitoring, they are faced with the problem of administering 

volunteers who have few sanctions to correct inappropriate behavior. The vast majority 

do an outstanding job, while a few do not. The plan also points out that site monitors 

themselves should be monitored by agency staff because stewardship programs can 

provide a good cover for looters and a place to discover previously unknown information 

on site locations. Despite these cautions, the majority of site stewards do an enthusiastic and valuable job of extending the “eyes and ears” of Federal staff to protect fragile 

heritage resources.

Law Enforcement for Cultural Resources

Federal agency law enforcement plays an important role in protecting archeological 

and historic remains from looting and vandalism. However, Federal heritage resource 

professionals believe that there are far too few agency LEOs (Swain 2007; USDI FWS 

2008). Agencies work with other law enforcement partners, such as other Federal enforcement agencies, state and local police, and sheriff’s departments, to augment their 

numbers, although many local police and sheriff’s departments are not trained in ARPA 

enforcement. In general, most law enforcement personnel from the Federal agencies 

have basic ARPA training (McGaha, personal communication 2012), as recommended 

by Swain (2007). 
180 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

There have been various successful ARPA prosecutions in recent years that have 

increased awareness of the problem of looting on archeological sites. BLM enforcement personnel have had some highly publicized and successful enforcement actions 

taken against organized thieves stealing archeological artifacts from public lands (Jarvis 

2006: 28). The USFS has successfully prosecuted an ARPA case resulting in replacement 

of a petroglyph to its original location. The NPS had a successful prosecution of a man 

sentenced to time in Federal prison and ordered to pay restitution for defacing petroglyphs 

with paintballs in the Grapevine Canyon area of Lake Mead National Recreation Area. 

“This sentence comes as a result of the hard work of park rangers, special agents of the 

National Park Service Investigative Services Bureau and the U.S. Attorney’s Office. We 

are pleased with the result,” said Bill Dickinson, superintendent of Lake Mead National 

Recreation Area. “What’s important about this case is that it started with a visitor calling 

911 to report the illegal activity” (USDI NPS 2011b). Despite such successes, there are 

still too few law enforcement officers to protect the cultural resources on the extensive 

public lands of the state (USDI FWS 2008). As discussed in a BLM report on Cultural 

Resources on Public Lands (Jarvis 2006: 28): “For every criminal caught in an ARPA 

(Archaeological Resources Protection Act) violation, it is believed that many more 

violations go un-discovered, much less un-prosecuted.”

In addition, as public access and criminal activity increase on public land, LEOs 

are spread even more thinly. Law enforcement priorities are now being focused on 

drug interdiction, homeland security issues, and control of undocumented immigrants 

(Jarvis 2006). To assist in closing the gap, Federal land managers have not only turned 

to volunteers but some are developing and using remote protection technology such 

as concealed video surveillance cameras, especially in remote areas that appear to be 

secluded and may lead thieves to feel that they will not be detected (Livingston and 

others 2005; USDI FWS 2008). 

Non-Destructive Techniques for Identifying, Recording, 

and Analyzing Archeological and Historic Remains

Standard non-collection archeological survey remains the preeminent technique used 

to identify surface remains and features. These techniques are well documented and 

will not be reviewed in this discussion. The focus here will be on select geophysical 

surveying systems that non-invasively and non-destructively map subsurface features. 

The following techniques are presented:

	 •	 Ground penetrating radar (GPR)

	 •	 Magnetometry

	 •	 Soil resistivity

These techniques are useful where excavation is undesirable, too costly, or otherwise 

not possible. They can assist managers in determining which areas to avoid during 

construction or other land-disturbing activities and which areas may require additional 

testing or excavation. Non-invasive methods do not destroy the archeological record as 

it is investigated, but they do require special equipment and training and can be costly 

(Archeology Mapping: http://www.archeologymapping.com 6-2-2011; Shott 1996). In 

addition, the land coverage rate is low owing to the nature of the methods and the time 

needed to implement them. Thus, they are mainly practical at small scales and are not 

cost-effective in replacing standard archeological survey techniques. They are better for 

defining features within known archeological sites than conducting large-scale surveys. 

Natural variations in soil texture, moisture, and soil inclusions affect the efficacy and 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 181

reliability of these techniques. Because they record archeological features as anomalies 

against the background soil, they must be recalibrated for each set of local soil conditions (Bevan 1996; Shott 1996). 

Ground Penetrating Radar (GPR)

GPR is a geophysical method that uses radar pulses to image the subsurface, generating cross-sectional views of underground features. GPR is able to detect a wider variety 

of buried materials than other geophysical instruments. It can detect metal, wood, stone, 

brick, and air-filled voids and is suitable for locating lenses of debris as well as refilled 

pits and ditches (Bevan 1996). As such, the technique has been used to locate graves, 

occupation surfaces, walls, floors, and foundations. The technique works best in sandy, 

weakly stratified soil or soil with horizontal strata. If the soil is clayey or is saline, the 

depth of penetration is so low or shallow that the technique is not useful. The radar 

antenna operates best when close to the ground, so areas with considerable brush or 

boulders are more difficult to survey (Bevan 1996).

As an example of GPR use, a study was conducted in southern Utah to examine the 

buried remains of religious/ceremonial architecture in one valley (Conyers 2009). The 

investigator thought that large circular depressions might be the remains of large kivas 

(ceremonial structures), indicating a connection to the influential Chacoan area to the 

south. The GPR analysis of the features showed that they were small, family-sized kivas 

with associated roomblocks, which did not support strong connections to Chaco Canyon. 

The study’s author states that the GPR analysis allowed placement of the structures within 

the landscape context of their local valley, facilitating the examination of prehistoric 

social context and inter-regional interaction without excavation (Conyers 2009).

Magnetometry

Magnetic surveying, or magnetometry, is one of the most popular of the geophysical 

methods used for rapid, non-destructive assessment of subsurface features. Magnetometry 

provides archeological information because various human activities can alter the local 

magnetic content of the soil. Every type of material has singular magnetic properties, 

even those that are not commonly viewed as magnetic. Distinct subsurface materials 

can cause local disturbances in the earth’s magnetic field, which are then detectable with 

magnetometers. The main limitation of the technique is that subtle features of interest 

may be obscured by highly magnetic geological or modern materials, such as iron. The 

technique is not affected by soil moisture or temperature. The only climatic problem is 

the decreased performance of batteries in very cold weather (Weymouth 1996).

Magnetic surveys are especially useful for locating ferrous materials; fired materials 

such as brick, roof tiles, kilns, hearths, and burned daub; middens, pits, trenches, activity 

areas, and graves. The technique also is able to locate structural features including walls, 

floor surfaces, and foundations (Archeology Mapping: http://www.archeologymapping.

com 6-2-2011).

A large-scale magnetometer survey in Germany mapped subsurface features dating 

to the period from 7500-6900 BP (5550-4950 BC) representing longhouses (Posselt 

2002). The maps produced from the survey showed considerable fine detail including 

postholes and small ditches related to the wood and plaster walls. This type of detail can 

be used to target future excavations or reduce the need for and/or the extent of excavations (Posselt 2002).
182 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Soil Resistivity

Soil resistivity survey, or resistivity survey, has grown in use since it was first introduced for archeological work in the mid-1940s in England. The technique can be used 

to locate compacted surfaces; graves; trails and pathways; structural features such as 

walls, floor surfaces, and foundations; and differences in soil compaction (Archeology 

Mapping: http://www.archeologymapping.com 6-2-2011; Gaffney 1996). Problems with 

the technique include the fact that archeological features may be masked by later activity 

at the site and some agricultural activities such as plowing may increase “soil noise” 

to the point that anomalies produced by buried features are not recognized (Gaffney 

1996).

In most systems, metal probes (electrodes) are inserted into the ground to obtain 

readings of local electrical resistance. Most systems use four probes mounted on a rigid 

frame. Soil resistance is affected by the presence of subsurface features that are higher 

or lower in resistivity than the surrounding soil. The patterns of soil resistance are 

recorded, plotted, and interpreted. Information from resistivity survey is often used to 

complement other geophysical methods, such as magnetometer surveys. Areas of beach 

on Rapa Nui (Easter Island) were successfully examined using this type of combined 

technique to locate subsurface features associated with the island’s large ceremonial 

platform and statues (Larson and others 2003).

Knowledge Gaps and Management Implications

Southern Nevada’s heritage resources are at risk from a variety of factors including 

large-scale urban development and sprawl, as well as increased recreation use and access to previously remote, undisturbed areas. The Federal agencies that manage these 

vast acreages and irreplaceable resources remain understaffed and underfunded resulting in substantial management challenges. Nonetheless, they have implemented public 

education and outreach projects, volunteer site monitoring efforts, and law enforcement 

programs in attempts to protect the areas at risk. Continued research is needed to assess 

the effectiveness of these programs and develop additional means of cultural resource 

protection that can be implemented with limited funding (Lancaster and others 2006, 

2007).

When implementing projects, managers must address issues associated with protection and preservation of known sites as well as identifying and protecting any newly 

discovered sites. There are significant knowledge gaps relating to southern Nevada’s 

past, as derived from the archeological record. Only 783,756 acres (317,174.8 hectares), 

or 7 percent of the lands under consideration, have been surveyed for archeological 

resources (fig.8.1). Thus, a large portion of the area has received no survey coverage.

Because of the sparse nature of archeological survey coverage, basic inventories 

of cultural resources are needed. In particular, inventories that are not associated with 

planned development projects are desirable to expand the acres of surveyed lands and 

address gaps in coverage. Complete coverage of the public lands in the study area is not 

a realistic goal owing to the cost involved and because SNAP offices manage over 7 million acres (2,832,799 hectares), a huge area to meet the “complete survey” expectation. 

That would be over 500 man-years to survey with 30-meter (32.8 yard) transects at 2 

miles (3.22 kilometers) per hour (Ronning, personal communication 2012). In addition, 

cultural resource recording standards, as well as the sites themselves, will continue to 

change over time. A more realistic goal for regional-scale inventory would be to expand and improve the sample of lands that have been examined and of sites that have 

been located and recorded. Because cultural resources represent finite, non-renewable 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 183

resources that must be protected for the future, an important goal of inventory is to 

provide baseline information for measuring changes in the condition of sites through 

time (Lancaster and others 2006, 2007).

By its nature, archeological survey locates surface remains, while additional information may lie buried beneath the surface. The geophysical surveying systems discussed in 

this chapter may prove useful in augmenting cultural resource information and assisting 

managers in determining which areas to avoid during construction or other land-disturbing 

activities and which areas may require additional testing or excavation. However, these 

methods are limited in applicability and do not replace standard archeological surveys.

A major recommendation from the working group on the Information and State-ofthe-Science Summary developed for the Ecosystem Health Assessment of Southern 

Nevada Project was to prepare a new Historic Context for the region to structure and 

promote research important to the agencies (Lancaster and others 2006). Such a context 

has been prepared in draft form (Roberts and Ahlstrom 2012).

References

Bevan, B.W. 1996. Ground penetrating radar. In: Fagan, B.M. (ed.). The Oxford Companion to Archaeology. New York: Oxford University Press: 704-705.

Conyers, L.B. 2009. Ground-penetrating radar for landscape archaeology: method and applications. In: 

Campana, S.; Piro S. (eds.). Seeing the unseen. London: Taylor and Francis Group: 245-255.

Gaffney, C.F. 1996. Soil resistivity survey. In: Fagan, B.M. (ed.). The Oxford companion to archaeology. 

New York: Oxford University Press: 703-704.

Jarvis, T.D. 2006. Cultural resources on the Bureau of Land Management public lands: an assessment and 

needs analysis. Washington, DC: National Trust for Historic Preservation. 36 p.

Lancaster, J.; Mouat, D.; Buck, P. (eds.). 2006. Information needs and state-of-the-science summary developed for the Ecosystem Health Assessment for Southern Nevada Project. Report on first workshop—

May 3-4, 2006. Reno, NV: Desert Research Institute. 31 p.

Lancaster, J.; Mouat, D.; Buck, P., (eds.). 2007. Ecological health assessment in southern Nevada. Final 

Report –FAA010017 (GBCESU). Reno, NV: Desert Research Institute. Appendix 3:3-35-38.

Larson, D.O.; Lipo, C.P.; Ambos, E.L. 2003. Application of advanced geophysical methods and engineering principles in an emerging scientific archaeology. First Break. 21: 51-62.

Livingston, S.; Quinlan, A.R.; Bengston, G. 2005. The Sloan Canyon National Conservation Area Cultural 

Resources Management Plan. Carson City, NV: Summit Envirosolutions. 35 p.

McAllister, M. 2012. Personal communication. [E-mail to Carol Raish]. January 27. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, 

Albuquerque, NM; RMRS-4853 files. 

McGaha, T. 2012. Personal communication. April 12. On file at: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 

files. 

Nevada State Historical Preservation Office (NVSHPO). 2004. Nevada Comprehensive Preservation Plan 

2003. Online: http://nvshpo.org/dmdocuments/HPPlan03.pdf [2012, Nov 15]. 

Nevada State Historic Preservation Office (NVSHPO). 2011. Preserve Nevada. Online: http://preservenevada.unlv.edu/ [2012, Nov 15].

Nevada State Historic Preservation Office (NVSHPO). 2012. Nevada Comprehensive Preservation Plan 

2012. Online: http://nvshpo.org/dmdocuments/Plan_2013.pdf [2012, Nov 15].

Phillips, G. 2011. Footnotes on cultural site stewardship in Southern Nevada. Paper presented at the 2011 

Three Corners Conference. Las Vegas, NV: University of Nevada, Las Vegas.

Posselt, M. 2002. Auxilliary method or sophisticated field method? Thoughts on the use of large scale 

magnetometer surveying in archaeology [Abstract #6541]. In: European Geophysical Society XXVII 

General Assembly; April 21-26, 2002; Nice, France.

Roberts, H.; Ahlstrom, R.V.N. (eds.). 2012. A prehistoric context for southern Nevada (draft). Las Vegas, 

NV: HRA, Inc., Conservation Archaeology and Carson City, NV: Gnomon Inc. 364 p.

Ronning, C. 2012. Personal communication. [Comment on manuscript]. July 9. Manuscript on file at: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 files. 
184 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Rowland, A. 2012. Personal communication. [E-mail to Carol Raish]. April 13. E-mail and handouts on 

file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque 

Laboratory, Albuquerque, NM; RMRS-4853 files. 

Seeb, S. 2012. Personal communication. April 12. On file at: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 

files. 

Shott, M.J. 1996. Introduction. In: Fagan, B.M. (ed.). The Oxford companion to archaeology. New York: 

Oxford University Press: 702-703.

Swain, T. 2007. Cultural resource damage on the public lands: what the statistics show. In: Hutt, S.;Tarler, 

D. (eds.). Yearbook of cultural property law 2007. Walnut Creek, CA: Left Coast Press: 201-220.

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/

SNAP-S-R-Strategy-2009r.pdf. [2011, April 6]. 

USDA Forest Service. 2011. Welcome to Passport in Time! U.S. Department of Agriculture, Forest Service. Online: http://www.passportintime.com/about.html [2012, Nov 15].

USDI Bureau of Land Management. 2000. Strategic paper on cultural resources at risk. U.S. Department of 

the Interior, Bureau of Land Management. 17 p. Online: www.blm.gov/heritage/docum/00atriskpaper3.

pdf [2012, Nov 15].

USDI Bureau of Land Management. 2011. Heritage education. U.S Department of the Interior, Bureau 

of Land Management. Online: http://www.blm.gov/wo/st/en/res/Education_in_BLM/Learning_Landscapes/For_Teachers/Heritage_Education.html [2012, Nov 15].

USDI Fish and Wildlife Service. 2008. Protecting habitat and history: a 2008 progress report responding 

to Section 3(c) of Executive Order 13287, “Preserve America.” U.S Department of the Interior, Fish 

and Wildlife Service. 24 p. 

USDI National Park Service. 2007. Southern Nevada Agency Partnership, Cultural Site Stewardship Program—Program Expansion and Steward Retention, Great Basin Cooperative Ecosystem Studies Unit 

Task Agreement No. J8R07070002. On file at: U.S. Department of the Interior, National Park Service, 

Lake Mead National Recreation Area, Boulder City, NV.

USDI National Park Service. 2011a. Preserve America grant program. U.S. Department of the Interior, National Park Service, Online: http://www.nps.gov/history/hps/hpg/preserveamerica/index.htm 

[2012, Nov 15].

USDI National Park Service. 2011b. Lake Mead National Recreation Area News Release: Arizona man 

sentenced to 15 months in prison for defacing Lake Mead National Recreation Area Petroglyphs. On 

file at: U.S. Department of Interior, National Park Service, Lake Mead National Recreation Area, Boulder City, NV. 

Weymouth, J.W. 1996. Magnetometer survey. In: Fagan, B.M. (ed.). The Oxford companion to archaeology. New York: Oxford University Press: 704.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 185

Chapter 10

Recreation Use on Federal Lands in 

Southern Nevada

Alice M. McSweeney

Introduction

Providing for appropriate, diverse, and high quality recreational use of southern Nevada’s lands and ensuring responsible visitor use is an ongoing challenge for the Federal 

agencies that manage the majority of the area (fig. 1.1). Over 87 percent (61,548,000 

acres out of Nevada’s 70,275,000) of Nevada’s lands are administered by the Federal 

government, which is the highest percentage in the nation (DeLoney 2004). Some of 

the largest values are for the counties of southern Nevada. The amount of Federal land 

in Clark, Lincoln, and Nye Counties estimated from the Nevada State Library and Archives in 2000 was 89.4 percent; 98.2 percent; and 92.4 percent respectively (http://nsla.

nevadaculture.org/index.php). This chapter addresses Sub-goal 2.4 in the SNAP Science 

Research Strategy which focuses on recreation use on Federal lands in southern Nevada 

(table 1.3; Turner and others 2009). The demands for various types of recreational opportunities are discussed and the ways in which Federal agencies can provide quality 

recreational experiences without compromising resources are explored. Also discussed 

are current visitor use patterns and services provided by the designated recreation areas 

in southern Nevada.

Nevada’s Population

There is a correlation between population growth and an increase in outdoor recreation. The rapidly growing population of southern Nevada results in an increase in 

recreational demands on the area’s public lands, and an associated shift in demographics 

brings changes in recreation tastes and preferences.

Two significant factors influence recreationists and the natural resource base that 

supports outdoor recreation in Nevada. One is the fact that the State of Nevada ranks 

first in Federal lands; and the second is the highly urbanized population of the state, in 

which 94 percent resided in urban areas in 2000 (DeLoney 2004). According to the 2010 

U.S. Census, the population of Nevada (2,700,551) grew by 35.1 percent since 2000. 

Nevada is the only state that has maintained a growth rate of 25.0 percent or greater for 

the last three decades and, until the recent economic downturn, was the fastest-growing 

state for five straight decades (U.S. Census Bureau 2011a). In southern Nevada, the 

population of Clark County (1,951,269) grew by 41.8 percent since the 2000 Census. 

The city of Las Vegas (population 583,756) grew by 22.0 percent; Henderson (population 257,729) grew by 47.0 percent; and North Las Vegas (population 216,961) grew 

by 87.9 percent since 2000 (U.S. Census Bureau 2011b).

 Nevada’s population is heavily concentrated in metropolitan counties and, while 

population growth has been significant across the state, population increases in Clark 

County far exceed those in other areas. Over 1.9 million people, or more than 72 percent 
186 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

of Nevada’s 2.7 million residents, live in Clark County. In addition, the state’s minority 

population has grown rapidly from 16.8 percent in 1980 to 45.8 percent in 2010. Growth 

of the Hispanic population has been especially rapid in Nevada. In 2010, 26.5 percent 

of the state’s residents were of Hispanic origin (WRDC 2011). The highest proportion 

of Hispanics (29.1 percent) resides in Clark County, which also has significant Black 

(10.5 percent) and Asian (8.7 percent) populations. Over 22 percent of Clark County 

residents are foreign born and 32.1 percent of persons above the age of 5 years speak 

a language other than English at home (U.S. Census Bureau 2012). The Clark County 

School District, 5th largest in the nation (Sable and others 2010) has a racial/ethnic 

distribution of 41% Hispanic, 14.1% Black, 34.6% White, 9.6% Asian, and 0.7% Native 

American. Just over 18% of students have limited English proficiency (CCSD 2010). 

The increasing demographic diversity of southern Nevada can lead to difficulties in 

educating a diverse urban population about recreational issues.

Outdoor Recreation Issues

The 2003 Statewide Comprehensive Outdoor Recreation Plan (SCORP) developed 

by the Nevada Division of State Parks (NDSP) is Nevada’s 8th edition of such a plan 

since the passage of the Federal Land and Water Conservation Fund Act of 1965. The 

plan provides review and study of recreational use within the State and presents the 

expectations of Nevadans regarding outdoor recreation. The plan’s goal is to increase 

and improve the quality of outdoor recreation opportunities to meet the needs of the 

citizens of Nevada as well as the State’s many visitors. SCORP identifies the top outdoor recreational issues facing Nevada and recommends actions to address each issue 

(DeLoney 2004).

The issues and recommendations reflect results of participant responses from a 

public input process through a mail-in survey titled “Nevadans Outdoors – a Survey 

on Outdoor Recreation in Nevada.” A function of the plan is to provide information 

and recommendations that will minimize uncertainty in the decision making process 

of allocating outdoor resources. The dominant concern of the respondents was to keep 

Federal lands open for a wide variety of outdoor recreation activities while protecting 

the state’s natural resources. According to the SCORP study, Nevadans understand the 

necessity of balancing recreational use with natural resource conservation (DeLoney 

2004).

The eight top recreation issues derived from the SCORP study are (1) public access to 

public lands for diverse outdoor recreation, (2) funding parks and recreation, (3) providing recreational trails and pathways, (4) balancing the protection of Nevada’s natural, 

cultural, and scenic resources with user demands, (5) protecting water resources as vital 

components of Nevada’s recreational base, (6) interpretation and education of outdoor 

recreation opportunities, (7) increasing demand from Nevada’s growing population on 

outdoor recreation resources and suppliers, and (8) coordination and cooperation among 

recreation providers (DeLoney 2004).

The following expanded discussion of the issues is drawn from participant responses 

in the 2003 SCORP report. Keeping Nevada’s abundant open space accessible was 

ranked as the most pressing issue. The growing need to protect, maintain, and increase 

public access to public lands in Nevada reflects a demographic population growth and 

reduction of open space nation-wide. Development, particularly in the urban interface, 

was cited as a major threat to public land access (DeLoney 2004).

Issue number two states that existing levels of funding for outdoor recreation are inadequate to meet the needs of Nevada. As noted by participants, maintenance of outdoor 

recreation areas and facilities (Federal, state, and local) has not kept pace with demands 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 187

created by a rapidly growing population and increasing numbers of out-of-state visitors 

(DeLoney 2004).

The third issue calls for provision of recreation trails and pathways throughout 

Nevada’s rural and urban areas. As with other issues, population increase is a major 

factor; the promotion of recreation-based tourism adds to the demand. Connectivity 

is important for recreational trails and for transportation needs in urban areas such as 

in Clark County. This requires cooperation between agencies when trails are to cross 

through differing jurisdictions (DeLoney 2004).

Respondents emphasized in the fourth issue that responsible use is essential to conserve 

the natural resources that make areas attractive to recreationists. Public education and 

active law enforcement were cited as means of protecting valuable resources. “There 

is no such thing as non-consumptive outdoor recreation activity...The degree of consumption is dependent on the outdoor recreational activity and the outdoor recreationist 

engaged in the activity” (DeLoney 2004: 26).

Water resources, listed as fifth, must be protected to maintain the quantity, quality, 

and accessibility needed for public recreation. However, recreational use of water often 

competes with other uses such as water for human and municipal consumption or for 

agricultural use. Another consideration is the fact that wildlife also depend on the limited 

water resources (DeLoney 2004).

The sixth issue involves provision for environmental, cultural, and heritage interpretation and educational programs. Suggestions include:

1. Educate the general population, the youth of the state, new residents, and visitors 

about natural resources and outdoor recreation activities;

2. Provide information that allows families to make safer choices concerning their 

outdoor recreation plans; and

3. Provide greater accessibility for those with impairments (DeLoney 2004).

As Nevada’s multi-cultural population continues to expand, there is an issue of

greater recreational demands on resources and suppliers. With an increasing number of 

recreationists, there is a change in the types of interests they choose to pursue. There is 

a shift from “the old traditional” uses of hunting, fishing, and camping to such activities as off road vehicle use and rock climbing. There are also changes in visitor types 

to a more urban population who expect recreation enhancements (toilets, developed 

campsites, brochures, and site interpretation). These increasing recreation demands 

require funding, planning, and staffing. At the same time, consideration must be given 

to reducing the added impacts to natural resources (DeLoney 2004).

Coordination and cooperation between public and private recreation providers was 

the final issue discussed in the SCORP study. There is concern that various recreation 

interests are becoming polarized against each other and that lack of cooperation and 

duplication of effort result in a waste of taxpayers’ money. Needs were expressed for 

more cooperation between agencies and more use of volunteers (DeLoney 2004).

SNAP Interagency Recreation and 

Wilderness Planning

There are four Federal land management agencies in southern Nevada that oversee 

eight congressionally designated resource areas. The Bureau of Land Management (BLM) 

oversees the Red Rock Canyon and Sloan Canyon National Conservation Areas (NCAs) 

and approximately 3.4 million acres of lands outside of the National Conservation Areas 

(Reardon, personal communication 2011b). The National Park Service (NPS) administers 

Lake Mead National Recreation Area (NRA). The United States Forest Service (USFS) 
188 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

manages Spring Mountains National Recreation Area (NRA). The United States Fish 

and Wildlife Service (USFWS) is responsible for the Desert National Wildlife Refuge 

Complex, which is comprised of four distinct National Wildlife Refuges (NWRs): Ash 

Meadows NWR, Desert NWR, Moapa Valley NWR, and Pahranagat NWR (SNAP 

2002).

In 2002 the Federal managers of SNAP directed the four agencies (BLM, NPS, 

USFW, and USFS) to conduct interagency recreation management and to form the Interagency Recreation Team. The team’s vision is to provide interagency collaboration 

in the planning and management of recreational opportunities, facilities, and services 

while honoring the natural setting and complementing the quality of life in southern 

Nevada. The team’s mission is for agencies to work together and with the surrounding 

communities to promote natural and cultural resource stewardship by providing appropriate and sustainable recreation opportunities (SNAP 2002).

Accomplishments include completion of the National Visitor Use and Monitoring 

Survey and an inventory of over 9,000 miles of roads and trails. The survey and inventory will serve as a foundation for Recreation Area Management Plans, which will 

identify roads and trails on Federal lands, including connections to adjacent urbanized 

communities. In addition to planning, the Recreation Team is working with the Education Team to provide public information for recreation opportunities on Federal lands 

through outreach products, including the OHV Adventure Guide and the forthcoming 

interactive and recreation opportunities maps and non-motorized trail guide (Reardon, 

personal communication 2011a).

The SNAP Recreation Team initiated recreation visitor sampling on all SNAP lands 

using a single monitoring program based on the USFS National Visitor Use Monitoring (NVUM) program. Collectively, these NVUM reports provide comprehensive 

statistics on recreation use, visit characteristics, visitor spending, and the satisfaction 

of recreationists with recreation opportunities and resource conditions. Although the 

individual Federal agencies have differing management objectives, this information is 

useful given the proximity of these lands to each other and the shared potential base of 

local recreationists and tourists (SNAP 2010).

Nearly 3,000 visitors were surveyed during the 2005-2008 sampling period; data 

collected were used to assess visitor use of the public lands that comprise SNAP. The 

2,896 visitor-completed surveys were fairly evenly distributed throughout the year, 

representing the full range of seasonal activities available on SNAP lands. Over all, the 

most popular activities reported were hiking and viewing natural features. There were 

differences in the popularity of recreation choices across agencies, because management objectives, topography, and recreation resources differ from agency to agency. For 

example, on BLM lands there was a greater percentage that listed driving for pleasure 

and rock climbing as primary activities; water-based recreation was most prevalent on 

NPS lands; viewing wildlife was listed as the primary activity on USFWS lands; while 

camping was listed as the primary activity on USFS land (SNAP 2010).

Based on the results of the NVUM sampling approach, recreation use on BLM, USFWS and USFS lands during the survey period (2005-2008) amounted to 2.7 million 

public land visits annually. The National Park Service has a locally developed estimate 

for recreation use and counted 6,263,530 visits to Lake Mead National Recreation Area 

in Nevada during 2009. When the NPS locally developed recreation estimate is combined 

with the estimates for the other agencies, using the NVUM sampling data, recreation 

use for the SNAP agencies sums to more than 9 million visits (SNAP 2010).

The BLM and NPS manage major land bases in southern Nevada, and account for 

nearly 90 percent of the area’s recreation use. The survey determined that approximately 53 percent of visits are by people who traveled less than 50 miles from home to 

participate in some form of recreation. More than half of the visits were from Nevada 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 189

residents. People traveling greater than 500 miles from home made up 25 percent of 

visits, and slightly over 5 percent were foreign visitors. Recreation visits to SNAP lands 

generate economic activity (motel/hotel, restaurant, fuel, groceries, etc.) to communities 

surrounding agency lands (SNAP 2010).

The overall satisfaction rating of the four SNAP agencies indicated that the vast majority of visitors surveyed were at least “somewhat satisfied” with their visit. Individually, 

the BLM had the highest rating. Visitor satisfaction for each was greatest at developed 

sites and lowest at undeveloped sites. Satisfaction was consistently lowest overall for 

services such as information, signage, and employee helpfulness. Areas identified as 

needing attention included restroom cleanliness, information provided, signage, and trail 

condition. Over 90 percent of responses indicated a satisfactory perception of safety 

(SNAP 2010). Informational maps and signage were the items most frequently cited as 

increasing the perception of safety.

Agencies also are working to develop interagency Wilderness Management Plans. 

The first interagency Wilderness Management Plan in the nation was completed for 

the Muddy Mountains Wilderness, which is jointly managed by the BLM and the NPS. 

Plans for North McCullough, South McCullough, and Wee Thump-Joshua Tree Wilderness Areas have also been completed by the BLM. Planning is underway for other 

jointly managed areas such as El Dorado, Ireteba Peaks, Spirit Mountain, Pinto Valley, 

Jimbilnan, Black Canyon, Bridge Canyon, and Nellis Canyon and the remaining six 

designated Wilderness areas—Mt. Charleston, Rainbow Mountain, La Madre, Jumbo 

Springs, Lime Canyon, and Arrow Canyon. Additionally, SNAP and the Friends of 

Nevada Wilderness are working in partnership to establish a Wilderness Steward Program. Wilderness maps with interpretive and educational information are also under 

development (Holland 2011, personal communication; SNAP 2011a).

Bureau of Land Management (BLM)

Red Rock Canyon National Conservation Area (NCA)—Red Rock Canyon National Conservation Area is located approximately 17 miles west of the Las Vegas strip. 

It was designated in 1990 to preserve the environmental, cultural, and scenic qualities 

of the area for present and future generations. Red Rock’s dramatic visual attraction is 

the result of a geologic thrust of grey limestone up and over younger red sandstone, 65 

million years ago (USDI BLM 2010a).

The NCA consists of two distinct areas. The northern portion is mostly undeveloped 

and primitive and includes designated wilderness areas. The southern portion features 

a 13-mile scenic drive, visitor’s center, picnic areas, camp sites, and over 100 miles 

of trails. The visitor’s center contains extensive interpretive exhibits and provides environmental education opportunities. Recreational activities include birding, hiking, 

horseback riding, and rock climbing. Also available to visitors are informative walks 

and talks, demonstration programs, and educational series (USDI BLM 2010a).

Red Rock Canyon NCA has three major goals. One is to provide for public enjoyment 

and visitor experience. This involves visitor safety and satisfaction, while promoting understanding and appreciation of the area. A second goal is the enhancement of appropriate 

recreational opportunities by improving and expanding the trail system, campground, 

and other high-use visitor areas. Also considered are the impacts of human activity, 

removal of public safety hazards, and coordination with other trails and maps within 

adjacent urban areas. The third goal is the preservation of Red Rock Canyon’s resources. 

This involves ecosystem restoration, landscape rehabilitation, wildlife management, 

and cultural resource protection. It is expected that proposed fee increases needed to 

achieve these goals will have a minimal impact on most visitors; social benefits should 

outweigh the economic costs (USDI BLM 2010a).
190 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Sloan Canyon National Conservation Area (NCA)—Sloan Canyon National Conservation Area was designated by Congress in 2002 to preserve a portion of southern 

Nevada’s Mojave Desert. The Northern McCullough Wilderness is entirely contained 

within the NCA. Sloan Canyon NCA encompasses 48,438 acres and forms the mountainous southern skyline of the cities of Las Vegas and Henderson. It contains scenic 

resources, wildlife habitat, and archaeological sites, most notably the Sloan Canyon 

Petroglyph Site. Sloan Canyon is located approximately 20 miles southeast of the City 

of Las Vegas and borders the City of Henderson, Nevada. It is situated at the edge of a 

rapidly urbanizing valley. Residential and business development is expected to border 

much of the northern and western edges of the Conservation Area (USDI BLM 2009).

Recreation in the form of hiking, mountain biking, equestrian, and illegal off-highway 

vehicle (OHV) use have become more prevalent in the northern portion of Sloan Canyon 

NCA as urban growth in the Las Vegas Valley encroaches. The more rugged and isolated 

southern portion receives limited visitation, primarily cross-country hiking and equestrian 

use (BLM 2010b). Activities encouraged in the North McCullough Wilderness include 

hiking, horseback riding, and wildlife observation. Vehicles, including mountain bikes, 

are prohibited within the Wilderness. (USDI BLM 2010b)

Red Rock Canyon and Sloan Canyon NCAs represent just two of the areas the BLM 

Southern Nevada District manages that are enjoyed by the public. Although most lands 

managed by BLM do not contain recreational improvements, hundreds of miles of trails 

are available for exploration as well as 15 wilderness areas and 22 Areas of Critical Environmental Concern, totaling over one million acres. BLM Public Lands located outside 

the National Conservation Areas comprise over 3.4 million acres and include popular 

recreation areas, such as Logandale and Gold Butte, that provide additional recreation 

opportunities such as OHV riding (Logandale), rock crawling, camping, hiking, hunting, 

cultural resources, and scenic driving. Other treasured areas include Nellis Dunes and 

Big Dune for OHV thrill-based recreation (Reardon, personal communication 2011a; 

Ronning, personal communication 2012).

In order to plan for these varying uses and link with the BLM’s 2001 Strategy for 

Motorized Off-Highway Vehicle Use, the agency is developing a non-motorized Trails 

Master Plan to meet the needs of hiking, equestrian, and mountain biking groups. The 

trail network would connect with the trails of Henderson’s Open Space and Trails Plan 

(City of Henderson 2005). The intention is to manage for public use and enjoyment 

while protecting the NCA’s sensitive resources (USDI BLM 2009).

The BLM’s 2001 Strategy for Motorized Off-Highway Vehicle Use was an effort to 

determine and implement management solutions designed to conserve soil, wildlife, 

water quality, native vegetation, air quality, heritage, and other resources, while providing for appropriate motorized recreational opportunities (USDI BLM 2001). The OHV 

Guide to Public Lands within Clark County provides users with information on where 

roads and trails are open to motorized recreation as well as tips on safety, responsible 

riding, and potential impacts to the environment (SNAP 2011c).

National Park Service (NPS)

Lake Mead National Recreation Area (NRA)—Established as America’s first National Recreation Area, Lake Mead NRA was set aside as a unit of the NPS in 1964 to 

provide recreation for visitors and to preserve the natural and cultural resources of the 

area. The NRA encompasses over 1.5 million acres of land and includes two man-made 

lakes. Hoover and Davis Dams backed up the Colorado River as it flows through this 

extremely arid region and created Lake Mead and Lake Mohave respectively. Open 

year round, these lakes/reservoirs provide a startling contrast with the surrounding 

desert ecosystem and are a great attraction to recreationists (USDI NPS 2011a).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 191

The western most portion of Lake Mead is located approximately 30 miles east of the 

city of Las Vegas at the base of the River Mountains. There are nine main access points 

to the lake. The NRA stretches north to Overton, east to the Grand Canyon National 

Park, and south to Laughlin and Bullhead City (USDI NPS 2011a). In 2010, visits to 

Lake Mead NRA totaled 7,080,758. The projected number for 2011, with an increase 

of 0.9 percent, is 7,146,008. In 2012, with an expected decrease of -1.9 percent, visitor 

numbers are forecast to total 7,011,264 (Street 2011).

According to the NPS Single Agency Report (2009) the primary activities, accounting for over half of visits to Lake Mead and Lake Mohave, are swimming, fishing, and 

motorized water activities. About 54 percent of visits to Lake Mead are by local area 

residents on day trips away from home; in contrast, there are a greater percentage of 

nonlocal residents on day trips to Lake Mohave (USDI NPS 2009). While the waters 

are a great attraction to many, Lake Mead NRA offers a myriad of other recreation opportunities to its visitors. Such activities as backcountry exploration driving, biking, 

camping, hiking, horseback riding, hunting, photography, and wildlife observation draw 

visitors to the desert landscape. In addition, the National Park Service offers a variety 

of ranger-led programs throughout the year. Guided hikes are presented at both Lake 

Mead and Lake Mohave throughout the fall and winter seasons (USDI NPS 2011a).

Recreation decisions at Lake Mead are based on the General Management Plan(USDI 

NPS 2011b). The NPS is addressing recreation and access within Lake Mead through 

development concept plans, such as plans for Katherine Landing and Cottonwood Cove 

(USDI NPS 2011c). The official website of Lake Mead NRA is an excellent source of 

information for the prospective visitor. Along with maps and facts about the area, the NPS 

offers detailed advice on safety precautions, essential equipment, and any regulations 

that pertain to various activities such as boating, fishing, hiking, hunting, or horseback 

riding. Throughout the literature there are reminders to respect the animals and plants 

that occur in the area (USDI NPS 2011a).

In a 1997 study by Graefe and Holland, the two most serious problems cited by lake 

users were crowding by personal watercraft operating too close together and litter along 

the shore. Forty-three percent reported observing unsafe boating situations. Shoreline 

litter was identified as a problem needing management attention at Lake Mead NRA. 

Lake users expressed great support for aggressive enforcement of safety rules and 

regulations (Graefe and Holland 1997).

U.S. Forest Service (USFS)

Spring Mountains National Recreation Area (NRA)—Spring Mountains NRA encompasses more than 316,000 acres in the Humboldt-Toiyabe National Forest. The 

General Management Plan (GMP) for Spring Mountains NRA includes goals, objectives, desired future conditions, and standards and guidelines for the entire NRA as 

well as specific direction for each of the four management areas: Developed Canyons, 

Mt. Charleston Wilderness, West-side, and Mt. Stirling (USDA FS n.d.a).

The Forest Service-managed NRA is located in Clark County, Nevada, 30 minutes 

west of downtown Las Vegas, and shares its eastern boundary with Red Rock Canyon 

NCA. The Spring Mountains, with its wide range in elevation, provides a haven for 

wildlife and a vital watershed fed by numerous springs. This mountain range serves as 

a quick get-away for urban residents of the Las Vegas metropolitan area. High elevations and cooler temperatures in proximity to the large population base offer visitors 

a welcome respite from the prevalent valley heat (http://www.fs.usda.gov/wps/portal/

fsinternet/).

Spring Mountains NRA contains three Federally designated wilderness areas; Mt. 

Charleston, La Madre Mountain, and Rainbow Mountain (also in the Red Rock Canyon 
192 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

NCA). Mt. Charleston, elevation 11,918 feet, is the third highest peak in Nevada and the 

only peak in southern Nevada that rises above treeline. The diverse life zones range from 

desert to alpine and support a wide variety of wildlife. The Spring Mountains provide 

habitat for more than 25 plants and animals found nowhere else on earth. Visitors are 

reminded to protect the animals and plants of the area that depend on Spring Mountains 

as an “island in the desert” (USDA FS n.d.b).

Spring Mountains NRA is a year-round recreation area and, owing to its great variation in elevation and temperature, offers a wider array of recreational opportunities 

compared with the rest of southern Nevada. Camping, picnicking, and hiking are available in the warmer months. Other activities include horseback riding, mountain biking, 

rock climbing, hunting, and wildlife viewing. There are opportunities for snow-based 

activities in winter (USDA FS n.d.b). According to the Single Agency Report, visitors 

to Spring Mountains NRA identified the top five recreation activities as viewing natural 

features, hiking/walking, relaxing, driving for pleasure, and viewing wildlife. Developed 

camping was also listed as a top “main” activity (USDA FS 2006).

There are 51 miles of hiking trails on Spring Mountains NRA. Most are open to horseback riding, with the exception of the upper section of the Bristlecone Trail. Riding is 

discouraged in areas of dangerously steep terrain or heavy visitor use. Mountain biking 

is limited to specific trails as posted and is prohibited in wilderness areas. Off-highway 

vehicle (OHV) use is restricted to roads and trails designated as “Motorized Trail” or 

“Forest Road.” The visitor guide lists travel advice, safety tips, trail and boundary restrictions, and warns against littering and disturbance of cultural sites (USDA FS n.d.b).

U.S. Fish and Wildlife Service (USFWS)

Desert National Wildlife Refuge (NWR) Complex—The Desert NWR Complex, 

encompassing more than 1.6 million acres of land, is located in Clark, Lincoln, and 

Nye Counties of southern Nevada. The Complex consists of four separate refuges, 

Ash Meadows NWR, Desert NWR, Moapa Valley NWR, and Pahranagat NWR. Visitor services are primarily focused on wildlife-dependent recreation and vary at each 

refuge. The four refuges also provide resources that are important to local culturally 

affiliated tribes (USDI FWS 2009a).

Ash Meadows National Wildlife Refuge (NWR)—The Ash Meadows NWR is located approximately 90 miles northwest of Las Vegas and 30 miles west of Pahrump 

in the Amargosa Valley of Nye County. A day-use area, the refuge currently expects 

over 50,000 visitors annually. Ash Meadows NWR is comprised of over 23,000 acres 

of spring-fed wetlands and alkaline desert uplands. Providing habitat for at least 24 

plants and animals found nowhere else in the world, Ash Meadows contains the greatest concentration of endemic life of any locale in the United States. This desert oasis is 

a major discharge point for an underground aquifer system stretching 100 miles to the 

northeast (USDI FWS 2011a).

Wildlife-dependent activities at Ash Meadows include bird watching, photography, 

wildlife observation, environmental education, interpretation, and hunting (in the fall). 

Picnicking and hiking are the major non-wildlife activities (USDI FWS 2009a). The 

refuge office (open weekdays 8AM to 4PM) offers brochures and leaflets, bird lists, an 

interpretive kiosk, and access to the Crystal Springs Interpretive Boardwalk Trail. Point 

of Rocks Boardwalk and Longstreet Boardwalk are two other interpretive trails (USDI 

FWS 2011a).

Rules, regulations, and safety advice are stated clearly in Ash Meadows NWR literature. Such activities as fishing, off-highway vehicles (OHVs), horseback riding, and 

collecting of artifacts or natural objects are prohibited on the refuge. Strict regulations 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 193

are enforced during hunting season, including restrictions regarding use of hunting dogs, 

and reminders regarding trespass on private land in-holdings (USDI FWS 2011a).

Ash Meadows NWR works with a variety of agencies and organizations in the management of the refuge. Partnerships include Death Valley Natural History Association, 

Death Valley National Park (NPS), Southern Nye County Conservation District, U.S. 

Geological Service (USGS), local land owners, and others (USDI FWS 2009b).

Desert National Wildlife Refuge (NWR)—The Desert NWR is located immediately 

north of the rapidly expanding cities of North Las Vegas and Las Vegas. The western 

portion of the Refuge contains military withdrawn lands that are closed to public access (USDI FWS 2009b). Currently the refuge expects over 68,000 visitors annually 

(USDI FWS 2011b).

The largest refuge in the contiguous United States, the Desert NWR includes more than 

1.5 million acres (over 2,300 square miles) of rugged mountain ranges and panoramic 

valleys. Elevations ranging from 2,200 feet to nearly 10,000 feet and corresponding 

variation in rainfall (less than 4 inches at lower elevations to greater than 15 inches on 

the highest peaks) have created diverse habitats that are suited to a wide variety of flora 

and fauna. Desert NWR is home to 52 species of mammals and over 320 species of 

birds. It forms one of the largest intact blocks of desert bighorn sheep habitat remaining 

in the southwest (USDI FWS 2005).

Wildlife-dependent recreational activities available on the Desert NWR include wildlife 

observation, photography, environmental education, interpretation, and hunting (limited). 

Non–wildlife-dependent recreational activities include primitive camping, picnicking, 

backpacking, and hiking (USDI FWS 2009a). “There are several unmaintained social 

trails used regularly by the public, including Hidden Forest, Gass Peak, Bird Song Loop 

and trails around Corn Creek” (Yost, personal communication 2012). Rules, regulations, 

and safety advice are stated clearly in Desert NWR literature. Cellular telephone coverage is limited in the area. The roads are primitive, no fuel or service is available in the 

refuge, and road warnings are posted for safety. Only licensed street-legal vehicles are 

allowed on the backcountry roads. Use of All-terrain Vehicles (cycles and quads) is not 

permitted within the refuge. Travel into the backcountry is best appreciated by foot or 

horseback (USDI FWS 2005).

Moapa Valley National Wildlife Refuge (NWR)—The Moapa Valley NWR is located approximately 60 miles northeast of Las Vegas in Clark County. The refuge is 

situated within the Moapa Valley south of State Highway 168 and the upper Muddy 

River, between Interstate 15 and U.S. Highway 93 (USDI FWS 2009b). Moapa Valley NWR is only open on Saturdays and Sundays (9 a.m. to 3 p.m.) from Labor Day 

through Memorial Day. This is due to the refuge’s small size, fragile habitats, and ongoing restoration work (USDI FWS 2011c).

Moapa Valley NWR encompasses 116 acres and is part of a system of thermal springs 

at the headwaters of the Muddy River, which eventually flow into Lake Mead. These 

springs provide riparian and aquatic habitats for sensitive birds, bats, and fish. Most 

notably, the refuge protects an endangered population of the endemic Moapa dace (a 

small fish commonly found throughout the waters of the Muddy River system) and supports a diversity of birds including breeding populations of the endangered southwestern 

willow flycatcher. Hiking, picnicking, interpretation, environmental education, wildlife 

viewing and photography are recreational activities available at Moapa Valley NWR 

(USDI FWS 2009b). Moapa Valley was the first refuge in the National Wildlife Refuge 

System to be created for an endangered fish (USDI FWS 2011c).
194 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Pahranagat National Wildlife Refuge (NWR)—The Pahranagat NWR is located approximately 90 miles north of Las Vegas at the southern end of the Pahranagat Valley 

in Lincoln County. Pahranagat NWR consists of 5,380 acres of marsh, open water, native grass meadow, cultivated cropland, and riparian habitat. This diversity of habitat 

supports over 230 species of migratory bird and other resident wildlife. There are four 

main water impoundments. The refuge expects over 32,000 visitors annually (USDI 

FWS 2011d).

Wildlife-dependent recreation activities include interpretation, environmental education, (USDI FWS 2009a) wildlife observation, fishing, and hunting. Bird watching is 

popular on this refuge; bird lists are available online, at the refuge office, or at information 

centers located throughout the refuge. Bird abundance and diversity are highest during 

spring and fall migrations. Camping and picnicking are permitted along the eastern 

shoreline of Upper Pahranagat Lake (USDI FWS 2011d). There are two unmaintained 

trails, Davenport and a loop around Upper Lake, but hiking is permitted throughout the 

refuge (Yost personal communication 2012).

Pahranagat NWR works with a variety of other agencies and organizations in the 

management of the refuge. Among others, these partnerships include National Audubon 

Society, Nevada Department of Wildlife, U.S. Bureau of Reclamation, Great Basin 

Bird Observatory, Bureau of Land Management, University of New Mexico, Northern 

Arizona University, and NPS Exotic Plant Management Team (USDI FWS 2009b).

Ongoing Recreation Issues on Federally Managed Lands

Population growth, development, proximity of urban areas to public lands, and growing popularity of outdoor recreation have translated into a high demand for a variety 

of recreational opportunities on Federal lands and waters. Over the past four decades, 

forms of motorized recreation such as OHVs, snowmobiles, and personal watercraft, 

as well as other recreational activities such as mountain biking and hang gliding, have 

gained in popularity. These newer forms of recreation intersect with more traditional 

forms of recreation such as fishing, canoeing, bird watching, hiking, horseback riding, 

hunting, and camping. Use of OHVs on Federal lands has been particularly contentious 

with critics raising concerns over potential damage to wildlife habitat and land and water ecosystems and diminished experience for recreationists seeking quiet and solitude 

(Calvert and others 2010). Despite differences in management objectives, topography, 

and recreation resources agencies are faced with many common issues. They struggle 

with needs for adequate facilities, funding, law enforcement, and staff. At the same 

time they must balance the demands of an ever increasing, dynamic population with 

stewardship of the various natural and cultural resources under their management. As 

the recreational preferences of the public evolve with greater interests in activities such 

as climbing, driving, and organized events, increased planning, education, and enforcement are required for effective management.

Regional Trail Planning and Outreach

Partnerships between agencies (Federal, state, regional, and local), non-profits, businesses, individual citizens, and community partners played a critical role in the establishment and management of trails in southern Nevada. An interest in preserving open 

space and in development of interconnecting trails has evolved over the past decade 

due primarily to the region’s population explosion and a desire for improving quality 

of life. The proposed 113-mile Vegas Valley Rim Trail would serve to bind many land 

management areas, recreational destinations, municipalities, and agencies together (Baca 

2010; Reardon, personal communication, 2011b).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 195

Because of its proximity and access to public lands, Las Vegas Valley is gaining recognition as an outdoor recreation destination. The Cities of Las Vegas and Henderson 

have both completed open space planning efforts. The ultimate goal of these plans is to 

create and maintain a world-class, interconnected open space and trails system through 

the action of citizens, the business community, and city, county, state, and Federal agencies. These municipal plans are designed to provide a ring of open space and wildlands 

that will encircle the Greater Las Vegas area and protect scenic, ecosystem, and cultural 

resources (City of Henderson 2005; Clark County 2009).

Most of the corridor rests on BLM-managed lands, suggesting the need for continual 

coordination between the local communities and the Federal agencies. Lands being considered in the plan are outside the congressionally defined land disposal boundary and are 

primarily BLM-managed lands that are not congressionally designated for conservation. 

Given the possibility that the disposal boundary might be expanded as it has in the past, 

those public lands with the highest resource values could remain in public ownership 

or in some other form of protection to protect recreational opportunities in addition to 

conserving resource values. Lands bordering Las Vegas Valley that are designated for 

conservation by Congress include the Desert NWR, Lake Mead NRA, Sloan Canyon 

NCA, and Red Rock Canyon NCA (Clark County 2009). Lands designated locally 

for conservation include the Rainbow Gardens and River Mountains Areas of Critical 

Environmental Concern (BLM) and the Boulder City Conservation Easement (Boulder 

City and Clark County).

Knowledge Gaps and Management Implications

Southern Nevada’s rapidly increasing population has resulted in an increase in recreational demands on public lands, while an associated shift in demographics has altered 

recreation tastes and preferences. There are changes in visitor types to a more urban 

population who expect more expensive recreation enhancements such as full-service 

camping facilities. In addition, an increasing number of visitors come from a wide range 

of cultural backgrounds. For example, subtle differences in leisure time preferences of 

Hispanics distinguish them from other ethnicities, and understanding such differences is 

a critical factor in serving the increasing Hispanic population (Adams and others 2006). 

Many new residents have recently migrated from other countries where English is not 

the primary language and who may or may not have experience with the traditional 

forms of recreation highlighted in this report. These changes to the profile of recreation 

in the area emphasize the need for additional information and management strategies 

to meet future demands and trends. Managers will need to plan for changes in facilities 

and recreation area emphases as well as additional education strategies to accommodate 

these new visitor preferences and types.

Stemming in part from southern Nevada’s population expansion, there is an accelerated impact on natural, cultural, and scenic resources. Although some impacts are 

being recorded through resource monitoring, it is not fully known if they are related 

to recreation use. In addition, protection and conservation of water resources must be 

considered owing to competing interests and conflicting demands of recreationists. 

Identification and protection of these resources need to be undertaken and accounted for 

in management plans. Public education and law enforcement are essential components 

of this process.

Increased urbanization and development adjacent to public lands provide the southern 

Nevada population with easy access to nearby public lands for recreation. As off-highway 

vehicle (OHV) use and recreational climbing gain in popularity, research is needed to 
196 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

identify the potential impacts of such activities (SNAP 2011b). These are forms of recreation that impact the environment and are a common concern of the agencies managing 

public lands. Research is needed to identify recreation trends on public lands and ways 

to meet the needs and demands of recreationists without compromising the resources 

(SNAP 2011b).

Recreational use of all-terrain vehicles (ATVs) has resulted in an increase in vandalism 

and illegal looting (unauthorized excavation and removal of artifacts) on cultural sites 

that were previously inaccessible ( NVSHPO 2004). These remote areas, once protected 

by distance, are now within easy reach of the off-road vehicle user and well-equipped 

urban/suburban resident. Cultural resource professionals look for positive effects from 

their heritage education programs. They believe that such education has the potential to 

reduce negative impacts and inadvertent damage from recreational use on public lands 

by making the public aware of the fragility and uniqueness of the resource. Frustration 

remains over insufficient funding for law enforcement and management actions such 

as closure of roads and trails or construction of physical barriers for prevention of site 

damage (Jarvis 2006).

Changes in communication technology have affected how people get information 

regarding potential visits to recreation areas and associated activities. For instance, 

visitor guides are now available online. “Online meet-up groups are a new way people 

find out about hikes and may be taking the place of commercial operators or demand 

for agency led activities. Understanding the volume of visitation, providing information 

to leaders to ensure resource damage is avoided, etc. is all needed” (Ronning, personal 

communication). There is a trend for recreationists to desire enhanced interactive interpretive and educational programs as well as upgraded visitor centers. Funding and 

staffing of recreation areas and facilities must be sufficient to keep pace with these 

increasing demands.

Administrative and political pressures on agencies that divert effort away from activity that directly benefits ecosystems affect long-term effective management of the 

land. Loss of landscape knowledge when agency staffs are transferred to other locations 

is another serious problem. Other needs are interagency cooperation and education of 

recreation visitors. Lack of resources such as staffing, infrastructure, and budget affect 

the ability of agencies to manage southern Nevada ecosystems (Lancaster and others 

2006).

Southern Nevada’s growing population influences recreation activity on Federal lands 

and impacts the area’s natural resources. The State of Nevada, with its great proportion 

of public lands, is blessed with an abundance of natural resources. The parks and open 

spaces of southern Nevada are valued as popular recreation and tourist destinations for 

Nevadans and visitors to the Las Vegas metropolitan area (DeLoney 2004). While these 

areas are beneficial to human populations as healthy retreats from urban life, they are 

essential as habitat for many native species of flora and fauna. Therefore, it is imperative 

to consider the effects of increasing recreation demands on natural resources. Cooperation and collaboration among the four Federal land management agencies and with 

southern Nevada’s adjacent communities is necessary to achieve the goals of promoting 

natural and cultural resource stewardship while providing appropriate and sustainable 

recreation opportunities (SNAP 2002).
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 197

References

Adams, L.; Baskerville, K.; Lee, D.; Spruiell, M.; Wolf, R. 2006. The Hispanic community and outdoor 

recreation. March 22, 2006. Presented to Outdoor Industry Foundation by UCLA Anderson School of 

Management Research Program. 51 p.

Baca, M. 2010. Historical context for the “Great Circle.” Unpublished draft on file at: Outside Las Vegas 

Foundation, Las Vegas, NV.

Calvert, K.; Vincent, C.H.; Gorte, R.W. 2010. Recreation on Federal lands. Congressional Research Service Report for Congress. 7-5700 www.crs.gov RL 33525. 24 p.

City of Henderson. 2005. Open space and trails plan: adopted December 6, 2005. Henderson, NV: Community Development Department. Online: http://www.cityofhenderson.com/community_development/

open_space_and_trails_plan.php [2011, May 5].

Clark County. 2009. Las Vegas Valley perimeter open space plan—Phase 1: Open space locations and 

Vias Verdes report. Las Vegas, NV: Clark County Department of Air Quality and Environmental Management and the Department of Comprehensive Planning. 48 p. Online: http://www.clarkcountynv.

gov/Depts/comprehensive_planning/advanced_planning/Documents/LVVPerimeterPhase1Report.pdf 

[2012, Nov 16].

Clark County School District (CCSD). 2010. Clark County School District Accountability Report 2009-

10 School Year.: 3,13. Online: http://ccsd.net/schools/pdf/acc_pdfs_2010/districtAcc2009-2010.pdf 

[2012, Nov 19].

DeLoney, J.A. 2004. Nevada’s 2003 statewide comprehensive outdoor recreation plan – assessment and 

policy plan. Carson City, NV: Nevada Division of State Parks, Department of Conservation and Natural 

Resources. 288 p.

Graefe, A. R.; Holland, J. 1997. An analysis of recreational use and associated impacts at Lake Mead 

National Recreation Area: a social and environmental perspective. U.S. Department of the Interior, 

National Park Service, Lake Mead Recreation Area. On file at: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station, Albuquerque, NM. 9 p.

Holland, J. 2011. Personal communication. [E-mail to Deborah Reardon forwarded to Carol Raish]. August 4. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 

Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 files.

Jarvis, T.D. 2006. Cultural resources on the Bureau of Land Management public lands: an assessment and 

needs analysis. Washington, DC: National Trust for Historic Preservation. 36 p.

Lancaster, J.; Mouat, D.; Buck, P. (eds.). 2006. Information needs and state-of-the-science summary developed for the ecosystem health assessment of southern Nevada project. Report on First Workshop—

May 3-4, 2006. Reno, NV: Desert Research Institute. 31 p.

Nevada State Historical Preservation Office (NVSHPO). 2004. Nevada Comprehensive Preservation Plan 

2003. Online: http://nvshpo.org/dmdocuments/HPPlan03.pdf [2012, Nov 15].

Reardon, D. 2011a. Personal communication. [E-mail to Carol Raish]. September 14. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, 

Albuquerque, NM; RMRS-4853 files.

Reardon, D. 2011b. Personal communication. [E-mail to Alice McSweeney]. October 13. On file at: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 files.

Ronning, C. 2012. SNAP review team. March 2. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM; RMRS-4853 

files.

Sable, J.; Plotts, C.; Mitchell, L. 2010. Table A-1. In: Characteristics of the 100 Largest Public Elementary 

and Secondary School Districts in the United States: 2008–09 (NCES 2011-301). U.S. Department of 

Education, National Center for Education Statistics. Washington, DC: U.S. Government Printing Office. P A-4. Online: http://nces.ed.gov/pubs2011/2011301.pdf [2012, Nov 19].

Southern Nevada Agency Partnership (SNAP). 2002. Interagency recreation team charter. On file at: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, NM. 6 p.

Southern Nevada Agency Partnership (SNAP). 2010. Southern Nevada visitor use monitoring. Understanding visitors to public lands in Clark County, Nevada. Southern Nevada Agency Partnership Recreation Team. On file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station, Albuquerque, NM. 4 p.

Southern Nevada Agency Partnership (SNAP). 2011a. Wilderness Team Accomplishments. Online: http://

snap.gov/projects/wilderness/accomplishments.cfm [2011, Oct 6].

Southern Nevada Agency Partnership (SNAP). 2011b. Science and research needs assessment, 2011. Science and Research Team.
198 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Southern Nevada Agency Partnership (SNAP). 2011c. OHV guide to public lands within Clark County. 

Online: http://www.snap.gov/upload/OHV-Brochure-Web-120327.pdf [2012, Nov 19].

Street, B. 2011. Statistical abstract: 2010. Natural Resource Data Series NPS/NRPC/SSD/NRDS--

2011/147. Fort Collins, CO: U.S. Department of the Interior, National Park Service, Natural Resource 

Program Center. 74 p. Online: www.nature.nps.gov/socialscience/docs/PUSO_Abstract_2010.pdf 

[2012, Nov 19].

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/

SNAP-S-R-Strategy-2009r.pdf [2012, June 5].

U.S. Census Bureau. 2011a. Population distribution and change: 2000 to 2010. Online: http://www.census.gov/prod/cen2010/briefs/c2010br-01.pdf [2012, Nov 19].

U.S. Census Bureau. 2011b. U.S. Census Bureau delivers Nevada’s 2010 census population totals, including first look at race and Hispanic origin data for legislative redistricting. Online: http://2010.census.

gov/news/releases/operations/cb11-cn51.html [2012, Nov 19].

U.S. Census Bureau. 2012. Clark County quick facts. Online: http://quickfacts.census.gov/qfd/states/32/32003.

html [2012, Nov 19].

USDA Forest Service. 2006. National visitor use monitoring results for Spring Mountains National Recreation Area. Single Agency Report. Southern Nevada Agency Partnership, Southern Nevada Visitor Use 

Monitoring. U.S. Department of Agriculture, Forest Service, Region 4. On file at: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque, NM. 43 p. Online: http://

www.fs.fed.us/recreation/programs/nvum/reports/year5/spring_mt_nra.htm#_Toc148252978 [2012, 

Nov 19].

USDA Forest Service. [n.d.a]. General management plan for the Spring Mountains National Recreation 

Area. Online: http://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5143059.pdf [2011, October 6].

USDA Forest Service. [n.d.b]. Spring Mountains National Recreation Area 2009-2010 visitor guide. Las 

Vegas, NV: U.S. Department of Agriculture, Forest Service, Humbolt-Toiyabe National Forest. Online: 

https://fs.usda.gov/Internet/FSE_DOCUMENTS/fsm9_026404.pdf [2011, April 29].

USDI Bureau of Land Management. 2009. Sloan Canyon National Conservation Area trails master plan. 

Final Environmental Assessment. Las Vegas, NV: U.S. Department of the Interior, Bureau of Land 

Management, Red Rock-Sloan Field Office. 199 p. Online: http://www.blm.gov/nv/st/en/fo/lvfo/blm_

programs/blm_special_areas/sloan_canyon_nca/sloan_canyon_nca_trails.html [2012, Nov 19].

USDI Bureau of Land Management. 2001. National management strategy for motorized off-highway vehicle use on public lands. Washington, DC: U.S. Department of the Interior Bureau of Land Management.

USDI Bureau of Land Management. 2010a. Red Rock Canyon National Conservation Area final business plan. Las Vegas, NV: U.S. Department of the Interior, Bureau of Land Management, Southern 

Nevada District Office. 87 p. Online: http://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/

las_vegas_field_office/red_rock/red_rock_business/2010_final_red_rock.Par.24616.File.dat/RRBP2010_final-online.pdf [2012, Nov 19].

USDI Bureau of Land Management. 2010b. Sloan Canyon National Conservation Area. [Homepage of 

Sloan Canyon NCA]. Department of the Interior, Bureau of Land Management, Southern Nevada District Office, Sloan Canyon National Conservation Area. Online: http://www.blm.gov/nv/st/en/fo/lvfo/

blm_programs/blm_special_areas/sloan_canyon_nca.html [2011, April 4].

USDI Fish and Wildlife Service. 2005. Desert National Wildlife Refuge. Las Vegas, NV: U.S. Department 

of the Interior, Fish and Wildlife Service, Desert National Wildlife Refuge. oOnline: http://www.fws.

gov/desertcomplex/desertrange/reference.htm [2011, May 20].

USDI Fish and Wildlife Service. 2009a. Desert National Wildlife Refuge Complex: Final comprehensive 

conservation plan and environmental impact statement summary—August 2009. Sacramento, CA: U.S. 

Department of the Interior, Fish and Wildlife Service, Pacific Southwest Region. 42 p. Online: http://

www.fws.gov/desertcomplex/ccp.htm [2011, April 4].

USDI Fish and Wildlife Service. 2009b. Desert National Wildlife Refuge Complex: Final comprehensive 

conservation plan and environmental impact statement volume I—August 2009 and volume II (appendices). Sacramento, CA: U.S. Department of the Interior, Fish and Wildlife Service, Pacific Southwest 

Region. 359 p.

USDI Fish and Wildlife Service. 2011a. Ash Meadows National Wildlife Refuge. Sacramento, CA: U.S. 

Department of the Interior, Fish and Wildlife Service, Pacific Southwest Region. Online: http://www.

fws.gov/desertcomplex/ashmeadows/ [2011, April 4].

USDI Fish and Wildlife Service. 2011b. Desert National Wildlife Refuge. Sacramento, CA: U.S. Department of the Interior, Fish and Wildlife Service, Pacific Southwest Region. Online: http://www.fws.gov/

desertcomplex/desertrange/ [Date accessed: April 4, 2011].
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 199

USDI Fish and Wildlife Service. 2011c. Moapa Valley National Wildlife Refuge. Sacramento, CA: U.S. 

Department of the Interior, Fish and Wildlife Service, Pacific Southwest Region. Online: http://www.

fws.gov/desertcomlex/moapavalley/ [2011, April 4].

USDI Fish and Wildlife Service. 2011d. Pahranagat National Wildlife Refuge. Sacramento, CA: USDI 

Fish and Wildlife Service, Pacific Southwest Region. Online: http://www.fws.gov/pahranagat/ [2011, 

April 4].

USDI National Park Service. 2009. Southern Nevada Visitor Use Monitoring—Southern Nevada application. Comparison of Lake Mead and Lake Mojave in Clark County, NV. Single Agency Report. 

Southern Nevada Agency Partnership, Southern Nevada Visitor Use Monitoring. U.S Department of 

the Interior, National Park Service. On file at: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station, Albuquerque, NM. 76 p.

USDI National Park Service. 2011a. Lake Mead Recreation Area. U.S. Department of the Interior, National Park Service. Online: http://www.nps.gov/lake/index.htm [2011, April 18].

USDI National Park Service. 2011b. Lake Mead Recreation Area. U.S. Department of the Interior, National Park Service. Online: http://www.nps.gov/lake/parkmgmt/park-management-plans.htm [2011, 

October 6].

USDI National Park Service. 2011c. Lake Mead Recreation Area: Park management plans. U.S. Department of the Interior, U.S. National Park Service. Online: http://www.nps.gov/lake/parkmgmt/docs.htm 

[2011, October 6].

Western Rural Development Center (WRDC). 2011. Trends in the western U.S. population brief. A Western Rural Development Center publication. Online: http://wrdc.usu.edu/htm/regional-data/nevada 

[2012, Nov 19].

Yost, A. 2012. SNAP review team. [Personal communication]. March 8. On file at: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station, Albuquerque Laboratory, Albuquerque, 

NM; RMRS-4853 files.
200 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 201

Chapter 11

Science-Based Management of Public Lands in 

Southern Nevada

Matthew L. Brooks and Jeanne C. Chambers

Introduction

Landmark legislation provides guiding principles for land management planning in 

southern Nevada and the rest of the United States. Such legislation includes, but is not 

limited to, the Forest Service Organic Administration Act of 1897 (16 U.S.C. 473-478, 

479-482 and 551), National Park Service Organic Act of 1916 (U.S.C. Title 16, Secs. 

1-4), Wilderness Act 1964 (P.L.88-577), National Environmental Policy Act of 1969 

(P.L 91-190), Endangered Species Act of 1973 (P.L. 91-205), National Forest Management Act of 1976 (P.L. 94-588), and Federal Land Policy and Management Act of 1976 

(P.L. 94-579). The acts establishing congressionally designated areas within southern 

Nevada, such as Lake Mead National Recreation Area, Spring Mountains National 

Recreation Area, and Desert National Wildlife Refuge, also contain guidelines for the 

management of these lands. These documents variously require preservation of natural 

and cultural resources and wilderness character, protection of species, and prevention of 

undesirable environmental effects from land management actions. These requirements 

must be met while allowing for multiple “uses” of certain public lands (e.g. recreation, 

ranching, resource extraction, renewable energy development, etc.) to the degree that 

they do not threaten preservation, protection, and prevention goals. Many considerations 

come into play in the development and implementation of land management plans and 

actions. The planning process requires a balancing act that sometimes pits one need or 

priority against another. When priorities align, management actions can have multiple 

benefits. In some cases, specific priorities can trump other needs and priorities and 

receive disproportionate consideration. Overall, the management of public lands is a 

very complicated and sometimes contentious process.

Science provides an objective way to help weigh quantifiable information and draw 

conclusions about the effects of past and potential future land management policies, 

decisions, and actions. When effectively integrated into adaptive management, sciencebased information can reduce uncertainties, increase knowledge, and improve decision 

making. However, the specific science information needed for effective management is 

often lacking or difficult to access or interpret. Science is typically reported in scientific 

journals as discrete units describing individual studies with other scientists as the primary 

audience. Translations of these studies and syntheses of multiple studies into formats that 

can be readily used in land management planning efforts are often lacking. Identifying 

and articulating the highest priority science and research needs is one of the primary 

purposes of the Southern Nevada Agency Partnership (SNAP; http://www.SNAP.gov) 

Science and Research Team (Chapter 1; Turner and others 2009). The SNAP Science 

and Research Strategy (Strategy) calls for a synthesis report to be written every 5 years 

summarizing the state of knowledge, information gaps, and management implications 

of scientific information as it relates to the SNAP Strategy goals (Turner and others 
202 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

2009). This General Technical Report serves as the first SNAP Science and Research 

Synthesis Report (Synthesis Report) commissioned by the Science and Research Team. 

The Synthesis Report is mostly based on information from the peer-reviewed scientific 

literature, and is itself peer reviewed and constitutes a new contribution to the scientific 

literature. This final chapter addresses Sub-goal 2.3, which is to manage current and 

future authorized southern Nevada land uses in a manner that balances public need and 

ecosystem sustainability, and Sub-goal 2.5, which is to promote an effective conservation 

education and interpretation program to improve the quality of resources and enhance 

public use and enjoyment of southern Nevada public lands. It summarizes information 

from the previous chapters on what scientific information is known currently and what 

remains largely unknown, and it discusses how science can be used to make future 

management decisions that balances public needs and ecosystem sustainability.

Current Scientific Understanding and Information Needs

Ecosystem stressors associated with human activities, wild horse and burro and 

livestock grazing, and altered fire regimes have been the traditional focus of land managers in southern Nevada. Concerns about invasive species emerged during the 1990s, 

and perhaps even greater concerns regarding climate change, energy development, and 

water development arose during the 2000s. The current challenge is to understand how 

to manage these many, and often interacting, stressors to maintain ecosystem sustainability. This task is more daunting today than it was only a few decades ago because 

of the rapidly expanding human population, the increase in the number of stressors of 

significant concern, and the need to address both public access and resource issues on 

Nevada’s public lands.

The effect of climate change on ecosystem sustainability is perhaps the greatest 

unknown stressor with respect to current management planning in southern Nevada. 

The science is clear that anthropogenic caused climate change is occurring on a global 

scale and that longer and more intense droughts and increased temperatures are becoming increasingly more likely in the deserts of southwestern North America (Chapter 2). 

However, the precise nature of these changes are not yet known and the scaled-down 

predictions necessary for determining the most effective management actions have 

yet to be developed. Also, it is not clear how these conditions will interact with other 

ecosystem stressors that land managers can potentially control. 

The current state of science can help tease out some of the most significant stressors 

threating ecosystem sustainability in southern Nevada (Chapter 2). However, there is 

much more that remains unknown regarding these stressors and potential ecosystem 

responses. The sections that follow summarize these primary knowns and unknowns, 

and suggest research priorities for the major management topics in southern Nevada.

Water and Water Use

The hydrology of southern Nevada is characterized by regionally limited recharge 

areas within mountain ranges, and interbasin flow from adjacent regions. Discharge occurs through seeps and springs, evapotranspiration, subsurface flow out of the region, 

and pumping (Chapter 3). The Colorado River (Lake Mead) and its tributaries (the 

Muddy and Virgin Rivers), along with Las Vegas Wash, form the major fluvial systems 

in the area. Although recharge from precipitation can vary widely among years, large 

subsurface aquifers historically buffered interannual fluctuations in ground water levels 

across much of southern Nevada. This means that the discharge from springs and seeps 
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 203

was maintained for long periods of time, supporting locally endemic species and their 

habitat (Chapter 6). Accelerated rates of ground water pumping during recent decades 

now affects discharge patterns threatening spring and seep ecosystems, and projected 

increases in pumping may pose even greater ecosystem threats in the future.

In order to effectively manage water resources in southern Nevada, it is important 

to understand future patterns of ground water recharge. Predictions of a warmer climate, potentially higher evapotranspiration rates, and more variable precipitation could 

dramatically alter ground water dynamics. An understanding of these potential future 

scenarios is critical to ensure that current planning decisions related to ground water 

pumping and water use do not adversely impact ground water resources or otherwise 

cause significant and potentially irreversible environmental degradation. (See Chapter 3 

for a detailed discussion of information needs related to water and water use in southern 

Nevada.)

Invasive Species

The concern associated with invasive species on wildlands in southern Nevada gained 

prominence following President Clinton’s Executive Order 13112 in 1999 and the 

development of a national strategy for management of this ecosystem stressor. At that 

time, the science to support this mandate was not very extensive, as invasion biology 

had only emerged as a major branch of ecology during the 1980s. During the past few 

decades there has been a tremendous amount of new information generated regarding 

biological invasions worldwide.

In southern Nevada it is now clear that the main invasive plants of concern in upland 

areas are annual species, especially red brome (Bromus rubens) and Mediterranean splitgrass (Schismus spp.), which are associated with altered fire regimes. Riparian areas 

are most threatened by perennial plants, especially Tamarisk (Tamarix spp.), which can 

compete with native plants, degrade wildlife habitat, and potentially alter hydrologic and 

fire regimes. Aquatic plants are not yet recognized as major threats to the degree that 

their invasive analogs in terrestrial ecosystems are. However, there are a few poised to 

invade southern Nevada that could become aquatic ecosystem transformers, including 

Eurasian water-milfoil (Myriophyllum spicatum) and giant salvinia (Salvinia molesta). 

Various non-native terrestrial animals are also of significant management concern in 

southern Nevada, ranging from ants, dogs, and cats, to free-roaming cows and equids 

(Chapter 4). The effects of species like ants and dogs and cats are related primarily to 

competition with or predation on native species, but habitat alteration by cows and 

equids is also a major concern. Non-native aquatic animals range from the quagga 

mussel (Dreissena rostriformis), American bullfrog (Rana catesbeiana), red swamp 

crayfish (Procambarus clarkia), to various fish species. Threats from these species 

include altered food web dynamics and predation on native species.

Perhaps one of the most significant unknowns relates to the ability to accurately 

predict future patterns of spread for existing invasives, establishment and spread of 

new invasives, and the relative and cumulative threats posed by all invasive species in 

southern Nevada. This information, and an understanding of the feasibility for controlling the different species, is critical for prioritizing management actions among the 

plethora of non-native and potentially invasive species in this region. (See Chapter 4 

for a detailed discussion of information needs related to invasive species management 

in southern Nevada.)
204 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

Fire History, Effects, and Management

It is generally understood that fire has been infrequent in most of southern Nevada 

since the last ice age, which ended approximately 10,000 years ago (Chapter 5). What 

is less recognized is that some landscapes have continuously experienced at least moderate fire frequencies during this time period. These include sagebrush, piñon-juniper, 

and mixed conifer ecosystems, and in these areas fire may be an important ecosystem 

process. However, the vast majority of the current southern Nevada landscape is dominated by blackbrush and lower elevation vegetation types that did not support frequent 

fire historically and where large and/or frequent fires are ecosystem stressors. Key fire 

management messages that can be derived from current science are that (1) potential 

effects of fire should be evaluated in the context of ecosystem type, fire behavior characteristics, and site-specific characteristics (e.g. fire history); (2) fire suppression is 

ultimately the most effective way to manage fire at middle and lower elevation where 

fire was historically infrequent, but wildland fire use or fire surrogates may be appropriate under certain circumstances at higher elevations; and (3) the post-fire rehabilitation/

restoration tools that are currently being used at middle to lower elevations appear to 

be ineffective or poorly evaluated (Chapter 5). 

Information is needed on both long-term ramifications of fire in middle and upper 

elevation vegetation types (i.e., blackbrush and above), and post-fire management of 

lower elevation vegetation types dominated by creosotebush (Larrea tridentata) and 

saltbush (Atriplex spp.). In all future fire studies, the potential influence of climate 

change should be considered to place the results in the context of climate projections 

for the next decades through the end of the current century. (See Chapter 5 for a detailed discussion of information needs related to fire history, effects, and management 

in southern Nevada.)

Species of Conservation Concern

Aside from the desert tortoise, which has been studied more than any other species 

in southern Nevada, relatively little is known about the life history characteristics and 

specific habitat requirements of most species in this region (Chapter 6). This includes 

the species covered under the Clark County Multiple Species Habitat Conservation Plan. 

Research has often focused on mitigation strategies to protect sensitive species without 

a full understanding of the life history and ecophysiological constraints on the species 

and the stressors that are causing their declining status.

With so many unknowns associated with the many species of concern in southern 

Nevada, it is a challenge to prioritize which species should be the focus of scientific 

research and which questions should be addressed. The default is often to focus on 

species that agencies have specific legal requirements to protect (e.g., Federally listed). 

Development of effective conservation plans requires an understanding of the life history 

characteristics, habitat requirements, and specific stressors affecting the listed species. 

These plans may initially lack the desired level of detail. However, critical information 

needs can be identified in the planning process and new research projects coupled with 

habitat and population monitoring can be used to develop an effective adaptive management program. (See Chapter 6 for a detailed discussion of information needs related to 

species of conservation of concern in southern Nevada.)
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 205

Maintaining and Restoring Sustainable Ecosystems

The overarching objective for land managers in southern Nevada is to maintain and 

restore sustainable ecosystems that are resilient to disturbance and resistant to invasion 

(Chapter 7). The ecosystems types within southern Nevada differ significantly in both 

their environmental characteristics and dominant stressors and, consequently, in their 

resilience to disturbance and resistance to invasive species. In order for restoration and 

management strategies to be effective, they must account for these differences. A useful 

decision support framework based on ecosystem resilience and resistance distinguishes 

among (1) protection from current and future stressors; (2) preventive management 

actions designed to increase resilience and resistance of areas with declining ecological conditions; and (3) restoration activities following disturbance or other ecosystem 

degradation (table 7.1). This framework allows for customized guidelines for each of 

the major ecosystems types in southern Nevada (table 7.2). An integrated and consistent 

assessment of southern Nevada ecosystems and their relative resilience and resistance 

can be used to prioritize management and restoration activities using this framework. 

Monitoring programs designed to track ecosystem changes in response to both stressors 

and management actions can be used to increase understanding of ecosystem resilience 

and resistance, realign restoration and management approaches, and implement adaptive 

management.

Cross-cutting information needs for restoration and management of southern Nevada’s diverse ecosystems include a better understanding of the factors that determine 

resilience and resistance and of the interacting effects of the region’s stressors. They 

also include knowledge of the environmental conditions required for establishment and 

persistence of native plant species and methods for their restoration. (See Chapter 7 for 

a detailed discussion of information needs related to maintaining and restoring sustainable ecosystems in southern Nevada.)

Human Interactions with the Environment Through 

Time and Preserving Heritage Resources

Southern Nevada has been continuously inhabited by humans at least since the 

end of the last ice age (Chapter 8). This period marks the shift from a more mesic and 

temperate climate to the more arid desert climate that exists today. During most of the 

post ice age Holocene (i.e., the last 12,000 years), human occupation was characterized by small nomadic bands that migrated seasonally following resources needed for 

subsistence. During the last few thousand years, larger settlements emerged that were 

associated with a move towards more agricultural societies in the riverine bottomlands. 

The first Europeans travelled to southern Nevada in the late 1700s, and by the middle 

1850s settlers were steadily migrating into the region along the Old Spanish Trail (later 

the Mormon Road) and displacing Native Americans from their agricultural, foraging, 

and hunting lands. Settlers also brought with them horses and livestock that were having 

significant effects on the landscape as early as the 1800s, and these stock animals have 

been continuously present on through to the present (Chapter 2). 

Population levels moved upward with the construction of Hoover Dam in the 1930s, 

but really increased substantially during the past few decades resulting in urban sprawl, 

increased development within public lands, and increased visitation to remote areas 

of southern Nevada (Chapter 9). This has resulted in the loss of cultural sites through 

development, looting, and vandalism. Public education, law enforcement, and monitoring of cultural sites are widely recognized as ways to minimize damage to these sites. 

However, agency resources are generally insufficient to address all of these needs.
206 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013

The major remaining information gap is the limited extent of archeological survey 

coverage; only 7 percent of Southern Nevada has been surveyed, primarily within the 

Las Vegas Valley and associated with development projects (Chapter 8). A complete 

survey for the region is not realistic, but additional targeted surveys that expand and 

improve the sample of lands examined would go a long way towards improving the 

baseline information in the region. More comprehensive links between archeological 

sites and their environmental settings would increase understanding of potential interactions between humans and ecosystem conditions. Also, continued research is needed to 

evaluate the effectiveness of public education and outreach, volunteer site monitoring, 

and law enforcement programs in achieving the objectives of reducing damage to and 

loss of cultural sites. (See Chapters 8 and 9 for a detailed discussion of information 

needs related to human interactions with the environment through time and preserving 

heritage resources in southern Nevada.)

Recreation Use on Federal Lands

The vast majority of lands are open to human use in southern Nevada. The burgeoning 

human population is increasing the use of these lands for recreational purposes, creating a very difficult challenge for Federal land managers (Chapter 10). Also, the human 

population is becoming more urban and multi-cultural, resulting in potential changes 

in recreational patterns that will require flexibility in current management approaches. 

To plan for these changes, land managers need information about how these changing 

demographics may affect the types and patterns of recreational use of public lands. (See 

Chapter 10 for a detailed discussion of information needs related to recreation use on 

Federal lands in southern Nevada.)

The Role of Science in Land Management

Management that balances public need and ecosystem sustainability is informed by 

the science information in this Synthesis Report. The goal of ecosystem sustainability 

has its origins in legislation mentioned at the beginning of this chapter, and subsequent 

national policies that call for natural resources, and by inference the ecosystem processes 

that sustain them, to be preserved unimpaired for future generations. However, land managers 

must balance the goal of ecosystem sustainability with other goals derived from other laws 

and national policies associated with recreation, resource extraction, and other land uses 

that collectively constitute the land management context of southern Nevada. Although 

science often plays a major role in the initial legislation and policy development and can 

form the foundation of initial planning goals and objectives, subsequent science produced 

through targeted research studies and monitoring for status and trend of resources has 

the greatest influence on deciding when a management response is warranted or when 

established management objectives may need to be modified (fig. 11.1).

Objectives should be written with specific science-based, objective, and measurable 

standards in mind, for example, allowing livestock grazing up to a limit of x percent 

vegetation biomass consumption based on a sliding scale that takes into account recent 

climatic conditions and other potential interacting stressors. Objective standards greatly 

simplify the process of monitoring and decision making because they are relatively 

unambiguous (fig. 11.1). The problem is that science is often insufficient to justify 

specific standards, and therefore standards are based on general scientific theory and 

are relatively subjective, for example, allowing grazing practices that do not negatively 

affect the health, productivity, and diversity of plant communities, which is subjective 

and hard to monitor. Subjective standards require more complicated monitoring and 

generally make decision making more difficult and controversial.
USDA Forest Service Gen. Tech. Rep. RMRS-GTR-303. 2013 207

Once management plans are implemented, monitoring plans that are specifically 

coupled with management objectives can help land managers monitor the status and 

trend of their ecosystem resources and determine if management responses or modifications of management objectives are warranted (fig. 11.1). With the advent of the 

information age and ability to archive and share data remotely, there has been a move 

towards more standardized monitoring methods to facilitate large scale analyses across 

multiple land management agency units. However, these standard methods are often 

not ideally suited for evaluating management objectives that are designed for smaller 

landscapes and their local land management contexts. Land managers must understand 

these potential limitations and choose their monitoring and data management methods 

carefully to ensure that they will give them the scientific information necessary to effectively evaluate their management objectives and management actions.

The Role of Science in Education

This Synthesis Report serves as an outreach document to inform stakeholders 

and the general public about the major ecosystem stressors, and natural, cultural, and 

recreational resources in southern Nevada. It also provides valuable information on 

management alternatives.

An educated populace makes it easier for land managers to communicate science-based 

management with the public, and should ultimately streamline the approval processes 

for land management plans. As mentioned above, science information is often written by 

scientists for scientists and science products are often not ideal for communication with 

the general public. There is, therefore, a need for science-based objective summaries 

of key land management topics that clearly distinguish between what is scientifically 

known and what is more generally derived from professional opinion and cultural influences. The mode of information delivery should also be varied to capture a wide range 

of audiences (e.g. print, radio, television, websites, and social media).

Reference

Turner, K.; LaVoie, A.M.; Ronning, C.J.; Sharp, R.M.; Palmer, C.J.; Miller, J.M. 2009. SNAP Science and 

Research Strategy (Strategy). Southern Nevada Agency Partnership. Online: http://snap.gov/upload/

SNAP-S-R-Strategy-2009r.pdf. [2011, April 6].

Figure 11.1—The role of 

science in the management 

of Federal lands in southern 

Nevada




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