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42° 4 78 9 80 1 IDAHO 80 78e Ecoregions of the Southwest OREGON 80a 9i 80e 80a 78i 78h 78g 9g Goose 78d 78d 80l 9h Lake math Rive 9t 9g 9g 1a Kla r Lower 80j 80j 80k 78d 4e Klamath 80l (Arizona, California, Nevada) 80g 80k 78d Lake Clear Lake 80a 80j 80b 78j 78l 4e 9s Reservoir 9g 80d 78i 78j 78d 80j 9k 9j 80j Ecoregions are areas where ecosystems (and the type, quality, and maps, publications, and GIS data for U.S. and North American 1 Coast Range 78m 78o 80j 80g 80a 41° 80k 80b quantity of environmental resources) are generally similar. They are 1a Coastal Lowlands ecoregions can be obtained at www.epa.gov/eco-research/ecoregions. K 78a 78p 80j 13c l 4e 9m a 80d 80g 80j designed to serve as a spatial framework for the research, assessment, 1i Northern Franciscan Redwood Forest m 4g REFERENCES a 4d 9l th 4e 80a 80b management, and monitoring of ecosystems and ecosystem 1j King Range/Mattole Basin 78k 80b 78i 78o 78o 78k 9o 13l 13c Bryce, S.A., Woods, A.J., Morefield, J.D., Omernik, J.M., McKay, T.R., 41° 1k Coastal Franciscan Redwood Forest R 80j 80j 13k components. These Level III and IV ecoregions, compiled at a scale of iv 9n e 78o 13k 13q Brackley, G.K., Hall, R.K., Higgins, D.K., McMorran, D.C., Vargas, K.E., 1l Fort Bragg/Fort Ross Terraces r 78l 4f 9q 13k 1:250,000, revise and subdivide an earlier, smaller-scale national 1i 78k 78n 9l 13q Petersen, E.B., Zamudio, D.C., and Comstock, J.A., 2003, Ecoregions of 1m Point Reyes/Farallon Islands 78l 13z 13q 13g 78m 80j ecoregion map (Omernik, 1987). The ecoregions were identified by 4f Nevada: Reston, Virginia, U.S. Geological Survey (map scale 1:1,350,000). 1n Santa Cruz Mountains 78o 9l 13k H 13m 80j 13k u 13o analyzing the spatial patterns and the composition of biotic and abiotic 80d 13j 13k m 1o San Mateo Coastal Hills 78l 78k 80j b 13h o 13a 13c Commission for Environmental Cooperation, 1997, Ecological regions of ld 13b phenomena that affect or reflect differences in ecosystem quality and Eureka t 13n 9r 13l 13a 13b North America – toward a common perspective: Montreal, Quebec, Canada, 4 Cascades 5 80d integrity (Omernik, 1987, 1995). These phenomena include geology, Shasta 4e 4g 80j 13k 13l 13l R 13q 13a 4f iv Commission for Environmental Cooperation, 71 p. (map revised 2006), 4d Cascade Subalpine/Alpine Lake 13k e 13q 4f 4f 80j r landforms, soils, vegetation, climate, land use, wildlife, and hydrology. www.epa.gov/eco-research/ecoregions-north-america. 1a 78l 4e 13q 13a 4e High Southern Cascades Montane Forest P 13k 13o Redding 13k 13q 13e The relative importance of each characteristic varies from one 4f Low Southern Cascades Mixed Conifer Forest 4f 9p 13l 13b 40° A 78l 5 4f 13k 13q 13b ecological region to another regardless of the hierarchical level. An Griffith, G.E., Omernik, J.M., Johnson, C.B., and Turner, D.S., 2014, 4g California Cascades Eastside Conifer Forest 78l 80g 13k 13l 13b 13a 13h 13k 13h Ecoregions of Arizona: U.S. Geological Survey Open-File Report 2014-1141, 78l 4d 13a 13b ecoregion framework is critical for structuring and implementing 4h Southern Cascades Foothills C 6ar 4h 4e 4f 80j 13l 13s 13a 13h 13h 13t 13q 13q with map, scale 1:1,325,000, http://dx.doi.org/10.3133/ofr20141141 80j 13l 13l 13q ecosystem management strategies across federal agencies, state 13l 13g 13p 5 Sierra Nevada I 5c 13aa 13k 13q 13q Griffith, G.E., Omernik, J.M., Smith, D.W., Cook, T.D., Tallyn, E., Moseley, 40° 78l 4e 5c 13h agencies, and nongovernment organizations that are responsible for Honey Lake 13z 13e 5a Sierran Alpine F 1j 6f 6e 5c 13h 13k K., and Johnson, C.B., 2016, Ecoregions of California (poster): U.S. Geological 6a 13h 13h 13k 13l 13e different types of resources within the same geographic areas 5b Northern Sierra Subalpine Forests 5c 13q 13a 13c Survey Open-File Report 2016–1021, with map, scale 1:1,100,000, I 4e 5d Pyramid 13s (McMahon and others, 2001; Omernik and Griffith, 2014). 5c Northern Sierra Upper Montane Forests 78q 13k 13q 13q 13b http://dx.doi.org/10.3133/ofr20161021. C 5f Lake 5d Northern Sierra Mid-Montane Forests 13x 13a 13a 7a 5c 5c 13k 13h 13s 13b A Roman numeral hierarchical scheme has been adopted for different 5e Northern Sierra Lower Montane Forests 5c 13h McMahon, G., Gregonis, S.M., Waltman, S.W., Omernik, J.M., Thorson, 78r 13x 13h 13t 13b 13p 13l 13z 13q levels of ecological regions. Level I is the most general level, dividing T.D., Freeouf, J.A., Rorick, A.H., and Keys, J.E., 2001, Developing a spatial 5f Northeastern Sierra Mixed Conifer-Pine Forests 7a 5c 13s 13b 13h 13s 13s North America into 15 ecological regions. Level II divides the continent framework of common ecological regions for the conterminous United 5g Central Sierra Mid-Montane Forests 13t 13e 7b 13ab 13x 13s 5h Central Sierra Lower Montane Forests 7b 13h 13a into 50 regions (Commission for Environmental Cooperation, 1997, 2006). States: Environmental Management, v. 28, no. 3, p. 293-316. 13aa 13s 13a 13g 13t 13z 5i Eastern Sierra Great Basin Slopes 13t At level III, the continent contains 183 ecological regions of which 105 39° 5e 5c Reno 13j 13z 13b Omernik, J.M., 1987, Ecoregions of the conterminous United States (map 5j Eastern Sierra Mojavean Slopes 13t 13r 13q 13b 5f 5 occur in the continental United States (United States Environmental supplement): Annals of the Association of American Geographers, v. 77, no. 1, 5k Southern Sierra Subalpine Forests 13s 13z 13t 13p 13e Protection Agency [U.S. EPA], 2013; Wiken and others, 2011). p. 118-125, scale 1:7,500,000. 1k 5b 13s 13z 13e 5l Southern Sierra Upper Montane Forests 7a 13h 13k 7c 5b 13b 7a 13x 13k 13h 13t 13h 13t 13q 13q Sacramento River 13z Omernik, J.M., 1995, Ecoregions – a framework for environmental 39° 5m Southern Sierra Mid-Montane Forests 5d 13h The Level III and IV ecoregions of the Southwest were mapped in 5n Southern Sierra Lower Montane Forest and Woodland Level III boundary 7c 13s 13q management, in Davis, W.S. and Simon, T.P., eds., Biological assessment 7f 5b Carson City 13k 13k 13e state-level projects in Arizona (Griffith and others, 2014), California 6g 13e 5o Tehachapi Mountains 7e Lake 13t and criteria-tools for water resource planning and decision making: Boca Level IV boundary 13k 13q (Griffith and others, 2016) and Nevada (Bryce and others, 2003). These Tahoe 13x 13t 13t International boundary Clear 13k 13h 13e 13e Raton, Florida, Lewis Publishers, p. 49-62. 6 Central California Foothills 6i Lake 6h 13s 13q 13e projects were conducted primarily by the U.S. EPA National Health and State boundary 1l 6m 13e and Coastal Mountains 6k 13h 13s 13b Environmental Effects Research Laboratory (Corvallis, Oregon) in Omernik, J.M., 2004, Perspectives on the nature and definition of ecological 5f 13h 6a Tuscan Flows County boundary 6f 5b Walker 13h 13t regions: Environmental Management, v. 34, Supplement 1, p. s27-s38. 7h Lake collaboration with U.S. EPA Region 9, state resource management 6b Northern Sierran Foothills 6j 13y 13t 13t 13s 13q 13q agencies, and other federal agencies, such as the U.S. Geological Omernik, J.M., and Griffith, G.E., 2014, Ecoregions of the conterminous United 6c Southern Sierran Foothills 13t 6b 13s 13c States ‒ evolution of a hierarchical spatial framework: Environmental 6d Camanche Terraces 13 Central Basin and Range 6g Sacramento 13y 13s Survey, U.S. Department of Agriculture (USDA)–Natural Resources 7g 7h 5b 5f 13h 13b Management, v. 54, no. 6, p. 1249-1266, http://dx.doi.org/10.1007/s00267-014-0364-1 38° 6e Tehama Terraces 13a Salt Deserts 13y 13v 13b Conservation Service, USDA–Forest Service, and the Bureau of Land 13y 13q 13b 6f Foothill Ridges and Valleys 13b Shadscale-Dominated Saline Basins 6g 13v Management. The mapping was associated with an interagency effort to U.S. Environmental Protection Agency, 2013, Level III ecoregions of the 6l 7a 5g 5c 13y 13s 6g North Coast Range Eastern Slopes 13c Sagebrush Basins and Slopes 6k 13w 13t 13s continental United States: Corvallis, Oregon, USEPA – National Health and 6k 13y 13h 13e develop a common framework of ecological regions (McMahon and 6h Western Valley Foothills/Dunnigan Hills 13d Woodland- and Shrub-Covered Low Mountains 5h 13p 13q 38° 6n 13y 13h 13h others, 2001). Although there are differences in the conceptual Environmental Effects Research Laboratory, 6i Clear Lake Hills and Valleys 13e High Elevation Carbonate Mountains 13y 13s 13u 13c 6p 5a 13aa 13y approaches and mapping methodologies used by the different federal www.epa.gov/eco-research/level-iii-and-iv-ecoregions-continental-united-states. 6j Mayacmas Mountains 13g Wetlands 6q 7j 13x 13e 6o 7k 5k 13h 6k Napa-Sonoma-Lake Volcanic Highlands 1m San Pablo 6d 13ad 13q agencies for developing their own regional frameworks, these Wiken, E., Jiménez Nava, F., and Griffith, G., 2011, North American 13h Lahontan and Tonopah Playas Bay 6d 5a 13h 13b Stockton Mono 13t 13h 13q collaborative ecoregion projects were a step toward attaining consensus Terrestrial Ecoregions - Level III. Commission for Environmental 6l Napa-Sonoma-Russian River Valleys 13j Lahontan Salt Shrub Basin 1k 6q Lake 13x 13v 13r 13q 13a 13p 5 13v 13s Cooperation, Montreal, Canada. 149 p., 6m Sonoma-Mendocino Mixed Forest 13k Lahontan Sagebrush Slopes 7l 13u 13s 13a 13d and consistency in ecoregion frameworks for the entire nation. 13ad 13h 13b http://ecologicalregions.info/htm/pubs/NA_TerrestrialEcoregionsLevel3_Final- 6n Bodega Coastal Hills 13l Lahontan Uplands Oakland 5m 13h 13r 13q San Francisco 5 5i 13q 5 13h 13v 13r 13h Explanations of the methods used to define these ecoregions are given 2june11_CEC.pdf 6o Marin Hills 13m Upper Humboldt Plains Sa 13v 13q n San 13w 6u J 5a 6p Bay Flats 13n Mid-Elevation Ruby Mountains 6s Francisco o 13aa in Omernik (1995, 2004) and Omernik and Griffith (2014). Additional a 13v Bay q 5 6q Suisun Terraces and Low Hills Fremont u 13w 13v 37° 13o High Elevation Ruby Mountains in Modesto 13u 5 13v 6r East Bay Hills/Western Diablo Range 13p Carbonate Sagebrush Valleys R 13y 20 iv 6b 13w 19 20 e 13ae 13v 6s San Francisco Peninsula 6p 6r r 13w Lake 13q Carbonate Woodland Zone 20h 20c 7o Powell 20h 6t Bay Terraces/Lower Santa Clara Valley 13r Central Nevada High Valleys San Jose 13ac 13v 20h 1o 6t 5 7n 13u 13h 14l 13v 13w 13g UTAH 20c 20h 37° 6u Livermore Hills and Valleys 13s Central Nevada Mid-Slope Woodland and Brushland 14b 20c 20d 20h 23c 6v Upper Santa Clara Valley 14j 13h 14b 14 13t Central Nevada Bald Mountains 1n 7m 5k 20d 6x 5l 14b 14b 20c 20e 22r 6w Monterey Bay Plains and Terraces 13u Tonopah Basin 5i 13w 14a 14b 14a 5m 5a 14c 20e 20c 22i 6x Leeward Hills 7d 14f 14a 20h 13v Tonopah Sagebrush Foothills 13v 14c 14b 6y Gabilan Range 5 13y 23c 13w Tonopah Uplands Santa 6z Diablo Range 6v 14l r 22d 20i 13x Sierra Nevada-Influenced Ranges Cruz 14a ive 20i 22x 22q 22t 22 14h R 23c 6aa Eastern Hills 14l in 13y Sierra Nevada-Influenced High Elevation Mountains MONTEREY 14f g 5n 14o r 22r O 6w Fresno 14d 14b i 6ab Pleasant Valley/Kettleman Plain BAY Salinas 5 14f V 20c 13z Upper Lahontan Basin 14b 23j 22q C 5a 23d 5 a 6c 14j 14f 14c 22v 6ac Temblor Range/Elk Hills Salinas River 6z 6aa 14o 14g 13aa Sierra Nevada-Influenced Semiarid Hills and Basins C li 22x fo 6ab r 23 6ad Grapevine Transition 6y n 36° 13ab Sierra Valley i 14l 14f a 14f 22y 6ae Tehachapi Foothills E 14b 14b 13ac Upper Owens Valley 7p 7d 14f 14b 22q 7q 14o Owens 6af Salinas Valley 5k 14c 13ad Mono-Adobe Valleys A Lake 14e A Visalia 14e 22w q 14k 14b Las Vegas 6ag Northern Santa Lucia Range u 14f 14f 14d 23c 13ae Bishop Volcanic Tableland e 5 22r N 6ah 6af d 5k 14f 14b 5 22d 36 6ah Santa Lucia Coastal Forest and Woodland u 14g 14b 14b 6ag c 14i 14b t 14b 14c 23j 22u 6ai Interior Santa Lucia Range 14 Mojave Basin and Range 14l 14j 14m Lake 23c 7d 5l Henderson 14b 6aj Southern Santa Lucia Range 14a Eastern Mojave Basins 6ab 14l 5 Mead 14a 14b 14f 14e 6ak Paso Robles Hills and Valleys 6al 7r 5l 14p 14b Eastern Mojave Low Ranges and Arid Footslopes 14l 14b 14b 22y 22z 6al Salinas-Cholame Hills 6aa 14f 23j 14c Eastern Mojave Mountain Woodland and Shrubland 7d 14b 14b 14n 14a 22p 6am Cuyama Valley 14d Eastern Mojave High Elevation Mountains 5i 14b 14b 22s 6an Carrizo Plain 14c 14b 14f 22aa L 23 14e Arid Valleys and Canyonlands 6ab 14j 14f itt 14f le 14o C 6ao Caliente Range 14f 14j o 14f Mojave Playas 14f 23i lo 14c 14b 23d r 7v ado 22z Ri 6ap Solomon-Purisima-Santa Ynez Hills 14g Amargosa Desert 6ae 14h 14b 22z 23d 23k ver 14c 14e 14a 23e 23i 6ai 6ak 14b 14f 14c 35° 6aq Santa Maria/Santa Ynez Valleys 14h Death Valley/Mojave Central Trough 7s r 78 Klamath Mountains/ 7u 7t e 5n 14b 22o 6ar Upper Sacramento River Alluvium 6aj iv 14k 14j 5 Flagstaff 14i Mesquite Flat/Badwater Basin California High North Coast Range Kern R 5m 5m 5i 14k 14b 14b 14b 23i 14j Western Mojave Basins 78a Rogue/Illinois/Scott Valleys Bakersfield 14b 5Winslow 22j 7 Central California Valley 5 Kingman 5j 14f 14k 14b 14c 5 14k Western Mojave Low Ranges and Arid Footslopes 78d Serpentine Siskiyous 14n 35° 7a Northern Terraces 6ac 14k 14b 14l Western Mojave Mountain Woodland and Shrubland 78e Inland Siskiyous 5o 14b Bullhead 23l 7b North Valley Alluvium 14k 14b 14f 5 23h 23e t 14k 14a City 23l Sedona 7v c 14b 14m Western Mojave High Elevation Mountains 78g Klamath River Ridges 6an u 14o 14b 23l 5 7c Butte Sink/Sutter and Colusa Basins d 14b 14b 23l e 14k 14f 14n Mojave Lava Fields 78h Border High-Siskiyous 6ao u 7d Southern Hardpan Terraces 7s q 14k 14f A 14b 14e 6aq s 14j 14o Mojave Sand Dunes 78i Western Klamath Low Elevation Forests e 14o 14a V l 14k e 7e Sacramento/Feather Riverine Alluvium e 14k rd 6ad 14f 14k 23l ng 14b 22z 23l e 14p Lower Grand Canyon 78j Western Klamath Montane Forests Santa 5 A 14k 81l R 7f Sutter Buttes 6am s 14b 14c iv 8f o 14k 14b e 23e 78k Eastern Klamath Low Elevation Forests Maria L 14f Prescott r 23h 7g Yolo Alluvial Fans 14f 14b 81l 81k 5 23c 20 Colorado Plateaus 8g 8f 8f 14b 14n 14b 78l Eastern Klamath Montane Forests 14k Lancaster 14k 14n 14a 7h Yolo/American Basin 14k 14f 20c Semiarid Benchlands and Canyonlands 78m Marble/Salmon Mountains-Trinity Alps 6aq 6ap 8b 8f 5 14k 14n 81i 23l 7j Delta 8f 81l 20d Arid Canyonlands 8b 14a 14b 7k Lodi Alluvium 78n Scott Mountains 14n 81g 23l 34° 20e Escarpments 14b 14h 14b 23b 23l 78o Klamath Subalpine 8a 14f 14f 23i 7l Stockton Basin 8c 81j 81k 23l 23b 20h Sand Deserts 23b 23i NEW MEXICO 14b 81k 81l 23l 23b 23d 7m San Joaquin Basin 78p Duzel Rock 85a 14f 5 14o 81i 23d 20i Cold Desert Sagebrush-Grasslands 78q Outer North Coast Ranges 85c 8e 14o 23d 7n Manteca/Merced Alluvium Santa 8f 14a 81h 23d Barbara 14b 23l 34° 7o Westside Alluvial Fans and Terraces 78r High North Coast Ranges 22 Arizona/New Mexico Plateau 8f 8c r 23b 85b 85c 14f e 81k 23c 85c 14o v 81d 7p Granitic Alluvial Fans and Terraces Oxnard 5 8e i 23l 79 Madrean Archipelago 5 R 23d

22d Virgin/Shivwits Woodland 8d 81d 81i 81i 81l 7q Panoche and Cantua Fans and Basins Pasadena 81i Santa Cruz Island 85l 14b 23 79a Apachian Valleys and Low Hills Los Angeles 85k o 23b 22i San Juan/Chaco Tablelands and Mesas Santa Miguel Island 5 85c d 7r Tulare Basin/Fresno Slough 85i a 81k 81l 23l 79b Lower Madrean Woodlands 85i SANTA r 81d 81l o 7s Kern Terraces 22j Semiarid Tablelands Anacapa Island MONICA 85c 5 Riverside l 81k 81l 81i 81i 23b 23l 85i 85d 85l o 79c Madrean Pine-Oak and Mixed Conifer Forests BAY 81i Scottsdale Anaheim C 7t South Valley Alluvium 22o Northeast Arizona Shrub-Grasslands 14b 81h 81i 81i 81k Santa Rosa Island 81d 5 23l 79d Willcox Playa Long Beach 5 8d Glendale 81k 81k 7u Antelope Plain 85l 81e Blythe 23b 23l 22p Little Colorado Valley/Painted Desert 79e Madrean Basin Grasslands 5 Santa Ana 85l 85k 8f 81k 5 Phoenix 23h 85c 5 81a 81h 81n 5 Mesa 23l 7v Southern Clayey Basins 22q Dinetah Tablelands 81k 23b 81l 79e 81j 81j 5 23b 23l 80 Northern Basin and Range 81i 81i 81l 81k 22r Mesa Highlands 81i 81g 81i 81i 81k Chandler 81l 8 Southern California Mountains 8f 5 23b 23l 22s Hopi Buttes 80a Dissected High Lava Plateau 85m 81k 33° 81i 81k 81n 8a Western Transverse Range Lower Montane 80b Semiarid Hills and Low Mountains 81b 79c 79b Shrub and Woodland 22t Chinle Valley and Mesas Santa Barbara Island 81i 81k 79b G 80d Pluvial Lake Basins 81i il 22u Kaibito/Moenkopi Sandy Plateaus 8f a 8b Western Transverse Range Montane Forest 8e 8f Salton 81n 80e High Desert Wetlands 85j 79e 79b Riv 24c 81k 79c 24c er 8c Arid Montane Slopes 22v Marble Platform 85f Sea 81i 81k 79b 33° 80g High Lava Plains Santa Catalina Island 81i 81i 81k 81i 81k 8d Southern California Subalpine/Alpine 22w Grand Canyon 85j 81m 81i 81o 80j Semiarid Uplands San Nicolas Island 81c 24a 81i 81i 81k 79b 8e Southern California Lower Montane Shrub and Woodland 22x Arizona Strip Plateaus 79b 79c 80k Partly Forested Mountains 81a 81i 81m 81f r 81n 81k 85g 8f 81j ive 8f Southern California Montane Conifer Forest 22y Uinkaret/Aubrey Montane Conifer Forest 80l Salt Shrub Valleys a R 81m il 81m 81k 79e 81d G 81k 81l 79c 79b 24 8g Northern Transverse Range 22z Chino/Coconino Grasslands and Shrubsteppe 81i 81i 85e El Centro 81g 81o 81k 79a 81 Sonoran Basin and Range San Clemente Island 81i 79b 22aa Hualapai/Coconino Woodlands 8f 5 81i 81a Western Sonoran Mountains 85j 81b 81d 81i 9 Eastern Cascades Slopes and Foothills San Diego 5 81i 81k 79c 79b 79e 79a 81b Western Sonoran Mountain Woodland 81g Yuma 81i 9g Klamath/Goose Lake Basins 23 Arizona/New Mexico Mountains 85 Southern California/Northern Baja Coast 5 85h 81a 81k 9h Fremont Pine/Fir Forest and Shrubland 5Chula Vista 81i 81i 81k 79b 23b Madrean Lower Montane Woodlands 81c Western Sonoran Basins 85a Santa Barbara Coastal Plain and Terraces 81j 81j Tucson BAJA CALIFORNIA 81k 79c 79e 79d 9i Southern Cascades Slope 81d 81i 5 79e 23c Montane Conifer Forests 81d Sand Hills/Sand Dunes 85b Oxnard Plain and Valleys 81i 81l 32° 9j Klamath Juniper Woodland/Devils Garden 23d Arizona/New Mexico Subalpine Forests 85c Venturan-Angeleno Coastal Hills 81k 79b 81e Upper Coachella Valley and Hills 81k 81k 9k Shasta Valley 81i 81i 85d Los Angeles Plain 81i S 79c 23e Conifer Woodlands and Savannas 81f Imperial/Lower Coachella Valleys a 81d n 9l Pit River Valleys 79b 23h Lower Mogollon Transition 81g Lower Colorado/Lower Gila River Valleys 85e Diegan Coastal Terraces 81m 81k P 79b e 81i 79a 32° d 9m Warner Mountains 81k r 23i Montane and Subalpine Grasslands 81h Sonoran Playas 85f Diegan Coastal Hills and Valleys o 79b 79b 9n High Elevation Warner Mountains 81l 79b R 81k i 79 81i Central Sonoran/Colorado Desert Mountains 85g Diegan Western Granitic Foothills SCALE 1:2,000,000 Support for the production of this map provided by: U.S. Geological Survey, 81k v 23j Northern Woodlands and Sagebrush 81l 79e e 9o Likely Tableland Western Geographic Science Center, Menlo Park, California, and U.S. 79b 79b r 23k Sunset Crater Volcanics 81j Central Sonoran/Colorado Desert Basins 85h Morena/Boundary Mountain Chaparral 0 50 100 150 SONORA 79c 79e 79b 9p Modoc/Lassen Juniper-Shrub Hills and Mountains Environmental Protection Agency, National Health and Ecological Effects 81k 79e Sierra Vista 81k Arizona Upland/Eastern Sonoran Mountains 85i Northern Channel Islands Miles 79a 79b 23l Mogollon Transition Conifer Forests Research Laboratory, Western Ecology Division, Corvallis, Oregon. 79a 79b 5 79e 9q Adin/Horsehead Mountains Forest and Woodland 81l Arizona Upland/Eastern Sonoran Basins 85j Southern Channel Islands Kilometers 79b 79b 9r Adin/Dixie Low Hills 0 75 150 225 79b 79a 24 Chihuahuan Deserts 81m Sonoran Lava Fields 85k Inland Valleys CITING THIS MAP: U.S. Environmental Protection Agency. 2016. Ecoregions of the Southwest (Arizona, California, Nevada). 79c 79b 79e 79e 9s Modoc Lava Flows and Buttes 24a Chihuahuan Basins and Playas 81n Gila/Salt Intermediate Basins 85l Inland Hills NAD 1983 California Teale Albers Projection U.S. EPA, National Health and Ecological Effects Research Laboratory, Western Ecology Division, Corvallis, Oregon. 5Nogales 9t Old Cascades 24c Low Mountains and Bajadas 81o Middle Gila/Salt River Floodplains 85m Santa Ana Mountains Standard parallels 34ºN and 40.5ºN Map scale 1:2,000,000. https://www.epa.gov/eco-research/ecoregion-download-files-region#pane-09.

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