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Study Areas
The pinyon-juniper and cheatgrass risk models were developed for 14 ecological provinces
encompassing southeastern Oregon, southwestern Idaho, western Utah, all of Nevada,
northeastern California, and a small portion of northwestern Arizona (fig. 1; Suring et al. 2005).
The province boundaries, adapted from Bailey (1980) and Anderson et al. (1998), reflect
attributes such as geologic age, lithology, regional climate, and potential natural communities
(Anderson et al. 1998, West et al. 1998). We focused our initial model evaluation on the John
Day and Mono Basin provinces, because they represent important but contrasting regions with
respect to land ownership patterns, sagebrush and pinyon-juniper communities, and associated
threats.
Figure 1─Ecological provinces in the Intermountain West, adapted from Bailey (1980) and Anderson et al. (1998).
John Day Ecological Province
The John Day province extends across much of central and eastern Oregon, encompassing 3.5 x
106 ha of diverse habitats ranging from coniferous forests to expansive shrubsteppe (fig. 6). The
area is mostly rural, with human populations centered at Bend, John Day, Madras, and Prineville.
Two primary communities, intermix and interface, have been identified as part of the Wildland
Urban Interface (WUI), defined as the area where structures and other human development meet
or intermingle with undeveloped wildland (Radeloff et al. 2005). In the John Day province,
intermix communities1 compose 1.7% (59,600 ha), whereas interface communities2 are less
1
Intermix communities are defined as places where housing and vegetation intermingle. In intermix, wildland
vegetation is continuous, >50% vegetation, in areas with >1 house per 16 ha.
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common, composing 0.7% (26,000 ha) (data from 2000; fig. 7). Both WUI types are further
divided by housing density; in the John Day province, the dominant category for both intermix
and interface is low density (<49.4 houses/km2).
Figure 6─The John Day Ecological Province in central and eastern Oregon.
Figure 7─Extent of intermix and interface communities of the Wildland Urban Interface in the John Day Ecological
Province in central and eastern Oregon.
2
Interface communities are defined as areas with housing in the vicinity of contiguous vegetation. Interface areas
have >1 house per 16 ha, have <50% vegetation, and are within 1.5 mi of an area (made up of one or more
contiguous Census blocks) over 1,325 acres (500 ha) that is >75% vegetated.
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Portions of Grant, Crook, Jefferson, and Wheeler counties cover 75% of the province, with
Grant County alone composing 28% (1.01 x 106 ha) of the area (fig. 6). Private lands dominate
the John Day province (47.2%), followed by lands managed by the USDA Forest Service
(32.8%). Nearly all of the Ochoco National Forest (NF), and 79% of the Malheur NF, are
contained within the province. About 13% of the province is managed by the Bureau of Land
Management (BLM); these lands are largely in the Central Oregon and Deschutes Resource
Areas of the Prineville District. Agencies that manage the remaining <7% of the province
include the Bureau of Indian Affairs, Oregon Department of State Lands, and the U.S. Fish and
Wildlife Service.
The topographically diverse province consists of valleys and dissected hills, with taller
buttes and plateaus common. Watersheds of the Crooked River and John Day River (with the
exception of the Upper North Fork) are contained within the John Day Province. Elevation
ranges from 335 to 3,060 m ( = 1,262 m), with the highest elevations in the Ochoco
Mountains. Average annual precipitation across the province is 48 cm, but can reach 76 cm in
mountainous areas. Over half of the rainfall occurs between November and March. Soils in the
province are primarily fine-textured and calcareous. (See Anderson et al. [1998] for further
descriptions of the John Day and other ecological provinces in Oregon.)
Ninety-two “ecological systems” (a mid-scale vegetation classification system, between
fine-grained ecological communities and coarse-grained ecoregions; see Comer et al. 2003)
occur in the province, as mapped by LANDFIRE (Rollins and Frame 2006). Most (76),
however, each comprise <1% of the study area. Coniferous forests dominate the vegetation, with
ponderosa pine (Pinus ponderosa) and mixed dry conifer forests together covering nearly 30% of
the province.
The most abundant (550,000 ha; 15.6%) single vegetation type is Inter-mountain Basins Big
Sagebrush Steppe, which is a widespread, matrix-forming system (i.e., a patch type forming
extensive and continuous cover; Comer et al. [2003]) composed primarily of Wyoming big
sagebrush (Artemisia tridentata wyomingensis) and basin big sagebrush (A. t. tridentata). Other
common sagebrush types in John Day include mountain big sagebrush (A. t. vaseyana), low
sagebrush (A. arbuscula), early sagebrush (A. a. longiloba), and scabland sagebrush (A. rigida).
All sagebrush types combined cover 1.23 x 106 ha (34.9%) of the province (fig. 2). The majority
of sagebrush is on private lands (60.7%), which is somewhat higher than expected given the
extent of private lands in the province (47.2%). The same is true for the percentage of sagebrush
managed by the BLM (21.2%) compared to the extent of BLM lands in the province (13.0%).
The Forest Service manages only 8% of the sagebrush in the John Day province; much of this is
mountain big sagebrush (16,180 ha).
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Figure 2─Sagebrush and western juniper woodlands in the John Day Ecological Province, as mapped by
LANDFIRE existing vegetation type.
Western juniper (Juniperus occidentalis) woodlands are widespread, covering 229,000 ha
(6.5%) of the province; the predominant juniper ecological system is Columbia Plateau Western
Juniper Woodland and Savanna (fig. 2). No other juniper or any pinyon pine species occur in the
province. Woodland encroachment has been identified as a threat to native shrublands in Oregon
(Anderson et al. 1998, Gedney et al. 1999, Miller et al. 2005). Western juniper woodlands and
savannas have undergone an estimated 12-fold increase in eastern Oregon from the mid 1930’s
to the late 1980’s (Gedney et al. 1999). Invasive plants, such as yellow star-thistle (Centaurea
solstitialis), spotted knapweed (Centaureu stoebe), and leafy spurge (Euphorbia esula) also
threaten native ecosystems and ecosystem services in the John Day province (e.g., see
http://www.fs.fed.us/wwetac/projects/completed/ogle.html for the Crook County weed-mapping
project).
Mono Basin Ecological Province
The Mono Basin Ecological Province (also referred to as the Mono-Walker-Owens Basin in
West et al. [1998]) straddles the border between Nevada and California, spanning 3.03 x 106 ha
(fig. 8). The province is both ecologically and economically diverse, ranging from high
wilderness peaks in the Sierra Nevada to dry lakebeds, e.g., Owens Lake, and the desert
landscapes of Death Valley National Park. Unlike the John Day province, it includes large
metropolitan areas such as Reno-Sparks and Carson City, Nevada and Bishop, California, as well
as sparsely populated areas in the arid lands north of Death Valley. The extent of interface
communities in the Mono Basin is similar to that of the John Day province, covering 0.8%
(24,500 ha) (fig. 9). By contrast, intermix communities are more prevalent (2.3%; 69,100 ha)
than in the John Day province, and contain a substantial (16,900 ha) component of medium
density housing (49.4-741 houses/km2).
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Figure 8─The Mono Basin Ecological Province in California and Nevada.
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Figure 9─Extent of intermix and interface communities of the Wildland Urban Interface in the Mono Basin
Ecological Province in California and Nevada
Inyo and Mono Counties in California comprise 52% of the province, with Mineral and
Washoe Counties in Nevada comprising another 23%. In contrast to the John Day province, the
BLM manages the largest percentage (43%) of the province, followed by the Forest Service
(24%) and National Park Service (14%). Landowner patterns of sagebrush roughly parallel the
landowner patterns for all lands in the province, e.g., the BLM manages most (48.7%) of the
sagebrush, followed by the Forest Service (26.1%). Private lands cover only 13% of the
province, but 20.5% of the sagebrush is on private lands. Most of the National Forest System
lands in the province are in the Humboldt-Toiyabe, Inyo, and Plumas National Forests. The
BLM-administered Carson City District in Nevada and the Bishop District in California cover
37% and 32% of the province, respectively.
The Mono Basin province is topographically diverse, with elevation ranging from 320 to
4,340 m; mean elevation is 1,834 m, considerably higher than that of the John Day province.
Climate regimes in the Mono Basin vary widely across the province, but on average the region is
more arid than the John Day province, with a mean annual precipitation of only 29 cm.
There are 78 ecological systems in the Mono Basin province, but as was true in the John
Day province, most (61, or 77%) cover <1% of the province. The most abundant single
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vegetation type in the Mono Basin province is Great Basin Pinyon-Juniper Woodland,
encompassing 16.9% (511,000 ha) of the area. Pinyon-juniper woodlands in the Mono Basin
province thus occupy a substantially greater percentage compared to the John Day province
(6.5%) (fig. 3). This woodland type, not found in Oregon, is dominated by singleleaf pinyon
(Pinus monophylla) and Utah juniper (J. osteosperma), and occurs in the eastern foothills of the
Sierra Nevada and the dry mountains of the Great Basin.
Figure 3─Sagebrush and pinyon-juniper woodlands in the Mono Basin Ecological Province, as mapped by
LANDFIRE existing vegetation type.
The extent of sagebrush in the Mono Basin province is similar to that in the John Day
province, covering 30.3% (0.92 x 106 ha) of the province (fig. 3). The two dominant sagebrush
ecological systems are Inter-mountain Basins Big Sagebrush Shrubland (456,000 ha) and Great
Basin Xeric Mixed Sagebrush Shrubland (268,000 ha). The latter type, not found in the John
Day province, is widespread, occurring from 1,000-2,600 m elevation in dry flats and plains,
alluvial fans, and upper-elevation saddles, ridges, and mountain tops.
Habitat threats identified in the Mono Basin province include woodland encroachment
(Nevada Sage-grouse Conservation Team 2004), long-term livestock grazing, exotic species,
wildland fire, urban growth (especially in the Reno-Sparks area), water distribution and quality
(e.g., salinization), fragmentation of high-elevation habitats, and off-road vehicle use (Ricketts et
al. 1999). Evidence suggests that populations of greater sage-grouse (Centrocercus
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urophasianus) in the Mono Lake area are genetically distinct from other populations of greater
sage-grouse (Benedict et al. 2003, Connelly et al. 2004). This species is under status review by
the U.S. Fish and Wildlife Service for potential listing under the Endangered Species Act
(Federal Register 2008a), with a separate status review initiated for the Mono Basin population
(Federal Register 2008b).
References:
Anderson, E. W., M. M. Borman, and W. C. Krueger. 1998. The ecological provinces of Oregon:
a treatise on the basic ecological geography of the state. Salem, OR: Oregon Agricultural
Experiment Station. 138 p.
Bailey, R. G. 1980. Description of the ecoregions of the Unites States. USDA Forest Service
Miscellaneous Publication 1391.
Benedict, N. G., S. J. Oyler-McCance, S. E. Taylor, C. E. Braun, and T. W. Quinn. 2003.
Evaluation of the eastern (Centrocercus urophasianus urophasianus) and western
(Centrocercus urophasianus phaios) subspecies of sage-grouse using mitochondrial
control-region sequence data. Conservation Genetics 4:301-310.
Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, M. Pyne,
M. Reid, K. Schulz, K. Snow, and J. Teague. 2003. Ecological systems of the United
States: A working classification of U.S. terrestrial systems. Arlington, VA: NatureServe.
Connelly, J. W., S. T. Knick, M. A. Schroeder, and S. J. Stiver. 2004. Conservation assessment
of greater sage-grouse and sagebrush habitats. Unpublished report. Western Association
of Fish and Wildlife Agencies, Cheyenne, Wyoming, USA.
Federal Register. 2008a. Department of the Interior, Fish and Wildlife Service, 50 CFR Part 17.
Endangered and Threatened Wildlife and Plants; Initiation of Status Review for the
Greater Sage-grouse as Threatened or Endangered. Federal Register 73(83):23172-23173.
Federal Register. 2008b. Department of the Interior, Fish and Wildlife Service, 50 CFR Part 17.
Endangered and Threatened Wildlife and Plants; 90-Day Finding on Petitions to list the
Mono Basin area population of the Greater Sage-grouse (C Centrocercus urophasianus)
as Threatened or Endangered. Federal Register 73(83):23173-23174.
Gedney, D. R., D. L. Azuma, C. L. Bolsinger, and N. McKay. 1999. Western juniper in eastern
Oregon. USDA Forest Service General Technical Report PNW-GTR-464.
Miller, R. F., J. D. Bates, T. J. Svejcar, F. B. Pierson, and L. E. Eddleman. 2005. Biology,
ecology, and management of western juniper. Oregon State University, Agricultural
Experiment Station, Technical Bulletin 152, Corvallis, OR, USA.
Nevada Sage-grouse Conservation Team. 2004. Greater sage-grouse conservation plan for
Nevada and eastern California. First edition. Prepared for Nevada Governor Kenny C.
Guinn by the Sage-grouse Conservation Team. 108 p.
Radeloff, V. C., R. B. Hammer, S. I. Stewart, J. S. Fried, S. S. Holcomb, and J. F. McKeefry.
2005. The Wildland-Urban Interface in the United States. Ecological Applications
15:799-805.
Ricketts, T. H., E. Dinerstein, D. M. Olson, C. J. Loucks, W. Eichbaum, D. DellaSala, K.
Kavanagh, P. Hedao, P. T. Hurley, K. M. Carney, R. Abell, and S. Walters. 1999.
Terrestrial ecoregions of North America: a conservation assessment. Island Press,
Washington, D.C., USA.
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Rollins, M. G., and C. K. Frame, technical editors. 2006. The LANDFIRE Prototype Project:
nationally consistent and locally relevant geospatial data for wildland fire management.
USDA Forest Service General Technical Report RMRS-GTR-175.
Suring, L. H., M. J. Wisdom, R. J. Tausch, R. F. Miller, M. M. Rowland, L. Schueck, and C. W.
Meinke. 2005. Modeling threats to sagebrush and other shrubland communities. Pages
114-149 in Wisdom, M. J., M. M. Rowland, and L. H. Suring, editors. 2005. Habitat
threats in the sagebrush ecosystem: methods of regional assessment and applications in
the Great Basin. Alliance Communications Group, Lawrence, Kansas, USA.
West, N. E., R. J. Tausch, and P.T. Tueller. 1998. A management-oriented classification of
pinyon-juniper woodlands of the Great Basin. USDA Forest Service General Technical
Report RMRS-GTR-12.