Study Area Description Page 1 of 9 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. Study Area Description Page 2 of 9 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. Study Area Description Page 3 of 9 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). Study Area Description Page 4 of 9 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). Study Area Description Page 5 of 9 Figure 8─The Mono Basin Ecological Province in California and Nevada. Study Area Description Page 6 of 9 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 Study Area Description Page 7 of 9 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.