3 Biological Characterization and Status 3.1 Biodiversity and Endemism Regional Context Two recent regional assessment efforts have identified portions of the Middle Snake subbasins as being areas of regional conservation importance based on high biodiversity and/or the presence of rare or endemic organisms. In 1994, the Interior Columbia Basin Ecosystem Management Project (ICBEMP) mapped centers of biodiversity and endemism/rarity across the interior Columbia Basin (ICBEMP 2003). In 1999, The Nature Conservancy (TNC) used the Biodiversity Management Area Selection (BMAS) model to develop a conservation portfolio for the Columbia Plateau Ecoregion; the middle and upper portions of the subbasins fall within this ecoregion. In 2003, the SITES model, an upgraded version of the BMAS model, was used to develop a conservation portfolio for the lower reaches of the subbasins. ICBEMP Centers of Biodiversity and Endemism Expert panels of agency and nonagency scientists for the ICBEMP were convened between October 1994 and May 1995 to identify areas of rare and endemic populations of plant, invertebrate, and vertebrate species (ICBEMP 1997). These panels of experts produced maps showing areas having unusually high biodiversity and areas containing high numbers of rare or locally or regionally endemic species (Figure 22 and Figure 23, respectively). The centers of concentration were identified within a short time frame and at a coarse scale, and those identifications were based mainly on the panel’s personal knowledge of areas and species locations. The panel suggested that the areas be considered a first attempt at identifying places having particularly diverse collections of rare or endemic species, or areas with high species richness. Centers of concentration might be candidates for Research Natural Areas or other natural area designations, pending further local assessment and refinement (ICBEMP 1997). Thirty percent of the Middle Snake subbasins were identified as centers of plant biodiversity, while 5% of the subbasins were selected as centers of animal biodiversity. Large areas of plant biodiversity are found in the lowermost portions of the subbasins, the Owyhee Face Drainage, and central-elevation areas of the Big Wood Drainage. Areas selected as centers of animal biodiversity are in the Birds of Prey Natural Conservation Area (Figure 22). Twenty-three percent of the subbasins were identified as areas of high plant endemism and rarity, and 9% of the subbasins are centers for animal endemism and rarity (Table 11). Plant areas of endemism and rarity occur along the Snake River corridor throughout most of the subbasins, while animal areas are more patchily distributed and include a large area in the lower subbasins, an area near the Birds of Prey Natural Conservation Area, and a small area just west of Browns Creek (Figure 23). Middle Snake Draft Assessment 59 May 2004 Figure 22. Centers of biodiversity in the ICBEMP analysis area and the Middle-Snake subbasins. Middle Snake Draft Assessment 60 May 2004 Figure 23. Centers of endemism and rarity in the ICBEMP analysis area and the Middle-Snake subbasins. Middle Snake Draft Assessment 61 May 2004 Table 11. Areas selected as centers of biodiversity or centers of endemism and rarity in the Middle-Snake subbasins. Interior Columbia Ecosystem Management Area of Middle-Snake Percentage (%) of Project Designation Subbasins Selected Middle Snake (acres) Subbasins Selected Centers of Biodiversity—Plants 2,482,634 30 Centers of Biodiversity—Animals 429,515 5 Centers of Endemism and Rarity—Animals 743,529 9 Centers of Endemism and Rarity—Plants 1,919,106 23 The Nature Conservancy’s BMAS/SITES Models TNC’s vision is to conserve a set of places that, if managed appropriately, will ensure the long- term survival of all native species and natural communities (TNC 2004). TNC has been working to develop conservation portfolios at the broad-scale ecoregional level. Three-quarters of the Middle Snake subbasins lie within the Columbia Plateau Ecoregion, while the lower portion lies within the Middle Rockies–Blue Mountain Ecoregion. In 1999, TNC used the Biodiversity Management Area Selection (BMAS) model to identify a portfolio of sites that, collectively and with appropriate conservation action, would maintain all viable native species and communities in the Columbia Plateau Ecoregion, a 72,019,000-acre area covering portions of Washington, Oregon, Idaho, Nevada, California, and Utah. The Columbia Plateau Ecoregional Assessment was the first attempt at developing a methodology for conservation portfolio selection. In 2003, further refinement of this methodology was employed in developing portfolios for the 52,989,000-acre Middle Rockies–Blue Mountain Ecoregion (TNC 1999). The refined site selection model is called the SITES model. The following discussion documents the methods used in developing the conservation portfolio for the Columbia Plateau Ecoregion, which dominates the subbasins (see TNC 2003 for details about the slightly different methodology used for selecting sites in the Middle Rockies–Blue Mountain Ecoregion). Conservation targets were selected using a coarse filter/fine filter approach. Targets representing fine filter aspects of biodiversity and comprising 154 plant species, 45 invertebrates, 49 vertebrates, 42 aquatic species, and 103 plant communities were identified for the purposes of selecting portfolio sites based on their occurrences. Coarse filter aspects of biodiversity were represented by Gap Analysis Program (GAP) cover types. An Aquatic Integrity Index developed by the ICBEMP was used to help establish aquatic targets (TNC 1999). Conservation goals were then chosen for the targets, based on their distribution in the Columbia Plateau Ecoregion. For targets found in only one section of the ecoregion, the goal was to have all target occurrences, up to five, contained in the conservation portfolio. For targets found in more than one section, the goal was to protect all occurrences up to three per section. Goals for coarse filter target representation were established based on percentage coverage of the cover type in the ecoregion. The Element Occurrence Databases maintained by state Natural Heritage/Conservation Data Center programs were the main source of data. Gap analysis Middle Snake Draft Assessment 62 May 2004 provided the vegetation layer information, and other sources supplied supplementary environmental data (TNC 1999). The BMAS model, a GIS-driven site selection model, was used to select conservation sites that meet the greatest amount of biodiversity target goals using the least amount of land. Areas identified by panels of regional biological experts as being of conservation importance were used as a starting place for the BMAS model, using 6th field HUCs as the site selection units. The initial portfolio developed by BMAS was then edited by TNC staff to address connectivity issues and account for differences in site quality. The final portfolio contained 139 sites and covered 20% of the ecoregion and ranged in size from 50 to over 1 million acres (Figure 24; TNC 1999). Eleven percent of the Middle Snake subbasins fall within areas selected for the Columbia Plateau Ecoregion, while 7% fall within areas selected for the Middle Rockies–Blue Mountain Ecoregion. Table 12 lists the Middle Snake subbasins conservation sites for both ecoregions. A number of conservation targets were not met by the final portfolio. However, most of these targets were at the edges of their ranges or had been poorly inventoried to date. During the next iteration of the ecoregion plan, TNC plans to focus on acquiring better information for these groups of targets (TNC 1999). Table 12. Sites that were identified in the TNC conservation portfolio for the Columbia Plateau and the Middle Rockies–Blue Mountains ecoregional assessments and that occur in the Middle Snake subbasins, as well as those sites’ protection status (TNC 1999, 2003). Ecoregion Site Name Protection Area of Site Total Percentage Status in Subbasin Area of (%) of Site (acres) Site in (acres) Subbasin Columbia Alkali Gulch partially 39,512 59,724 66 Plateau protected Big Wood Wild and Scenic protected 608 608 100 River Birds of Prey Natural partially 160,718 160,771 100 Conservation Area protected Bruneau River–Jacks Creek partially 109,184 433,169 25 protected Craters of the Moon partially 172,543 356,544 48 protected Dietrich Dunes not protected 1,970 14,207 14 Dry Creek Wild and Scenic protected 1,092 1,092 100 River/Research Natural Area Jarbidge Creek partially 57,145 428,100 13 protected Middle Snake River Corridor partially 217,273 794,071 27 protected Salmon Falls Creek partially 211,389 211,389 100 protected Middle Snake Draft Assessment 63 May 2004 Ecoregion Site Name Protection Area of Site Total Percentage Status in Subbasin Area of (%) of Site (acres) Site in (acres) Subbasin Succor Creek partially 373,260 724,922 51 protected TNC Silver Creek Preserve protected 1,857 1,857 100 TNC Stapp–Soldier Creek protected 90 90 100 Preserve Weiser Sand Hills partially 14,138 114,582 12 protected Middle Basin Gulch Research Natural protected 1,175 1,175 100 Rockies– Area Blue Big Smoky Creek not protected 14,831 57,445 26 Mountain Big Wood River partially 9,696 9,696 100 protected Carey Lake Wildlife protected 292 292 100 Management Area Copper Basin not protected 35,346 241,493 15 Cuddy Mountain Research protected 1,053 1,053 100 Natural Area Fox Creek/Rocking M Ranch partially 69,538 69,542 100 protected Hells Canyon partially 238,984 1,155,396 21 protected ID-53-005 - WSA protected 9,515 9,666 98 Little Wood River partially 48,616 48,616 100 protected Lost Basin Grassland Research protected 62 62 100 Natural Area River’s Edge Ranch protected 4 4 100 Sawtooth National Recreation protected 61,925 531,083 12 Area Silver Creek, TNC partially 12,284 12,284 100 protected Trail Creek Canyon protected 813 813 100 Wallowa Mountains partially 100,461 628,764 16 protected Willow Creek protected 15,518 15,518 100 Middle Snake Draft Assessment 64 May 2004 Figure 24.