Appendix ESN. The East Of Sierra Nevada Region

The climate is cooler than the Mojave Desert to the south, causing most of the precipitation to be winter snow (Schoenherr 1992). The Sierra Nevada range creates a rain-shadow effect, however, so the region is extremely dry. Bishop, in the Owens Valley, receives an annual average of just 14 cm of precipitation. The crest of the Sierra Nevada and White Mountain Peak both exceed 4,000 m, while the intervening Owens Valley is only ~1,500 m. Thus the high relief of the region produces a wide diversity of habitats. Alpine dwarf scrub and subalpine conifer forests of Bristlecone and Limber pines occur at the highest elevations. Below this is a band of pinyon-juniper woodland, consisting of Singleleaf pinyon and either Western juniper on the eastern face of the Sierra Nevada or Utah juniper elsewhere. There is also extensions of Jeffrey pine and other conifer forests in the Sweetwater Mountains and south of Mono Lake. Blackbush scrub is found in the Owens Valley below the pinyon-juniper zone, and below that is the hallmark of the Great Basin­sagebrush scrub, often in conjunction with Antelope Brush (Purshia tridentata). Shadscale (Atriplex confertifolia) replaces sagebrush on more alkaline soils closer to intermittent lakes. In the wettest locations in these alkaline basins, alkali sink scrub communities with succulent leaves form. Some communities characteristic of the Mojave Desert occur at the margins of the region, such as creosote scrub and Joshua tree woodland. Wetland and riparian communities are extremely critical in this arid environment, including montane meadows, alkali meadow, freshwater and alkali marshes, aspen, black cottonwood, and riparian scrub.

Despite the harshness of the environment, the region has nevertheless experienced significant human impacts on its biodiversity. Water is a primary resource conflict, with competition between urban consumers, recreationists, and wildlife. A large proportion of water in the Owens River system has been diverted since 1913 by the City of Los Angeles Department of Water and Power aqueduct. This diversion has resulted not only in a significant drop in the water level in Mono Lake, but has also changed the volume and timing of flows in streams, which in turn has affected riparian habitats. Since the 1970s, groundwater has also been exported to supplement surface water diversions into the Los Angeles Aqueduct. Groundwater pumping has adversely affected or eliminated phreatophytic shrubs and grasses that depend on groundwater in favor of species with lower water requirements, including many weedy species (Groeneveld 1992).

Public agencies manage almost the entire ESN region (94.5%), distributed among USFS (43.1% of the region), BLM (31.1%), NPS (6.8%), Indian reservations (0.1%), California Fish & Game and other state agencies (1.0%), and local governments (11.1%, largely managed by the City of Los Angeles Department of Water and Power in the Owens Valley). The remainder is privately owned (5.5%) or water bodies (1.2%). Private land occurs mostly in the Antelope and Bridgeport valleys at the northern end of the region.

Status	Area (km²)	%
1	2,112	16.3
2	640	4.9
3	9,435	72.8
4	781	6.0
Total	12,968	100.0

Management profiles by elevation zone are somewhat atypical in the ESN region compared to other regions where higher elevations tend to be better represented than lower elevations. In the ESN (Figure ESN-3), all zones except between 2000-2500 m are represented proportional to their area. This pattern of less status 1 and 2 management at middle elevations reflects the allocation of biodiversity management at the lower elevations in Death Valley National Park and the wilderness areas and botanical areas in the White-Inyo Mountains.

Plant Community Types

Landscapes on the eastern flank of the Sierra Nevada range south of Mono Lake were generalized from the 1980 Vegetation Resource Inventory (U. S. Forest Service, unpublished maps). The White-Inyo Mountains were mapped from the Landsat TM-based Inyo National Forest vegetation map. The floor of the Owens Valley was derived from the 1:24,000 scale BLM-SCS soil-vegetation mapping. The remaining areas were delineated subjectively by photointerpretation of patterns in the satellite imagery in conjunction with the CALVEG map (Parker and Matyas 1981), another BLM soil-vegetation map published in the Bodie/Coleville Grazing EIS for the Bodie and Antelope Valley areas, and the VTM maps. Final delineation of a landscape unit was an iterative process based on evidence from the satellite imagery, existing vegetation maps, and field reconnaissance.

Floristic information was derived mainly from the Inyo Vegetation Resource Inventory, the BLM soil-vegetation maps, unpublished maps produced by the VTM survey and from our own field survey. These sources all contained dominant species data. For the White Mountain area, the Forest Service map was classified by CALVEG type (Parker and Matyas 1981). We ascribed dominant species to each of the vegetation types because we felt the types were relatively simple and consistent. The BLM-SCS data for the Owens Valley represented plots which they extrapolated to landscapes of the same community type. Researchers at UCSB then summarized the three dominant species associated with each community type. Of the 1,371 landscapes in the region, 175 were visited in the field during 1995, covering 44% of the region. These landscapes tend to be larger than average because of the absence of detailed existing maps.

Because source information ranged widely in date and reliability, the current database is uneven in both level of detail and accuracy. We did not have the resources to assess the statistical accuracy of the vegetation map and associated database. However, we have appraised the product using less formal methods that have guided our use of it. Classes are probably more accurate than species data in the White Mountains where species were inferred from CALVEG classes. Forest Service maps depict Pinyon-juniper types which may contain patches dominated by either species alone or co-dominated by both. In the absence of field data to the contrary, both species were coded in the database and assigned to the more general Great Basin Woodlands type. Subalpine Sagebrush Scrub, which is well-developed in the White-Inyo Mountains (Holland 1986), was not identified in existing map sources; therefore this type does not appear in the gap analysis database. Portions of the region without existing vegetation maps such as east of the White Mountains have the least spatial detail and were assigned species attributes from sparse field reconnaissance. These areas will tend to be the most generalized and least accurate.

We classified 12,191 km² (92.8%) of the ESN region as vegetated other than agricultural or horticultural land cover. In other words, 7.2% has been converted to urban or agricultural uses or contains open water or bare ground. The vegetation layer was delineated into 1,371 landscape units with an average size of 967 ha. Distributional information is provided on 72 dominant plant species, 38 community types and 9 land use/land cover types.

Based on our system for converting dominant species assemblages into natural community types, we mapped 38 community types within the ESN region. Twenty-four of the 38 types were mapped with an area greater than 25 km². Great Basin Woodlands, Great Basin Mixed Scrub, and Shadscale Scrub are the most extensive types, covering 2,429 km², 2,223 km², and 1,053 km², respectively. Eight community types contribute 76% of the region's total vegetated area. Two new community types were described by the Gap Analysis project to supplement the Holland (1986) classification for this region­Low Sagebrush Scrub and Cercocarpus ledifolius Woodland.

CNDDB Code	CNDDB Community Name (Holland 1986)	CNDDB Rank	Status 1 %	Status 2 %	Status 3 %	Status 4 %	Total Mapped Distribution (km²)	Status 1+2 %
34100	Mojave Creosote Bush Scrub	S4	85.0	0.0	14.8	0.2	644.6	85.0
34210	Mojave Mixed Woody Scrub	S3.2	7.0	2.3	88.1	2.5	718.3	9.3
34300	Blackbush Scrub	S3.2	3.7	1.0	91.7	3.6	284.5	4.7
35100	Great Basin Mixed Scrub	S4	11.6	6.4	75.2	6.9	2,223.0	18.0
35210	Big Sagebrush Scrub	S4	17.6	0.5	75.5	6.4	949.0	18.1
35211	Low Sagebrush Scrub *	--	1.9	8.1	77.8	12.2	196.6	10.0
35400	Rabbitbrush Scrub	S5	30.0	0.0	67.9	2.1	8.2	30.0
35500	Cercocarpus ledifolius Woodland *	--	10.3	3.6	82.6	3.5	408.3	13.9
36110	Desert Saltbrush Scrub	S3.2	13.2	13.0	70.4	3.3	602.9	26.2
36120	Desert Sink Scrub	S3.1	43.8	2.0	51.0	3.1	399.6	45.8
36130	Desert Greasewood Scrub	S3.2	0.6	12.8	72.0	14.5	342.6	13.4
36140	Shadscale Scrub	S3.2	7.3	5.0	85.3	2.4	1,053.1	12.3
42200	Non-Native Grassland	S4	0.0	80.6	19.3	0.1	2.9	80.6
43000	Great Basin Grassland	S1.1	0.0	1.2	98.2	0.6	17.5	1.2
45100	Montane Meadow	S3.2	0.4	3.2	64.7	31.7	33.3	3.6
45200	Subalpine or Alpine Meadow	S3.2	5.9	0.0	86.7	7.3	13.5	5.9
45310	Alkali Meadow	S2.1	0.0	10.9	82.1	4.0	429.0	10.9
52320	Transmontane Alkali Marsh	S2.1	2.2	20.6	54.0	23.2	13.4	22.8
52420	Transmontane Freshwater Marsh	S2.2	0.0	0.0	30.6	69.4	98.9	0.0
61520	Aspen Riparian Forest	S3.2	0.9	6.5	76.4	16.2	59.3	7.4
61530	Montane Black Cottonwood Riparian Forest	S3.2	0.0	7.4	26.3	66.3	20.2	7.4
61610	Modoc-Great Basin Cottonwood-Willow Riparian Forest	S2.1	0.0	0.0	99.9	0.1	14.9	0.0
63500	Montane Riparian Scrub	S4	0.0	0.0	100.0	0.0	1.4	0.0
63600	Modoc-Great Basin Riparian Scrub	S2.1	0.0	18.9	63.5	17.6	60.3	18.9
71150	Interior Live Oak Woodland	S3.2	100.0	0.0	0.0	0.0	0.2	100.0
72100	Great Basin Woodlands	S3.2/4	16.1	3.8	74.9	5.2	2,428.5	19.9
72200	Mojavean Pinyon and Juniper Woodlands	S3.2/4	71.8	0.0	28.2	0.0	10.8	71.8
73000	Joshua Tree Woodland	S3.2	88.3	0.0	11.0	0.8	50.0	88.3
81320	Canyon Live Oak Forest	S4	64.3	0.0	35.7	0.0	0.9	64.3
81B00	Aspen Forest	S3.2	0.4	0.7	96.2	2.7	59.2	1.1
85100	Jeffrey Pine Forest	S4	1.4	5.8	89.3	3.5	617.3	7.2
85210	Jeffrey Pine-Fir Forest	S4	0.3	59.0	39.1	1.6	12.2	59.3
86100	Lodgepole Pine Forest	S4	2.6	0.7	89.3	7.4	53.3	3.3
86220	Whitebark Pine-Lodgepole Pine Forest	S4	8.5	0.0	89.9	1.6	43.4	8.5
86400	Bristlecone Pine Forest	S2.3	32.9	17.6	49.5	0.0	95.3	50.5
86600	Whitebark Pine Forest	S4	10.1	0.0	87.6	2.3	7.3	10.1
86700	Limber Pine Forest	S2.3	0.0	0.0	100.0	0.0	0.4	0.0
94000	Alpine Dwarf Scrub	S4	11.5	2.5	85.9	0.0	217.1	14.0
	Regional Total-Natural Communities						12,191
	Regional Total (incl nonvegetated)		16.3	4.9	72.8	6.0	13,128	21.2

1. Plant community types mainly on status 4 (primarily private) lands. Because most of the region is publicly owned, few of the 38 types have the majority of their distributions on private land. The two exceptions are Transmontane Freshwater Marsh and Montane Black Cottonwood Riparian Forest, although the latter covers slightly less than 25 km².

2. Scrub and herbaceous types mainly located in unprotected areas. Three of the 21 scrub and herbaceous types were mapped with areas greater than 25 km² and with less than 10% of their distribution in Status 1 and 2 managed areas, which are designated for conservation of native biodiversity. These include Blackbush Scrub, Low Sagebrush Scrub, and Montane Meadow. Blackbush (Coleogyne ramosissima) is a paleoendemic or a relict species whose range was formerly much wider (Stebbins and Major 1965). Mojave Mixed Woody Scrub also meets these criteria but is considered to be a marginal type in this region. Alkali Meadow has 10.9% of its mapped area in managed areas but is also of concern because of the potential adverse impact of groundwater pumping. Lowering the water table can reduce cover or eliminate entirely the native grasses and Atriplex lentiformis ssp. torreyi (Groeneveld 1992). Other wetland and riparian types also appear poorly represented on Status 1 and 2 lands but have mapped distributions below the criterion. Therefore, we have less confidence in the accuracy of their management profiles. Slight errors in mapping could make significant differences in whether or not they appear protected.

3. Forest and woodland types mainly located in unprotected areas. Three of the 16 forest and woodland types were mapped with areas greater than 25 km² and with less than 10% of their distribution in Status 1 and 2 areas. These include Aspen Riparian Forest, Aspen Forest and Jeffrey Pine Forest. These types are almost exclusively on public lands, and are of management concern primarily because of grazing, which is widespread. Lodgepole Pine Forest and Whitebark Pine-Lodgepole Pine Forest also meet these criteria but are more characteristic of the Sierra Nevada and tend to be outliers in the ESN region.

4. Community types that appear well-protected. Five types were mapped with areas greater than 25 km² and with more than 25% of their distribution in Status 1 and 2 areas. These include Mojave Creosote Bush Scrub, Desert Saltbush Scrub, Desert Sink Scrub, Joshua Tree Woodland, and Bristlecone Pine Forest. These types represent the lower elevation sites in Death Valley National Park and the higher elevations in the White-Inyo Mountains. These types are of relatively low priority for additional land acquisition or allocation to Status 1 and 2. Other types common in the Great Basin such as sagebrush and the piñon-juniper woodlands are also relatively well-represented but not to the same level as the types listed above.

The ESN Region is the southernmost portion of the Great Basin Province in California (Hickman 1993). The management status of community types in the ESN region may not be representative of the province as a whole. Therefore, our findings should be considered tentative and apply only to the California portion of the ecoregion. However, most Great Basin types are not well-represented in managed areas in other states within the ecoregion either (Caicco et al. 1995. Edwards et al. 1995).