Appendix SN. The Sierra Nevada Region

Contributing Authors: Frank Davis and David Stoms

Regional Character
Land Stewardship
Plant Community Types

The Sierra Nevada Region encompasses 63,118 km² extending from Tejon Pass at the southern end to the North Fork of the Feather River at the north (Figure SN-1). Because of the size and biological heterogeneity of the Sierra Nevada, we conducted gap analyses for a northern versus a central/southern subregion divided at the Stanislaus River. In The Jepson Manual the Stanislaus River divides the northern from the central and southern Sierra Nevada.

Figure SN-1. Shaded relief image of the Sierra Nevada Region and the two subregions.

The following digital geospatial data were compiled for this analysis:

topography (100 m grid)
vegetation (classified to Holland types using a 100 ha minimum mapping unit [MMU]. The MMU is the nominal extent of the smallest mapped feature).
dominant plant species (100 ha MMU)
land ownership and administrative designation in terms of conservation (200 ha MMU)
U.S. Forest Service grazing allotment boundaries (1 ha grid)
USFS land suitability classes (1 ha grid)

These data were analyzed to address the following specific questions:

1. How do land ownership and land management vary among elevation zones?

2. What are the sizes and locations of existing parks, wilderness areas, and reserves?

3. How is each terrestrial plant community type distributed with respect to land ownership and conservation management?

4. Which major terrestrial plant community types may be vulnerable to degradation of habitat and which types appear to be relatively well protected based on their current management profile?

Land Stewardship

GAP classifies land ownership and management into four categories intended to capture the degree to which the land is managed to maintain biodiversity (Scott et al. 1993). We depart slightly from the GAP categories by distinguishing lands based on permitted use. We assume that the most pervasive land uses affecting the status and trends of terrestrial biodiversity in the Sierra Nevada are grazing, fire suppression, timber harvest, and urban, residential, and agricultural development. Other activities such as recreation, trapping, and mining, are certainly important but more localized and/or less readily mapped. Thus we have distinguished five ownership/management classes based on fire policy and on potential for development, timber harvest, or grazing.

Class 1: Public or private land formally designated for conservation of native biodiversity and within which economic activities such as development, grazing, and timber harvest are precluded. Natural disturbance events are generally allowed to proceed without interference or are mimicked through management. The areas may be used for primitive recreational activities. Examples include national parks, national monuments, ungrazed lands within USFS wilderness areas, USFS research natural areas, USFS wild and scenic rivers, Blue Ridge National Wildlife Refuge, The Nature Conservancy preserves, and state parks and ecological reserves.

Class 2: national forest land that is generally managed for its natural values but is not formally designated for conservation of native biodiversity. Development and grazing are excluded, and timber harvest is generally excluded because it conflicts with other multiple-use objectives. Wildfires are generally suppressed. The distribution of recreational activities on Class 2 lands is unknown, but a small fraction of the land is developed for recreational facilities.

Class 3: public land that is generally managed for its natural values, is treated in existing management plans as unsuitable for timber harvest, and may be grazed. Wildfires may be actively suppressed. Examples include grazing allotments within USFS wilderness areas, grazing allotments on national forest lands classified as unsuitable for timber harvest, the San Joaquin Experimental Range, Bureau of Land Management (BLM) areas of critical environmental concern, and BLM wilderness areas.

Class 4: Other public lands not included in Classes 1 through 3, mainly multiple-use federal lands managed by the Bureau of Indian Affairs (BIA), Bureau of Reclamation, BLM, and USFS. National forest lands in this category include areas that are classified in existing plans as suitable for timber harvest. These USFS areas can also be within existing grazing allotments. Wildfires are actively suppressed.

Class 5: private lands other than those in Class 1. In the absence of more detailed zoning data, we assume that these lands are potentially available for development, timber harvest, and grazing and that wildfires are actively suppressed.

The base map for land ownership/management is 1:100,000 BLM surface management status maps. A statewide digital coverage was provided by the Teale Data Center. This map was updated and enhanced to include boundaries of managed areas such as wilderness areas and research natural areas that do not coincide with ownership boundaries. To do this, we consulted national forest maps and digital databases and U.S. Geological Survey (USGS) topographic maps. We obtained additional maps and information from many agencies, conservation organizations, and land trusts. All managed areas in the resulting regional map of land ownership/management were described in an associated database containing fields for the managing agency, the management level with respect to biodiversity conservation, and a managed area code assigned by the California Department of Fish and Game Natural Heritage Division.

Figure SN-2. Management classes of lands in the Sierra Nevada Region. See text for definitions of management classes.

The map of land management levels was converted to a 1 ha grid and intersected with 1 ha grids of USFS land suitability class maps and grazing allotments. Digital land suitability class maps were obtained directly from the USFS. Digital grazing allotment data were obtained from the USFS for all of the national forests except Lassen, Modoc, and the Lake Tahoe Basin. We digitized the grazing allotment boundaries on these forests from paper maps provided by USFS range conservation staff.

Maps of timber harvest suitability and grazing allotments were converted back to a vector (polygon) representation and overlaid with land ownership. The derived product was reclassified into the five classes defined above.

Thirty-seven percent of the region is privately owned (Table SN-1). The remainder, in public lands, is largely national forests (47%) and national parks (10%). The Bureau of Land Management administers 5% of the region. Native American tribes, other Department of Interior agencies, and state oversee the remaining 2% of the region's land base.

Table SN-1. Area and percentage of land surface by management status level of the Sierra Nevada Region and two subregions.

Class % in Sierra Nevada % in Northern Subregion % in Central/ Southern Subregion

1 15.4 2.1 25.7

2 6.7 10.1 4.1

3 21.4 16.8 24.9

4 20.0 25.7 15.6

5 36.5 45.3 29.8

Total 100.0 100.0 100.0

We found that 15% of the region is in Class 1 management status (Table SN-1, Figure SN-2). Yosemite and Sequoia/King's Canyon National Parks account for 89% of the Class 1 area. The size distribution of Class 1 areas is strongly skewed toward parcels less than 200 ha (Figure SN-3). These account for nearly half of the Class 1 parcels but contribute less than 1% of the total Class 1 area.

Figure SN-3. Frequency of Class 1 areas by size class (bars) and cumulative area (curve) in the Sierra Nevada region.

An additional 7% of the Sierra Nevada region is in Class 2 lands in national forests. By summing Classes 3, 4, and 5, we estimate that roughly 80% of the region is available for grazing (89% of vegetated lands). Summing Classes 4 and 5, we estimate that 56.5% of the land area (63.3% of vegetated lands) is available for timber harvest, although not all of this land is actually timberland.

Plant Community Types

Vegetation types were classified based on overstory structure, cover, and dominant species composition. The overstory is described by one to three species, each contributing greater than 20% of the relative canopy cover. These species assemblages (Davis et al. 1995) were subsequently reclassified into natural plant community types described by the California Department of Fish and Game Natural Heritage Division (Holland 1986).

Maps of actual vegetation were produced using summer 1990 Landsat Thematic Mapper satellite imagery, 1985-1990 high altitude color infrared photography (1:58,000 scale), draft and published maps of the California vegetation type mapping survey (Wieslander 1946), miscellaneous recent vegetation maps (notably the vegetation databases from the national forests and parks), and ground surveys of selected areas.

Floristic information was derived mainly from published and unpublished maps produced by the vegetation type mapping survey. Where these maps were lacking we relied on USFS soil and vegetation survey notes (alpine and subalpine areas surveyed by R. Taskey), our own 1994/95 field reconnaissance surveys, forest patch type descriptions from the SNEP late seral old growth database (Franklin and Fites-Kaufmann 1996), and the map of foothill woodland types prepared by Pillsbury et al. (1991). Our draft map was extensively updated in timber-producing areas using USFS maps of timber plantations and shrub-dominated timberlands.

The database for the Sierra Nevada Region consists of 7,021 landscape units providing distributional information on 150 dominant species and 77 plant community types. Analysts can query the database to retrieve distribution data on individual species, unique combinations of species, or vegetation types defined by physiognomy and/or composition.

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 the product. Based on UCSB field surveys in 1994 and 1995 and on comparisons with independent sources of vegetation data, the vegetation map probably overestimates the extent of conifer forest types and underestimates the extent of shrubland and mid-elevation hardwood types. Floristic information is more reliable in the northern and central subregion than in the southern subregion, which was only partially covered by the vegetation type mapping survey. Floristic information is also more reliable on public lands than private lands, and better for the national parks than for the national forests. The data on upland community types and wildlife habitat types are more reliable than information on individual species or on wetland or meadow habitats.

Sierra Nevada Region as a Whole

We mapped the Jepson Sierra Nevada Region over an area of 63,118 km². We classified 56,658 km² (89.7%) of this area as vegetated (Table SN-2). Non-vegetated areas included urban areas, lakes, reservoirs, rock outcrops, and alpine areas with little or no vascular plant cover.

Table SN-2. Percentage area of each CNDDB community type at each management class level in the Sierra Nevada Region and the northern and southern subregions. * indicates an addition to the standard CNDDB classification (Holland 1986)

CNDDB Code	CNDDB Community Name (Holland 1986)	Class 1			Class 2			Class 3			Class 4			Class 5			Total Mapped Distribution (km²)
		N	S	Total	N	S	Total	N	S	Total	N	S	Total	N	S	Total	N	S	Total

	SCRUB
34100	Mojave creosote bush scrub		0.1	0.1					50.0	50.0					49.9	49.9		7	7
34210	Mojave mixed woody scrub					0.2	0.2		68.4	68.4		3.3	3.3		28.1	28.1		278	278
34300	Blackbush scrub								63.2	63.2		1.9	1.9		34.9	34.9		164	164
35100	Great Basin mixed scrub	0.1	13.3	2.7	1.9	22.0	5.9	20.3	14.0	19.1	32.5	48.5	35.7	45.2	2.2	36.7	243	60	303
35210	Big sagebrush scrub	1.5	4.5	3.3	6.0	2.3	3.8	32.6	45.3	40.3	27.8	17.2	21.3	32.2	30.7	31.3	391	607	998
35211	Low sagebrush scrub *	0.1		0.1	4.3		4.3	30.2		30.2	10.1		10.1	55.4		55.4	77		77
35212	Silver sagebrush scrub *		7.0	5.2		0.3	0.2	9.8	78.3	60.3	7.2	13.7	12.0	83.0	0.7	22.3	11	30	41
35220	Subalpine sagebrush scrub	3.6	0.2	3.5	5.6	39.5	6.6	38.2		37.1	37.9	59.5	38.5	14.7	0.8	14.3	100	3	103
35400	Rabbitbrush scrub	0.9		0.9	3.6		3.6	23.6		23.6	65.0		65.0	7.0		7.0	46		46
35500	Cercocarpus ledifolius woodland *	0.5	42.5	17.7	2.4	40.8	18.2	33.5	7.9	23.0	53.2	7.7	34.5	10.4	1.1	6.6	156	109	264

	CHAPARRAL
37110	Northern mixed chaparral		12.7	11.9	1.7	11.5	10.9	0.9	20.5	19.3	15.4	29.0	28.1	82.0	26.3	29.8	15	219	234
37200	Chamise chaparral	0.1	10.4	5.8	0.8	2.7	1.9	3.4	24.1	14.9	14.4	34.8	25.7	81.3	28.0	51.7	364	457	821
37400	Semi-Desert chaparral		11.8	11.8		1.9	1.9		17.9	17.9		19.1	19.1		49.1	49.1		77	77
37510	Mixed montane chaparral	6.2	31.6	12.6	15.8	13.5	15.2	21.6	33.9	24.7	29.1	13.4	25.1	27.3	7.6	22.4	1,036	345	1,381
37520	Montane manzanita chaparral	0.1	9.0	4.7	9.9	7.6	8.8	8.0	20.5	14.4	19.2	37.3	28.5	62.8	25.6	43.6	229	244	473
37530	Montane ceanothus chaparral	1.2	8.2	1.4	3.7	14.8	4.2	21.3	13.3	21.0	44.5	48.7	44.6	29.4	15.0	28.8	191	8	199
37541	Shin oak brush		36.2	36.2		1.3	1.3		6.3	6.3		3.0	3.0		53.1	53.1		46	46
37542	Huckleberry oak chaparral		42.3	23.0	26.6	0.7	12.5	17.8	45.5	32.9	6.7	11.4	9.2	48.8	0.1	22.3	81	97	178
37550	Bush chinquapin chaparral	4.6	48.9	6.0	5.9		5.7	26.2	48.4	26.9	48.4	2.6	46.9	14.9		14.4	75	3	77
37620	Leather oak chaparral				47.8		47.8				6.8		6.8	45.4		45.4	4	3	6
37810	Buck brush chaparral		1.2	1.1	0.9	17.7	15.3	15.9	50.4	45.6	14.9	16.0	15.8	68.3	14.7	22.1	21	133	155
37900	Scrub oak chaparral				39.8	3.9	6.4	36.6	4.0	6.2	18.8	16.7	16.8	4.9	75.4	70.6	3	45	48
37A00	Interior live oak chaparral		4.4	4.3		7.6	7.5	18.4	8.3	8.5	14.4	9.9	10.0	67.2	69.7	69.7	5	197	202
37B00	Upper Sonoran manzanita chaparral		4.7	4.4	1.5	4.4	4.2	1.1	28.8	27.4	28.9	47.8	46.8	68.5	14.4	17.2	9	172	181
37D00	Ione chaparral										3.8		3.8	96.2		96.2	1		1
37E00	Mesic north slope chaparral		11.5	10.2	8.2	10.1	9.8	6.8	48.9	44.2	8.9	20.7	19.4	76.1	8.8	16.3	15	118	132
39000	Upper Sonoran subshrub scrub								5.1	5.1		15.6	15.6		79.4	79.4		8	8

	HERBACEOUS
42200	Non-native grassland		0.8	0.4	0.3	1.2	0.7	6.0	8.4	7.1	1.6	2.7	2.1	92.1	86.9	89.7	1,026	898	1,923
45100	Montane meadow	0.8	73.0	41.3	3.8	4.3	4.1	16.3	17.8	17.1	17.8	1.5	8.6	61.3	3.5	28.9	74	94	168
45200	Subalpine or alpine meadow	1.1	34.0	16.6	6.0	2.4	4.3	35.4	45.9	40.4	16.0	13.5	14.8	41.6	4.2	23.9	118	106	224
45310	Alkali meadow		4.9	4.9					8.8	8.8		3.9	3.9		82.4	82.4		2	2
51110	Sphagnum bog	92.2		92.2	7.8		7.8										1		1
52310	Cismontane alkali marsh										0.6		0.6	99.4		99.4	11		11
52320	Transmontane alkali marsh		3.9	3.9					17.3	17.3		0.4	0.4		78.4	78.4		6	6

	RIPARIAN WOODLAND
61410	Great Valley cottonwood riparian forest		19.8	9.9	0.7	0.8	0.8	0.2	31.9	16.0	1.2	0.5	0.9	97.9	46.9	72.5	10	10	19
61420	Great Valley mixed riparian forest								37.0	37.0		0.5	0.5		62.5	62.5		12	12
61430	Great Valley Valley oak riparian forest								2.6	2.6		0.4	0.4		97.0	97.0		16	16
61510	White alder riparian forest		65.3	65.3					0.3	0.3					34.4	34.4		5	5
61520	Aspen riparian forest							85.0		85.0	15.0		15.0				0.1		0.1
61530	Montane Black cottonwood riparian forest	0.7	100.0	56.7	0.6		0.3	1.4		0.6	0.4		0.2	96.8		42.2	2	3	6
63500	Montane riparian scrub	3.2	40.2	22.7	3.6	2.0	2.8	22.2	13.6	17.7	12.7	10.1	11.3	58.3	34.0	45.5	49	54	103

	BROAD-LEAVED WOODLAND
71110	Oregon oak woodland							26.8	70.3	41.3	2.8	3.2	2.9	70.3	26.5	55.8	18	9	27
71120	Black oak woodland	1.3	8.2	3.9	8.6	12.2	9.9	9.6	21.8	14.1	14.4	28.5	19.6	66.2	29.3	52.6	449	263	712
71130	Valley oak woodland					0.1	0.1	6.5		1.8	0.9	0.4	0.5	92.6	99.4	97.6	93	243	336
71140	Blue oak woodland		1.5	1.3		0.6	0.6	3.8	6.6	6.3	2.4	3.1	3.0	93.8	88.1	88.9	633	3,941	4,573
71150	Interior live oak woodland		1.3	0.9	0.1	6.9	5.0	6.3	18.5	15.0	4.7	9.7	8.3	88.9	63.6	70.8	380	952	1,332

	CONIFER WOODLAND
71310	Open Foothill pine woodland		1.9	1.4	0.7	6.4	4.9	2.6	21.2	16.4	5.1	24.3	19.3	91.7	46.3	58.1	114	327	441
71322	Non-serpentine Foothill pine-chaparral		12.9	8.4	1.8	4.4	3.5	18.9	31.1	26.9	9.4	23.4	18.5	69.8	28.2	42.7	87	162	249
71410	Foothill pine-oak woodland		0.7	0.4	0.1	1.9	1.1	5.9	14.9	10.8	3.0	6.7	5.0	90.9	75.8	82.6	1,820	2,205	4,024
71600	Oak-piñon woodland *		8.0	8.0		3.5	3.5		76.4	76.4		3.9	3.9		8.2	8.2		136	136
72100	Great Basin woodlands	0.3	8.4	6.3	0.9	3.4	2.7	21.3	46.2	39.8	61.6	31.4	39.1	16.0	10.6	12.0	249	726	975
72220	Mojavean pinyon and juniper woodlands		0.8	0.8		0.2	0.2		41.4	41.4		19.9	19.9		37.7	37.7		558	558
73000	Joshua tree woodland								85.8	85.8		4.9	4.9		9.3	9.3		73	73

	BROAD-LEAVED FOREST
81320	Canyon live oak forest	5.3	23.9	18.7	22.1	9.3	12.9	23.3	32.4	29.9	15.1	13.8	14.2	34.2	20.5	24.3	262	674	936
81330	Interior live oak forest		3.2	1.8	0.9	3.7	2.5	4.3	22.6	14.6	5.3	6.0	5.7	89.5	64.4	75.3	677	876	1,553
81340	Black oak forest	2.2	14.5	8.4	17.6	10.4	14.0	21.0	23.8	22.4	23.0	27.7	25.3	36.2	23.6	29.9	666	676	1,342
81400	Tan-oak forest				10.4		10.5	43.0		4.3	17.1		17.1	68.2		68.2	46		46
81B00	Aspen forest	1.9	27.4	18.0	13.3	23.2	19.6	30.6	25.3	27.3	41.6	20.8	28.5	12.7	3.3	6.7	37	63	99

	CONIFER FOREST
83210	Knobcone pine forest		0.8	0.6	40.3	2.1	12.6	7.8	5.2	5.9	22.4	34.1	30.8	29.5	57.8	50.0	5	12	17
83330	Southern interior cypress forest		3.5	3.5		1.1	1.1		39.1	39.1		33.4	33.4		22.8	22.8		3	3
84210	Westside Ponderosa pine forest	1.1	17.2	8.4	6.0	4.3	5.2	8.7	26.7	16.8	25.7	35.1	29.9	58.6	16.7	39.7	3,151	2,592	5,744
84220	Eastside Ponderosa pine forest	0.9		0.9	4.4	42.8	4.6	17.9	26.8	17.9	50.0	29.8	49.9	26.9	0.6	26.7	1,609	9	1,618
84230	Sierran mixed coniferous forest	1.1	21.2	7.1	11.1	6.2	9.7	12.4	24.2	15.9	34.6	31.6	33.7	40.8	16.8	33.6	5,596	2,379	7,975
84240	Sierran White fir forest	0.5	28.9	7.7	15.9	5.1	13.1	17.9	15.1	17.2	38.0	40.4	38.6	27.8	10.5	23.4	406	138	544
84250	Big tree forest		33.7	33.7		12.0	12.0		26.1	26.1		22.8	22.8		5.3	5.3		171	171
85100	Jeffrey pine forest	3.7	35.4	18.1	7.1	5.4	6.3	32.9	28.2	30.7	38.1	26.1	32.6	18.3	4.9	12.2	1,152	963	2,115
85120	Red fir-Western white pine forest *	12.3	52.4	28.7	10.7	3.2	7.6	48.3	33.8	42.3	17.8	10.4	14.8	10.8	0.3	6.5	946	653	1,599
85210	Jeffrey pine-fir forest	3.1	22.3	15.4	13.2	5.4	8.2	27.9	35.6	32.8	30.2	34.1	32.7	25.6	2.6	10.9	1,095	1,935	3,030
85310	Red fir forest	2.4	49.0	33.1	13.7	2.0	6.0	23.9	32.7	29.7	35.9	15.2	22.3	24.1	1.0	8.9	1,159	2,231	3,390
86100	Lodgepole pine forest	4.1	60.1	53.6	11.6	3.1	4.1	39.8	30.7	31.7	23.2	5.6	7.7	21.4	0.4	2.9	252	1,901	2,152
86210	Whitebark pine-Mountain hemlock forest	20.8	72.4	62.0	5.7	1.9	2.6	61.5	19.3	27.8	8.6	6.4	6.8	3.4	0.1	0.7	76	301	377
86220	Whitebark pine-Lodgepole pine forest	4.2	56.1	48.9	3.8	14.5	13.1	70.3	24.2	30.5	15.1	5.0	6.3	6.5	0.3	1.1	72	453	525
86300	Foxtail pine forest		92.6	92.6		1.0	1.0		5.2	5.2		0.1	0.1		1.1	1.1		238	238
86600	Whitebark pine forest	9.7	67.7	58.3	7.3	7.3	7.3	36.1	2.9	8.3	44.5	22.1	25.7	2.4		0.4	36	183	218
86700	Limber pine forest		5.4	5.4		16.9	16.9		77.6	77.6		0.1	0.1					21	21

	ALPINE HABITATS
91120	Sierra Nevada fell-field		27.6	27.4	0.7			16.5	54.2	53.9	82.8	17.6	18.1		0.5	0.5	1	122	123
94000	Alpine dwarf scrub		89.5	89.5		7.1	7.1		3.1	3.1		0.1	0.1		0.2	0.2		394	394

	TOTAL AREA
	(vegetated lands)																25,444	31,214	56,658
	(vegetated and unvegetated lands)	2.1	25.7	15.4	10.1	4.1	6.7	16.8	24.9	21.4	25.7	15.6	20.0	45.3	29.8	36.5	27,488	35,630	63,118

	* addition to the standard CNDDB classification.

Based on our system for converting dominant species combinations to natural community types, we mapped 77 natural plant community types within the region. Sixty types were mapped over an area greater than 25 km². Sierran mixed conifer forest and Westside Ponderosa Pine Forest are the most extensive types, covering 7,975 km² and 5,744 km², respectively. Nine community types collectively contribute 62% of the region's total vegetated acreage (Table SN-3). Most of the types mapped at less than 25 km² are riparian or wetland communities or are marginal types that spillover from neighboring regions. Note that the findings are slightly different that reported in the SNEP report (Davis and Stoms 1996b) because they results here are based on the revised version of the land-cover map. The biggest difference between the two analyses is caused by some reassignment of community types to increase the statewide consistency of the map. Thus there are fewer types reported in this gap analysis and their mapped area and management profiles may be slightly changed.

Table SN-3. Nine widespread plant community types that collectively cover 63% of the vegetated portion of the Sierra Nevada Region.

CNDDB Code CNDDB Community Name (Holland 1986) Area (km²) % of region

84230 Sierran mixed conifer forest 7,975 14.1

84210 Westside ponderosa pine forest 5,744 10.1

71120 Blue oak woodland 4,573 8.1

71410 Foothill pine-oak woodland 4,024 7.1

85310 Red fir forest 3,390 6.0

85210 Jeffrey pine-fir forest 3,030 5.3

86100 Lodgepole pine forest 2,152 3.8

85100 Jeffrey pine forest 2,115 3.7

42200 Non-native grassland 1,923 3.4

The ownership profiles of Sierran plant communities systematically reflect the concentration of private lands at lower elevations and of national parks in the central and southern portion of the range. Many of the foothill community types fall largely on private lands, notably non-native grassland (90% of mapped distribution on private lands), valley oak woodland (98%), blue oak woodland (89%), interior live oak woodland (71%), and foothill pine-oak woodland (83%). These percentages differ somewhat from the statewide estimates of private ownership provided by Bolsinger (1988). His estimates are lower for valley oak woodland (86% private ownership) and blue oak woodland (75%) and higher for interior live oak woodland (82%). Our estimates of private ownership and conservation of blue oak and blue oak-foothill pine community types are comparable to those of Greenwood et al. (1993).

A number of relatively widespread community types fall disproportionately on national forest lands, notably low sagebrush scrub (77%), subalpine sagbrush scrub (75%), rabbitbrush scrub (93%), Cercocarpus ledifolius woodland (91%), mixed montane chaparral (73%), montane Ceanothus chaparral (70%), bush chinquapin chaparral (82%), aspen forest (89%), eastside ponderosa pine (72%), Jeffrey pine forest (72%), Jeffrey pine-fir forest (80%), red fir-western white pine forest (75%), whitebark pine-lodgepole pine forest (86%), and alpine dwarf scrub (99%).

Foxtail pine forest is the only widespread type whose distribution falls mainly inside the national parks (78%). The BLM controls the largest portion of the distribution for a few community types that are marginal to the Sierra Nevada region, notably Mojave mixed woody scrub (69%), blackbush scrub (61%), oak-piñon woodland (58%), and Joshua tree woodland (91%).

The mapped community types display a wide range of land management profiles. We would call special attention to four distribution types:

1. Upland rangeland plant community types mainly in areas that can be grazed. Table SN-4 lists 21 out of 60 types with areas greater than 25 km² and with more than 90% of the distribution in Classes 3-5 and therefore potentially grazed. These types merit special attention for grazing management and conservation. The main distribution for several of the types lies outside of the Jepson Sierra Nevada Region (e.g., Mojave mixed woody scrub, Joshua tree woodland, blackbrush scrub, and the sagebrush types). While we have less confidence in our mapping of riparian and wetland types, we should note that all riparian types and most wetland habitats were also mapped with more than 90% of their distribution in Classes 3-5.

Table SN-4. Upland rangeland plant community types in areas that can be grazed in the Sierra Nevada Region. These types are greater than 25 km² with more than 90% of their mapped distribution potentially grazed.

Percentage of Mapped Distribution by Land Management Class

CNDDB Code CNDDB Community Name (Holland 1986) Class 1 (Protected) Class 1-2 (ungrazed) Class 3-5 (potentially grazed)

Total Mapped Distribution (km²)

34210 Mojave Mixed Woody Scrub 0 0.2 99.8 278

34300 Blackbush Scrub 0 0 100.0 164

35100 Great Basin Mixed Scrub 2.7 8.6 91.4 303

35210 Big Sagebrush Scrub 3.3 7.1 92.9 998

35211 Low Sagebrush Scrub * 0.1 5.4 94.6 77

35212 Silver Sagebrush Scrub * 5.2 5.4 94.6 41

35400 Rabbitbrush Scrub 0.9 4.5 95.5 46

37200 Chamise Chaparral 5.8 7.7 92.3 821

37900 Scrub Oak Chaparral 0 6.4 93.6 48

37B00 Upper Sonoran Manzanita Chaparral 4.4 8.6 91.4 181

71110 Oregon Oak Woodland 0 0 100.0 27

71130 Valley Oak Woodland 0 0.1 99.9 336

71140 Blue Oak Woodland 1.3 1.9 98.1 4,573

71150 Interior Live Oak Woodland 0.9 5.9 94.1 1,332

71310 Open Foothill Pine Woodland 1.4 6.3 93.7 441

71410 Foothill Pine-Oak Woodland 0.4 1.5 98.5 4,024

72100 Great Basin Woodlands 6.3 9.0 91.0 975

72200 Mojavean Pinyon and Juniper Woodlands 0.8 1.0 99.0 558

73000 Joshua Tree Woodland 0 1.0 99.0 73

81330 Interior Live Oak Forest 1.8 4.3 98.7 1,553

84220 Eastside Ponderosa Pine Forest 0.9 5.5 94.5 1,618

2. Forest plant community mainly located in unprotected areas. Table SN-5 lists 6 types with areas greater than 25 km² and with less than 10% of their distribution in Class 1 land, which is designated for conservation of native biodiversity. These types are of special management concern related to timber harvest and/or fire suppression. However, except for interior live oak forest, these types are widely distributed on national forest lands that in current forest plans are classified as unsuitable for timber harvest (Class 2).

Table SN-5. Forest plant community types mainly located in unprotected areas in the Sierra Nevada Region. These types are greater than 25 km² with less than 10% of their mapped distribution in areas formally designated for conservation (i.e., Class 1 land).

Percentage of Mapped Distribution by Land Management Class

CNDDB Code CNDDB Community Name (Holland 1986) Class 1 (Protected) Class 1-3 (not available for timber harvesting) Class 4-5 (available for timber harvesting)

Total Mapped Distribution (km²)

81330 Interior Live Oak Forest 1.8 18.9 81.1 1,553

81340 Black Oak Forest 8.4 44.8 55.2 1,342

84210 Westside Ponderosa Pine Forest 8.4 30.4 69.6 5,744

84220 Eastside Ponderosa Pine Forest 0.9 23.4 76.6 1,618

84230 Sierran Mixed Coniferous Forest 7.1 32.7 67.3 7,975

84240 Sierran White Fir Forest 7.7 38.0 62.0 544

3. Chaparral community types mainly located in unprotected areas. Table SN-6 lists 8 types with areas greater than 25 km² and with less than 10% of their distribution on Class 1 land. The policy of suppressing wildfire on Class 2-5 public and private lands and the widespread conversion of chaparral to grasslands on private ranchlands raise concern for the long term sustainability of these fire-adapted plant communities. A similar concern arises for knobcone pine forest, a fire-dependent community that is also very poorly represented in Class 1 areas.

Table SN-6. Chaparral plant community types mainly located in unprotected areas in the Sierra Nevada Region. These types are greater than 25 km² with less than 10% of their mapped distribution in areas formally designated for conservation (i.e., Class 1 land).

Percentage of Mapped Distribution by Land Management Class

CNDDB Code CNDDB Community Name (Holland 1986) Class 1 (Protected) Class 5 (Private available for timber harvesting, grazing, or urban development)

Total Mapped Distribution (km²)

37200 Chamise Chaparral 5.8 51.7 821

37520 Montane Manzanita Chaparral 4.7 43.6 473

37530 Montane Ceanothus Chaparral 1.4 28.8 199

37550 Bush Chinquapin Chaparral 6.0 14.4 77

37810 Buck Brush Chaparral 1.1 22.1 155

37900 Scrub Oak Chaparral 0.0 70.6 48

37A00 Interior Live Oak Chaparral 4.3 69.7 202

37B00 Upper Sonoran Manzanita Chaparral 4.9 17.2 181

4. Plant community types that are well protected. Table SN-7 lists 12 types with areas greater than 25 km² and more than 25% of their distribution in Class 1 areas. These types are of relatively low priority for additional land acquisition or redesignation to reserve status. Most of these types are characteristic of higher elevation zones.

Table SN-7. Well-represented plant community types in the Sierra Nevada Region. These types are greater than 25 km² with more than 25% of their mapped distribution in areas formally designated for conservation (i.e., Class 1 land).

CNDDB Code CNDDB Community Name (Holland 1986) Percentage of Mapped Distribution in Class 1 (Protected) Total Mapped Distribution (km²)

37541 Shin Oak Brush 36.2 46

45100 Montane Meadow 41.3 168

84250 Big Tree Forest 33.7 171

85120 Red Fir-Western White Pine Forest * 28.7 1,599

85310 Red Fir Forest 33.1 3,390

86100 Lodgepole Pine Forest 53.6 2,152

86210 Whitebark Pine-Mountain Hemlock Forest 62.0 377

86220 Whitebark Pine-Lodgepole Pine Forest 48.9 525

86300 Foxtail Pine Forest 92.6 238

86600 Whitebark Pine Forest 58.3 218

91120 Sierra Nevada Fell-field 27.4 123

94000 Alpine Dwarf Scrub 89.5 394

Northern Sierra Subregion

The northern subregion totals 27,488 km² in area and is largely national forest or private land. Only 2.1% of the land in this subregion is in Class 1 areas (Table SN-2). An additional 10.1% is Class 2. Potentially grazed lands (Classes 3-5) account for 88% of the area, while 71% is eligible for intensive timber harvesting (Classes 4-5). Private lands constitute 45% of the total area.

Ownership and management vary systematically by elevation zone. More than 80% of the land below 1000 m is unreserved private land (Class 5), while less than 0.1% is in Class 1. In contrast, Class 5 constitutes less than 10% of areas above 2,000 m. The bias in representation in Class 1 lands towards mid- to high-elevations zones is shown in Figure SN-4.

Figure SN-4. Comparison of the proportion of class 1 areas with all lands in the northern Sierra Nevada subregion by elevation zones.

Land-cover was mapped into 4,014 polygons with a median polygon size of 356 ha. Of the 58 community types mapped, 41 had mapped distributions greater than 25 km² in extent. Sierran mixed coniferous forest was mapped over 5,596 km² or 22% of vegetated lands. Other widespread types include westside ponderosa pine forest (12% of vegetated lands), eastside ponderosa pine forest (6%), foothill pine-oak woodland (7%), red fir forest (5%), Jeffrey pine forest (5%), and Jeffrey pine-fir forest (4%). These 7 community types make up roughly 60% of the total vegetation. Only 4 of the 41 types with areas greater that 25 km² have more than 5% of mapped distribution in Class 1 land.

Many of the rangeland types are largely on land available for grazing, notably Great Basin mixed scrub (98% of distribution), big sagebrush scrub (93%), low sagebrush scrub (96%), chamise chaparral (99%), non-native grassland (100%), black oak woodland (90%), valley oak woodland (100%), blue oak woodland (100%), interior live oak woodland (100%), open foothill pine woodland (99%), foothill pine-oak woodland (100%), and Great Basin woodlands (99%).

Of the major forest types, interior live oak forest is distinctly concentrated on private lands (90%). Over half of the area in westside ponderosa pine forest is privately held. The middle-elevation forest types are more concentrated in the national forests (60% to 90% on public lands).

Treating the 4 major low-to-middle elevation conifer timber types (westside ponderosa pine, eastside ponderosa pine, Sierran mixed conifer, and Sierran white fir) collectively, we estimate that 22% of lower montane timberlands are in reserve status or are on national forest land classified as unsuitable for intensive timber harvest.

The 4 high-elevation conifer types that may be used for timber production include red fir-western white pine, red fir, Jeffrey pine, and Jeffrey pine-fir forests. Currently 49% of the total area in these types is reserved or withdrawn from intensive timber harvesting.

Central and Southern Sierra Subregion

We mapped a total of 35,630 km² as Jepson central or southern Sierra Nevada subregions. Because both Yosemite and Sequoia/Kings Canyon National Parks fall within this area, its land management profile is strikingly different from that of the northern subregion. Class 1 areas and private lands are roughly equal in extent, respectively 25.7% and 29.8% of the area. Like those in the northern subregion, Class 1 lands are concentrated at higher elevations (Figure SN-5).

Figure SN-5. Comparison of the proportion of class 1 areas with all lands in the central/southern Sierra Nevada subregion by elevation zones.

Approximately 12% of the region was classified as non-vegetated (mainly land at high elevation with little or no ground cover). Land-cover was mapped into 3,254 polygons with a median size of around 496 ha. The central/southern polygons tend to be larger than their northern counterparts mainly because much of the region was not mapped by vegetation type mapping crews and thus we relied more heavily on USFS timber type maps and on our own field visits to about 700 polygons to define polygon boundaries and composition.

Of the 70 mapped community types, 52 are greater than 25 km² in extent. Taken together, blue oak woodland, foothill pine/oak woodland and non-native grassland occupy 7,044 km², or 23% of the vegetated portion of the subregion. The other extensive community types include westside ponderosa pine forest (8%), Sierran mixed coniferous forest (8%), red fir forest (7% of vegetated area), lodgepole pine forest (6%), and Jeffrey pine/fir forest (6%).

Private lands and public grazing allotments cover roughly three-fourths of the vegetated area. Thus, practically the entire distribution of many plant community types is potentially grazed here, as it is in the northern subregion. Especially noteworthy are the valley and blue oak woodland, foothill pine-oak woodland and grassland types (more than 97% of mapped area available for grazing), Mojavean mixed woody scrub and pinyon and juniper woodland types (99%), and blackbush scrub (100%).

The largest difference between the northern and central/southern subregion lies in the management profiles of the major forest types. Virtually all of the timber-producing community types have at least 15% of their distribution on Class 1 land, and many have greater than 50%.

A number of community types are very well represented in Class 1 areas. Twenty of 52 extensive communities show at least 25% of their mapped distribution on Class 1 land, notably montane chaparral types, mixed conifer forest types, and subalpine woodland types.

The databases used in this gap analysis comprise the most spatially and taxonomically detailed land management and vegetation maps ever assembled for the region as a whole. Nevertheless, producing these maps involved a great deal of generalization, simplification, and distortion of the true complexity of the region. Without a statistically designed accuracy analysis we cannot state with confidence that the data are adequate to answer our assessment questions. For this reason we have tried to focus on very gross differences in ownership and management among subregions and among widespread plant communities, since these are not likely to be severely affected by the mapping scale or by minor errors in the geospatial data.

The Jepson Sierra Nevada Region spans nearly 600 km from south to north, rises over 4000 m in elevation, and encompasses a very wide range of soil and vegetation conditions, human land uses, and land management patterns. The genetic and species composition of Sierran plant community types varies systematically from the northern to southern end of the range (e.g., Taylor 1977, Walker 1992). For example, Walker (1992) estimated the average plant species turnover in Sierran mixed conifer forest to be one species per kilometer along the long axis of the range. The mixed conifer flora of the far northern Sierra Nevada shares only half of its plant species with its southern counterpart. Many plant taxa are endemic to one subregion. For this reason, the status of plant community types of the Sierra Nevada is best viewed on a subregional basis. Similarly, strategies for maintaining native Sierran biodiversity must account for the systematic and often profound differences, both administrative and biological, between the northern and the central/southern subregions, as well as between the foothill zone and higher elevations, between lower and middle elevation mixed hardwood-conifer and conifer community types, and between community types with predominantly west-side versus east-side distributions.

Our general conclusions are that:

Fifteen percent of the Sierra Nevada is in designated conservation lands. An additional 7% is in national forest lands that are not grazed and/or are deemed unsuitable for timber production.
More than 80% of designated Class 1 areas are less than 200 ha in size. These small parcels collectively contribute less than 1% of total Class 1 area. Yosemite and Sequoia/Kings Canyon National Parks contribute 89% of Class 1 lands. Most remaining Class 1 areas are high-elevation, ungrazed parcels within wilderness areas in the national forests.
Eighty-nine percent of the vegetated area of the Sierra Nevada is privately held or is public land where grazing is legally permitted.
Less than 1% of the foothill zone of the Sierra Nevada is in designated reserves or other areas managed primarily for native biodiversity.
Roughly 80% of the lands at elevations below 1000 m are privately held. Biodiversity management in this zone is thus largely in the hands of private landholders as regulated by state and county governments. Over 95% of the distribution of most plant community types in the foothills is potentially grazed.
Viewed over the entire range, low and middle elevation Sierran forests are not well represented in Class 1 areas. However, substantial areas of most of these forest types are classified as unsuitable for intensive timber harvesting on USFS land suitability class maps. These Class 2 lands appear to be the de facto reserves for lower montane forest types, especially in the northern Sierra Nevada.
Land ownership and management patterns contrast sharply between the northern Sierra Nevada and the central/southern subregions. Class 1 lands contribute less than 2% of the northern region versus 27% of the central/southern.
Based on our land management classification, biodiversity of the lower montane forests of the northern Sierra Nevada is considerably more vulnerable than forest biodiversity elsewhere in the range.
Many high-elevation forest and shrubland types are well represented in parks and ungrazed wilderness areas. In the central/southern subregion, 20 of 52 widespread community types are especially well protected, with over one-quarter of their distribution on Class 1 lands.

Acknowledgments

Financial support for this research was provided by the USFS Sierra Nevada Ecosystem Project, the Gap Analysis Program, and the California Department of Fish and Game. Computing support was provided by a grand from the IBM Corporation Environmental Research Program.

The following UCSB staff and student research assistants worked long and hard to prepare the land-cover and land ownership maps and databases: David Court, Josh Graae, Violet Gray, Nicole Griffin, Allan Hollander, Curtice Jacoby, Paul Mills, Dennis Odion, Daniel Sarr, Jim Thorne, Joe Walsh, Laurie Schwalm, Yvonne Thompson, Rich Walker, Eric Waller, Katherine Warner, and Dan Wolnick. Additional GIS data and support were provided by the staff of the SNEP GIS lab. Special thanks to Karen Gabriel, John Gabriel, and Russ Jones for prompt handling of our requests for data.

USFS personnel provided field data, advice and support to our field crews. We would especially like to thank Ralph Warbington, JoAnn Fites-Kaufmann, Jim Shevock, Connie Millar, Lenea Hansen, Beth Corbin, Stacey Scott, Terry Hicks, Bob Rogers, Lou Jump, Joanna Clines, Ron Taskey, and Neil Sugihara.

The draft manuscript for the SNEP report benefitted from the careful and constructive reviews of Zipporah Collins, Michael Barbour, Laurel Ames, William Stewart, and an anonymous reviewer.

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