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Appendix NW. The Northwestern California Region


Contributing Authors: Jim Thorne, David Stoms, and Frank Davis

Regional Character
Land Stewardship
Plant Community Types

Regional Character

The Northwestern California Region (NW) is bounded on the east by Interstate 5 and the Sacramento River north of Redding, Oregon to the north, and the Pacific Ocean to the west. To the south the region extends into southern Sonoma, Napa, and Solano Counties and is delineated primarily by foothills rising north of the Sonoma and Napa Vallies in the eastern section of the border and those rising north of Salmon Creek in the west (Figure NW-1). The Northwestern California region is differentiated from the Cascades to the east by a contact between the volcanic rock of the Cascades and the metamophic rock of the Klamath Mountains. Differentiation of the Great Central Valley from the Northwest is defined by the beginning of Blue oak woodlands at the edge of the Valley's grasslands. Differentiation between the Central Western Region and Northwestern Region is less clearly demarcated, but generally results from three factors, topography, a higher precipitation in the NW region due to maritime influences (which extend across almost the entire southern boundary due to the proximity of San Pablo Bay) and associated stands of Redwood and Douglas-fir.


Figure NW-1. Shaded relief of Northwestern California Region.

The region encompasses 55,938 km² and is composed of three subregions: North Coast, Klamath Ranges, and North Coast Ranges. The latter is further divided into three districts: Outer North Coast Ranges, Inner North Coast Ranges, and High North Coast Ranges. The North Coast subregion is a narrow strip along the immediate coastline which contains truly coastal communities such as coastal prairie, fir/spruce forest, and closed cone pine or cypress. The Klamath Ranges contains a variety of montane conifer forests characterized by hemlock, grand fir, and chinqapin. The Outer North Coast Ranges receive high precipitation and therefore contain redwood and hardwood forests. The High North Coast Ranges are floristically more similar to the high Sierra Nevada with montane and subalpine conifer forests. The Inner North Coast Ranges adjacent to the Great Central Valley are hotter and drier than the rest of the region and are characterized by chaparral and pine/oak woodlands.

The Northwestern California region is well known as one of the highest centers of endemism and biodiversity in North America. In this region are found the majority of California's redwoods, pygmy coniferous forests in Mendocino, and a series of coastal confiers associated with forests further north including Sitka spruce, Western hemlock, Grand fir, and the more interior Port Orford cedar. Serpentinites and associated endemic plants are extensively distributed throughout the Northwest region, and contribute to the rich vegetation mosaic. Above 1300m lies a mixure of conifer stands, montane chaparral types, alpine meadows, and small, species rich wetlands. It is in this zone that the famous Enriched Conifer Forests of northern California are found. These stands contain up to 17 species of conifer growing in close proximity, several of which are endemic.

Historical uses of land in the region include timber, mining, fishing, and some grazing and agriculture, though these latter tend to be less extensive than in other regions due to the ruggedness of much of the terrain. All of these land uses are still practiced at varying rates. Timber is probably the dominant resource extraction. An infusion of people into the southern part of the region (developing housing along much of the Coast Ranges) and extensive utilization of valley lands for viticulture or grazing (and increasingly for urban and residential use) is raising concern for native biodiversity in these environments. Watershed management to conserve native anadromous salmonids is another pressing, regional conservation priority.

Land Stewardship

Figure NW-2 shows the management status of lands in the Northwestern California Region. Less than half of the region is publicly owned, comparable to the state as a whole. The public ownership is widely distributed among U.S. Forest Service (34.0% of the total region), BLM (4.5%), Indian reservations (0.8%), National Park Service (1.3%), Department of Defense (0.2%), state parks (1.2%), California Fish & Game (0.1%), and other state land (0.6%). The Nature Conservancy (TNC) and other non-governmental organizations own 0.1% of the land area.

Table NW-1. Area by management status level of the Northwestern California Region.

Status Area (km²) %
1 5,046 9.0
2 1,290 2.3
3 17,021 30.5
4 32,536 58.2
Total 55,893 100.0

The region has the fifth largest proportion of status level 1 land in the state, and a very similar profile to the Southwestern California region. We mapped 111 status 1 managed areas for the Northwestern California Region, covering 9.0% of the entire region. There are 12 privately owned managed areas, 8 Fish & Game ecological reserves, 32 USFS Research Natural Areas, and 10 USFS wilderness areas. Status 1 managed areas are dominated by 6 units greater than 10,000 ha: the Trinity Alps, Siskiyou, Marble Mountains, and Yollo-Bolly-Middle Eel wilderness areas, Redwoods National Park, the BLM King Range Conservation Area and Humboldt Redwoods State Park. Seventy-nine status 1 areas are less than 1000 ha in size (although a few of these also extend beyond this region).

Northwestern Region Managed Areas

Figure NW-2. Management status of lands in the Northwestern California Region. See text for definitions of management levels.

Another 2.3 percent of the region is in 112 status 2 managed areas, consisting primarily of 27 state parks, 5 BLM ACEC's, and 8 Fish and Game wildlife areas. Status 2 areas are dominated by 4 units: the BLM King Range National Conservation Area, Humboldt Redwoods State Park, and the Whiskeytown Shasta Trinity National Recreation Area.

Elevation Bias in NW Region

Figure NW-3. Comparison of the proportion of managed areas with all lands in the Northwestern California Region by elevation zones.

The representational bias in the NW region is made quite obvious in Figure NW-3. The majority of status 1 and 2 lands in the region occurs above 1000 m, while most of the land area in the region falls below this elevation. Most of the lower elevation lands are privately owned and subject to commercial logging and some agricultural development. This elevational pattern reflects the wilderness designations in the higher mountains, and the relative lack of protection at low elevations along the coast, with the exception of Redwoods National Park and the King Range.

Plant Community Types

Land-cover polygons were attributed using the VTM maps, a map of hardwoods (Pillsbury et al. 1991), a map of redwoods (Fox 1988), field surveys by UCSB staff (562 polygons were checked in the field), and aerial photography. In addition, the GIS Potential Natural Vegetation coverage for the Six Rivers National Forest and GIS coverages of timber types for the Klamath and Shasta Trinity National Forests were used. Expert opinion was solicited from Max Creasy, ecologist; Ed Biery, Phil Purcell, and Carlos Carrol, botanists for the Klamath National Forest; David Isle, botanist for the Mendocino National Forest; Ed Philbrook, botanist for the Six Rivers National Forest; and Tom Atzet, ecologist for the Rogue and Siskiyou National Forests. See Thorne (1997) for greater detail on mapping methods.

We classified 53,506 km² (95.6%) as natural plant communities, 775 km² (1.4%) as agriculture, and 829 km² (1.5%) is developed. The land-cover layer is broken into 1,629 landscape units, averaging 3,514 ha in size (median = 2,070 ha). Seventy-three plant community types were mapped in the region. Seventeen other land use/cover types were mapped as well.

Table NW-2. Percent area of each CNDDB community type at each management status level in the Northwestern California Region.

CNDDB Code CNDDB Community Name (Holland 1986) CNDDB Rank Status 1 % Status 2 % Status 3 % Status 4 % Total Mapped Distribution (km²) Status 1+2 %
21210 Northern Foredunes S2.1 8.4 7.5 0.0 84.1 3.2 15.9
21310 Northern Dune Scrub S1.2 3.6 7.7 0.2 88.5 106.9 11.3
32100 Northern (Franciscan) Coastal Scrub S4/3.2/2.3 1.5 1.0 0.8 96.7 45.8 2.5
35210 Big Sagebrush Scrub S4 0.0 0.0 8.0 92.0 10.8 0.0
37110 Northern Mixed Chaparral S4 0.1 0.0 13.3 86.6 192.7 0.1
37200 Chamise Chaparral S4 1.0 0.0 34.2 64.8 764.6 1.0
37510 Mixed Montane Chaparral S4 40.5 2.4 44.2 13.0 216.8 42.9
37520 Montane Manzanita Chaparral S4 30.0 0.0 46.8 23.2 216.4 30.0
37530 Montane Ceanothus Chaparral S4/3.3 40.0 5.9 34.8 19.3 186.4 45.9
37541 Shin Oak Brush S3.3 0.0 0.0 95.6 4.4 28.7 0.0
37542 Huckleberry Oak Chaparral S3.3 30.1 0.0 51.1 18.8 109.3 30.1
37550 Bush Chinquapin Chaparral S3.3 62.2 0.0 37.8 0.0 21.0 62.2
37610 Mixed Serpentine Chaparral S2.1 0.0 0.0 35.2 64.8 155.3 0.0
37810 Buck Brush Chaparral S4 0.5 4.7 40.4 54.3 225.4 5.2
37820 Blue Brush Chaparral S4 0.0 0.0 0.0 100.0 6.0 0.0
37900 Scrub Oak Chaparral S3.3 86.4 0.0 0.3 13.3 10.7 86.4
37E00 Mesic North Slope Chaparral S3.3 21.5 0.2 34.2 44.1 175.2 21.7
41000 Coastal Prairie S2.1 5.7 9.3 0.3 84.8 131.1 15.0
42200 Non-Native Grassland S4 0.9 0.2 9.7 89.3 1,531.7 1.1
45100 Montane Meadow S3.2 31.6 0.0 20.3 48.1 34.5 31.6
52110 Northern Coastal Salt Marsh S3.2 1.3 33.0 0.0 65.8 4.4 34.3
52200 Coastal Brackish Marsh S2.1 0.9 2.9 0.0 96.2 43.5 3.8
52410 Coastal and Valley Freshwater Marsh S2.1 16.5 81.6 0.0 1.9 6.3 98.1
61110 North Coast Black Cottonwood Riparian Forest S1.1 0.0 1.2 39.8 59.1 11.0 1.2
61130 Red Alder Riparian Forest S2.2 5.4 12.5 1.1 81.0 18.0 17.9
61420 Great Valley Mixed Riparian Forest S2.2 0.0 0.0 0.9 99.1 1.0 0.0
63100 North Coast Riparian Scrub S3.2 1.4 2.5 7.9 88.2 99.3 3.9
71110 Oregon Oak Woodland S3.3 1.8 0.6 29.7 67.9 1,970.1 2.4
71120 Black Oak Woodland S3.2 1.7 0.9 31.1 66.3 630.9 2.6
71130 Valley Oak Woodland S2.1 0.0 0.3 0.4 99.3 350.0 0.3
71140 Blue Oak Woodland S3.2 0.1 0.9 18.6 80.4 2,646.4 1.0
71150 Interior Live Oak Woodland S3.2 0.0 0.0 20.3 79.7 219.0 0.0
71160 Coast Live Oak Woodland S4 0.0 0.0 0.1 99.9 87.9 0.0
71310 Open Foothill Pine Woodland S4 2.2 0.2 28.7 68.9 235.7 2.4
71321 Serpentine Foothill Pine-Chaparral Woodland S3.2 0.1 2.0 41.5 56.3 803.7 2.1
71322 Non-Serpentine Foothill Pine Woodland S4 1.3 1.4 33.2 64.1 369.8 2.7
71410 Foothill Pine-Oak Woodland S4 1.1 0.9 13.7 84.3 3,042.7 2.0
71420 Mixed North Slope Cismontane Woodland S3.2 0.8 0.9 19.6 78.6 1,005.2 1.7
72100 Great Basin Woodlands S3.2/4 0.0 0.0 20.5 79.5 577.0 0.0
81100 Mixed Evergreen Forest S4 4.9 2.0 27.4 65.6 2,964.9 6.9
81200 California Bay Forest S3.2 0.0 1.5 0.0 98.5 4.0 1.5
81310 Coast Live Oak Forest S4 1.4 1.7 7.2 89.7 699.4 3.1
81320 Canyon Live Oak Forest S4 4.5 1.4 31.4 62.7 475.1 5.9
81330 Interior Live Oak Forest S4 0.4 0.4 6.3 92.9 1,007.2 0.8
81340 Black Oak Forest S4 4.8 1.9 41.1 52.2 3,540.1 6.7
81400 Tan-Oak Forest S4 6.2 0.8 35.3 57.7 1,735.2 7.0
82100 Sitka Spruce-Grand Fir Forestt S1.1 10.4 11.6 0.0 78.0 339.3 22.0
82310 Alluvial Redwood Forest NR 1.3 3.6 8.1 87.0 742.0 4.9
82320 Upland Redwood Forest S2.3 4.9 5.5 4.5 85.2 4,607.7 10.4
82410 Coastal Douglas-Fir-Western Hemlock Forest S2.1 1.4 7.0 29.4 62.2 32.4 8.4
82420 Upland Douglas-Fir Forest S3.1 7.9 1.9 17.2 73.0 294.6 9.8
82500 Port Orford Cedar Forest S2.1 88.2 0.0 10.7 1.1 5.5 88.2
83110 Beach Pine Forest S2.1 0.0 32.0 0.0 68.0 14.0 32.0
83120 Bishop Pine Forest S2.2 1.1 4.8 3.3 90.8 136.1 5.9
83161 Mendocino Pygmy Cypress Forest S2.1 4.3 6.2 10.7 78.9 10.5 10.5
83210 Knobcone Pine Forest S4 1.2 0.5 60.6 37.7 268.6 1.7
83220 Northern Interior Cypress Forest S2.2 0.0 0.0 7.2 92.8 167.7 0.0
84110 Coast Range Mixed Coniferous Forest S4 11.7 2.9 48.4 36.9 13,528.8 14.6
84130 Coast Range Ponderosa Pine Forest S3.2/1.1 7.0 15.8 31.8 45.4 426.3 22.8
84160 Ultramafic White Pine Forest S3.2 51.5 0.0 24.4 24.1 22.2 51.5
84171 Northern Ultramafic Jeffrey Pine Forest S3.2 24.2 0.0 52.0 23.9 496.3 24.2
84180 Ultramafic Mixed Coniferous Forest S4 7.6 0.6 81.9 9.9 236.5 8.2
84210 Westside Ponderosa Pine Forest S2.1 29.3 0.2 46.5 24.0 1,332.4 29.5
84220 Eastside Ponderosa Pine Forest S2.1 55.5 0.0 26.4 18.1 23.6 55.5
84230 Sierran Mixed Coniferous Forest S4 19.8 0.7 46.2 33.3 1,762.2 46.9
84240 Sierran White Fir Forest S4 51.7 0.0 40.6 7.7 315.7 51.7
85100 Jeffrey Pine Forest S4 4.3 0.0 90.0 5.7 5.7 4.3
85210 Jeffrey Pine-Fir Forest S4 16.7 0.0 68.1 15.2 383.0 16.7
85310 Red Fir Forest S4 56.2 0.0 34.8 9.0 316.5 56.2
85410 Siskiyou Enriched Coniferous Forest S1.2 44.3 0.0 48.5 7.2 245.1 44.3
85420 Salmon-Scott Enriched Coniferous Forest S1.2 55.1 0.0 31.5 13.4 1,047.1 55.1
86100 Lodgepole Pine Forest S4 10.1 0.5 78.7 10.8 21.2 10.6
91110 Klamath-Cascade Fell-field S4 100.0 0.0 0.0 0.0 5.0 100.0

Regional Total-Natural Communities


Regional Total (incl nonvegetated)
9.0 2.3 30.5 58.2 55,926 11.3

Of the 73 natural plant communities, 56 have a mapped distribution greater than 25 km². These 56 plant communities are the focus of the vegetation analyses in this report. The most extensive community types mapped are Coast Range Mixed Coniferous Forest (84110), 13,529 km² (25.3% of native community types), Upland Redwood Forest (82320), 4,608 km² (8.6%), Black Oak Forest (81340), 3,540 km² (6.6%) and Foothill Pine-Oak Woodland (71410), 3,042 km² (5.7%).

It should be noted, however, that of the 17 plant community types mapped over less than 25 km² area, several are of conservation interest: Northern Foredunes (21210), Northern Coastal Salt Marsh (52110), Coastal and Valley Freshwater Marsh (52410), North Coast Black Cottonwood Riparian Forest (61110), Great Valley Mixed Riparian Forest (61420), Mendocino Pygmy Cypress Forest (83161), Beach Pine Forest (83110), Port Orford Cedar Forest (82500), Ultramafic White Pine Forest (84160), and Lodgepole Pine Forest (86100). The communities (inclusive) from Northern Foredunes to the Beach Pine Forests represent types that generally have a narrow extent where they occur. Because of the mapping resolution, they may be more extensive than indicated here.

The remaining communities under 25 km² are of interest for other reasons. All occur on ultramafic soils and potentially take a long time to reach maturity under these conditions. Port Orford Cedar (Cupressus lawsoniana) is a valuable commercial tree. These species do occur in the wider matrix of Mixed Coniferous Forest, but generally in limited extent. Where they tend to form dominant stands they may have associated serpentine endemics. Lodgepole and White Pine that are located on serpentines occu at lower elevations than when they occur on non-ultramafic soils. Port Orford Cedar is subject to a root rot, Phytophthora lateralis, which has spread through much of the cedar's range. Susceptibility to this pathogen is an additional concern assessing the vulnerability of Port Orford Cedar (Hawk 1977; Zobel et al. 1985).

Four categories of distribution are examined here for plant communities mapped over greater area than 25 km².

1. Plant community types mainly on status 4 (primarily private) lands. Seven types out of 56 have more than 90% of their mapped distribution on status 4 lands. These include: Valley Oak Woodland (71130, 99%), Coast Live Oak Woodland (71160, 100% in status 4), Northern (Franciscan) Coastal Scrub (32100, 96%), Coastal Brackish Marsh (52200, 96%), Interior Live Oak Forest (81330, 91%), Bishop Pine Forest (83120, 91%), and Northern Interior Cypress Forest (83220, 93%). Ten other community types are found to be at least 80% on status 4 lands. Thirty-three of the 56 types have greater than half of their mapped distributions on private land.

The degree to which chaparral lands in this region are being converted (i.e., to grasslands) or are vulnerable to grazing is unknown. Chamise Chaparral (62% on private lands) did not appear to be undergoing conversion and so may not be as vulnerable as indicated by this analysis. Species chararcteristic of Northern Mixed Chaparral (75%) are found in many other CNDDB community types. This type seems to fit less well in the Northwestern region than it does in regions further south.

Coast Live Oak (71160) and Valley Oak (71130) Woodlands are the two types at greatest risk, having virtually no formal protection in this region. Blue Oak (71140) and Interior Live Oak (71150 and 81330) woodlands and forests are frequently subject to livestock grazing and to a lesser extent to firewood cutting.

Of the conifer types that are mostly on status 4 lands, many are coastal, a reflection of general land ownership patterns. Redwood Forests (82310 and 82320) are about 85% on status 4 lands, and much of the remainder is on public lands available for logging. Most Redwood Forests on private land are in early successional stages.

2. Scrub, chaparral, and herbaceous types mainly located in unprotected areas. Nine of the 17 scrub, chaparral, and herbaceous types mapped to areas greater than 25 km² are represented by less than 10% in status 1 or 2. Shin Oak Brush (37541) and Mixed Serpentine Chaparral (37610) are both unrepresented (0%) in status 1 and 2 within this region. Northern Mixed Chaparral (37110) is virtually unprotected in the region as well. Other types in this category include Northern (Franciscan) Coastal Scrub (32100), Chamise Chaparral (37200), Buck Brush Chaparral (37810), Non-Native Grassland (42200), Coastal Brackish Marsh (52200), and North Coast Riparian Scrub (63100).

Scrub and chaparral types are potentially at risk in the long-term due to fire suppression. The majority of the types (except for Coastal Brackish Marsh and North Coast Riparian Scrub) are fire-adapted communities, which tend to undergo a seral shift when fire is suppressed.

3. Forest and Woodland types located mainly in unprotected areas. Twenty-five of 37 forest and woodland types identified as over 25 km² in area have less than 10% status 1 or 2 representation. This includes the 15 oak and foothill pine types mentioned in category 1 above. Several types have no representation in this region, including Interior Live Oak Woodland (71150), Coast Live Oak Woodland (71160), Great Basin Woodlands (72100), and Northern Interior Cypress Forest (83220). Alluvial Redwood Forest (82310) is represented by 4.9%, and Ultramafic Mixed Coniferous Forest (84180) by 8.2%. These types are of particular interest due to their limited presence outside the region.Coastal Douglas Fir-Western Hemlock (82410) is represented in status 1 or 2 by 8.4% and Upland Douglas Fir Forest (82420), 9.8%. These types extend into Oregon, and so their vulnerability in California represents less than 1/2 of their entire range. Knobcone Pine Forest (83210), 1.7%, is a type that typically appears after fire, and is relatively short lived. As with other disturbance related vegetation types, it is difficult to say if a vulnerability analysis based on management status is appropriate, since human caused disturbances may have either a positive or negative effect on their distribution, depending on the perturbation and the ecological conditions on a site. Fires suppression tends to have a negative effect, however.

4. Community types that appear well protected. Eleven plant communities of the 56 in the region with areas greater than 25 km² have more than 25% of their extent in status 1 and 2. These 11 types are clumped into montane chaparral and coniferous forest communities, generally at higher elevations. Four montane chaparral types (37510, 37520, 37530, and 37542) are well-represented, with over 30% each. Montane meadows are repesented by 32% of their extent, but these may be subject to grazing impacts. None of the oak types are included in this category. Westside Ponderosa Pine Forest (84210), Sierran Mixed Coniferous Forest (84230), Sierran White Fir Forest (84240), and Red Fir Forest (85310) are well represented, and also occur in extensive tracts beyond the region. Siskiyou Enriched Coniferous Forest (85410) and Salmon-Scott Enriched Coniferous Forest (85420) are well-represented with approximately 50%, but have narrow overall distributions (245 and 1,047 km²). As they are found nowhere else in the world, their conservation is still a management concern, despite the high level of representation.

The biggest single implication from this analysis is that all oak types in the region are to be considered at risk. This is not surprising, as the normal procedure by which protected areas have been designated involves selecting sites on public lands at minimum cost to human activities. This tends to place all the reserves at high elevation. Oaks grow on lower elevations and so generally fail to have had reserves sited around them.

Other implications of interest include the adequate representation of enriched conifer types in protected status, inadequate representation of serpentine vegetation associations, and the relatively small representation of Redwood types in protected status- given their regional status and narrow distribution. Land-cover types below the resolution of the analysis which are none the less important at this scale include the Mendocino Pygmy Forest, Port Orford Cedar Forest, and all riparian types.

Seral condition is an important component of the conservation status in forested vegetation types. Chaparral and grassland types in the Northwestern California region often occur in locations where disturbance (usually fire) is frequent enough that seral estimates are less relevant. For forest types, however, seral condition is an indicator of the structural complexity of the forest. The more advanced the seral condition, the more potential habitat spaces are available, and often, the greater the species richness of a stand. Late seral condition is often associated with areas which have not been logged, or which have had little disturbance under current management regimes. From a conservation perspective, late seral is desirable, as is evidenced by the fact 16 out of 19 Forest Service RNAs in the Klamath region that focus on forest types have late seral forests within them. The other three represent either serpentine outcrop locations or forests which are relatively younger because of fire or logging earlier in the century (Keeler-Wolf 1990).

Perhaps the most salient example of the importance of seral condition is the assessment of Redwood types. We mapped two types: 742 km² of Alluvial Redwood Forests and 4,608 km² of Upland Redwood Forests. Alluvial Redwood Forests have 4.9% in status levels 1 and 2, and Upland Redwood Forests are 10.4% protected.

Estimates of total late seral, or old growth forests in the Pacific Northwest (~228,000 km² ) range from about 7-14% of the region (Forest Ecosystem Management Assessment Team 1993). There is probably between 6-10% old growth Redwood left, almost all of which is located on protected federal lands. We know that 14% is an overestimate, because old growth Redwoods on private lands are well documented (see below), there is practically no old growth Redwood on Status 3 lands, and Redwoods on Status classes 1 and 2 (10.4% of total) are not all old growth.

Redwood holdings on private land account for 4659.6 km² or 85.3% of all redwoods in the region, very little of which is old growth. The fate of the small amount which is on private land is currently being debated. The last intact groves, located around the Headwaters Grove, are variously reported as 12-16 km² (3000-4000 acres) in extent. All other old growth fragments on private land are considerably smaller than this. The tremendous value of redwoods has created an intense competition for the trees and federal and state governments attempting to arrange a compromise at Headwaters.

Given that old growth redwood has both ecological importance to the region and high tourism value, what might seem a slightly under-represented combination of types under the normal gap analysis, takes on considerably more importance when the age and value of the stands is taken into consideration. It will be useful for policy makers to examine the GAP data in conjunction with seral data in dealing with this issue.

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