Executive Summary
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Humboldt Regional Transportation Plan – 2013/14 Update Draft EIR Section 4.2 Biological Resources 4.2 BIOLOGICAL RESOURCES 4.2.1 Setting a. Habitats. Humboldt County is part of the Klamath/North coast bioregion. In general, this bioregion is characterized by its rocky coastline, forested montane areas, and relatively sparse human settlement. Much of this mountainous bioregion is covered by forest. It is considered one of the wettest areas in the State of California. Humboldt’s coastal area is characterized as having a cool and moist climate with a tendency for fog, while inland the climate is drier. The bays, estuaries, and other tidal inlets of the Humboldt coastal area provide a variety of habitats for resident and migratory wildlife species. Humboldt Bay, one of California’s largest coastal estuaries, is home to diverse and resource-rich habitats that support invertebrates, fish, birds, and mammals. The Humboldt Bay National Wildlife Refuge, established in 1971 within the Humboldt Bay area, provides almost 4,000 acres of conserved habitats, including mudflats, estuarine eelgrass meadows, saltmarsh, brackish marsh, seasonally flooded freshwater wetlands, riparian wetlands, streams, coastal dunes, and forest. These habitats support over 316 species of birds and 40 species of mammals. The refuge also provides habitat for approximately 100 species of fish and marine invertebrates, including steelhead, coho, chinook salmon, and Dungeness crab (USFWS, 2014; Humboldt County General Plan Update Draft EIR, 2012). The inland areas of Humboldt County are composed mainly of coastline and mountainous areas with dense coniferous forests interspersed with grass or chaparral covered slopes. Six wild rivers run through the County, providing habitats for fish and wildlife as well as important water resources. Over 400,000 acres of the County’s undeveloped forest and coastline habitats are designated as parkland in the State and National Park systems, leaving large tracts of undisturbed habitat (Humboldt County General Plan Update Draft EIR, 2012). Twenty-eight terrestrial habitat types are mapped using the California Department of Fish and Wildlife (CDFW; formerly referred to as the California Department of fish and Game) California Wildlife Habitat Relationships (CWHR) habitat classification system within Humboldt County (CDFW, 2008) (Figure 4.2-1). Because of the scale of this programmatic EIR, the habitat categories presented in Figure 4.2-1 depict a broad illustration of the CWHR types found within Humboldt County. Below, we describe each of the habitats adapted from A Guide to Wildlife Habitats of California (Mayer and Laudenslayer, 1988). It should be noted that these habitats are generalized and that site-specific variation is likely present. Also note that the CWHR classification system maps habitats from a broad perspective and that in many areas it is expected that two or more habitats may blend with one another. Habitats which occur within populated areas can also show variation because of a greater exposure to anthropogenic influences, such as the introduction of exotic plant species. Tree Dominated Habitats. Tree dominated habitats are the predominant vegetation type in Humboldt County. Fir forest and redwood represent over 50 percent of the county (Figure 4.2-1). Redwood areas generally occur from the coast eastward to the ridgeline. Fir and montane hardwood occur in the eastern and southeastern areas of the county. Fir and hardwood forests HCAOG 4.2-1 Section 4.2 Biological Resources CHWR Classifications ST ± ST ST ST P a c i f i c O c e a n ST ST ST ¤£ ST Data background elements provided by ESRI and its licensors © 2014. US Department of Agriculture, 2014. California Wildlife Relationship Classifications Figure 4.2-1 HCAOG Humboldt Regional Transportation Plan – 2013/14 Update Draft EIR Section 4.2 Biological Resources support sensitive species such as goshawk, red tree vole, and spotted owls. Old growth redwood and Douglas fir forests provide prime breeding grounds for numerous sensitive species. Most of the old growth forestland is protected by State and federal park designation (e.g., Redwoods State Park, Headwaters, and Redwood National Park). However, there are a few pockets of unprotected old growth forestlands near the Headwaters land and adjacent to other protected areas. Hardwood and conifer forests are not considered as sensitive as fir and redwood forests, in terms of habitat quality (Humboldt County General Plan Update, Natural Resources and Hazards, Biological Resources, 2002). The following describes types of tree-dominated habitats that occur within Humboldt County. Riparian areas are critical to many species of wildlife. The vegetation provides cover and nesting habitat for birds and creates corridors for animal movement including travel to and from different habitat types. These areas are important for wildlife migration and dispersal. While riparian habitat occurs as linear strips through various vegetation types, the adjacent upland habitat is often different. The edges where riparian habitat meets with upland habitat are known as ecotones, or edge habitats, which are important for many wildlife species (Humboldt County General Plan Update, Natural Resources and Hazards, Biological Resources, 2002). Douglas Fir Forest. This habitat typically exhibits a spatial variation due to geologic, topographic, and successional variation typical within its range. Structure within this habitat types typically consists of a lower overstory of dense, sclerophyllous, broad-leaved evergreen trees such as tanoak (Lithocarpus densiflorus) and Pacific madrone (Arbutus menziesii), with an irregular, often open, higher overstory of tall needle-leaved evergreen trees such as Douglas fir (Pseudotsuga menziesii). Klamath Mixed Conifer. This habitat type is typically composed of tall, dense to moderately open, needle-leaved evergreen forests with patches of broad-leaved evergreen and deciduous low trees and shrubs. The overstory layer is characterized by a mixture of conifers. Dominant conifers in the western range of this habitat are typically white fir (Abies concolor) and Douglas fir. In the east, dominant conifers consist of white fir, Douglas-fir, ponderosa pine (Pinus ponderosa), incense cedar (Calocedrus decurrens) and sugar pine (Pinus lambertiana). Coastal Oak Woodland. Coastal oak woodlands are common to mesic coastal foothills of California. The woodlands do not form a continuous belt, but occur in a mosaic closely associated with mixed chaparral, coastal scrub and annual grasslands. These woodlands are commonly dominated by coast live oak (Quercus agrifolia). At drier sites other species such as blue oak and foothill pine (Pinus sabiniana) may also be interspersed. The understory of dense stands tends to be composed of shade tolerant shrubs and herbaceous plant species such as California blackberry (Rubus ursinus), miner’s lettuce (Claytonia perfoliata) and toyon. In areas with more open canopies the understory may be more dominated by grassland and shrub species such as California blackberry (Rubus ursinus), and poison oak. Closed-Cone Pine-Cypress Forest. This habitat type is typically dominated by a single species of closed-cone pines (Pinus sp.) or cypress (Cupressus sp.) and the height and canopy closure of these series are variable depending upon site characteristics including soil type, the age of the stand and the floristic composition. Closed-cone pine-cypress forests are considered fire climax or fire-dependent vegetation types. This habitat type is typically found within rocky HCAOG 4.2-3 Humboldt Regional Transportation Plan – 2013/14 Update Draft EIR Section 4.2 Biological Resources and infertile soils along the extreme coast or on very shallow infertile soils contain stunted, wind-pruned individuals. Montane hardwood-conifer. This habitat type includes both conifers and hardwoods often as a closed forest. Composition is comprised of at least one-third conifers and at least one-third broad-leaved tree species. The habitat often occurs in a mosaic-like pattern with small pure stands of conifers interspersed with small stands of broad-leaved trees. This diverse habitat consists of a broad spectrum of mixed, vigorously growing conifer and hardwood species. Most of the broad-leaved trees are sclerophyllous evergreen, but winter-deciduous species also occur. Relatively little understory occurs under canopy. Steeper slopes are normally devoid of litter; however, gentle slopes often contain considerable accumulations of leaf and branch litter. Redwood. Second growth redwood habitats are characterized by an even-aged structure with an open park like appearance. Coast redwood (Sequioa sempervirens) is the dominant tree species. Understory vegetation in old-growth redwood is usually very dense and composed of tall shrubs. Redwoods are very vigorous sprouters; sprouts eventually form the dominant canopy. Redwood and associated conifers also reproduce well by seed. Montane Hardwood. A typical montane hardwood habitat is composed of a pronounced hardwood tree layer, with an infrequent and poorly developed shrub stratum, and a sparse herbaceous layer. In the Coast Ranges, canyon live oak (Quercus chrysolepis) often forms pure stands on steep canyon slopes and rocky ridge tops. It is replaced at higher elevations by scattered huckleberry oak (Quercus vacciniifolia) amongst an overstory of various conifers including ponderosa pine (Pinus ponderosa), Coulter pine (Pinus