Before European settlement, these forests experienced frequent, low- to mid-intensity wildfires (primarily surface fires) that were a major factor influencing stand density, structure, and species composition. A policy of fire exclusion, or suppression, during the 20th century, along with the selective harvest of many large pines, has significantly changed fire behavior and led to an increase in fire severity and the number of infrequent but high-intensity, stand-destroying fires. In areas where fire has been prevented for many years, shade-tolerant white firs and incense cedars often outnumber the pines and oaks. In many ponderosa pine forests, kit-kit-dizze (a member of the rose family) covers the forest floor, and its pungent odor permeates the forest and clings to boots and clothing, earning it another name: “mountain misery.”
Large snags (i.e., greater than 24 inches diameter-at-breast-height) and decaying portions of living trees offer nesting cavities for Pileated Woodpeckers, Northern Flickers, and Western Screech-Owls. A variety of woodpeckers, Red-breasted Nuthatches, and Brown Creepers patrol the bark of conifers, while Warbling Vireos, Yellow-rumped Warblers, Black-headed Grosbeaks, and Western Tanagers make music from above. Near campgrounds and other developed areas, Steller’s Jays squawk and patrol their picnic tables, and Brewer’s Blackbirds strut across the pavement.
Pine-Oak Woodlands
North 2,000 to 6,500 feet; South 3,000 to 7,000 feet
Within the Lower Conifer zone, hardwood species like California black oaks, Pacific madrones, and bigleaf maples often intermingle with pines and other conifers. Black oaks, with dark trunks and bright green leaves, grow in patches mixed in with conifers—especially on open, rocky ridges and in forest clearings. These deciduous oaks turn gold in fall like the aspens, willows, and cottonwoods. The madrones and maples favor cool, wet drainages. Black oaks harbor hordes of caterpillars and flying insects that attract Nashville Warblers, Black-throated Gray Warblers, and Cassin’s Vireos to forage and sing. The high diversity of birds in these habitats is driven by an abundance of insects and nutrient-rich acorns. Accordingly, such acorn-consuming species as Western Scrub-Jays, Steller’s Jays, Acorn Woodpeckers, Mountain Quail, and Band-tailed Pigeons are common residents.
FIGURE 2 Lower Conifer zone
Oaks also provide nutritious sap that exudes from wounds in the bark caused by insects, tree falls, fire, and Red-breasted Sapsuckers. The sap provides feeding opportunities for the sapsuckers as well as for hummingbirds and warblers like Yellow-rumps and Orange-crowns. The high-protein seeds of many broadleaved trees are eaten by a long list of birds, including White-breasted and Red-breasted Nuthatches, Chestnut-backed and Mountain Chickadees, Dark-eyed Juncos, and Spotted Towhees.
UPPER CONIFER ZONE
Mixed Conifer Forests
North 5,500 to 7,500 feet; South 6,000 to 8,000 feet
As one proceeds up the West Side, ponderosa pines of the Lower Conifer zone blend into the cooler, moister, mixed conifer forests of the Upper Conifer zone. Mixtures of four or five species of conifers are typical in these forests, as the name of this habitat suggests. At places such as Crane Flat in Yosemite (Highway 120) and near the Giant Forest in Sequoia National Park, Jeffrey pines, with large cones and an aroma like vanilla rising from their bark, out-number ponderosas. Shade-tolerant white firs are often the most abundant trees, but usually incense cedars, Douglas-firs, sugar pines, and even a few red firs grow there, too. Black oaks reach this high but are fewer than farther down. Where the soil is rocky or wet, especially near meadows, lodgepole pines may grow in scattered stands. Giant sequoias, the world’s largest known living things, occur naturally only in the western Sierra, primarily in the Upper Conifer zone. A few grow as far north as Placer County, but most of the 75 groves are south of the Kings River and the largest, most majestic stands are in Sequoia National Park and Giant Sequoia National Monument.
Historically, many mixed conifer forests were comprised of large, thick-barked, fire-resistant trees, which were widely spaced with open understories. Fire suppression throughout the Sierra in the past century has greatly reduced the number and frequency of beneficial, low- to moderate-intensity fires that may have burned for weeks, or even months, cleansing the forest of the excess buildup of “ladder fuels” such as dead branches, small trees, and brush that fuel severe crown fires. There has also been a widespread increase in shade-tolerant tree species such as incense cedars and white firs within formerly pine-dominated stands.
In unburned and/or unlogged mixed conifer forests, huge conifers provide nesting habitat for Northern Goshawks, Spotted and Great Horned Owls, and foraging habitat and singing perches for Western Tanagers, Black-headed Grosbeaks, and Warbling Vireos. Hermit Warblers sound their buzzy songs from the deeper, shaded woods while White-headed and Pileated Wood-peckers call loudly from ancient snags. Golden-crowned Kinglets thrive in these forests, whispering high-pitched notes throughout the day.
FIGURE 3 Upper Conifer zone
Red Fir Forests
North 6,500 to 8,500 feet; South 7,000 to 9,000 feet
Red fir forests receive the heaviest Sierra snows. In these shady groves deep drifts often last long into summer, gradually releasing moisture into the soil. Small numbers of red firs grow on north slopes in the mixed conifer zone, but higher up their dark, silent columns reign supreme. Entire forests consist of only these trees, with rings of chartreuse lichen circling their trunks above the snow line. Often lodgepole and western white pines are mixed in, as are white firs at the lower edge of these forests. Particularly common in the northern and central Sierra, red firs grow only in limited areas farther south. At Porcupine Flat and Badger Pass in Yosemite and near Soda Springs on Interstate 80, impressive stands of red firs and lodgepole pines grow together. Lodgepole pines may form extensive stands in this zone, particularly in cold sites, around meadows, and on dry, rocky slopes. Heavy snows and deep forest litter prevent much growth of shrubs, grasses, or flowers; most birds in red fir forests search bark surfaces and sprays of conifer needles for food.
Red fir forests often seem lacking in birds, but if one listens carefully, rhythmic tapping of Williamson’s Sapsuckers may be heard. The characteristic sounds of Mountain Chicka-dees, Hermit Thrushes, Townsend’s Solitaires, Yellow-rumped Warblers, and Golden-crowned Kinglets echo through towering trees, and the complex, hyperspeed song of Pacific Wrens rises from the deep drainages. Flocks of Pine Siskins, Red Crossbills, or Evening Grosbeaks may fly overhead. Open areas with shrubs, wildflowers, and grasses draw Dark-eyed Juncos, Chipping Sparrows, and Cassin’s Finches that search the ground for insects and seeds. Some “edge” species such as Mountain Quail and “Mountain” White-crowned Sparrows use trees and shrubs for cover but feed in open areas nearby. At dusk, listen for the peents and booms of Common Nighthawks overhead and, as darkness comes, the incessant tooting of Northern Saw-whet Owls.
Mountain Chaparral
North 4,500 to 8,500 feet; South 5,000 to 9,500 feet
Brushfields of huckleberry oak, greenleaf manzanita, snowbrush, or chinquapin occupy steep, rocky slopes or forest clearings created by treefalls, logging, or fire. Especially prevalent on south-facing exposures, montane chaparral habitats may grow in impenetrable thickets but can be quite open on steep slopes or recently established sites. Some soil types are capable of only supporting chaparral. Although usually dry, these shrubfields are cooler than their foothill counterparts. Widespread above the foothills, montane chaparral habitats can be easily seen along Interstate 80 near Dutch Flat, Highway 120 west of Crane Flat in Yosemite, and on the slopes below Giant Forest in Sequoia National Park. Here the whistled melodies of Fox Sparrows may mingle confusingly with the similar songs of Green-tailed Towhees. Although they are often found in moist streamside habitats, Yellow Warblers and MacGillivray’s Warblers also nest in montane chaparral. Mountain Quail sneak through the underbrush and nest under this protective cover. At the edges where chaparral meets forest, you may find species such as Dusky Flycatchers and Western Wood-Pewees.
In some places, montane chaparral is an early stage of succession following