Forests of the Sierra Nevada

California Geography

• Coast Range

• Sierra Nevada

• Great Basin

Environmental factors predict forest type

• Climate

  • Temperature

  • Precipitation

  • Growing season

• Geology and soil

• Disturbance (or lack of)

  • natural

  • human

• Time and space (geography)

Chaparral

• Dense shrubland shaped by a Mediterranean climate

• Fire plays an important role with a 30-50 year, catastrophic interval

• Location: southern Cali

• Woodland zone: >100 species of closely spaced evergreen shrubs (many in Ericaceae)

Sierra Nevada Mountains

• Mountain ranges 1500-14,494 ft (Mt. Whitney)

• Forest types delineated by elevation

  • Woodland

  • Submontane

  • Montane

  • Subalpine

Principal forest types

• Forest Zone | Description | Elevation

• Woodland | Oak/Foothill Pine | 500-4000 ft

• Submontane | Ponderosa pine, CA black oak | 3000-5000 ft

• Montane | Mixed coniferous —most extensive | 5000-7500 ft

• Sub-alpine | Fir and pine forest | 7500-12000 ft

Sierra Nevada Woodland Zone

• Transition between chaparral and conifer forest

• Elevation depends on latitude

• Tree canopy is closed, with short, broad crowns

• Annual precipitation: 15-40 inches, little during growing season

• Principal species

  • foothills or gray pine

  • blue oak

Sierra Nevada Submontane Zone

• Transition between woodland and coniferous montane zone

• 3000-5000 ft elevation (depends on latitude)

• Structure:

  • closed canopy; secondary growth

  • shrub and small tree layer

  • minimal herbaceous layer

  • woody fuel and litter layer

• Principal species: Ponderosa pine, California black oak

Sierra Nevada Montane Zone

• 5000-7500 ft elevation

• Most extensive forest type in CA, but extends into OR

• Much more variable and diverse than the Rocky Mountains

• Closed canopy forest

• Principal species: Ponderosa pine, Douglas-fir, Jeffrey pine, sugar pine, giant sequoia, and many more

Sierra Nevada Subalpine Zone

• 7500-12000 ft elevation (wide range based on latitude)

• Open forest, widely scattered trees

• No understory, except scattered alpine wildflowers

• High snowfall, which comprises most of the annual precipitation

• No spruce!

• Principal species

  • red fir

  • lodgepole pine

  • mountain hemlock

  • whitebark pine

Threats to forests in the Sierra Nevada

• Threats

  • insects and disease

  • drought

  • wildfires

  • climate change

  • wildland-urban interface

  • interactions

  • current fire map