Biomes, Belts (Life Zones) and Plant Communities
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- Biomes -
largest biological communities (largest ecosystems)
- general examples:
forests, tundra, deserts, grasslands
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Belts (Life Zones) Across
Elevation Change in the Sierra Nevada Mountains
- distinct variation in plant communities as found at various elevations
- similar to latitude changes from temperate to Arctic regions
- Great Valley (Lower
Sonoran Zone)
- original native bunch
grasses replaced by non-native annuals
- oak woodlands and
riparian - valley oak, sycamore, cottonwoods,willows, elderberry,
wild roses...
- wetlands & marshes
- migratory ducks, geese, elk, antelope, bears, salmon, beaver...
- Foothill
Belt (Upper Sonoran Zone)
- xeric (sunny, dry)
conditions
- characterized by
shrubby plants and pines-oak
woodlands
- dotted with blue
oaks and chaparral (manzanita, chamise, ceanothus)
- frequent fires
to clear out brush and extra "fuel"
- drought adapted
species for rainless summers;
- Calif. buckeye, redbud,
blue oaks, digger (gray) pines, interior
- live oak; fox, coyote,
ring-tail (cat), brush rabbit, turkey vulture, hawks, wrentit
...
- Yellow Pine Belt (transitional)
- 2000 to 6500 feet
- mesic (moderate moisture)
conditions
- characterized by
giant pines & firs: ponderosa, sugar, Douglas fir
- more shaded creating
some broadleaf (deciduous) trees mixed with taller trees,
- black oaks, maple,
dogwood, incense cedar, cottonwood, alder, madrone, white
fir,
- lizards, rattlesnakes,
red-back voles, bark beetles, stellar jays, spotted owl...
Subalpine / Boreal Forest Belt - also > Canadian, Hudsonian, Arctic-Alpine)
- receive snow and
continuous frost, harsh growing conditions
- lodgepole pine, Western
White (silver) pine, red fir, whitebark pine
- foxtail pine, mountain
hemlock, grasses & flowers, corn lilies, paintbrush
- black bear, chipmunks,
yellow-bellied marmot, deer, grouse, woodpeckers...
- Jeffrey Pine Belt
(east slope, more arid regions or poor soils)
- Sierra Nevada Mtns.
in more arid regions; poor soils
- looks like Ponderosa
but more reddish, aromatic bark,
- mixed with other
conifers such as Ponderosa and even Douglas fir
- Sagebrush
Belt (rainshadow and steppe climates)
- little
precipitation (less than 15"; dry, even alkaline (basic) soils
- mixed with pinon
pine, junipers, and other scattered shrubs
- sagehens, sparrow,
jackrabbits, kangaroo rats and other desert/steppe species
- Bridgeport in Sierra
Nevada; Yreka in Klamath Region
Plant Communities commonly
referred to by naturalists and botanists (based on criteria - see map)
- needleleaf [conifers]
evergreen forests (douglas fir, western white pine)
- coastal redwood forests
(coast redwood, spruce, red alders)
- mixed needleleaf and
broadleaf (evergreen & deciduous)
- valley oak (woodlands)
or savannas
- grasslands and tule marshes
- seashore and coastal
formations (estuaries, sand dunes, salt marshes)
- riparian forests
- shrub, creosote bush
and other arid plant communities
- alpine meadow (elevation)
- Biomes
and Belts Worksheet
next
Subalpine / Boreal Forest Belt - also > Canadian, Hudsonian, Arctic-Alpine)
