Images © by James L. Reveal, Norton-Brown Herbarium, University of Maryland, unless otherwise credited.

BSCI 124 Lecture Notes

Department of Plant Biology, University of Maryland

LECTURE 35 - TERRESTIAL BIOMES - Part 2
Montane Conifer Forests

Reflections in a Mountain Lake, Colorado

V. Montane Forests

A. General features: [Note: "Northwest Coast" is what is called here "Temperate Rain Forest, see below.]
- 1. Most complex biome in North America; widespread in the world.
  2. Fragmented in three major montane cordillera, each with a distinct fauna and flora; composed of many subcommunities or associations.
  3. General trending north/south, high elevation.
  4. Moist west slope, dry eastern slope - rain shadow effect.
  5. Influenced by recent glacial events; refugia and/or escape routed.
  6. Composed primarily of conifer species; often with some hardwoods
  7. Fire is often a major factor.
  8. Temperatures warmer than tundra, but often as cold and much more windy.
  9. Summary:
  - a. Origin.
    b. Environment.
    c. Biota.
    d. Population and community development and structure.
    e. Biological productivity.
B. Appalachian Mountains
- 1. Location: Higher mountains and ridges stretching from Vermont and New Hampshire to the Smoky Mountains of Tennessee and North Carolina.
  2. Features:
  - a. Conifers and deciduous hardwoods.
    b. Elevations most 2600-6000 ft (800-1800 m)
    c. Cool; average winter temperature is about 23° F, average high for the warmest month around 60° F. Extremes can reach -30° F and more than 100° F.
    d. Precipitation 60-100 in (150-255 cm); snow and rain; summer snow rare.
    e. Soils shallow and often over bedrock.
    f. Exploitation mainly in the forms of historical grazing, mining and lumbering; modern exploitation due to recreational use.
  3. Vegetation: (See the vegetation map of Maryland's Catoctin Mountain Park for a summary of local forest diversity.)
  - a. Dominated by spruce and fir, like the taiga - Table Mountain pine and Fraser fir are endemic; all "old growth" forest gone.
    b. Several species of hardwoods (e.g., birch)
    c. Understory of shrubs (e.g., azaleas, rhododendron, blueberries)
    d. Wild flowers occur in early spring and in mid to late summer
  4. Animals:
  - a. Numerous resident birds, most migratory species continue into the taiga or tundra
    b. Bear, deer, moose are the larger mammals
  5. History:
  - a. Northern mountains either covered with ice or were nunataks; southern mountains with ice caps or free of ice.
    b. Vegetation pushed elevationally down slope and southward into Mexico.
    c. Several montane species on the Coastal Plains
High elevation "park" in the Rocky Mountains -- Colorado

C. Rocky Mountains
- 1. Location: A massive complex from northern Alberta, Canada, to New Mexico, defined by the Great Plains in the east, western edge less sharply demarcated. North of South Pass, Wyoming, termed the "Canadian Rockies" to the south "Colorado Rockies." Includes isolated ranges in Idaho and Utah.
  - a. Northern Rocky Mountain Forest-Steppe
    b. Middle Rocky Mountain Steppe
    c. Southern Rocky Mountain Steppe
  2. Features:
  - a. Scenic mountains, heavily glaciated, (Jasper National Park, Glacier National Park).
    b. Numerous ranges over 13,000 ft (4000 m) in elevation; "parks" - broad valley bottoms - occur above 9000 ft (2750 m).
    c. Well-marked timberline.
    d. Precipitation (15-60 in or 40-150 cm) falls mainly as winter snow. Dry summers with lightening storms
    e. Variable soils.
  3. Vegetation:
  - a. Dominated by spruce and fir, but different species than in Appalachian or taiga; diversity of pines. Quaking aspen (see left), scrub oak and large shrubs common; willow in moist areas. Many areas of "virgin" forest still extant.
    b. Profusion of wild flowers throughout the growing season; grasses common.
    c. Well-defined zones: alpine tundra, timberline with "krumholz" growth (figure to the left) - old trees deformed by winds and blowing snow and ice subalpine forests, forest and meadows.
    d. Many arctic and Old World species.
  4. Animals:
  - a. Deer, elk (hear an elk!), bear - all larger in size than in other montane forests; beaver and other fur-bearing species. Wolves and grizzly bear now largely gone.
    b. Numerous resident birds, including several raptors (eagles [as in the golden eagle] and hawks [as in the sharp-shinned hawk]); several seasonal migrants.
  5. History:
  - a. Heavily glaciated with localized ice caps; glaciers and snow fields present today; numerous refugia and nunataks formed.
    b. Timberline has changed latitudinally and elevationally over time.
    c. Hot, rapid fires have played a major role; "crown fires" can created their own fire storm.
Afternoon reflections on Yellowhammer Lake, Sierra Nevada, California

D. Sierra Nevada and Cascade Ranges
- 1. Location:
  - a. Narrow band from northern British Columbia to northern Baja California, Mexico. Sierra Nevada: continuous mountain range restricted to California and the Lake Tahoe region of Nevada. See Sierra Nevada.
    b. Cascade Ranges: Southern Oregon to British Columbia as a series of fragmented, volcano-dominated montane islands; transitional ranges join the two in northern California. See Cascade Ranges.
  2. Features:
  - a. Scenic mountains - a daily view; glaciated.
    b. Many peaks over 14,000 ft (4270 m).
    c. Cool, moist winters and seasonable summers.
    d. Precipitation mainly as winter snows, 10-50 in (25-125 cm).
    e. Variable soils; granitic and volcanic soils common.
    f. Great diversity of plants and animals.
    g. Fire a significant factor with many species adapted to fire.
    h. Gentle, moist western slope; steeper, drier eastern slope.
    i. Numerous streams and lakes.
    j. Numerous volcanic peaks (e.g., Mount Rainier National Park, Mount St. Helens.
  3. Vegetation:
  - a. Numerous species of conifers (e.g., sugar pine; big tree; foxtail pine; whitebark pine (see right); and incense cedar
    b. Diverse array of shrubs and wild flowers
    c. Numerous endemic species
  4. Animals:
  - a. Numerous resident species.
    b. Deer, elk, bear all still common in places; fur-bearing animals never numerous.
  5. History:
  - a. Combination of volcanic and glacial activities.
    b. Numerous refugia, nunataks and escape routes so few species rendered extinct by Holocene changes.