Lecture 2: World Biomes and North American Plant Communities

Define a biome and list examples

A large biogeographic unit defined by the structure of its vegetation and dominant species

Example: Grassland, Desert shrubland, Tundra. Forest, Deciduous, Evergreen

list the 18 Major Global Biomes (varies)

Tropical rainforest

Tropical deciduous forest

Thorn forest

Tropical savannah

Hot desert

Chaparral

Cold desert, arid shrublands and grasslands

High mountains (taiga and alpine tundra)

Temperate evergreen forest

Temperate deciduous forest

Taiga

Arctic tundra

Temperate grassland

Ice

what are the prominent terrestrial biomes

Tropical rainforest

Coniferous forest

Deciduous forest

Grassland, savannah, shrubland

Tundra

what are the main vegetation types of a Coniferous Forest

Taiga

Subalpine and montane

Temperate low elevation

what are the main vegetation types of a Deciduous Forest

Mixed mesophytic

Oak-hickory

Southern mixed-hardwood

Beech-maple

Hemlock-northern hardwood

Oak Savannah / woodland

what are the main vegetation types of Grassland, savannah, shrubland

Tallgrass

Mixed grass

Short grass

Palouse

California grassland

Desert grassland

what are the main vegetation types of tundra

arctic

alpine

what are the main vegetation types of deserts and scrub

Great Basin

Mojave Desert

Sonoran Desert

Chihuahuan Desert

Arctic tundra and alpine tundra have similar

vegetation and soils:

• Low diversity

• Shrubs, sedges, grasses, lichens, herbaceous perennials

• Less than .5 meters tall (often much less though sometimes more)

• Vegetation typically not very tall

• Summer season is very short

• Winter season is covered in ice and snow, temps as low as -76 degrees C

• Soils

  • Histosols and entisols

  • Permafrost - permanently frozen soil layer below 25-30 cm

    • Roots can’t go very deep because of this

what are tundra polygons

a distinctive feature of the tundra landscape, characterized by their geometric patterns formed by the repeated freezing and thawing of permafrost

describe the arctic tundra climate

Short growing season (1.5-2.5 months)

Low temperatures (-32C - 4C) / (-25F - 40F)

Moderate solar radiation

Lower precipitation

describe the alpine tundra climate

Short growing season (1.5-2.5 months)

Low temperatures (-18C-7C) / (0F-45F)

High solar radiation

Higher precipitation

define timberline- the location of timberline is

variable

• it rises in elevation with decreasing latitude

• Also rises with distance from coast

Krummholz vegetation

“crooked trees” - occurs when trees grow in abnormal growth patterns due to nature, typically wind blowing strongly

what are the main threats of conservation

energy development, tourism, warming

describe the three types of coniferous forests:

taiga, sub-alpine and montane, and temperate low elevation / low elevation coniferous forests

location of taiga, subalpine, montane, and low elevation

About 45 degrees north latitude

Below alpine tundra

Below subalpine zone

Varies: especially Pacific NW coast

precipitation of taiga, subalpine, montane, and low elevation

38-50 cm

20%-50% more precip

<similar but more

200-300 cm

temperature of taiga, subalpine, montane, and low elevation

Very cold, -50-20 degrees celsius

At least 5 degrees warmer

<similar but more

2-20 degrees

growing season of taiga, subalpine, montane, and low elevation

3-4 months

Similar but more variable

< similar but more

longer

soils of taiga, subalpine, montane, and low elevation

Spodosols (very acidic)

Inceptisol

<similar

varies

western slope elevation - 1,000-3,500:

foothill, woodlands, chaparral

western slope elevation - 3,500-6,000:

lower montane

western slope elevation - 6,000-8,500:

upper montane

western slope elevation - 8,500-10,500:

subalpine

western slope elevation - >10,500:

Alpine

Soils in taiga are very

acidic, not a lot of life can tolerate it

taiga means

boreal forest, means coniferous forest

Generally the transition from deciduous to coniferous forests depends on

temperature but there are some exceptions

describe the eastern mixed forest

Location: south of the taiga, east of the northern Great Plains, Appalachian Mts.

Composition: dominated by Coniferous and Deciduous Trees

Climate: warm, humid summers; cold snowy winters

describe taiga vegetation (short)

Vegetation

• Dense, closed forests

• Lots of spruce species

describe subalpine and montane forest

Vegetation

• Greater diversity

• Grasses and forbs in valleys and meadows

describe the low-elevation region

Location is very variable and typically gets a lot more rainfall

Great lakes region

Location

• South of the taiga, east of the northern great plains

• Appalachian mountain

identify a mixed forest region

Wisconsin: pine trees, mixed deciduous trees

list the New Forest Regions

Mesophytic

Appalachian Oak Section

Oak-hickory

Southern mixed

Oak-pine section

Mississippi alluvial plain

Subtropical evergreen

Beech-maple-basswood

Northern hardwoods-red pine

Northern hardwoods-hemlock

Physiognomy of a typical second-growth eastern deciduous forest, the dominant overstory trees may reach 60 cm or more in height, but commonly are 30 m

• Dominant overstory trees such as

oak, hickory, maple, elm, basswood, hemlock, beech

• Shrubs are common such as kalmia, rhododendron, and viburnum

• Herbs, mosses, ferns about 30 cm tall or less

• Subdominant trees such as dogwood and hornbeam

• Vines such as Virginia creeper, ivy, briar

Pacific coastal forest

Coniferous forests

• Vegetation

Get a lot of rainfall, have a lot of ferns and mosses

Find sequoia and redwood trees here

Southeastern mixed evergreen forest

From Connecticut to

East Texas

New Jersey Pine Barrens

• Historically south eastern mixed forests are more open like a savannah

• Pines can be very large but these sites are typically low fertility

Southeastern Pine Forests

• Good pines, lots of grasses and shrub in the understory

the eastern deciduous forest used to cover about

30 states

Very little is left due to disease and overlogging

Has the most extremes in climate swings

describe the crosstimbers

Savannah has more woody, shorter vegetation, should be more open

Forest has more closed canopy, lot of understory

list attributes of the grassland and steppes

More herbaceous vegetation for grazers

Fire keeps it more of a savannah than a forest

Large amount of grassland has been converted to agriculture

Extent of Prairie to European Settlement

• Shortland Prairie into Mixed Prairie into Tallgrass Prairie