Instructions for printer-friendly copy.

x

x

x

    Biomes

    A biome is a major ecosystem spread over a wide geographic area, and characterized by specific, dominant plant life.

    Geographic distributions of biomes correspond closely to major climate zones.

x

x

x

x

x

x

x

x

x

x

x

x


(click for larger image)
(By Peter Halasz)

    Holdridge Life Zones

    The earliest biome concept was published by Leslie Holdridge in 1947.

    The life zone system assumption:

      If climate is known, soil and vegetation can be predicted and mapped.

    Three axes:

    • precipitation (log annual)
    • biotemperature (all To above freezing; log mean annual)
    • potential evapotranspiration (PET) : mean total annual precipitation (ratio)

x

x

x

x

x

x

x

x

x

x

x

x


    Whittaker Biome System

    Robert Whittaker based his biome classifications on
    temperature and precipitation.

    He matched vegetation type to regional climate
    to create a triangular figure within which all biomes fall.

    Whittaker terms:

    • physiognomy: characteristics or appearance of ecological communities or species

    • biome: grouping of terrestrial ecosystems on a given continent that is similar in vegetation structure, physiognomy, environmental features, and animal community characteristics.

    • formation: a major type of plant community on a given continent

    • biome type: grouping of convergent biomes or formations from different continents, defined by physiognomy

    • formation type: a grouping of convergent formations

x

x

x

x

x

x

x

x

x

x

x

x


    Whittaker Biome System

    In the Whittaker system...

    • Tropical/Equatorial climate zones have
      • mean annual temperatures of 20o - 30oC
      • mean annual precipitation of 0 - 400+ cm

    • Temperate climate zones have
      • mean annual temperatures of 5o - 20oC
      • mean annual precipitation of 0 - 300+ cm

    • Boreal and Polar climate zones have
      • mean annual temperatures of < 5oC
      • mean annual precipitation < 200 cm

x

x

x

x

x

x

x

x

x

x


(Wikipedia Commons)


(click for source)

    Fire Where it's Drier

    Fire is an important influence in warmer, drier biomes.

    In grassland and chaparral/shrubland biomes

    • moisture is intermediate (but sufficient for fuel to accumulate)
    • seasonal droughts occur (dries out fuel)

    This promotes seasonal fires.

    • grasses and herbaceous forbs are favored
    • woody plants may be fire-adapted (<-- required link)
      • fire-activated seed release or germination
      • fire-resistant insulation (bark, dead leaves, etc.)
      • storage roots or protected buds for re-sprouting
      • fire-activated flowering
      • tall crown with little low foliage

x

x

x

x

x

x

x

x

x

x

Major Terrestrial Biomes

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)

x


(click for more)

    Tropical Rainforest

  • Latitude: between 23.5o north - 23.5o south
  • Climate: stable year-round temperature; very high rainfall
  • Dominant vegetation: High-canopy trees
  • Biodiversity: extremely high (> 50% of terrestrial species)
  • Productivity: high
    • heavily laterized, nutrient-leached soils
    • even large trees have shallow root systems
  • Keystone species: seed-dispersing birds and mammals (agouti, bats, orangutan)
    • most ancient of earth's biomes
    • species have been co-evolving for millions of years
    • many strategies for predation and avoiding predation
    • Mature forest floor is relatively clear of plants,
      as upper canopy blocks most sunlight.
      A large treefall can allow germination of pioneer species
      that may have lain dormant for many years, waiting.

  • Typical animals (far too many to list):

    • Great Apes
    • Jaguar
    • Ocelot
    • Sloths
    • Tapir
    • Capybara

      Thousands of
    • bat species
    • bird species
    • amphibian species
    • reptile species
    • insect species

x

x

x

x

x

x

x

x

x

x

    Tropical Rainforest in Peril

    Tropical rainforest is currently disappearing at a rate of
    ~6000 acres (4000 football fields) per hour.

    The global consequences could be dire and difficult to reverse.

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)

x


(click for more)

    Tropical Grassland/Savanna

  • Latitude: ~ 25o north - 25o south
  • Climate: Extreme seasonal variation.
    • Mean monthly temperature > 18oC (64oF)
    • pronounced dry season (< 60mm/month)
    • Fire is a major abiotic feature; many plants are fire-adapted.
    • wet season has < 100 mm/month
    • very deep, humus-rich O horizon

  • Dominant vegetation: Grasses, sclerophyllous trees and shrubs.
    • Trees often have high canopies due to herbivory by large browsing mammals

  • Biodiversity: very high
  • Productivity: high
  • Keystone species: Grasses; large, grazing ungulates
  • Typical animals (too many to list!):

    • Antelope (many species)
    • Zebra
    • Wildebeest
    • Kangaroo (Australia)
    • Cape Buffalo
    • Rhinoceros

  • African Elephant
  • African Lion
  • Leopard
  • Hyena
  • Hunting Dog
  • Cheetah
  • Warthog
  • Aardvark
  • Secretary Bird
  • Various raptors (hawks, eagles)
  • Vultures
  • Elapid snakes
  • Rock Python
  • Many insects and arachnids

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)

x


(click for more)

    Temperate Shrubland

  • Latitude: ~ 30o - 45o north
    • arid regions with Mediterranean climate
      • southern California
      • European and African Mediterranean regions
      • southern tip of Africa
      • southwestern edge of Australia

  • Climate: hot and dry, with mild, rainy winters
    • Fire is a major abiotic formative feature; many plants are fire-adapted.
    • Droughts are common

  • Dominant vegetation: sclerophyllous, xerophytic shrubs

  • Biodiversity: moderate to high
  • Productivity: high
  • Keystone species: Grasses; large, grazing ungulates
  • Typical animals:

    • Mule Deer
    • Black-tailed Jackrabbit
    • Chipmunk
    • Ground squirrels
    • Brush Rabbit
    • Peccary (wild pig)

  • Coyote
  • Gray Fox
  • Alligator Lizard
  • Horned Lizard
  • Many colubrid snakes
  • Several pit viper species
  • Road Runner
  • Many migratory birds
  • Drought-adapted insects and arachnids
    • Praying mantis
    • Ladybugs
    • honey bees
    • bumblebees
    • scorpion

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)

x


(click for more)

    Desert

  • Latitude: ~ 30o north - 30o south
  • Climate: very dry; temperature extremes
    • precipitation < 100cm/year
    • Summer: extremely hot, dry days, cooler nights
    • Winter: hot, dry days; nights can be extremely cold

    Desertification is the anthropogenic change
    of non-desert ecosystems into deserts via

    • overgrazing
    • urbanization
    • poor agricultural practices

    • overuse of ground water
    • excessive deforestation
    • climate change

  • Dominant vegetation: xerophytes

  • Biodiversity: moderate
  • Productivity: low
    • counterintuitively, desert soils can be very rich in nutrients
    • lack of rainfall allows slow accumulation of cations
    • just add water: Bloom!
    • Spring rains can bring spectacular, short-lived blooming of annuals.
    • Keystone species: tortoises, vultures, coyotes, dingos
    • Typical animals:

      • Coyote
      • Desert foxes (e.g., Fennec)
      • Black-tailed Jackrabbit
      • Desert Cottontail
      • Kangaroo Rat
      • Jerboa

    • Camel
    • Addax
    • Oryx
    • Meerkat
    • Many colubrid snakes
    • Many viperid snakes
    • Road Runner
    • Bighorn Sheep
    • Armadillo
      • Praying mantis
      • Ladybugs
      • honey bees
      • bumblebees
      • scorpion
    • Famous North American examples include

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)

x


(click for more)

    Temperate Grassland

  • Latitude: ~ 25o - 50o north
  • Climate: Four distinct seasons; harsh, cold winters, very hot summers;
    typically very dry (precipitation < 100cm/year)
  • Dominant vegetation: Grasses, flowering forbs. Very few trees or shrubs
    • Fire plays an important role in maintaining this biome.
    • Very deep, rich O horizon

    Examples:

    • South African veldt
    • Hungarian puszta
    • Argentinian pampas

    • Mongolian/Central Asian steppe
    • North American prairie
    • (Most has been converted to farmland.)

  • Biodiversity: moderate to high
  • Productivity: high
  • Keystone species: Grasses; large, grazing ungulates
  • Typical animals:

    • Bison
    • Pronghorn Antelope
    • Przewalski's Horse (Mongolia)
    • Mule Deer
    • Prairie Dog (spp.)

  • Praire Vole
  • White-tailed Jackrabbit
  • Coyote
  • Red Fox
  • Black-footed Ferret
  • Prairie Chicken
  • Burrowing Owl
  • Meadowlark
  • Various raptors (Buteo, Accipiter spp.)
  • Prairie Rattlesnake
  • Great Plains Toad
  • Box Turtles
  • Many insects and arachnids

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)


(click for more)

    Temperate Deciduous Forest

  • Latitude: ~ 25o - 50o north and south
  • Climate: Relatively high rainfall; four distinct seasons
  • Dominant vegetation: Deciduous anthophyte trees and shrubs
    • Anthophytes have a selective advantage over conifers here because of their greater rate of photosynthesis.
    • Average photoperiod favors flowering plants over conifers.

  • Biodiversity: high
  • Productivity: seasonally moderate to high
  • Keystone species: Anthophyte plants
  • typical animals:

    • Red Fox
    • Grey Wolf
    • Black Bear
    • Bobcat
    • Wild pig

  • Minks, badgers, and other mustelids
  • White-tailed Deer
  • Elk
  • Tree squirrel species
  • Insects, spiders, slugs
  • Wild turkeys
  • Cottontails
  • Many migratory birds
  • Turtles, colubrid snakes
  • Salamanders, frogs
  • Insects, spiders, slugs

x

x

x

x

x

x

x

x

x

x


(click on colored bit for more)

x


(click for more)

    Temperate Rainforest

  • Latitude: ~ 40o - 60o north
  • Climate: cool and very wet
  • Dominant vegetation: Large coniferous trees; mosses, ferns
    • Acidity of organic matter deters decomposition
    • O horizon is thick, spongy, and very wet
  • Biodiversity: moderate/high
  • Productivity: moderate/high
  • Keystone species: Red-backed Vole; Spotted Owl
  • Typical animals:

    • Black Bear
    • Grizzly Bear
    • Grey Wolf
    • Red Fox
    • Lynx
    • Wolverine

  • Moose
  • Elk
  • Spotted Owl
  • Trumpeter Swan
  • Bald Eagle
  • Golden Eagle
  • Tree squirrels
  • Many migratory birds
  • Aquatic turtles
  • Many amphibians
  • Many insects and arachnids

x

x

x

x

x

x

x

x

x

x


(^ click on colored bit for more information ^)


(click for more)

    Taiga/Boreal Forest

  • Latitude: ~ 50o - 75o north and south
  • Climate: freezing winter (6-7 months); rainy, hot summer; brief autumn; brief, fertile spring with abundant flowering.
  • Dominant vegetation: coniferous trees
    • Conifers have a selective advantage over "broadleaf" (Anthophyte) plants here because they are not deciduous. They can photosynthesize all year, even when days are very short.
    • Anthophytes, being deciduous, cannot photosynthesize in autumn/winter.

  • Biodiversity: moderate
  • Productivity: moderate to high in growing season
  • Keystone species: conifers
  • typical animals:

    • Red Fox
    • Grey Wolf
    • Grizzly Bear
    • Black Bear
    • Lynx
    • Tiger (Siberia)

  • Minks and other mustelids
  • Caribou
  • Moose
  • Deer (White-tailed; Elk)
  • Tree squirrel species
  • Eagles, Hawks, Falcons (raptors)
  • Cottontails
  • Many migratory birds
  • Turtles
  • Salamanders, frogs
  • Insects more diverse than in tundra

x

x

x

x

x

x

x

x

x

x


(^ click on colored bit for more information ^)


(click for more)

    Tundra and Polar Ice

  • Tundra latitude: ~ 75o - 60o north (arctic) and south (antarctic)
  • Polar Ice latitude: ~ 60o - 90o north (arctic) and south (antarctic)

    Tundra:

  • Climate: cold, windy, arid; short growing season with abundant flowering forbs
  • Dominant vegetation: lichens, mosses, grasses, seasonal forbs
    • Permafrost (<--required link) is a thick layer of permanently frozen soil beneath an active layer of seasonally thawed topsoil.
    • It prevents penetration of deep roots, so limits the size of woody plants.

  • Biodiversity: moderate; higher than polar zones
  • Productivity: moderate in growing season
  • Keystone species: lichens, lemmings
  • typical animals:

    • Arctic Fox
    • Arctic Wolf
    • Grizzly Bear
    • Polar Bear
    • Ermine

  • Lemming
  • Caribou
  • Musk Ox
  • Snowshoe Hare
  • Arctic Ground Squirrel
  • Snowy Owl
  • Gyrfalcon
  • Ptarmigan
  • Harlequin Duck
  • Many migratory birds
  • Bees, mosquitos and other flies (seasonal)

x

x

x

x

x

x

x

x

x

x