Terrestrial Biomes

Terrestrial zones characterized by particular types of vegetation and animals

• What determines the presence of a particular biome?
  • Precipitation - total amount, form, and seasonal distribution
    • rain
    • snow, etc.
      
  • Temperature
    • latitude
      • tropical areas have relatively unchanging temperatures throughout the year
      • polar areas have long, extremely cold winters with short cool summers
    • altitude
      
  • Fire?
    
  • Soil Type
    • Formed by:
      • physical breakdown of rocks
      • dead organic material-humus
    • Supplies inorganic nutrients for plants
    • Retains moisture
      

• TYPES OF BIOMES
  • Treeless
    • Deserts
    • Chapparal
    • Tundra
    • Savanna
    • Prairie
      
  • Forested
    • Taiga
    • Other Coniferous
    • Temperate Deciduous
    • Tropical Deciduous
    • Tropical Rain Forest

• Tundra
  • means marshy plain
  • this biome lies largely north of 60 degrees North latitude
  • characterized by
    • absence of trees
    • presence of dwarf plants
    • upper ground surface that is spongy and uneven, or hummocky, as a result of freezing and thawing of this poorly drained land
    • soils of this biome are often permanently frozen (permafrost) to a depth of a few inches to several feet
      • the permafrost line is the ultimate limit of plant root growth.
        
  • while there is variation from place to place within the biome, temperature, precipitation, and evaporation are characteristically low, the warmest months averaging below 10 degrees Celsius and the wettest with about 25 millimeters of precipitation
    
  • the vegetation consists of relatively few species: a few species of dwarf shrubs, a few grasses, sedges, and mosses are characteristic of the numerous marshes and poorly drained areas
    
  • the most characteristic arctic tundra plants are lichens
    
  • lots of herbivorew: caribou, musk ox, arctic hare, voles, and lemmings
    
  • carnivores: arctic fox, polar bear and wolves
    
  • reptiles and amphibians are few or absent because of the extremely cold temperatures
    
  • alpine tundra is quite similar to arctic tundra. It differs in the absence of permafrost and in the presence of better drainage.

• Boreal Coniferous Forest
  • moist-cool, transcontinental coniferous forest
  • lies largely between the 45th and 57th north latitudes
  • The climate of this biome is cool to cold with more precipitation than the tundra, occurring mainly in the summer from mid-latitude cyclones
    
  • The predominant vegetation of boreal biome is evergreen
  • the understory is relatively limited as a result of the continual low light penetration.
    • However, among common understory associates are orchids, shrubs like rose, blueberry and cranberry.
      
  • Mammals include moose, bear, deer, wolverine, marten, lynx, wolf, snowshoe hare, vole, chipmunks, shrews, and bats
    
  • Reptile are rare, once again, because of cold temperatures
    
  • Boreal forest soils are characterized by a deep litter layer and slow decomposition. They are acidic and mineral deficient, the result of the large movement of water and subsequent leaching.

• Temperate Deciduous Biome
  • this biome is characterized by a moderate climate and deciduous trees
    
  • occupies the eastern half of the United States, central Europe, Korea and China.
    
  • This biome has been very extensively affected by human activity, and much of it has been converted into agricultural fields
    
  • The understory of shrubs and herbs in a mature deciduous forest is typically well developed and richly diversified.
    
  • Many different types of herbivores and carnivores, and some reptiles and amphibians exist here
    
  • Brown forest soils characterize deciduous forests. The surface litter layer is thin due to rapid decomposition.

• Grassland
  • In central North America are the grasslands, the tall grass prairie toward the east and the short grass prairie westward.
    
  • In Europe and Asia some grasslands are called Steppes; in South America, grasslands are called pampas.
    
  • Prior to modern humans, the tall grass prairie was dominated by species that formed dense covers 1.5 to 2.0 meters tall. Trees are now limited to moist river valleys.
    
  • The soils of this biome, known as black earths, are among the richest in nutrients and consequently the most fertile in the world.
    
  • Grassland mammals are dominated by smaller burrowing herbivores (prairie dogs, jack rabbits, ground squirrels, and gophers) and larger running herbivores such as bison, pronghorn antelope, and elk. Carnivores include badger, coyote, ferret, wolves, and cougar.

• Desert
  • In its most typical form, the desert consists of shrub covered land in which plants are quite dispersed with much bare ground between them. The major desert biomes of the earth are found primarily at 30 degrees North and South latitude, in the interiors of continents.
    
  • Climatically, deserts are influenced by descending air currents and have less than 25 millimeters of precipitation annually.
    • Rain in the form of thundershowers at infrequent intervals
    • Large temperature variations
      
  • Dominant shrubs: creosote bush (Larrea divaricata), sagebrush (Artemisia tridentata)
    
  • Other dominant plants are water storing succulents (cactus); many species are short lived annuals that complete their life cycles during infrequent and short rainy periods.
    
  • Most mammals tend to be nocturnal to avoid the high temperatures. There is a rich lizard and snake fauna because high temperatures promote cold blooded life forms.
    
  • Because productivity is low, the litter layer is comparably thin and poorly developed. As a result, the organic content of the soil is very low. Also, evaporation tends to concentrate salts at or near the soil surface.

• Tropical Rainforest
  • Tropical rainforests occur near the equator.
    
  • Annual rainfall, which exceeds 2000 to 2250 mm, is generally evenly distributed throughout the year.
    
  • Temperature and humidity are relatively high through the year.
    
  • The flora is highly diverse: a square kilometer may contain as many as a 100 different tree species as compared to 3 to 4 in the temperate zone. Tropical rainforests are also typically well stratified into a continuous canopy of trees 25 to 35 meters tall, with an interrupted emergent layer of very tall trees with buttressed bases.
    
  • Most plants are evergreen with large, dark green, leathery leaves.
    
  • Decomposition is rapid and the soils are subject to heavy leaching and so are acidic and nutrient poor.

• Tropical Savanna
  • Tropical savannas are grasslands with scattered drought-resistant trees that normally do not exceed 10 meters in height.
    
  • Climatically, they are characterized by distinct wet and dry seasons. Temperatures are hot all year long.
    
  • Savanna constitutes extensive areas in eastern Africa, South America, and Australia. These areas support the richest diversity of grazing mammals in the world.
    
  • The soils are more nutrient rich than tropical forest soils. Some soils become extremely dry during the winter season and form laterite layers.