Biomes Flashcards
mid-term review
What are biomes?
world’s major communities, classified according
to climate (temp & precip) and the predominant
vegetation and adapted organisms
What variables determine the biome?
temperature and precipitation
8 biomes
Tundra and ice, Taiga, Chapparal, Temperate deciduous forest, Desert, Tropical rain forest, grassland, temperate rainforest
Tundra
- polar regions
- low precipitation (less than 12 cm /year)
- long, cold, dark winters (6 to 10 months with mean
monthly temperatures below 0° C) - extremely short growing season (6 to 10 weeks)
- strong, drying winds.
- No trees, low-growing plants, migratory birds, caribou,
reindeer, wolves.
Taiga: Boreal forest, northern coniferous forest
- exists as a nearly continuous belt of coniferous trees across North
America and Eurasia. - wide range of temperatures between the lows of winter and highs of
summer. - Mean annual precipitation is 40 to 50 cm (15 to 20 in.)
- low evaporation rates make this a humid climate.
- Overlying formerly glaciated areas and areas of patchy permafrost.
- Long, severe winters (up to six months with mean temperatures
below freezing) and short summers (50 to 100 frost-free days) - Vegetation: coniferous trees. spruce, fir, pine, larch.
Temperate Deciduous Forest
known for the turning of the colors of its leaves.
* There is an approximately 6 month growing season.
* The 50 to 120 cm (20 to 60 in.) of precipitation is distributed
evenly throughout the year.
* Vegetation: oak, maple, beech, chestnut, hickory, elm, etc.
* Distribution: Western and Central Europe; Eastern Asia, and
Eastern North America.
Almost all the forests of eastern North America are second
growth, but they preserve the world’s greatest diversity of TBDF
flora and fauna. The Great Smoky Mountains have been
designated a world biosphere reserve to help protect the rich
assortment of species.
Temperate Grasslands
Semiarid, between 25 to 50 cm (10 and 20 in.) of precipitation a
year (much as snow).
there are great seasonal temperature extremes
Vegetation. Perennial grasses and perennial forbs.
Temperate grasslands have some of the world’s most fertile soils.
Most have been converted to agricultural lands.
Major regional expressions. North America: prairies. Eurasia:
the steppes from Ukraine eastward through Russia and Mongolia.
South America: the pampas of Argentina and Uruguay. Africa:
the veld in the Republic of South Africa.
Deserts
Arid climates average less than 25 cm (10 in.) of precipitation a year.
Evaporation exceeds precipitation.
rainfall is unpredictable when it occurs warm and dry
Desert plants and animals have evolved various mechanisms for
tolerating or avoiding the extremes of aridity and temperature:
1) Air descending from the upper atmosphere at 20° and 30° latitude
causes evaporation to exceed precipitation (Sahara and the
Australian desert can be associated with this phenomenon).
2) Rainshadows of high mountain ranges.
3) Interiors of continents
Mediterranean Biome, Chapparal (scrub grasslands)
annual precipitation 40 and 100 cm (15 and 40 in.) per year.
The Mediterranean Climate is unique in that the wet season coincides
with the low sun or winter period. Summers are dry.
Predictable, growing season in which many plants are adapted to
withstand drought.
The Mediterranean biome is characterized by shrubs.
Mediterranean regions have long been impacted by humans especially
through the use of fire and the grazing of livestock. Now used
extensively for olive and wine production.
Tropical Rainforest
Mean monthly temperatures are above 18 °C (64 °F)
precipitation is often in excess of 250 cm (100 in.) a year.
Sunlight is a major limiting factor. A vertical stratification of four-five
layers of trees is apparent.
Regional expressions
Amazonia into Central America
African (Zaire Basin with an outlier in West Africa; also eastern
Madagascar)
Indo-Malaysian (west coast of India, southeast Asia, New Guinea and
Queensland, Australia).
Emergents: Widely spaced trees 30 to 36m tall and
with umbrella-shaped canopies extend above
the general canopy of the forest. Since they
must contend with drying winds, they tend to
have small leaves and some species are
deciduous during the brief dry season.
Closed canopy of 24m foot trees. Light is readily
available at the top of this layer but reduced
below it.
Shrub/sapling layer: Less than 3 percent of the light
intercepted at the top of the forest canopy
passes to this layer, humidity is constantly high.
Ground layer: sparse plant growth. Less than 1
percent of the light penetrates to the forest
floor. One third of the precipitation is
intercepted before it reaches the ground.
Tropical rain forest is the earth’s most complex
biome in both structure and species diversity.
No annual rhythm to the forest; each species has
evolved its own flowering and fruiting seasons.
Tropical Grasslands or Savannah
Mean monthly temperatures are at or above 18 °C
annual precipitation averages between 75 and 125 cm.
Tropical grasslands or savannas are associated with the tropical wet
and dry climate type.
Savannas are characterized by a continuous cover of perennial
grasses, often 1 to 2m tall at maturity. Dominant taxon in the tree
layer: palm savannas, pine savannas, and acacia savannas.
Fauna. The world’s greatest diversity (over 40 different species) of
ungulates (hoofed mammals) is found on the savannas of Africa.
Regional expressions.
East African savannas are typically, perhaps stereotypically,
acacia savannas. Many survive in the famous game parks of
Kenya and Tanzania, and also those of Zimbabwe, Botswana,
South Africa, and Namibia.
The famous Serengeti Plains in Tanzania are a grass savanna.
Llanos of the Orinoco basin of Venezuela and Colombia are
grass savannas.
Brazil’s cerrado is an open woodland of short-stature, twisted
trees.
What does a climatograph show?
Shows temperature and precipitation on different axes
