What is Biomes?
• Scientists have developed the term Biome to
describe areas on the earth with similar climate,
plants, and animals.
• The plants and animals that live in a specific
biome are physically well adapted for that area.
• Plants and animals that live in a specific biome
share similar characteristics with other plants and
animals in that biome throughout the world.
• The types of biomes that will be explored during
this exercise include: Tundra, Deserts, Grasslands,
Forest , Freshwater and Marine
The tundra biome
• Tundra is the coldest of all the biomes. Tundra
comes from the Finnish word tunturi, meaning
treeless plain. It is noted for its frost-molded
landscapes, extremely low temperatures, little
precipitation, poor nutrients, and short
growing seasons. Dead organic material
functions as a nutrient pool. The two major
nutrients are nitrogen and phosphorus.
Nitrogen is created by biological fixation, and
phosphorus is created by precipitation.
Characteristics of tundra include:
Extremely cold climate
Low biotic diversity
Simple vegetation structure
Limitation of drainage
Short season of growth and reproduction
Energy and nutrients in the form of dead
• Large population oscillations
Tundra is separated into two types:
• Arctic tundra is located in the northern hemisphere,
encircling the north pole and extending south to the
coniferous forests of the taiga. The arctic is known
for its cold, desert-like conditions.
• There are about 1,700 kinds of plants in the arctic
• Animals are adapted to handle long, cold winters and
to breed and raise young quickly in the summer.
• Alpine tundra is located on mountains
throughout the world at high altitude where
trees cannot grow. The growing season is
approximately 180 days. The nighttime
temperature is usually below freezing. Unlike
the arctic tundra, the soil in the alpine is well
The grassland biome
• Grasslands are characterized as lands
dominated by grasses rather than large shrubs
There are two main divisions of grasslands:
Tropical grasslands or savannas
• Savanna is grassland with scattered individual
trees. Savannas of one sort or another cover
almost half the surface of Africa.
• Savanna has both a dry and a rainy season.
• The soil of the savanna is porous, with rapid
drainage of water. It has only a thin layer of
humus (the organic portion of the soil created
by partial decomposition of plant or animal
• Temperate grasslands are characterized as
having grasses as the dominant vegetation.
Trees and large shrubs are absent.
• Temperatures vary more from summer to
winter, and the amount of rainfall is less in
temperate grasslands than in savannas.
The forest biome
• Earth's most complex land
• forests occupy approximately one-third of Earth's
land area, account for over two-thirds of the leaf
area of land plants, and contain about 70% of
carbon present in living things.
• There are three major types of forests, classed
according to latitude:
Boreal forests (taiga)
• Tropical forest
Tropical forests are characterized by the
greatest diversity of species. They occur near
the equator.One of the major characteristics
of tropical forests is their distinct seasonality:
winter is absent, and only two seasons are
present (rainy and dry). The length of daylight
is 12 hours and varies little.
• Temperate forests occur in eastern North
America, northeastern Asia, and western and
central Europe. Well-defined seasons with a
distinct winter characterize this forest biome.
Moderate climate and a growing season of
140-200 days during 4-6 frost-free months
distinguish temperate forests.
Boreal forest (taiga)
• Boreal forests, or taiga, represent the largest
terrestial biome. Occuring between 50 and 60
degrees north latitudes, boreal forests can be
found in the broad belt of Eurasia and North
America: two-thirds in Siberia with the rest in
Scandinavia, Alaska, and Canada. Seasons are
divided into short, moist, and moderately
warm summers and long, cold, and dry
winters. The length of the growing season in
boreal forests is 130 days.
The desert biome
• Deserts cover about one fifth of the Earth's
surface and occur where rainfall is less than 50
cm/year. Soils often have abundant nutrients
because they need only water to become very
productive and have little or no organic
matter. Disturbances are common in the form
of occasional fires or cold weather, and
sudden, infrequent, but intense rains that
• Desert biomes can be classified
according to several characteristics.
• There are four major types of deserts:
Hot and dry
Hot and dry desert
• The seasons are generally warm throughout
the year and very hot in the summer. The
winters usually bring little rainfall.
• Temperatures exhibit daily extremes because
the atmosphere contains little humidity to
block the Sun's rays.
• Soils are course-textured, shallow, rocky or
gravely with good drainage and have no
• The major deserts of this type include the
sagebrush of Utah, Montana and Great Basin.
• The soil can range from sandy and finetextured to loose rock fragments, gravel or
• The spiny nature of many plants in semiarid
deserts provides protection in a hazardous
• These deserts occur in moderately cool to
warm areas such as the Nearctic and
Neotropical realm. A good example is the
Atacama of Chile.
• The cool winters of coastal deserts are
followed by moderately long, warm summers.
• The soil is fine-textured with a moderate salt
content. It is fairly porous with good drainage.
• These deserts are characterized by cold
winters with snowfall and high overall rainfall
throughout the winter and occasionally over
the summer. They occur in the Antarctic,
Greenland and the Nearctic realm.
• The winters receive quite a bit of snow.
• The plants are widely scattered. In areas of
shadscale, about 10 percent of the ground is
The marine biome
• Marine regions cover about three-fourths of the
Earth's surface and include oceans, coral reefs,
and estuaries. Marine algae supply much of the
world's oxygen supply and take in a huge amount
of atmospheric carbon dioxide. The evaporation
of the seawater provides rainwater for the land.
• The largest of all the ecosystems, oceans are
very large bodies of water that dominate the
Earth's surface. Like ponds and lakes, the
ocean regions are separated into separate
zones: intertidal, pelagic, abyssal, and benthic.
• All four zones have a great diversity of
The intertidal zone is where the ocean meets the
land — sometimes it is submerged and at other
The pelagic zone includes those waters further
from the land, basically the open ocean.
The benthic zone is the area below the pelagic
zone, but does not include the very deepest
parts of the ocean
The deep ocean is the abyssal zone. The water in
this region is very cold (around 3° C), highly
pressured, high in oxygen content
• Coral reefs are widely distributed in warm
shallow waters. the dominant organisms in
coral reefs are corals. Corals are interesting
since they consist of both algae (zooanthellae)
and tissues of animal polyp.
• Since reef waters tend to be nutritionally poor,
corals obtain nutrients through the algae via
photosynthesis and also by extending
tentacles to obtain plankton from the water
• Estuaries are areas where freshwater streams
or rivers merge with the ocean. This mixing of
waters with such different salt concentrations
creates a very interesting and unique
ecosystem. Microflora like algae, and
macroflora, such as seaweeds, marsh grasses,
and mangrove trees (only in the tropics), can
be found here. Estuaries support a diverse
fauna, including a variety of worms, oysters,
crabs, and waterfowl.
The freshwater biome
• Freshwater is defined as having a low salt
concentration — usually less than 1%. Plants and
animals in freshwater regions are adjusted to the
low salt content and would not be able to survive
in areas of high salt concentration (i.e., ocean).
There are different types of freshwater regions:
• Ponds and lakes
• Streams and rivers
Ponds and lakes
• These regions range in size from just a few square
meters to thousands of square kilometers.
Scattered throughout the earth
• Ponds and lakes may have limited species
diversity since they are often isolated from one
another and from other water sources like rivers
and oceans. Lakes and ponds are divided into
three different “zones” which are usually
determined by depth and distance from the
• The topmost zone near the shore of a lake or
pond is the littoral zone. This zone is the
warmest since it is shallow and can absorb
more of the Sun's heat. It sustains a fairly
diverse community, which can include several
species of algae (like diatoms), rooted and
floating aquatic plants, grazing snails, clams,
insects, crustaceans, fishes, and amphibians.
• The near-surface open water surrounded by
the littoral zone is the limnetic zone. The
limnetic zone is well-lighted (like the littoral
zone) and is dominated by plankton, both
phytoplankton and zooplankton. Plankton are
small organisms that play a crucial role in the
food chain. Without aquatic plankton, there
would be few living organisms in the world,
and certainly no humans. A variety of
freshwater fish also occupy this zone.
Streams and rivers
• These are bodies of flowing water moving in
one direction. Streams and rivers can be found
everywhere — they get their starts at
headwaters, which may be springs, snowmelt
or even lakes, and then travel all the way to
their mouths, usually another water channel
or the ocean. The characteristics of a river or
stream change during the journey from the
source to the mouth.
• Wetlands are areas of standing water that
support aquatic plants. Marshes, swamps, and
bogs are all considered wetlands. Plant species
adapted to the very moist and humid conditions
are called hydrophytes. These include pond lilies,
cattails, sedges, tamarack, and black spruce.
Marsh flora also include such species as cypress
and gum. Wetlands have the highest species
diversity of all ecosystems. Many species of
amphibians, reptiles, birds (such as ducks and
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