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Biology
Chapter
4
4-3 Biomes
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Biome – a large group of ecosystems that are
characterized by certain soil, climate conditions, plants and
animals
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The climate of a region is an important factor in determining
which organisms can survive there
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Latitude is an important abiotic factor to both land and
aquatic biomes
60°N
30°N
0° Equator
30°S
60°S
Tropical rain forest
Temperate grassland
Temperate forest
Tropical dry forest
Desert
Tropical savanna
Temperate woodland
and shrubland
Mountains and
ice caps
Northwestern
coniferous forest
Boreal forest
(Taiga)
Tundra
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The Terrestrial Biomes
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Tropical Rain Forest
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Precipitation – 200-400cm of rainfall annually
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Soil – low in nutrients
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Plants – broad-leaved evergreen trees, ferns, large
woody vines and climbing plants, orchids
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Animals – birds, snakes, monkeys, frogs, ants
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Temperature – warm year round 25-29ºC
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Located near equator
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One small acre may support 100 species of plants
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Species live at various levels
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Contains more species of organisms than anywhere
else
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Fig. 50.16, p. 908
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Desert
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Precipitation – less than 10cm of rain per year
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Soil – sandy soil, low in nutrients and very little or no
topsoil
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Plants – succulent plants that have needle shaped
leaves to reduce water loss
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Animals – rattlesnakes, lizards, spiders, roadrunners
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Temperature – humidity is very low so suns rays
penetrate and heat the ground quickly so its hot during
the day and cold at night
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Plants are adapted to growing, flowering and
producing seed quickly
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Plants are deep rooted
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Desertification – conversion of grasslands and other
productive biomes to desertlike wastelands
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Fig. 50.13, p. 905
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Grassland
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Precipitation – 25-100cm of rain per year
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Soil – very rich in nutrients and deep layer of topsoil
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Plants – tall and short grasses and small plants
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Animals – bison, wolves, prairie dogs, foxes, coyotes
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Temperature – warm summers and very cold winters
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Found in the interior of continents
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Also called prairies
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Not enough rain to support trees
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•
Savanna
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Precipitation – 30-50cm of rain per year
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Soil – compact soils
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Plants – grasses, scattered trees
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Animals – lions, cheetahs, elephants, giraffes, zebras,
ostriches, rhinoceros
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Temperature – warm year round, 24-29ºC
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•
Woodland and Shrubland
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Precipitation - 25-60cm of rain per year
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Soil – low in nutrients and highly acidic
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Plants – hardened tough evergreens, wildflowers,
grasses
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Animals – coyotes, foxes, bobcats, mountain lions
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Temperature – hot dry summers with periodic fires and
cool moist winters
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Western or southern coastal region
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Also called chaparral in areas dominated by shrubs
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•
Deciduous Forest
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Precipitation – 70-200cm of rain per year
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Soil – moist and fertile, rich in humus (decaying leaves
and other organic matter)
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Plants – birch, maple, oak, elm, evergreens
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Animals – deer, foxes, raccoons, squirrels, birds
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Temperature – warm during the summer and cold in
the winter, 0-30ºC
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Deciduous Trees – lose their leaves annually
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¼ of bird species
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Fig. 50.17, p. 909
• Coniferous (Taiga) Forest
• Precipitation – 30-70cm of rain per year, frequent
droughts
• Soil – low in nutrients and highly acidic
• Plants – cone bearing trees, pines, firs, spruces
• Animals – moose, bears, timberwolves, migratory
birds
• Temperature – warm during the summer and cold in
the winter
• Needle shape leaves is adaptation for water loss
• Lies south of the tundra
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Fig. 50.18, p. 910
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Tundra
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Precipitation – 20-60cm of rain per year
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Soil – thin moist and nutrient poor
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Plants – mosses, lichens, and grasses that survive in
soggy soil
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Animals – caribou, reindeer, artic fox
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Temperature – cool in summer and freezing in winter
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Permafrost – permanently frozen ground
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Treeless land
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Long summer days and short periods of winter
sunlight
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Fig. 50.19, p. 911
4-4 Aquatic Ecosystems
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Freshwater Ecosystems
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Flowing-Water Ecosystems
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Rivers, streams, creeks, and brooks
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Originate in mountains or hills
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Fig. 50.23, p. 913
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Standing-Water Ecosystems
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Lakes and ponds
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A Lake has 3 Zones
1. Littoral
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All around the shore
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Water is shallow and well lit
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Diversity is greatest
2. Limnetic
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Open water
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Sunlit water that extends to where photosynthesis
takes place
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Plankton, diatoms, green algae
3. Profundal
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Open water
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Below depth of photosynthesis
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Bacterial decomposers
LITTORAL
LITTORAL
LIMNETIC
limit of effective
light penetration
PROFUNDAL
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Fig. 50.21, p. 912
Freshwater Wetlands
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Wetland – water covers the soil or is present at or near the
surface of the soil at least part of the year
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3 Types of Freshwater Wetlands
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Bog – wetland that form in depressions where water
collects
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Marsh – shallow wetland along river
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Swamp – look like flooded forests, water flows slowly
Estuaries
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Estuary – a place where salt water mixes with fresh
water
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The salinity of an estuary changes with the tides so a
large range of salt tolerant organisms live there
SALT MARSH (estuary)
open
ocean
sound
shallow
bay
creek
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tidal
cover
Fig. 50.29, p. 918
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Mangrove – coastal wetland that occur in bays and
estuaries across tropical regions
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In southern Florida and Hawaii
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Dominant plants are salt-tolerant trees, called
mangrove
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Fig. 50.28, p. 917
Marine Ecosystems
• Intertidal Zone
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Portion of the shoreline between the high and low tides
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High levels of sunlight, nutrients, and oxygen but
productivity may be limited by waves crashing against
the shore
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Organisms that live here have to be adapted to
changing conditions
Benthic Zone
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Includes all sediments and rocks of the ocean bottom
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Starts at continental shelves and extends to deep sea
trenches
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Pelagic Zone
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Full volume of ocean water
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Divided into 2 zones
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Includes photic and aphotic zone
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Most of the photosynthetic activity on Earth occurs
in the photic zone of the open ocean by the smallest
producers
Largest marine zone
Community Interactions
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Competition – occurs when organisms of the same or
different species attempt to use the same resources
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Predator – eat other animals
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Prey – the animal a predator eats
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Symbiosis – close association between two or more
species during part or all of their life
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Three Types of Symbiosis
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Mutualism
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Both species benefit from the relationship
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Example: plants and bacteria on roots
anemone and fish
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Commensalism
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One organism benefits and the other is neither
helped nor harmed
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Example: tree and bird nest
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Parasitism
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One organism benefits and the other is harmed
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Example: tick, ringworm
Fig. 48.12, p. 862
4-2 What Shapes an Ecosystem?
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Ecological Succession
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Succession – changes that occurs in a community over
time
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Pioneer Species – first species to populate the area
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Climax Community – a stable mature community that
undergoes little or no change in species
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Two Types of Succession
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1. Primary Succession
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Occurs on surfaces where no soil exists
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Example: rock surfaces formed after volcanoes
erupt, land exposed after glaciers retreat
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Secondary Succession
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Succession following a disturbance that destroys a
community without destroying the soil
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Because soil already exists, secondary succession
usually takes less time than primary succession
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Example: fires, floods, farming, construction,
hurricanes, tornadoes