Transcript Chapter 3: Communities and Biomes

Chapter 3:
Communities
and Biomes
Community
• interacting population in an area at
one time
Limiting Factors
• factors that affect an organism’s ability to
survive in its environment
– Availability of water and food
– predators
– temperature
• Any biotic or abiotic factor that restricts
the existence, numbers, reproduction, or
distribution of organisms
Example –
Plant life
• Limiting factors
– low temperature
–
strong winds
- soil can’t support growth
- fire
- pollution
-
Factors that limit one population may
also have an effect on other populations
Ranges of Tolerance
• the ability of organisms to withstand fluctuations
in biotic and abiotic environmental factors
Succession: Changes over time
• ecologists can predict changes over time
• Ex. Grass was allowed to grow without
cutting
1. Grass gets taller, weeds start to grow.
Resembles a meadow
2. Later – bushes grow, trees appear, and
different animals enter area to live
3. Then – bushes and trees change the
environment, less light reaches the ground.
The grass slowly disappears
4. Thirty years later – the area is a forest
Succession
• orderly natural changes and species
replacement that takes place in
communities of an ecosystem
– occurs in stages
– at each stage different species of animals and
plants may be present
– as succession progresses – new organisms
move in and others may die or move out
– can take decades or centuries
Two types of Succession
1. Primary
2. Secondary
Primary Succession
• colonization of barren land by
communities of organisms
• Takes place on land where there are no
living organisms
• Ex. Lava from a volcano destroys
everything in its path
– Forms barren land
• First species to take hold- pioneer species
– Lichen – first species to move in
– Eventually die and settle into cracks
– Promotes the first stage of soil development
• New Soil – enables small weed plants to
move in
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–
–
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Plants
Ferns
Insects
fungi
• Primary Succession slows down and
the community becomes fairly stable
or reaches equilibrium = CLIMAX
COMMUNITY
Secondary Succession
• the sequence of changes that takes place
after an existing community of organisms
inhabiting an area is severely disrupted in
some way
• fire destroys a community
• field is not replanted
• Occurs in areas that previously contained
life
• land still contains soil
• soil already exists so takes less time than
primary succession
Secondary Succession
1. 1988 - Fire destroys Yellowstone Park
2. annual wildflowers first to grow back
3. 3 years later – perennial wildflowers,
grasses, ferns, and thousands of pine
seedlings are growing
– Once the trees grow past the shade of the
grasses and perennials, they will grow more
quickly
Biome
• a large group of ecosystems that
share the same type of climax
community
• Biomes on land – terrestrial biomes
• Biomes in water – aquatic biomes
Aquatic Biomes
• water – covers 75% of
earths surface
• most of water is salty
• oceans, seas, and
some inground lakes –
salt water
• Freshwater – rivers,
streams, ponds, and
most lakes
Marine Biomes – salt water biomes
• Oceans:
– Abiotic Factors – salinity, depth,
availability of light, temperature
– Biotic Factors – plants and animals
– Large amounts of Biomass – living
material
• Study different zones
1. shallow, sunlit zones – photic zones
2. deeper, unlit zones – aphotic zones
Photic Zones
• shallow enough for
sunlight to penetrate
• along coastlines of
most landmasses on
earth
• bays, rocky shores,
sandy beaches,
mudflats, and estuaries
• coral reefs
Aphotic Zone
• deepest, least explored areas of the
ocean
Estuaries
• fresh water mixes with salt water
–
Ex. Where a river joins an ocean
• Estuary – coastal body of water, partially
surrounded by land, in which fresh and salt water
mix
• Salinity – amount of salt
– Ranges between that of salt water and that of freshwater
– Also changes with
tide
– How much freshwater
is brought in from
the river
– Can support a
wide range of
organisms
Tides
• gravitational pull of sun and moon
causes a rise and fall of the ocean
• Intertidal Zone – portion of the
shoreline that lies between the high
and low tides
– Size depends on slope of land and
difference between high and low tide
– high levels of sunlight, nutrients, and
oxygen
Tide Pools
• pools of water left when the tide is low
• can isolate org. until the next high tide
• Animals –
– snails, sea stars, and barnacles have adaptations to
keep them anchored in the intertidal zone
– clams, worms, snails, crabs, and others burrow in
sand
Marine Biome - Light
• shallow water region, that is less
affected by waves
• Nutrient runoff from the land
contributes to abundant life
Plankton
• most of the organisms
that live in the marine
biome
• small organisms that drift
and float in the waters
• autotrophs, diatoms,
eggs, & juvenile stages of
marine animals
• base of all aquatic food
chains
• consumed by small and
large animals
• baleen whales and sharks
feed on plankton
Marine Biome – Dark
• darkness blacker than night
• extreme pressure
Freshwater Biomes
• shallow water on the shoreline
• tadpoles, insects, turtles, worms and
crayfish
• water a few feet below surface remains
cold
• Temperature – abiotic factor that limits the
kind of organisms that can survive
• Light – abiotic factor that limits
photosynthesis
• Bacteria- at bottom break down dead
organisms
Other Aquatic Biomes
• Wetlands- where land and water meet
• swamps – have trees
• marshes – no trees, but have water
flowing through them
– Both – highly productive
– Source of food for many migrating birds
and other animals
• bogs – water from rain only
Terrestrial Biomes
• Latitude and Climate –
• Latitude - describes your position in
degrees north and south of the equator
• At different latitudes the sun strikes the
earth differently
• Climate is different –
–
–
–
–
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Wind
Cloud cover
Temperature
Humidity
Precipitation
• Latitude and Climate – abiotic
factors
• affect plants & animals
• small differences create different
biomes
Tundra
• first area that circles the
•
•
•
•
North Pole
treeless areas with long
summer days and short
periods of winter sunlight
temperatures never rise
above freezing for long
only uppermost layer of
soil thaws in the
summertime
soil underneath top layer –
permafrost- that is
permanently frozen ground
Top layer
• thin – can only support shallow rooted grasses
and other small plants
• soil – lack nutrients
• decay – slow – due to low temperatures
• nutrients are not recycled quickly
• limits types of organisms
• Growing Season is Short
– limits the types of plants
– grasses and dwarf shrubs
– resistant to drought and cold
• Insects – mosquitoes and black flies
• Animals – small mammals
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–
–
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rat like lemmings
weasels
artic foxes
snowshoe hares
birds – snowy owls and hawks
• Why is the tundra treeless?
Taiga
• just south of the tundra
• circles the north pole
• Taiga – called the boreal or northern coniferous
forest
• Continuous belt of coniferous trees worldwide
• Common trees –
–
–
–
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Larch
Fir
Hemlock
Spruce
• Soil- waterlogged
• warmer and wetter than the tundra
• still has harsh, long, severe winters
• Stretches across- Canada, Northern Europe, and Asia
• Top Soil – acidic and poor in minerals b/c of decaying
coniferous needles
• Trees – provide food and shelter for more animals
• Animals – lynx, snowshoe hare, Caribou, weasels, red
squirrels, wolves, elk, red deer, moose, and variety of
migratory birds
Desert
• arid region with
sparse to almost
nonexistent plant life
• driest biome
• less than 25 cm of rain
a year
• Vegetation varies
• More rain, more
vegetation
• Shrub communities
• Less rain – scattered
plant life
Desert Plants
• annual plants that can
germinate from seed and
grow to maturity quickly
after sporadic rainfall
• adaptations to conserve
water
• Cacti – waxy leaves,
photosynthetic stems
• Spines, thorns, or poisons
• Leaves curl up or drop off
altogether
Desert
Animals
• emerge at night
• Herbivores - Obtain water from the food
they eat. Ex. kangaroo rat
• coyotes, hawks, owls, and roadrunners –
carnivores that eat lizards, snakes, small
animals
• scorpions – venom to capture prey
Grassland
• large communities covered with rich soil,
grasses, and similar plants
• receive approx. 25-75 cm of rain
• experience a dry season
• few trees
• grasses die off in winter and put nutrients into
soil
• ideal for growing cereal grains: oats, rye, and
wheat
• breadbaskets of the world- each grain is a
species of grass
Grassland Animals
grazing animals –
bison
• prairie animals – jack
rabbits, deer, elk, and
prairie dogs
• insects, birds, and
reptiles
• Prairie = grassland =
savanna = steppes =
pampas
Temperate Forest
• precipitation ranges from 70-100 cm/year
• Temperate or deciduous forests
• Dominated by broad-leaved trees
hardwood trees that loose their foliage
annually
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–
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Maple
Oak
Birch
Elm
Ash
Temperate Forest
• Soil – rich top layer and some clay
• Animals – squirrels, mice, deer, rabbits,
bears,
and many
birds
Rain Forests
• home to more organisms than any other biome
2 types
1. Temperate
rain forest
2. Tropical
rain forest
• extensive
rainfall
Tropical Rain Forest
•
•
•
•
warm temperature (25ºC)
wet weather (200-600 cm rain/year)
lush plant growth
near the equator
Hypothesis as to why tropical rain forests
contain so many species
1. Due to their location near the
equator, they were not covered
during the last ice age. Species
had more time to evolve and
biodiversity exists
2. Warm weather permits year
round growing conditions
which permits a greater food
supply
3. they provide a multitude of
habitats and niches for diverse
organisms
Rainforest
• Vertical Layering –
– creates a large number of niches
– canopy, understory, ground layers
• Few nutrients in soil – all in living things
• Hot, humid environment – ants, termites,
fungi, bacteria, and other decomposers to
break down dead material quickly
• Most species rich places on earth
Biomass
• total weight of organisms living in the area is
high
• important sources of medicinal products and
hardwood trees
• Not suitable farmland – little organic material in
the soil
– w/out org material – soil becomes exposed
– soil will eventually become hard, almost brick-like