Chapter 3: Communities and Biomes

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Chapter 3 Communities and Biomes
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Community

• interacting population in an area at one time

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Limiting Factors

• factors that affect an organisms 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

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Example Plant life

• Limiting factors
• low temperature
•      strong winds
• -     soil cant support growth
• -     fire
• -     pollution
• -       Factors that limit one population may
  also have an effect on other populations

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Ranges of Tolerance

• the ability of organisms to withstand
  fluctuations in biotic and abiotic environmental
  factors

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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

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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

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Two types of Succession

• 1. Primary
• 2. Secondary

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Primary Succession

• colonization of barren land by communities of
  organisms
• Takes place on land where there are no living
  organisms

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• 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
• Plants
• Ferns
• Insects
• fungi

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• Primary Succession slows down and the community
  becomes fairly stable or reaches equilibrium
  CLIMAX COMMUNITY

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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

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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

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Biome

• a large group of ecosystems that share the same
  type of climax community
• Biomes on land terrestrial biomes
• Biomes in water aquatic biomes

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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

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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

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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

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Aphotic Zone

• deepest, least explored areas of the ocean

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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

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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

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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

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Marine Biome - Light

• shallow water region, that is less affected by
  waves
• Nutrient runoff from the land contributes to
  abundant life

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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

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Marine Biome Dark

• darkness blacker than night
• extreme pressure

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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

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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

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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
• Wind
• Cloud cover
• Temperature
• Humidity
• Precipitation

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• Latitude and Climate abiotic factors
• affect plants animals
• small differences create different biomes

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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

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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
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• Growing Season is Short
• limits the types of plants
• grasses and dwarf shrubs
• resistant to drought and cold

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• Insects mosquitoes and black flies
• Animals small mammals
•   rat like lemmings
• weasels
• artic foxes
• snowshoe hares
• birds snowy owls and hawks
• Why is the tundra treeless?

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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
• Larch
• Fir
• Hemlock
• Spruce

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• 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
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• Animals lynx, snowshoe hare, Caribou, weasels,
  red squirrels, wolves, elk, red deer, moose, and
  variety of migratory birds

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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

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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

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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

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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

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Grassland Animals

• grazing animals bison
• prairie animals jack rabbits, deer, elk, and
  prairie dogs
• insects, birds, and reptiles
• Prairie grassland savanna steppes pampas

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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
• Maple
• Oak
• Birch
• Elm
• Ash

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Temperate Forest

• Soil rich top layer and some clay
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• Animals squirrels, mice, deer, rabbits,
• bears,
• and many
• birds

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Rain Forests

• home to more organisms than any other biome
• 2 types
• 1. Temperate
• rain forest
• 2. Tropical
• rain forest
• extensive
• rainfall

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Tropical Rain Forest

• warm temperature (25ºC)
• wet weather (200-600 cm rain/year)
• lush plant growth
• near the equator

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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
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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

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Biomass

• total weight of organisms living in the area is
  high
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• important sources of medicinal products and
  hardwood trees
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• Not suitable farmland little organic material
  in the soil
• w/out org material soil becomes exposed
• soil will eventually become hard, almost
  brick-like

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