Communities and Biomes
Community
Collection of several interacting
populations that inhabiting a
common environment.
Abiotic factors and biotic factors
determine an organisms ability to
survive
Limiting Factors
Environmental factors that affect the
organism’s ability to survive in its
environment.
(food availability, temperature, and
predators)
Limiting Factors
• Biotic or abiotic
• Restrict existence, numbers, reproduction
or distribution of an organism.
• Factors that limit one population in a
community, may indirectly effect another
– E.g. Lack of water limits grass growth—
reducing seed growth, mice need seeds for
food, no food, populations reduce.
Ranges of Tolerance
Organisms ability to withstand
fluctuations in biotic and abiotic
environmental factors
Populations varies according to its
tolerance for environmental changes.
Succession
Orderly, natural changes and
species replacements that take
place in communities over time.
Succession
• Occur in stages; different species at
different stages create conditions that are
suitable for some organisms and not
suitable for others.
• Difficult to observe; happen over long
periods of time.
Primary Succession
Initial colonization of new sites
• Lava from volcano; Avalanche
• Pioneer species—First species in the area (e.g. Lichen)
• Climax Community—A stable, mature community that
undergoes little or no change in species.
• Over time as a community or organisms change and
develop (additional habitats emerge, new species move
in, and old species disappear) Areas become forest of
vines, trees, and shrubs, inhabited by birds and other
forest-dwelling animals.
• Gradual changes over time.
Pioneer species colonize
Growth continues until
community becomes
fairly stable.
Pioneering organism dies,
decaying into soil.
Presence of soil makes
it possible for weedy plants,
small ferns, and insects to
become established
Soil builds up,
seeds borne by wind blow into soil,
and begin to grow
Area becomes forest of vines,
trees, and shrubs.
Birds and other animals.
Secondary Succession
Sequence of changes that take place
after a community is disrupted by
natural disaster or human actions.
Secondary Succession
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Gradual changes over time
Area previously contained life
Land that contains SOIL
Different pioneer species
May have same climax community, with
similar climate.
• Faster to develop because soil exist.
Biomes: Large areas that have
characteristics of climax
communities
Biome Factors
• Altitude and Latitude
• Temperature and
Precipitation
– Major limiting factors
Biomes
• Aquatic Biomes—Marine, Freshwater,
Estuaries (3/4 of Earth’s surface covered
by aquatic biomes)
• Terrestrial Biomes—Tundra, Taiga,
Desert, Grassland, Deciduous Forest,
Tropical Rain Forest.
Marine Biomes
• Oceans
• Photic Zone—Portion of marine biome that
is shallow enough to penetrate sunlight
(coastlines-Shore, beaches, mudflats)
• Aphotic Zone—Deeper waters that do not
receive sunlight. (Deep, least explored
oceans)
• Phos—Light (Greek)
• A—without (Greek)
Marine Life
• Largest amounts of biomass (living
materials) though often very small
• Whales, seals, sea otters, sea cows
• Kelp, algae, sea grass
Estuary
• Bay, sound, fjord, salt marshes, wetlands
• Freshwater mixes with salt water (some
land)
• Brackish Water ( more salt than
freshwater; but less than marine)
• Salinity ranges
– Amount of freshwater vs.. Saltwater
– Tides
– Biodiversity
Estuary Life
• Eelgrass, smooth cordgrass, sea lavender
• Shiner Perch, Starry Flounder Orange
Striped Jellyfish, Purple Shore Crab,
Scallop
• Predators—cranes and other birds
• Decay of dead organisms is quick,
nutrients recycled through food web.
Tides: Gravitational pull of sun and
moon cause the rise and fall of
ocean tides.
Intertidal zone—Portion of the
shoreline that lies between the high
and low tide lines
• Size depends on slope of the land and tide
height.
• High levels of sunlight, nutrients and oxygen
(But productivity may be limited by waves/tides)
• Differ in rockiness and wave actions
• Snails, sea stars, mussels, barnacles, clams,
worms, crabs
Tide Pools: Pools of water left
when the water recedes at low tide,
can land lock organisms until next
tide.
Vary greatly in nutrient and oxygen
levels
Ocean Bottom/Photic Zone
• Less affected by waves and tides
• Nutrients washed from the land by rainfall
contribute to abundant life and high
productivity.
• Plankton—Small organisms that live in
waters of photic zone.**removal great
impact
– Autotrophs—diatoms
– Heterotrophes—juvenile stages of many
marine animals.
Ocean Bottom/Aphotic Zone
• Almost 90 % of ocean is > than a km
deep.
• Animals living there far and few, depend
on photic zone where plankton live for
food (directly or indirectly)
• Fish adapted to darkness and scarcity of
food
Freshwater Biomes
• Major abiotic factors: temperature and light
• Not enough sunlight penetrates to bottom
to support photosynthesis
– few aquatic plants or algae grow
– Population density lower
• Bacteria break down dead organisms and
recycle nutrients.
Freshwater Life
• Concentric bands of species
• Cattails, sedges
• Tadpoles, aquatic insects, turtles,
worms, crayfish, beetles, dragonflies,
minnows, bluegill, carp.
Terrestrial Biomes
Tundra
• Treeless land; long summer days; short
periods of winter sunlight
• Temperatures never rise above freezing
Permafrost
Underneath topsoil is a layer of
permanently frozen ground. (Mammoths)
http://news.bbc.co.uk/2/hi/science/nature/6284214.stm
Tundra Organisms
• Shallow-rooted grasses (sedges), small
plants, reindeer moss (lichen)
– Soil lacking in nutrients; decay process slow
due to cold temperatures.
• Mosquitoes, lemmings, weasels, artic
foxes, snowshoe hares, musk oxen,
caribou, reindeer.
Taiga/Boreal Forest
• South of tundra
• Warmer and wetter than tundra
• Climatic conditions—long, severe winters,
short, mild summers.
• Canada, Northern Europe, Asia.
• Permafrost absent
• Topsoil—decaying coniferous needles
Pines/evergreens (acidic and poor in
minerals)
Taiga Organisms
PLANTS
• Northern coniferous (cone bearing) forest
• Larch, fir, hemlock, spruce trees
• Fire/Logging disrupts taiga-first trees to recolonize are birch, aspen, or other
deciduous species.
ANIMALS
• Raccoons, bears, lynxes, wolves, rufflegged buzzards, caribou, ox, artic fox
Desert
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Arid region
Sparse to almost nonexistent plant life
Less than 25 cm of precipitation annually
Atacama Desert (Chile)—one of dryest
places in the world.
Desert Organisms
PLANTS
• Drought-resistant trees—mesquites, cacti,
creosote bush
ANIMALS
• Lizards, tortoises, snake, coyotes, hawks,
owls, roadrunners, scorpions.
Grasslands/Prairies/
Steppes/Pampas/Savannas
• Large communities covered by grasses and
similar small plants
• Yellowstone National Park
• Fewer than 10 to 15 trees per HECTARE!
(a unit of surface, or land, measure equal to 100 areas,
or 10,000 square meters: equivalent to 2.471 acreswww.dictionary.com)
• Most terrestrial area
• Higher biological diversity than desert—more
than 100 species per acre.
Animals: herd animals, fox, prairie dogs, coyotes, weasels, Redtailed Hawks, bison, lions, antelope and lynx.
Plants: buffalo grass, ryegrass, foxtail, wild oats, and purple
needlegrass
Wildflowers: wild indigos, clovers, sunflowers, goldenrods, blazing
stars, and asters
SPECIES
Temperate Forests
• Many types
• Precipitation: 70 to 150 cm annually
• Dominated by broad-leaved Hardwood tress that lose
their foliage annually.
• Soil—top layer rich in humus and deep layer of clay.
• Animals—Black bears, deer, squirrels, salamanders,
mice, blue jays
• Plants—birch, hickory, oak, beech and maple.
Tropical Rain Forest
• More species of organisms anywhere
• Warm temperatures (25C), high humidity, and
abundant rain fall, lush plant growth
• Biodiversity makes important protect
• Near equator
• Precipitation: 200 cm annually (some 600 cm)
Why so many species in rain
forest?: Hypothesis
• Location near equator—not covered with ice during last
ice age—more time to evolve
• Warm weather, do not drop leaves, year round growing
conditions for plants, creates greater food supply,
therefore supports more organisms.
• Provide a multitude of possible habitats for diverse
organisms.
• More layers allowing more for organisms to exist. (Many
organisms find their niche)
Tropical Rain Forest Continued
• Nutrients are tied up in living materials (few soil)
• Decomposers do their work
• Rainforest trees have roots and mycorrhizae that enable
them to absorb nutrients.
• Trees are cut for their hardwoods (mahogany), for farming,
and to produce grasslands for cattle.
Layers of the Rain Forests
EMERGENT LAYER
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Highest layer.
Tallest trees.
Resemble umbrellas
Researcher built towers and
aerial walkways in the trees.
• Birds, butterflies and small
monkeys live with bats, snakes
and bugs.
Kapok Tree
Brazil Nut Tree
CANOPY
• Trees : 25- 35 meters
• Only a few taller trees
push to make the
emergent layer
• Treetops stop a lot of the
light from entering the
forest.
• Protects the soil from
erosion from rains.
• Birds, monkeys, frogs,
and sloth, as well as
lizards, snakes and many
insects
Howler Monkey
Spider Monkey
Understory
• Trees that reach the canopy.
• Wait until a gap appears which they can
then grow into.
• Small, thin trunks.
• 20 meters tall.
• This layer is the home to birds, butterflies,
frogs and snakes.
hummingbirds
SHRUB LAYER
• Grows between the smaller trees of the
understory and the forest floor.
• ferns and small shrubs
FOREST FLOOR
• Very dark (Estimated that only 2% of the sunlight
actually reaches the floor)
• Layer of leaves, twigs and dead plants, which rot
down quickly to provide nutrients for the plants
(Home to invertebrates and microorganisms,
which quickly rot down this surface layer)
• The soil is very sandy with only a thin layer of
rotting vegetation. Without the trees, the soil
quickly loses its ability to support plants and
turns to desert-like conditions.
Rainforest floor Organisms
• Plants—Ferns and Mosses
• Animals—tigers and elephants in Asia,
gorillas and leopards in Africa and tapirs
and jaguars in South America.
Amazon River Dolphin