Communities and Biomes
Community
• Community: A collection of several interacting
populations that inhabit a common
environment.
Limiting Factors
– Factors that affect an organism’s ability to
survive in its environment, such as the
availability of water and food, predators, and
temperature, are called limiting factors.
• A limiting factor is any biotic or abiotic factor that
restricts the existence, numbers, reproduction, or
disturbance of organisms.
Ranges of Tolerance
• The ability of an organism to withstand
fluctuations in biotic and abiotic
environmental factors is known as tolerance
Ecological Succession
• Ecosystems are constantly changing in response to
natural and human disturbances.
• As an ecosystem changes, older inhabitants
gradually die out and new organisms move in,
causing further changes in the community.
Ecological Succession
• Ecological succession is the series of predictable
changes that occur in a community over time.
– Primary succession takes place on bare rock
surfaces where no soil exists. Pioneer species are
the first species to live in these areas.
– Secondary succession occurs when a disturbance
changes a community without removing soil.
Primary Succession
Secondary Succession
Biotic and Abiotic Factors
• Organisms in ecosystems are affected by both biotic
and abiotic factors.
• Biotic factors are all of the living things with which
organisms interact.
• Abiotic factors are nonliving, physical things. (Ex.
temperature and soil type)
• Together, biotic and abiotic factors determine the
survival and growth of an organism and the
productivity of the ecosystem in which and organism
lives.
Abiotic and Biotic Factors
Abiotic Factors
Biotic Factors
ECOSYSTEM
Ecological Succession Video
• http://www.youtube.com/watch?v=V49IovRSJ
Ds
Climate
• In the atmosphere, temperature, precipitation,
and other environmental factors combine to
produce weather and climate.
• Weather: is the day-to-day condition of Earth’s
atmosphere at a certain time and place.
• Climate: is the average yearly condition of
temperature and precipitation in a region.
• Climate affects ecosystems.
The Greenhouse Effect
• Carbon dioxide and other atmospheric gases trap
heat energy and maintain Earth’s temperature range.
• These gases function like the glass windows of a
greenhouse.
• The trapping of heat by gases in the atmosphere is
called the greenhouse effect.
• This greenhouse effect helps temperatures on Earth stay
within a range that supports life.
The Greenhouse Effect
The Effect of Latitude on Climate
• Latitude also affects climate. Earth has 3 main
climate zones: polar, temperate, and tropical.
– Polar Zones are cold areas where the sun’s rays
strike Earth at a very long angle.
– Temperate Zones sit between the polar zones and
the tropics. The climate in these zones ranges
from hot to cold, depending on the season.
– The Tropical Zones or tropics, is near the equator.
The climate here is almost always warm.
The Effect of Latitude on Climate
90°N North Pole
Sunlight
66.5°N
Arctic circle
Sunlight
Tropic of Cancer
Most direct sunlight
Equator
0°
Tropic of Capricorn
Sunlight
Arctic circle
Sunlight
23.5°N
66.5°S
90°S South Pole
23.5°S
Heat Transport in the Biosphere
• Unequal heating of Earth’s surface also causes
winds and ocean currents.
• Wind and ocean currents move heat through
the biosphere.
Biomes
• A biome is a group of land communities that covers a
large area and has a certain soil type and climate
• Within a biome, there maybe microclimates
• A microclimate is a small area where the climate
differs from that of the surrounding area.
The Major Biomes
• There are ten major biomes:
– Tropical Rain Forest, Tropical Dry Forest, Tropical
Savanna
– Desert
– Temperate Grassland, Temperate Woodland and
Shrubland, Temperate Forest
– Northwestern Coniferous Forest, Boreal Forest (or
Taiga)
– Tundra
• Each biome has its own set of abiotic factors and a
typical collection of organisms.
• Some areas, such as mountains and polar ice caps,
do not fall neatly into the major biomes
Compare/Contrast Table of Biomes
Ten Major Biomes
Biome
Precipitation
Temperature
Soil
Diversity
Trees
Grasses
Tropical Rain Forest
high
hot
poor
high
dense
sparse
Tropical Dry Forest
variable
mild
rich
moderate
medium
medium
Tropical Savanna
variable
Desert
low
Temperate Grassland moderate
mild
variable
summer hot
clay
poor
rich
moderate
moderate
moderate
sparse
sparse
absent
dense
sparse
dense
Temperate woodland
and Shrubland
summer low,
winter moderate
summer hot
poor
low
medium
medium
Temperate Forest
moderate
summer moderate, rich
winter cold
high
dense
sparse
Northwestern
Coniferous Forest
Boreal Forest
high
rocky, acidic
low
dense
sparse
poor, acidic
moderate
dense
sparse
Tundra
low
summer mild,
winter cold
summer mild,
winter cool
summer mild,
winter cold
poor
low
absent
medium
moderate
The World’s Major Land Biomes
Tropical rain forest
Temperate grassland
Temperate forest
Tundra
Tropical dry forest
Desert
Mountains and
ice caps
Tropical savanna
Temperate woodland
and shrubland
Northwestern
coniferous forest
Boreal forest
(Taiga)
Aquatic Biomes
• Unlike land biomes, which are grouped
geographically, aquatic biomes are grouped by the
abiotic factors that affect them.
• Aquatic biomes are described mainly by the depth,
flow, temperature, and chemistry of their water.
Aquatic Energy
• In many aquatic biomes, tiny free-floating swimming
organisms can be found. These organisms are called
plankton.
• There are 2 types of plankton (phytoplankton and
zooplankton)
– Phytoplankton are single-celled algae that use nutrients in
water to make food. They form the base of many aquatic
food webs.
– Zooplankton are animals that feed on phytoplankton
Aquatic Biomes
• There are 3 main groups of aquatic biomes:
• 1. Freshwater biomes can be divided into several
types.
– Flowing-water biomes (rivers and streams) flow
over land.
– Standing-water biomes include lakes and ponds
– Freshwater wetlands include bogs, marshes, and
swamps. In wetlands, water covers the soil or is
present at or near the surface for at least part of
year.
Bogs, Marshes, and Swamps
Aquatic
Biomes
2. Estuaries are wetlands formed where rivers meet the sea.
They contain a mixture of fresh and salt water. Most food
made in estuaries enters food webs as tiny pieces of organic
matter, called detritus.
– Salt marshes are temperate estuaries. Salt-tolerant
grasses and sea grasses are the dominant plant life in salt
marshes.
– Mangrove swamps are tropical estuaries. The dominant
plant life in mangrove swamps includes several species of
salt-tolerant trees, called mangroves, and sea grasses.
Aquatic Biomes
3. Marine biomes exist in the ocean. The ocean is divided
into zones based on how much light penetrates the water.
– The photic zone is the well-lit upper layer of water.
Photosynthesis can take place here.
– The aphotic zone is the permanently dark lower layer
of water. Producers here use chemosynthesis to make
food.
Oceans
• The ocean is also divided into zones based on depth and
distance from shore: the intertidal zone, the coastal
ocean, and the open ocean, and benthic zone.
Marine Biomes
Organisms in the intertidal zone are exposed to regular and
extreme changes in their surroundings. (tides)
The coastal zone is relatively
shallow, lies entirely within the
photic zone, and is often rich in
plankton and other organisms.
Coral reefs grow in tropical
coastal oceans.
Marine Biomes
The open ocean is the largest zone, covering more than 90
percent of the surface area of the world’s oceans. These
areas typically have low levels of nutrients and support only
small producers.
Benthic zone is the bottom of the ocean, contains organisms
that live attached to or near the bottom.
Zones of a Marine Biomes
land
Coastal
ocean
Open
ocean
200m
1000m
Photic zone
4000m
Aphotic zone
6000m
Ocean
trench
Continental
shelf
Continental slope and
continental rise
Abyssal
plain
10,000m