Download Ecosystems, Biomes and Our Impact

Ecosystems, Biomes and Our
Impact
Environmental Factors
• Biotic: features of the environment that are
alive or once were.
– Ex: communities and populations within
ecosystems
• Abiotic: nonliving, physical features of the
environment.
– Air, water, soil, sunlight, temperature, climate
Cycles in Nature
• The Water Cycle
• The Nitrogen Cycle
Cycles in Nature
• The Carbon Cycle
• The Food Chain
Biomes
• Biome: large geographic areas that have
similar climates and ecosystems
Major Biomes
• Tundra: a cold, dry, treeless
region, sometimes called a
cold desert.
– Less than 25 cm of
precipitation
– Mosses, grasses, small shrubs
– Biting insects fill the air in the
summer
– Migratory birds nest during the
summer
– Mice, arctic hares, caribou,
reindeer
Our Impact on the Tundra
• Overgrazing: when plants
are exposed to intensive
grazing for extended periods
of time, without sufficient
recovery periods.
– Fences, roads and pipelines
have disrupted the migratory
routes of animals and have
forced them to stay in a
limited area.
– Because the growing season is
so short, plants and other
vegetation can take decades
to recover from damage.
Major Biomes
• Taiga: a cold, forest region
dominated by cone-bearing
evergreen trees.
– The largest biome, more
precipitation (snow) than in
tundra (35-100 cm/year).
– Most soils thaw completely
during summer, trees are so
dense that sunlight doesn’t
penetrate to reach forest floor.
– Mosses, moose, lynx, bears,
foxes
Major Biomes
• Temperate Deciduous
Forest: forests in which
trees loose their leaves
every autumn.
– Usually in places that
experience all four seasons
– 75-150 cm of precipitation
each year
– Mostly east of the Mississippi
River in the US
– Amphibians, deer, birds roam
these forests…several moss
and fern species.
Our Impact on Forests
• Deforestation: the clearing or
removal of trees
– When European settlers came to the
United States, they cut down trees to
create farmland and to supply wood.
– As the settlers moved west, trees
started to grow back in the east.
– The logging industry provides jobs for
many people, but removes large parts
of the forest and destroys the habitat
of many organisms.
– Some forests are protected as national
parks and forests meaning no one can
build on that land or cut down any
trees.
Major Biomes
• Temperate Rain Forests: average
temperature ranges from 9-12
degrees Celsius and precipitation
ranges from 200-400 cm per
year.
– Found in New Zealand, southern
Chile, Pacific Northwest of USA.
– Trees with needle like leaves
– Black bear, cougar, bobcat, owl
live here.
– Logging companies use these
trees most often but are required
to replant trees to replace the
ones they cut down.
Major Biomes
• Tropical Rain Forests: forests
that contain warm
temperatures, wet weather
and lush plant growth.
– Near the equator
– 200-600 cm of rain each year
– One of the most biologically
diverse places in the world
– 4 layers: Forest Floor,
Understory, Canopy,
Emergents
Our Impact on Rain Forests
• Farmers that live in tropical areas
clear the land to farm and to sell
valuable wood.
– After a few years, the crops use up
the nutrients in the soil and the
farmers must clear more land.
• Through education, people are
realizing the value and potential
of preserving the species of the
rain forest.
– Some areas are protected from
logging and farmers are taught new
methods of farming.
Major Biomes
• Desert: receive less than
25 cm of rain each year
and support little plant life.
– Driest biome on
Earth…most plants are able
to store water
– Soil contains little to no
organic matter
– Barren, windblown sand
dunes
– Most animals are active
only during the night
• Kangaroo rat, scorpions,
cactus
Our Impact on the Desert
• In order to provide water for desert cities,
rivers and streams have been diverted.
– Wildlife tends to move closer to cities in their
search for food and water.
Major Biomes
• Grasslands: temperate and
tropical regions that receive
between 25-75 cm of precipitation
each year and are dominated by
communities of grasses.
– Have a dry season where little to
no rain falls…lack of moisture
prevents the development of
forests.
– Kangaroos, zebras and most
animals graze on the stems, leaves
and seeds of grass plants.
– Perfect for growing many
crops…overgrazing and lack of
nutrients.
Our Impact on Grasslands
• Grasslands are perfect for growing many crops
such as wheat, rye, oats, barley, and corn.
• Grasslands are also used to raise cattle and
sheep.
• Overgrazing can result in the death of grasses
and the loss of valuable top soil from erosion.
Freshwater Ecosystems
• Rivers and Streams
– Flowing freshwater environments
– Clear water, high oxygen content
• Lakes and Ponds
– Lower places where land fills with
rainwater, snowmelt or water
from overflowing streams.
– More open water as plants tend
to grow just around the outside in
lakes while ponds are more
shallow
• Wetlands
– Regions that are wet for all or
most of the year…swamps
Saltwater Ecosystems
• Open Oceans
– Divided into different zones based on
depth
• Lighted zone (home of plankton, the
foundation of the food chain), dark zone
(animals here feed on what sinks from lighted
zone)
• Coral Reefs
– Formed over long periods of time…one of
the most diverse ecosystems in the world.
• Seashores
– At the border between the ocean and a
landmass
– Shallow waters are influenced by tides and
waves so organisms must be adapted to
dramatic changes in temperature, moisture
and salinity and must be able to withstand
the force of wave action.
Our Impact on Water
• People use streams and rivers for a
variety of activities.
– Although many regarded rivers to be a
place do dump garbage and sewage,
people now know the damage that
caused.
– Fertilizer filled runoff from farms and
lawns pollute the water or cause
excessive algae to grow (blocking
oxygen from entering the water)
• Many wetlands were drained and
destroyed before people recognized
the importance of their ecosystem
to the rest of the environment.
How ecosystems change…
• Succession: refers to the
normal, gradual changes that
occur in the types of species
that live in an area.
– Occurs differently in different
places around the world.
– Primary Succession: the process
of succession that begins in a
place previously without plants.
• Pioneer species: the first living
things to inhabit an area…they
survive drought, extreme heat and
cold and other harsh conditions
How ecosystems change…
• Secondary Succession: succession
that begins in a place that already
has soil and was once a home of
living organisms.
– Rebuilding after a fire
• Climax Communities: a community
of plants that is relatively stable and
undisturbed and has reached a stage
of succession.
– New trees grow where others die
– Few changes of species as long as the
community isn’t disturbed by fire,
avalanche or human activities.