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.