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 ( 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 – 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 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 – 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 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.