Humans in the Biosphere Ch. 6 1.37, 1.38, 1.40, 1.41, 1.43, 1.45, 1.46

Changing Landscape Many species of organisms have become extinct or scarce because of human actions of resource use and cutting down trees.

Human Activities We affect the biosphere by: Hunting and Gathering Agriculture- farming Industry Urban Development

Hunting and Gathering In N. America mammoths, giant ground sloths, saber-tooth cats extinct. Cheetahs, zebras, and yaks disappeared.

Agriculture Began about 11,000 years ago at the end of the Ice Age. Monoculture- large fields are planted with a single variety year after year. Fertiliziers, chemicals

The Green Revolution Modern agricultural techniques were introduced, increasing the world’s food supply. Provided better nutrition. Ecological challenges Insect pest and diseases- add pesticides. Finding enough water for irrigation.

Industrial Growth and Urban Development During 1800’s the Industrial Revolution took off. What are some ways the Industrial Revolution has effected the environment?

Resources Non-renewable- cannot be replenished by natural processes. Fossil fuels. Renewable- can regenerate if they are alive, or can be replenished by biochemical cycles if they are non-living. Water, other examples? Are they unlimited?

Sustainable Development Way of using natural resources without depleting them, and of providing for human needs without causing long term environmental harm. Human activities can affect the quality and supply of renewable resources such as land, forests, fisheries, air and fresh water. How?

Land Resources Soil erosion- wearing away of soil surface by water and wind. Desertification- occurs in dry climates by farming, overgrazing and drought. Soil is a renewable resource if managed properly. Fertile soil- mixture of sand, clay, rock particles and humus (material decayed organisms.)

Forest Resources Wood is still used in many parts of the world for burning for energy. Slashing and burning of forests to build homes or for agriculture. In the tropical rainforests, we lose many chances to find cures for diseases. Deforestation- loss of forests. Severe erosion when exposed to heavy rains. Erosion washes away nutrients in topsoil. Grazing or plowing after deforestation causes permanent changes to soil and microclimate that can prevent regrowth of trees. .

Fishery Resources Overfishing- reduces number of fish because harvesting fish faster than they can reproduce. There are guidelines for US commercial fishing. Aquaculture- raising of aquatic animals for human consumption.

Air resources Smog- mixture of chemicals that occurs as a gray-brown haze in the atmosphere. Primarily due to automobile exhausts and industrial emissions. Pollutant- harmful material that can enter the biosphere through the air, land, and water. Acid Rain- occurs when the burning of fossil fuels combines with water vapor in the air and form nitric and sulfuric acids. Affects fish reproduction and plants if acidic enough.

Freshwater Resources Americans use billions of liters of freshwater daily. Important to protect it from chemicals and pollutants.

Biodiversity Biodiversity is the sum total of the genetically based variety of all organisms in the biosphere. Ecosystem diversity- habitats, communties and ecological processes in living world. Species diversity- number of species in the biosphere. 1.5 million named and identified. Genetic diversity- sum total of all of the different forms of genetic information carried by all organisms living.

Biodiversity is one of Earth’s greatest natural resources. Species of many kinds have provided us with foods, industrial products and medicines- including painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs. Rosy Perwinkle plant helps treat cancers.

Threats to Biodiversity Human activity can reduce biodiversity by alternating habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments. Extinction- occurs when species disappears from all or part of its range. Endangered species- population size is declining in a way that takes place it in a danger of extinction. Examples?

Habitat Alternation How do humans alter habitats? Habitat fragmentation is the splitting of ecosystems into small fragments. What happens to the animals in the habitats?

Demand for Wildlife Products How have humans pushed animals to extinction? Examples?

Pollution Biolgoical magnification- Toxic compounds acculumate in the tissue of organisms as it travels through the food chain. DDT- fist widely used pesticide. Nonbiodegradable When it is picked up by organisms, they do not eliminate it from their body.

Invasive Species In 1988, small freshwater zebra mussels were introduced to Lake Erie from Europe. They spread to all great lakes in less than 10 years. They compete with other species for food. They clog up water-intake pipes and farm-irrigation pipes. One benefit- filter-feeding action h as made water cleaner. Gypsy moths 1.38

Conserving Biodiversity Why is it important to preserve entire ecosystems? See the timeline on page 154 for efforts made to improve the earth. Today, conservation efforts focus on protecting entire ecosystems as well as single species. Protecting an ecosystem will ensure that all the natural habitats and the interactions of many different species are preserved.