Humans in the Biosphere

Do Now Read the article and answer the questions below: What is the main idea of the article? Provide two to three evidences from the article that support your main idea. Can the changes seen on Hawaii islands happen to the rest of the Earth? Why or why not?

Human Activities Among human activities that affect the biosphere are hunting and gathering, agriculture, industry and urban development. Hunting and Gathering: have changed environment since pre- historic times. Ex: Human hunters arrived in North America about 12,000 years ago. They caused one of major mass extinctions of large animals (woolly mammoths, giant ground sloths, sabertooth cats, cheetahs, zebras, etc.)

Human Activities 2. Agriculture: humans began practicing farming 11,000 years ago (after last ice age) Domestication of Animals- sheep, goats, cows, pigs, horses, dogs (led to overgrazing, eroded soils, large demands on water) Modern Agriculture- In 1800’s, advancement in science led to remarkable changes in agriculture and increased yields (irrigation, new crop varieties, invention of farm machines) Green Revolution- global effort to increase food production for fast- growing world population (new, intensive farming practices that increase yields)

Human Activities 3. Industry and Urban Development: With the growth of civilizations was the need for machines and factories. This need led to the exploitation of energy: a. Renewable- can regenerate (are replaceable) not necessarily unlimited. b. nonrenewable- one that cannot be replenished by natural processes (ex. Fossil fuels, oil and natural gas)

This proud, tall tree is no match for a huge chainsaw This proud, tall tree is no match for a huge chainsaw. Once cut, it will be used to make many consumer products A tiny tree will be placed in its stead. Varieties of trees that reach harvesting size in fewer years have been developed

Impacts of human activities

desertification- in certain parts of the world with dry climates, a combination of farming, overgrazing, and drought have turned once productive areas into deserts

deforestation- loss of forest. Can lead to severe erosion.

Compromised Air Quality:

Compromised water quality: Acid rain- acidic gasses released into air and combine with water vapor forming drops of nitric and sulfuric acid. Can kill plants, change chemistry of soils and standing water ecosystems Photomicrograph of drop of acid rain. Serious threat to environment

Global Warming:

Biodiversity- sum total of the genetically based variety of all organisms in the biosphere 1. Forms of diversity a. Ecosystem diversity- includes variety of habitats, communities, and ecological processes in the living world b. Species diversity- number of different species in the biosphere c. Genetic diversity- sum total of all the different forms of genetic information carried by all living organisms

2. Biodiversity is one of Earth’s greatest natural resources 2. Biodiversity is one of Earth’s greatest natural resources. Species of many kinds have provided us with foods, industrial products, medicines, etc. 3. Threats to Biodiversity- human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species into new environments

By what number is the concentration of DDT multiplied at each successive trophic level?

Kudzu was introduced into the U. S Kudzu was introduced into the U.S. from Russia and Japas as an ornamental and to reduce soil erosion. It grows and reproduces rapidly, smothering areas of native plants Zebra mussels were introduced into Great Lakes from ballast of ships. Fast-growing mussels filter food from the water, blocking many food chains

Charting a Course for the Future- two major concerns 1. Ozone depletion- naturally occurring ozone gas (20-50 km above Earth’s surface) absorbs good deal of harmful ultraviolet radiation from sunlight before it reaches Earth’s surface.

2. Global Warming- an increase in average temperature of the biosphere.

The Value of a Healthy Biosphere 1. Human society depends on healthy, diverse, and productive ecosystems because of the environmental and economic benefits they provide 2. People need to make wise choices in use of resources and disposal or recycling of materials