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Humans in the Biosphere 6-1 Changing the landscape Humans depend on and participate in food webs and chemical cycles. Activities that affect the biosphere – Hunting and gathering – Agriculture – Industry – Urban development Hunting and Gathering Our ancestors obtained food by hunting and gathering They hunted for birds and mammals, and fished in rivers and oceans They also gathered seed, fruits and nuts These activities changed the environment. Agriculture Agriculture = farming – One of the most important developments in human history Why? Monoculture is when a large field is used to plant one type of plant year after year The Green Revolution The introduction of monoculture and the use of chemical fertilizers became know as the green revolution This is because it greatly increase the worlds food production. Challenges for the Future Large scale monoculture lead to problems with pests and diseases – Chemical pesticides can damage beneficial insect, contaminate water and accumulate in the environment Finding enough water for irrigation also became a problem Industrial growth and urban development These have provided us with many of the modern conveniences such as homes, clothes, electronics, machines cars, etc. The down side is the pollution put in the air, water, and land due to this Also human growth takes up natural habitats that puts stress on plants and animals ability to survive. 6-2 Classifying Resources Environmental goods and services may be classified as either renewable or nonrenewable. Renewable resources Resources that can regenerate if they are alive or can be replenished by biochemical cycles if they are nonliving. Example – a tree can grow in place of an old tree that dies or is cut down Nonrenewable resource A resource that cannot be replenished by natural processes. Example – fossil fuels (coal, oil, and natural gas) formed over hundreds of millions of years from deeply buried organic materials, when they’re gone they’re gone forever. Classifying a resource renewable or nonrenewable This depends on the context, a single tree is renewable, a population of trees in a forest ecosystem may not be renewable. If a community of organisms depends on the trees, the ecosystem may change forever once those trees are gone Land Resources Land is important b/c it gives us space to live on and materials for industry. It also includes soil which crops are grown in Soil is renewable if managed properly, but can be permanently damaged if mismanaged Soil erosion is the wearing away of surface soil by water and wind – Plowing the land removes roots and plants which hold soil in place A combination of farming, overgrazing, and drought has turned productive areas in to deserts – this is known as desertification Forest Resources Forests are important for the products they provide and for the ecological functions they perform Loss of forest, deforestation, leads to soil erosion which washes away nutrients Fish Resources Fish and other animals that live in water are valuable sources of food for humanity Overfishing means we are taking fish out of the water faster than they are reproducing – Fish populations are decreasing because of this Sustainable development is a way to try and maintain the worlds fish supply There are guidelines/rules which tell fishermen how many and what size fish they can catch Aquaculture, the raising of aquatic animals for human consumption, is helping to sustain fish resources Air resources Air is a common resource that we use every time we breathe, the condition of the air affects people’s health Smog- a mixture of chemicals that occurs as a gray-brown haze in the atmosphere. Smog is a pollutant, it is a harmful material that can enter the biosphere through the land, air or water. Causes of air pollution The burning of fossil fuels can release pollutants into the atmosphere Burning fossil fuels releases sulfur and nitrogen compounds into the air Acid rain is caused by these substances combining with water vapor 6-3 Biodiversity Biodiversity = total of the genetically based variety of all organisms in the biosphere Bio = life Diversity = variety Biodiversity is the earths greatest natural resource Species of many kinds have provided us with foods, industrial products and medicines – such as painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs Threats to biodiversity Human activities can reduce biodiversity – Altering (changing) habitats – Hunting species to extinction – Introducing toxic compounds into food webs – Introducing foreign species to new environments Habitat alteration When humans develop land habitants are destroyed As habitats disappear, the species that live there disappear. When a habitat is split into pieces by development it is called habitat fragmentation. Pollution Humans add many toxic chemicals into the environment that threaten biodiversity Biological magnification – concentrations of toxins increase in organisms at higher trophic levels in a food chain or web Each step up in the food chain magnifies the toxin Introduced Species Plants and animals that seem harmless are transported around the world by humans. These organisms can end up altering native communities. Invasive Species Species that are introduced into new habitats and reproduce rapidly. This happens because their new habitat lacks the parasites and predators that normally control their population “back home”. Conservation Conservation – the wise management of natural resources, including preserving of habitat and wildlife. Conservation focuses on protecting ecosystems, which will ensure that the natural habitat and the interactions of many different species are preserved at the same time 6-4 Ozone depletion Ozone layer protects the Earth from the Sun’s Ultra-violet radiation Ozone layer has been broken down by pollutants put in the air by humans, mainly cfc’s Results of Ozone Depletion Ultra-violet radiation causes cancer – Skin cancer in humans has increase over the last 20 years. Global warming = the average temperature of earth’s surface is rising Effects of Global Warming Higher temperatures Sea levels may rise Ecosystems could change Value of a Healthy Biosphere The environment provides both environmental and economic benefits to humans Such as -Insects that pollinate our crops -Organisms that provide us with new medicine - new varieties of crops How can we help Avoid using excess water (showering, watering plants) Plant trees to replace ones cut down Reuse/recycle trash and other wastes Dispose chemicals in ways that don’t harm ecosystems Cut down on use of fossil fuels