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CH.3: Human Impact on Ecosystems 1.1: Human population growth presents challenges The human population is increasing • Increase in birth rate (more babies being born) • People are living longer due to better healthcare. • It’s estimated by 2050, nine billion humans will have to
share Earth’s resources.
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Human populations can put pressure on ecosystems resources • Food • Water • Living space (shelter)
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Pressures of Waste Disposal • As the human population increases so does natural
waste.
• Landfills may take up a lot of space, can release methane gases into the air, and leak harmful chemicals into the groundwater.
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• Incineration is a way to get rid of garbage by burning it, but burning is harmful, by releasing harmful gases & chemicals into the air.
Pressures on Resources • Natural Resources: any type of material or energy that
humans use to meet their needs. o Water (only three percent of all the water on Earth is
fresh water) o Food o Energy (coal, natural gas, oil, gas) o Wood.
Pressure of Urban Growth • Population Density: the measure of the number of
people in a given area.
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o When a population is spread out the population
density is typically lower. The lower the population density, the less
pressure on the environment
o When a population is large and more compact, the population density is higher. The higher the population density, the more
pressure on the environment.
Pressures on Expanding Land Use • Land development affects the environment
o Forests are cut down to build homes or shopping centers, affecting the carbon cycle (more CO2 in the environment due to less trees)
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o Soil erosion increases.
As land is cleared, rain-washes away nutrients on the top layer of the soil
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o Less land is available for farms
Indian Farm Changed to new Indian city
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3.2: Human activities affect the environment Humans use many resources • Humans use many natural resources,
o Water (only three percent of all the water on Earth is fresh water)
o Food o Energy (coal, natural gas, oil, gas)
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o Wood.
• Scientists classify natural resources into two categories: o Renewable resources: resources that can be used over again, or replenished.
Solar (sun)
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Water (power turbine engines)
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Wind
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o Nonrenewable resources: resources that cannot be used over again, or replaced. Coal Petroleum (oil) Natural gases (fossil fuels), and minerals like copper and gold.
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Pollution endangers biodiversity • Pollution: Substances that harm air, water, or land.
o Chemicals o Bacteria
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o Dirt. • Pollution can cause living things (organisms/species) to die.
• Biodiversity: The number and variety of life forms within an ecosystem. o Biodiversity increases as the number of species increase.
o Biodiversity decreases as the number of species decreases.
o Healthy ecosystems have a high biodiversity. o Greater biodiversity increases the likelihood of a species survival. (WHY?)
Air quality • The main sources of air pollution
o Motor vehicles o Factories o Power plants. o The fossil fuels they burn release sulfur dioxide, nitrogen dioxide, and carbon monoxide. (These are all harmful gasses for living organisms)
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• Acid rain: occurs when air pollutants such as sulfur dioxide and nitrogen dioxide mix with water in the atmosphere to form acid droplets of rain, ice, snow, or mist.
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Water quality • Causes of water pollution
o Chemicals or waste that drain off of farm fields, animal feedlots, and landfills
o Oil spills o Chemical spills
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Pollution across systems • Pollution can also move between air and water
o Chemical pollutants run off land, into water, and the polluted water then evaporates transporting the pollutants into the atmosphere.
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Habitat loss endangers biodiversity • Reasons for habitat loss
o Farming o Housing
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• Affects of habitat loss o Living space is limited
Less trees, bushes, grass to use as shelter
o Food source is removed Plants are no longer available to eat, thus grazing animal’s leave.
When the grazing animals are gone, there is no longer food for predators.
o The number of species will be reduced due the loss of living space and food.
Changing habitat • Native species: A species that naturally lives, grows, and reproduces in an ecosystem.
• Invasive species: A species that moves to a new place and replaces native species. o Invasive species can decrease biodiversity.
Purple Loosestrife
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