Human Impact on Ecosystems Chapter 3 Section 1
Human population growth presents challenges
Human population is increasing Just 200 years ago the human population was only 1 billion. Today it is estimated that the current population is 6 billion. This increase has happened in a very short time. It is expected for the population to grow to 9 billon by the year 2050.
Humans put pressure on ecosystems Resources such as food, water, and space can be limiting factors for biological populations. As the human population grows, it uses more resources; the activities of the growing human population are putting pressure on Earth's ecosystems.
Pressure #1: Waste Disposal Most garbage and trash ends up in landfills. Why are landfills bad? They take up a lot of space. Decomposing trash can release dangerous chemicals into the air as well as harmful chemicals into the ground.
Pressure #2: Resources are limited A natural resource is any type of material or energy that humans use to meet their needs. Natural resources that humans take from their environment include water, food, wood, stone, metal, and minerals
Pressure #2: Resources
Pressure #3: Urban Growth Population density: the measure of the number of people in a given area. High population density = _____________ impact on ecosystem Low population density = ____________ impact on ecosystem
Pressure #3: Urban Growth Population density is high in cities. Buildings are spaced close together and there are a large number of people in a small area. This changes the landscape. Resources exceed what is available in the local environment so they must come from farther away.
Pressure #3: Urban Growth
Pressure #4: Expanding Land Use Natural habitats are destroyed by expanding communities. Cutting down trees affects the carbon cycle. Soil that was held by roots may now wash into lakes and rivers.
Pressure #4: Expanding Land Use Productive farmland is lost to urban development. When cities spread out there is more need for cars. This adds to the pollution in our air