1.1: Human population growth presents challenges

Transcription

1 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.

2 Human populations can put pressure on ecosystems resources Food Water Living space (shelter)

3 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.

4 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.

5 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 CO 2 in the environment due to less trees)

6 o Soil erosion increases. As land is cleared, rain-washes away nutrients on the top layer of the soil

7 o Less land is available for farms Indian Farm Changed to new Indian city

8 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)

9 o Wood. Scientists classify natural resources into two categories: o Renewable resources: resources that can be used over again, or replenished. Solar (sun)

10 Water (power turbine engines)

11

12 Wind

13 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.

14

15

16 Pollution endangers biodiversity Pollution: Substances that harm air, water, or land. o Chemicals o Bacteria

17 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)

18 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.

19 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

20 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.

21 Habitat loss endangers biodiversity Reasons for habitat loss o Farming o Housing

22 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

23