Unit 4 Human Impact on the Environment

Population

• Three factors that affect population:– Number of births– Number of deaths– Number of individuals that enter or leave an

area

Carrying Capacity

• The largest number of individuals that a given environment can support.

• As resources become less available, the growth of a population slows or stops.

Limiting Factors

• A factor that causes population growth to decrease.

• Types of Factors:– Competition for resources –Nonrenewable and

renewable– Predator – Prey– Disease– Climate Extremes

Non/renewable Resources

• Renewable resources can regenerate and therefore replaceable (not necessarily unlimited)– Trees, fresh water

• Nonrenewable cannot be replenish by natural processes– Coal, oil, natural gas (fossil fuels)

GREENHOUSE EFFECT

• Carbon dioxide-methane-water vapor and other atmosphere gases trap heat energy and maintain Earth’s temperature range. The natural situation in which heat is retained by this layer of greenhouse gases is called the greenhouse effect.

Global Warming

• An increase of the average temperature of the biosphere

• Caused by human activities by adding Carbon Dioxide and other greenhouse gases into the atmosphere

Global Warming

• Climate Change

• Increase of carbon dioxide and other greenhouse gases into the atmosphere.

• www.epa.gov/students/

Ozone Depletion

• Caused by chlorofluorocarbons (CFCs)

• CFCs are found in refrigerants, solvent, insulating foam

• This compound allows UV light to break apart the ozone layer

Deforestation

• Loss of trees

• Leads to soil erosion

• Erosion can wash away nutrients

• Grazing and plowing can change composition of soil to prevent regrowth of trees

Causes of Deforestation

Acid Rain

• Burning of fossil fuels release gases, nitrogen oxide and sulfur dioxide, to combine with water vapor in the air

• Kill plants and leaves

• Dissolve and release toxins, like mercury from soil into biosphere

What is Biodiversity?

• A variety of living species in an ecosystem

Threats to Biodiversity

• Endangered Species

• Extinction

• Introducing a foreign species

• Pollution

• Biological Magnification

Endangered Species are a species population size that is declining in a way

that places it in danger of extinction

Extinction – occurs when a species disappears from all or part of its range.

Invasive Species – species introduced into a non-native habitat (foreign

species)• Zebra Mussels

• Purple Loosestrife

Biomagnification

Bioaccumulation:

increase in concentration of a pollutant from the environment to the first organism in a food chain

Biomagnification: increase in concentration of a pollutant from one link in a food chain to another

Conserving Biodiversity

• Conservation is the wise management of our natural resources including the

preservation of habitats and wildlife

Biological Control

• Biological Control is using one species (hopefully native species) to control the population of another unwanted/harmful species

• Advantages – no need for pesticides (toxic chemicals)

• Disadvantages – no natural predator so it may overpopulate, disrupting food chain