In the past, most people did not worry about the effects of human activities on the environment.  Forests were cut down, rivers were dammed, and soil erosion was not prevented.  Wastes from mines and other industries were dumped on the land, into waterways, and into the air.  Within the last 30 years or so, however, more and more people have come to realize that the environment cannot be used thoughtlessly any longer.  Human ecology deals with the relationship between humans and their environment.

What are limiting factors and how do they affect human growth?
· Some factor that halts any further growth in a population
· Ex. Lack of food, sunlight, space, water, etc…
· Populations will continue to grow unless there is a limiting factor.

What is carrying capacity?
· The size of a population that can be supported by the environment.
· Populations usually go above the carrying capacity and are then brought back down by limiting factors.

What are some things that have contributed to the increase in growth of the human population?
· Improvement in medical care, food production, and sanitation.
· This has increased the rate of survival while birth rates have remained high.
· Many children born now live to adulthood b/c of these conditions

How can human growth be controlled?
· Reduce the birth rate to reproductive replacement.
· One child for each parent.  For every person that is born one person dies.   
· China - 1birth for every 2 parents

What would be some problems if human population continues to grow?
· Starvation - lack of food would be a limiting factor and would bring the population back to carrying capacity.
· Faster use of natural resources.
· More pollution

How has urbanization affected existing ecosystems?
· Development of cities has caused the destruction of habitat. 
· Ecosystems such as wetlands have been destroyed which affects the balance of nature
· Food chains have been disrupted.
· Introduction of new species.  (No predators)

What are some of the problems associated with poor farming practices, such as overgrazing and overfarming?
· When soil is overfarmed or overgrazed nutrients are robbed from the soil.
· Soil then becomes less fertile and eventually becomes useless.
· Without any vegetation, topsoil can easily erode.

What does the use of DDT tell us about the misuse of pesticides?
· Anything we put in our environment can be passed along the food chain.   Birds that ate insects that ingested DDT where poisoned.
· Kills organisms that may not be pests.

What are the six major sources of water pollution?
· Organic wastes    · inorganic chemicals
· Disease-causing microorganisms
· Changes in water temperature · oils spills
· Radioactive wastes

What are organic wastes? 
· Waste products from plants or animals.  Usually biodegradable

What does it mean to be biodegradable?
· Materials that can broken down by bacteria and other decaying organisms into simpler substances.

What are the problems with large amounts of organic waste?
· Large amounts of organic wastes will cause the build up of bacteria and other organisms of decay.
· These organisms use up the oxygen supply of the water.

Describe Eutrophication.
· Some organic waste speed up the growth of algae.  When these organisms die the sink to the bottom and build up
· This can speed up succession in lakes.
· Eutrophication is the accelerated aging of a lake