Ecology of Populations

What is Ecology? “Ecology” the study of the interactions of organisms w/ its environment.

Population Growth Populations grow when birth rate exceeds rate of mortality DEATH

Humans are part of the Earth's ecosystem. Human activities can either deliberately or inadvertently alter the balance of an ecosystem.

Conserving Land and Soil Less than a 1/4 of Earth's surface is dry land. 1.Except for the small amount added when volcanoes erupt, new land cannot be created. 2.All the people on Earth must share this limited amount of land to… –Produce their food –Build shelter –Obtain other resources Land is a precious resource!

Human impacts on the Environment Global warming Use of machinery by humans seems to be increasing CO 2 levels in the air. CO 2 prevents heat from escaping, causes slight world wide temperature increases Rising water temperatures causes coral bleaching

Human impacts on the environment Deforestation Caused by demand for wood products, need for space, farmland, housing, roads Deforestation causes habitat fragmentation Animals and plants are forced into confined areas

Habitat Fragmentation

Agriculture 4.Since land is the source of most food, agriculture is an important land use. New farmland must be created by clearing forests, draining wetlands, and irrigating deserts.

Mining It removes nonrewable resources from the land. It exposes soil that can be blown or washed away.

Soil Management Importance Soil takes hundreds of years to form a few centimeters Has nutrients for plants to grow Also absorbs, stores and filters water Bacteria fungi and other organisms break down wastes and remains of living things (decomposers)

If Soil is Misused Erosion Nutrient depletion – soil becomes less fertile when used over and over again Fertilizers may help or alternate crops Desertification – If soil becomes depleted of moisture and nutrients (all is removed) it becomes a desert Drought sometimes causes desertification.

Land Reclamation More difficult and expensive than just taking care of land May never be returned to original state.

Human impacts on the Environment Ozone depletion Caused by aerosol chemicals called chlorofluorocarbons (CFCs) CFC’s – Escape into atmosphere, reacts breaking down the ozone (O 3, a protective atmospheric layer) – UV rays penetrate the atmosphere and cause harm to many organisms

“HOLE” in the ozone (O3)

Human impacts on the Environment Fishing activities Demand for fish and shellfish Commercial Fishing be harmful to environment in many ways

Importance of the environment Natural resources: Non-renewable includes fossil fuels (petroleum, coal) Renewable includes animals, plants, water, wind, etc. –even renewable resources can run out

Importance of the Environment Natural resources Renewable energy sources include wind power, geothermal energy, ocean currents Less than a 1/4 of Earth's surface is dry land. 1.Except for the small amount added when volcanoes erupt, new land cannot be created. 2.All the people on Earth must share this limited amount of land to… Produce their food Build shelter Obtain other resources

Pollution: Agricultural –DDT –Fertilizers –Animal wastes (nitrogen) Homes –Strong cleaning agents Industry –Toxic gases and wastes –Acid rain

Water Pollution Eutrophication: when nutrients build up in a lake that grows algae that then forms a layer on lake’s surface.

Scarcity 97% of it is Salt Water It is renewable because of water cycle Water shortages occur when use more than water cycle can replace it.

Sources of Water Pollution Pesticides and fertilizers Sewage – if not treated, it can cause people to get ill Industry and mining wastes Sediments – can cover up food supply and block sunlight Oil and gasoline Heat – heated water kills organisms.