Ecosystems

Definitions  Ecology - Study of interactions between organisms & environment  Population – same organisms, living together  Community – several populations, living together  Ecosystem - abiotic & biotic components of an area

Definitions  Biotic factors – Living things  Abiotic factors – Non-living things  Soil  Water  Weather

Definitions  Habitat – where a population lives  Niche – function of a species in its community (its job)

Succession  Process where species are gradually replaced by other species  Primary Succession : Begins in lifeless area  Secondary Succession : Occurs in areas of previous growth

Primary Succession

Secondary Succession

Energy in an Ecosystem  Primary productivity  Rate in which organic material is made by photosynthesis  Determines amount of energy available in an ecosystem  Producers – make energy by photosynthesis  Consumers – eat to obtain energy

Regional annual net primary production for Earth

Food Chains & Trophic Levels

Food Webs

Energy Pyramid 10% of energy is passed on to next trophic level

An overview of ecosystem dynamics

Biological magnification of DDT in a food chain

Biogeochemical Cycles  Pathways where chemicals cycle between living things and non-living things.  Water cycle  Carbon cycle  Nitrogen cycle

The water cycle

The carbon cycle

The nitrogen cycle

Human Disturbance of Chemical Cycles  Acid precipitation  pH is too low for organisms to live  Toxins in the environment  Biological magnification  Increasing carbon dioxide  Global warming  Depletion of atmospheric ozone  Sunburn, among other things