Section 3 – Ecology
Ecology – the study of the complex relationships between living
things and their non-living, or abiotic, environment
Ecosystems
A community of organisms and their abiotic environment
Producers – organisms that can make their own food
Consumers – organisms that get their energy by eating other
organisms
Decomposers – organisms that get their energy by breaking
down dead organisms
Balancing Forces in Ecosystems
Carrying capacity – the largest population that an
environment can support at any given time
Ecological Responses to Change
- ecosystems react to changes in ways to maintain or
restore balance in the ecosystem
- predictable patterns of return to a damaged
ecosystem
o grasses and fast growing plants start to grow
o shrubs and small animal species will return
o larger tree species and larger animals return
Energy Transfer
- ultimate source or energy is the sun
- photosynthesis – plants using sunlight to produce
food
- energy pyramid
o producers form the base
o consumers form the next level
o decomposers form the top of the pyramid
 as you move up the pyramid, more
energy is lost at each level
Food Chains and Food Webs
- food chain – the sequence in which organisms
consume other organisms
- food web – a diagram that shows the feeding
relationships among organisms in an ecosystem
Human Stewardship of the Environment
- Ecological balances can be disrupted by human
activity
o Overconsumption of resources
o Conversion of natural areas to agriculture or
urban areas
o Pollution – the contamination of the
environment with harmful waste products or
impurities