Ecology The study of interactions of living things and their environments Abiotic factors – nonliving things in the environment Biotic factors – living things in the environment

Levels of Organization Organisms  populations  communities  ecosystems  biomes  biosphere

Organisms Live in a habitat. Have a niche – a role in their environment. Can only occupy one niche at a time.

Matter and Energy Flow Food chains are used to show matter and energy flow through an ecosystem Ex. Grass  rabbit  snake Each link represents a trophic level.

Trophic Levels 1 st order autotrophs (producers)  1 st order heterotrophs (herbivores)  2 nd order heterotrophs (carnivores)  3 rd order heterotrophs (consumers)

Energy Loss Food chains can typically have three links but never more than 5 (there is not much energy left in the fifth link). Energy is lost as heat at each link.

Food Webs Show all possible energy transfers at each trophic level (many food chains linked and intertwined)

Ecological Pyramids Energy pyramid: energy decreases as trophic level increases p. 54 Number pyramid: population size decreases as trophic level increases (more grass than humans) Biomass pyramid p. 55: biomass decreases as trophic level increases