Chapter 54 ECOSYSTEMS
Human impacts
Ecosystems
*Definition: all of the organisms that live in an area and their chemical/physical
environment.
*4 components linked by the flow of energy, fig 54.1:
Energy Flow in Ecosystems
o
Energy sources = trophic levels
, fig 54.7
o
Organisms that obtain energy from the same type of source occupy the
same trophic level.
o
Food chains
– connect different trophic levels and energy flows from the
producers upward.
o
Food webs
– most organisms eat more than one type of food and feed at
more than 1 trophic level, fig 54.8.
Food Web
o
Energy flow from 1 trophic level to the next is inefficient, declining as
much as 90% from 1 level to the next, fig 54.9
*Examples:
o
Food chains consist of no more than 3-4 trophic levels. Limits:
*Inefficiency of energy transfer (loss as heat energy)
*Stability of the environment
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- Fall '09
- DINI
- trophic level, Greenhouse gas, Global Biogeochemical Cycles
-
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