Chapter Outline

24.1 The Nature of Ecosystems

An ecosystem is a community of organisms along with their physical and chemical environment. 477

Starting on bare rock or disturbed land, complex communities arise by a series of successive stages. 478

Living components contribute to an ecosystem in their own way. Some are autotrophic and produce organic nutrients. Others are heterotrophic and consume organic nutrients. 480

24.2 Energy Flow and Chemical Cycling

Energy flow begins when autotrophs use solar energy to produce organic nutrients for themselves and all living things. Eventually this nutrients is broken down and solar energy returns to the atmosphere as heat. 481

Chemical cycling begins when autotrophs take in inorganic nutrients and use them to make organic nutrients. With death and decay, the inorganic nutrients return to autotrophs once more. 481

24.3 Global Biogeochemical Cycles

Biogeochemical cycles are gaseous (carbon cycle and nitrogen cycle) or sedimentary (phosphorus cycle). 484

The addition of carbon dioxide (and other gases) to the atmosphere is associated with global warming. 486

The production of fertilizers from nitrogen gas is associated with acid deposition, photochemical smog, and temperature inversions. 489

Fertilizer also contains mined phosphate; fertilizer runoff is associated with water pollution. 491

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