PCB 4043 Chapter Notes - Chapter 20: Cellular Respiration, Geochemistry, Chemosynthesis
15 Jun 2016
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The term ecosystem was first used by tansley (1935) to refer to all the components of an ecological system, biotic and abiotic, that influence the flow of energy and elements. The ecosystem concept integrates ecology with other disciplines such as geochemistry, hydrology, and atmospheric science. 20. 1: energy in ecosystems originates with primary production by autotrophs. Primary production is the chemical energy generated by autotrophs during photosynthesis and chemosynthesis. It is the source of energy for all organisms, from bacteria to humans. Gross primary production (gpp) total amount of carbon fixed by autotrophs: gpp depends on photosynthetic rate, photosynthetic rate is influenced by climate and leaf area index (lai) leaf area per unit of ground area. Lai varies among biomes: less than 0. 1 in arctic tundra (less than. 10% of the ground surface has leaf cover): 12 in boreal and tropical forests (12 layers of leaves between the canopy and the ground, on average).
