APBI 200 Lecture : Biol 121- 2010.01.20- Ecology- Community Ecology- Biogeochemical Cycles. Human Impact (Ch. 54).docx
Document Summary
Energy is not the only thing transferred in a food web/chain. Ingested matter also contain carbon, nitrogen, phosphorus, calcium, and other elements that act as nutrients. Atoms are constantly reused as they cycle through trophic levels and air, water, and soil. Path element takes as it moves from abiotic systems through organisms (biotic) and back again is the biogeochemical ( life-earth-chemical ) cycle. Cycle starts when nutrients taken up from soil by plants and assimilated into plant tissue. If plant eaten, nutrients pass to animal members of ecosystem"s consumer food web; if plant dies then nutrients enter decomposer food web. Once consumed by animal, nutrients excreted and taken up by parasite or predator, or added to the dead biomass reservoir when the animal dies. Nutrients in plant litter, animal excretions, dead bodies are used by primary composers like bacteria. The combo of microscopic decomposers and ions/mcules released form the soil organic matter.
