BIO 309 Lecture Notes - Lecture 23: Plant Litter, Nitrogen Cycle, Defragmentation
29 Nov 2018
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Document Summary
Exchange of nutrients between organisms is one of the essential aspects of ecosystem function. Remember that energy makes a one way trip, sun to entropy. Phosphorus, carbon, nitrogen, potassium, and iron are constantly cycled. Nutrient cycles involve the storage of chemical elements, in nutrient pools, or compartments, and the flux, or transfer, of nutrients between pools. Nutrient sink: part of the biosphere where nutrients are absorbed faster than they are released. Not labile to plants for uptake, where mycorrhizae helps a little. Important to the structure and function of ecosystem, and limited resource to plants. Forms nucleic acids, amino acids, and porphyrin rings of hemoglobin and chlorophyll. Nitrogen fixers: cyanobacteria, free living bacteria in soil, leguminous associated bacteria, actinomycetes. Part of all organic molecules, carbon compounds, and methane. Carbon moves between organisms and the atmosphere as a result of two reciprocal processes: photosynthesis and respiration. The ocean has acted as a sink for excess carbon.
