BIOL 215 Lecture Notes - Water Vapor, Heterotroph, C4 Carbon Fixation
Document Summary
Nitrogen cycle is interesting to ecologists because nitrogen is a limiting resource and we"ve seen how human activities have modified the natural nitrogen cycle in the plant. Human activities have altered it in such a way to make nitrogen more available via fossil fuel, practicing agriculture, and crop fertilizer in fixed nitrogen forms. Humans have exploited the ability to produce nitrogen as a fertilizer to enhance crop production. Since humans add way more fertilizer then necessary, some of the nitrogen from fertilizer make their way into waterways. Plant litter is primary basis of terrestrial detritus (dead organic matter) food chains: detritus broken down more rapidly in tropical soil (right), due to high temperatures, humidity year-round. Once nutrients are released during decomposition, they are rapidly reassimilated by primary producers thus ecosystems tend to retain nutrients - particularly nutrients that are limiting to primary production. Disturbed forests lose their abilities to retain nutrients.