2. Nutrient Cycling Biogeochemical Cycles

3. Energy vs. Matter  Energy flows throughout an ecosystem in ONE direction from the sun to autotrophs to heterotrophs  Matter is recycled  WHY?

4. Biogeochemical Cycles  “Matter can cycle through ecosystems because organisms don’t USE it, they TRANSFORM it.”  Matter/Nutrient cycled includes:  Water  Nitrogen  Carbon  Phosphorous

5. Water Cycle  Processes involved:  Evaporation-water changes from liquid to atmospheric gas  Transpiration- water evaporates OUT of plant leaves  Also, condensation, precipitation, runoff…

8. Carbon Cycle  Key ingredient of living tissue, found in many places  Found in animal skeletons, rocks, carbon dioxide, carbohydrates, etc.  Processes Involved That Take Up and Release Carbon:  Biological- photosynthesis, respiration, decomposition  Geochemical- erosion, volcanic activity  Mixed- burial and decomposition  coal and petroleum  Human Activities- mining, cutting and burning forests, burning fossil fuels

10. Nitrogen Cycle  All organisms require nitrogen to make amino acids  Occurs in many forms: N 2 (78% atm gas), Ammonia (NH 3 ), Nitrate and Nitrite (NO 3 - and NO 2 - ) are found in waste products and fertilizers  Processes involved:  Nitrogen Fixation: conversion of nitrogen gas into ammonia by bacteria (occurs in the roots of legumes) also can occur thru lightning  Ammonia can be converted into nitrates and nitrites, which are taken up by plants and enter the food web  Denitrification: bacteria in soil convert nitrates into nitrogen gas

12. Phosphorous Cycle  All organisms require phosphorous to create DNA and RNA  Does not enter atmosphere, not very common  Exists inorganic form in land rock and soil minerals and ocean sediment  Processes involved:  Erosion: sediment washes into rivers, streams, and ocean  Absorption: Plants and marine organisms take up the phosphorous and it moves through the food web