1. Cycles in Nature: NUTRIENT CYCLES

2. NUTRIENT CYCLES: ECOSYSTEM TO BIOSPHERE Nutrient cycling occurs at the local level through the action of the organisms. Nutrient cycling occurs at the global level through geological processes, such as atmospheric circulation, erosion and weathering.

3. Matter on Earth is Limited Has to be used over and over again Unlike energy, which is provided in an endless supply from the sun

4. NUTRIENT CYCLES The path atoms take from the living (biotic) to the non-living (abiotic) world and back again is called a biogeochemical cycle.

5. A GENERALIZED MODEL OF NUTRIENT CYCLING IN AN ECOSYSTEM

6. The WATER CYCLE

7. GLOBAL WATER CYCLE interesting facts Oceans contain a little less than 98% of the earth’s water. Around 1.8% is ice; found in the two polar ice caps and mountain glaciers. Only 0.5% is found in the water table and ground water. The atmosphere contains only 0.001% of the earth’s water, but is the major driver of weather.

8. GLOBAL WATER CYCLE keeping score

9. Importance of water Organisms are composed mostly of water Helps transport nutrients and wastes Helps regulate temperature

10. The CARBON CYCLE All but a small portion of the earth’s carbon (C) is tied up in sedimentary rocks; but the portion that circulates is what sustains life. Organic molecules contain carbon The cycle is the exchange of carbon between the environment and living things

11. GLOBAL CARBON CYCLE

13. The NITROGEN CYCLE Organisms need nitrogen to build proteins and DNA (genetic material) The movement of nitrogen between the environment and living things is the nitrogen cycle

14. NITROGEN CYCLE

15. Sources of Nitrogen to the Soil Natural ecosystems receive their soil nitrogen through biological fixation and atmospheric deposition. Agricultural ecosystems receive additional nitrogen through fertilizer addition.

16. Biological Sources of Soil Nitrogen Only a few species of bacteria and cyanobacteria are capable of nitrogen fixation. Some are free-living and others form mutualistic associations with plants. A few are lichens.