This means that plants store a large amount of energy per unit land compared to animals higher up the food chain. When we look at the case studies on how much land it takes to grow our food, we will see why this has major applied issues. Global Elemenal Cycles Chapter 3 does a good job explaining the global cycles of carbon, nitrogen, phosphorus, and water. Be sure to understand the major pools and fluxes of materials throughout the cycles and how they link life on earth with the abiotic environment. I will add a couple of points here that will be important when we discuss human alterations to ecosystems later on.
Carbon is one of the most important elements for life.
When plants photosynthesize, they create sugars made from carbon. Plant matter serves as the food basis for the rest of the animal kingdom. Therefore, there is quite a bit of carbon tied up in living biomass and as dead biomass that is broken down in soils. The atmospheric pool of carbon is relatively small. Because CO2 is an important greenhouse gas, we may now face a seriuos threat of global warming.