Cycles within the ecosystem

• The carbon cycle


  Carbon is an essential element for all life, so understanding how it moves helps us to understand biological processes and factors that influence them.One form carbon takes is the greenhouse gas carbon dioxide, CO2. Increased levels of carbon dioxide insulate the Earth, causing temperatures to rise. Understanding how carbon dioxide is absorbed and released helps us understand the climate and predict global warming.Carbon is not in balance, so it's important to learn where it is being stored and released. The rate at which carbon is deposited into living organisms is not the same as the rate it is returned to the Earth. There is about 100x more carbon in living matter than in the Earth. Burning fossil fuels releases massive amounts of carbon into the atmosphere and to the Earth. Trees store carbon, removing it from circulation during their lifetime.The carbon cycle is tied to the availability of other elements and compounds. For example, the carbon cycle is tied to the availability of oxygen in the atmosphere. During photosynthesis, plants take carbon dioxide from the air and used it to make glucose (stored carbon), while releasing oxygen.

  
• The water cycle

  1. Water evaporates into the airThe sun heats up water on land, in rivers, lakes and seas and turns it into water vapour. The water vapour rises into the air.2. Water vapour condenses into cloudsWater vapour in the air cools down and changes back into tiny drops of liquid water, forming clouds.3. Water falls as precipitationThe clouds get heavy and water falls back to the ground in the form of rain or snow.4. Water returns to the seaRain water runs over the land and collects in lakes or rivers, which take it back to the sea. The cycle starts all over again.

  
• The nitrogen cycle

  Most nitrogen is found in the air as a gas. Most plants obtain nitrogen in the form of nitrates from the soil and use them to produce proteins. Animals obtain nitrogen as part of the proteins they consume.The movement of nitrogen between the air, soil compounds and compounds in the bodies of living organisms is called the nitrogen cycle. Different groups of bacteria are very important for keeping the cycle going so that nitrogen is always available in a form that living organisms can use.