Decay and the Carbon Cycle Many trees shed their leaves each year and most animals produce droppings at least once a day. All plants and animals also eventually die. Microbes play an important part in decomposing this material so that it can be used again by plants. The same material is recycled over and over.   Living things remove materials from the environment for growth and other processes. These materials are returned to the environment either in waste materials or when living things die and decay. Materials decay because they are broken down (digested) by micro-organisms. Microorganisms digest materials faster in warm, moist conditions. Many microorganisms are also more active when there is plenty of oxygen. • The decay process releases substances which plants need to grow.

Decomposers Many trees shed their leaves each year, and most animals produce droppings at least once a day. Animals and plants eventually die as well. Fortunately all materials are recycled and returned to the environment. We can thank a group of organisms called decomposers for this.

Decay When we say that things decay, they are actually being broken down and digested by microorganisms. Decompose – to split up or break down organisms or waste material. Decomposers – microorganisms that break down waste products and dead bodies. Include bacteria and fungi. The decomposers are a group of microorganisms which include bacteria and fungi. They feed on waste droppings and dead organisms

Decay Detritus feeders (maggots and some types of worm) start process. Decomposers then digest everything. They use some of the nutrients to grow and reproduce. They also release waste products. Waste products are carbon dioxide, water and minerals which plants can use. Decomposers then digest everything (dead animals, plants and detritus feeders and their wastes). The recycling of materials through the process of decay makes sure that the soil remains fertile and plants can grow. It is also thanks to decomposers that we are not wading through dead bodies of all animals and plants that have ever lived!!!

What would it be like if there were no decomposers??? The recycling of materials through the process of decay makes sure that the soil remains fertile and plants can grow. It is also thanks to decomposers that we are not wading through dead bodies of all animals and plants that have ever lived!!!

Why has this mammoth being preserved? The decomposers cannot function at low temperatures, so if an organism like this mammoth was frozen as it died – preserved with very little decay. Why has this mammoth being preserved?

Conditions for decay Temperature Moisture Oxygen Chemical reactions in microorganisms work faster in warm conditions. Reactions are controlled by enzymes. Moisture Most microorganisms grow better in moist conditions. The moisture makes it easier to dissolve their food and prevents them from drying out. Oxygen Most decomposers respire, therefore need oxygen to release energy, grow and reproduce. The speed at which things decay depends partly on the temperature. The chemical reactions in microorganisms are like those in most other living organisms. They work faster in warmer conditions. They slow down or even stop in cold conditions. This is because the reactions are controlled by enzymes, they will stop altogether if the temperature gets to high, because the enzymes will be denatured. Moist conditions – the moisture makes it easier to dissolve their food and also prevents them from drying out

Conditions for decay Decay happens fastest in warm, moist conditions and when there is plenty of oxygen available.

The importance of decay in recycling Decomposers are vital for recycling resources in the natural world. Whats more, we can take advantage of the process of decay to help us recycle our waste.

What do these all have in common?

Amount of carbon on Earth is fixed. The Carbon Cycle All the main molecules that make up our bodies (carbohydrates, proteins, fats, DNA) are based on carbon combined with other elements. Amount of carbon on Earth is fixed. Some is locked up in fossil fuels (coal, oil, gas). Carbon is combined with other elements in carbonate rocks. It is in the air – carbon dioxide. Dissolved in water of rivers, lakes and oceans. Imagine a stable community of plants and animals. The processes which remove materials from the environment are balanced by processes which return materials. Materials are constantly cycled through the environment. One of the most important of these is carbon.

The Carbon Cycle Carbon cycle - all the time a relatively small amount of available carbon is cycled between living things and the environment.

Photosynthesis – green plants use carbon dioxide from the atmosphere in photosynthesis. They use it to make carbohydrates which n turn make biomass. This is passed onto animals which eat plants. The carbon goes on to become part of the carbohydrates, proteins and fats in their bodies. This is how carbon is taken out of the environment. Respiration – animals and plants respire all the time. They use oxygen to break down glucose providing energy for their cells. Carbon dioxide is produced as a waste product and is returned to the atmosphere. Also when animals and plants die their bodies are broken down by the decomposers. These decomposers release carbon dioxide into the atmosphere as they respire. All the carbon dioxide released by the various types of organisms is then available again. It is ready to be taken up by plants in photosynthesis. Combustion – fossil fuels contain carbon, which was locked away by photosynthesising plants millions of years ago. When we burn fossil fuels, we release some of that carbon back into the atmosphere Fossil fuel or wood + oxygen gives carbon dioxide and water (+energy) Write the three equations on the board. For thousands of years the carbon cycle has regulated itself. However, as we burn more fossil fuels we are pouring increasing amounts of carbon dioxide into the atmosphere. Scientists fear that the carbon cycle will not cope. If the levels of carbon dioxide increase it may lead to global warming.

Mammals & Birds Carnivores Herbivores Plants Energy (96KJ/m2) Decomposers – microorganisms and detritus feeders Heat transfer to environment from respiration Herbivores Energy (8000KJ/m2) Energy (5000KJ/m2) Energy transfers It isn’t just carbon that passes through all living organisms. The energy from the sun also passes through all the different types of organisms. It starts with photosynthesis in plants, and is then transferred into animals. It is then transferred into the detritus feeders and decomposing microorganisms. They recycle the materials as plant nutrients. All of the energy originally captured by green plants is eventually either: transferred into the decomposers or transferred as heat into the environment by respiration. Energy is transferred from one type of organism to another. Along the way large amounts are transferred as heat to the environment through the process of respiration. Energy (15 000 KJ/m2) Energy (52000KJ/m2) Energy (23000KJ/m2) Plants