Decomposers

The breakdown of dead organic matter into usable nutrients What is decomposition? Who does it? The breakdown of dead organic matter into usable nutrients Decomposers (also called saprobes or saprotrophs) These are bacteria (heterotrophic), fungi and some worms break down the dead organic matter to get nutrients for itself Why do they decompose? If they do not decompose? To get nutrients for themselves The remaining nutrients that the decomposers do not use enter the soil Nutrients such as Nitrogen (the plants need it for growth) will remain locked within the dead organism. New plants will not grow (food chain disruption)

Example of Decomposition Decomposition of leaves. Fragmentation : Earthworms and other soil animals break the leaves into smaller pieces. The smaller fragments have more surface area to support the growth of bacteria and fungi. Bacterial growth is especially affected by fragment size, since fungi can penetrate substances more easily than bacteria. Leaching : Rainwater percolates through the leaves, dissolving and carrying away some of the chemicals in the leaves Mixing : The movements of earthworms and other soil animals stir the leaf fragments and mineral soil particles together Changes: The fallen leaves started out whole, and were green, yellow or red. They were reduced to small dark brown shreds as their fragments became heavily colonized by fungi. - Decomposition end: fine black particles of soil organic matter

Smarter than Humans? Fungus growing ants collect leaves and inoculate them with a fungus that decomposes the leaves. The ants harvest the fungus for food and discard the decayed leaves. Can you think of a way to you decomposition to benefit us? Discuss in groups of four (5mins) how? Present to class.