energy and nutrient cycling in an ecosystem

• nutrients and energy tend to flow in the same direction for most of an ecosystem
• nutrients are ultimately recycled in the ecosystem while energy is ultimately lost from the ecosystem to the universe at large
• energy in any ecosystem comes from the sun. sunlight is converted into food by plants. energy from the sun then becomes chemical energy in the form of food. primary consumer then eat the plants for energy
• the energy moves up the levels of the food chain as larger animals eat smaller ones
• much of the food energy is lost as work done by the animals bodies and as body heat - this can also be shown through using trophic levels
• nutrients follow a similar path in the beginning
• plants take nutrients from the soil and chemically combine them with water and carbon dioxide from the air to make food
• the nutrients are then passed to animals and along the food chain as animals eat each other
• all the while, chemicals from the food are passed back to the soil as animals excrete waste and also from their decomposing bodies when they die
• bacteria and fungi called decomposers break down the organic matter from animals for food, releasing the chemicals back into the soil or into the atmosphere. these chemicals are then ready to be used again by plants to create food and start the cycle again
• within trophic levels, the weight of biomass gets less at each level because: many parts of the plant or animal arent eaten e.g roots or bones and energy is lost at each level through breathing, running, heat and day to day living
• rapid changes to ecosystems may cause the displacement or loss of many species
• scavengers are for example, insects that eat dead wood, wheras detritivores are for example, bacteria
• physical reasons that affect the balance of an ecosystem is floods, storms, droughts, pests, diseases, natural wildfires
• human reasons that affect the balance of an ecosystem are deforestation, use of pesticides and insecticides and poaching
• periods of extreme weather or climate change can disturb the balance of ecosystems e.g a drought can kill trees which mean population numbers decline for many consumer species. this can recover though due to ecosystem resilience
• ecosystems are sometimes damaged in permanent ways such as deforestation, the removal of the forest exposes the soil beneath to rainfall which washes it away, making it impossible for the ecosystem to recover
• if something happens to one component of a food chain or web, this can have knock on effects higher up the chain/web