This is an excellent diagram to show the relationships between the four natural components

Climate goes at the top, because on a world scale this is the most important factor. It determines the nature and extent of the vegetation cover and the soil type.

The arrows show that some of the relationships are two way. For example, vegetation is strongly affected by climate because plants can't grow without heat and moisture. However vegetation also affects the climate. Leaves release water into the atmosphere by transpiration, which provides moisture for more rain. There is evidence in some tropical areas, where the vegetation has been cleared that the rainfall is lower than it used to be.

Energy Flows

All living things need energy to survive. Energy flows through an ecosystem along a food chain. Each stage of a food chain is called a trophic level.

• Trophic level 1 This is where solar energy is transferred into plant growth

• Trophic level 2 Plants are eaten by animals and insects

• Trophic level 3 Carnivores eat the herbivores and energy is transferred.

• Trophic level 4 Top carnivores eat other carnivores

Nutrient Cycling

Nutrients are essentially minerals such as nitrogen, calcium and sodium which are needed by all living things.
Nutrients occur naturally in rocks, water and the atmosphere and can enter an ecosystem from any of these sources.
Nutrients may also be lost from an ecosystem. They can be washed away in surface run off or by leaching, which washes them down to the lower layers of the soil, out of reach of plant roots.
Leaching takes place especially in areas such as Coniferous and Tropical forests where excess water can turn make the soil less fertile.