by Karen Jones

Created on: July 21, 2008

It is almost impossible to imagine our fertile planet basking in the Sun's heat, stripped bare of trees. Life would struggle to exist in such unfavourable atmospheric conditions; our familiar ecosystems becoming irreparably unbalanced. There is a finite balance between global diversity and nurturing the Earth's valuable assets; plants, trees and shrubs, both on-land and within our oceans (in the form of seaweed).

All year round, trees extend a lifeline to a host of species; mammals, birds, reptiles, insects, bacteria, fungi, in fact any organism which requires oxygen for respiration falls into this category.

Our unique planet Earth has facilitated the emergence of such a varied populous through several factors; an ability to retain an atmosphere, a water supply (seas, rivers, ice and vapour), the correct balance of atmospheric gases, a temperate climate and a stable land mass. Trees contribute to the majority of these categories; adjusting the oxygen and carbon dioxide levels within the atmosphere, a reduction of the global warming effect, stabilising loose soils and volcanic ash, reducing the risk of flooding, and also by stabilising the climate. I will discuss each of these in turn.

Green plants produce oxygen, an essential commodity for virtually all life forms on the planet (excepting a few anaerobic micro-organisms). This occurs in the chloroplasts within leaves in a process known as photosynthesis. The chloroplasts contain a green pigment, chlorophyll, which synthesises hydrocarbons for the plant's growth requirements in the presence of four factors: sunlight, carbon dioxide, water and heat. Oxygen is a waste product of this process, and is librated in high amounts: the more leaves there are on a tree, the more oxygen will be released if the four factor conditions are met. During darkness the opposite reaction occurs, slowly; carbon dioxide is liberated as the plant cells utilise the synthesised hydrocarbons and oxygen. As a tree grows, more carbon dioxide is absorbed than released to the atmosphere (the residue is locked up as plant material).

Carbon dioxide is a referred to as a greenhouse gas, since it has the ability to absorb infrared energy from sunlight entering our atmosphere, which caused the bond between the carbon and oxygen atoms to vibrate vigorously (thus trapping this energy in our atmosphere). It is the trapping of this infra-red energy that causes our planet to retain heat (which would otherwise be reflected back from the planet surface into

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