The functioning of natural ecosystems provides services essential to human survival. Collectively, these services maintain the Earth in a state that can support life. Ecosystem services maintain the atmosphere, provide clean water, control soil erosion, pollution and pests, pollinate plants, and much more. Their total annual value in Australia has been estimated by the CSIRO to be $1327 billion and they are free!
Consider the atmosphere. Terrestrial animals need air with the correct balance of gases, which includes at least 20% oxygen. Oxygen is provided by plants and algae through photosynthesis. So clearing vegetation and polluting the ocean may threaten the very air we breathe.
Water is also essential for survival. The water cycle of rain and evaporation is partly controlled by vegetation. For example, forests can affect entire regional climates because they pump enough water from the soil to the air, causing more rainfall. Large-scale deforestation could cause serious drying of regional climates.
The transpiration stream of trees keeps the water table down, but only if there are enough trees. This prevents the salinisation of topsoil, already a huge problem in the mostly treeless Murray-Darling farmlands. Vegetation also controls soil erosion, which is another huge problem. Every year, over 20 billion tonnes of the Earth's topsoil erodes and a centimetre of new soil takes possibly a millennium to form. Vegetation and soil ecosystems purify water. For example, wetlands are increasingly being used to treat sewage effluent, and vegetated water catchments supply much cleaner water to water storages than cleared catchments. The quality of our drinking water is directly affected by the quality of our catchment areas.
The scale of most of these services is so large that it would be impossible to find technological substitutes. In addition, many of our aesthetic, educational and spiritual needs are provided for by the natural environment. Our wellbeing and future are inextricably linked with that of our ecosystems. Consequently, we need to protect ecosystems and their natural services for future generations.
Katy Crass and Alan Jones
Marine Ecology
Australian Museum
Copyright © Australian Museum, 2003
This page: http://www.amonline.net.au/factsheets/ecosystem_services.htm
