The root systems of plants and the mechanical and chemical effects of water percolating through bedrock create new soil layers. Ecosystems therefore help to recycle chemicals needed by living things to survive, redistribute waste products, control many of the pests that cause disease in both humans and plants, and offer a huge pool of resources for humans and other living creatures. However, the stability and balance of ecosystems can be altered by large-scale natural events such as El Ni o, volcanic eruptions, fire, or drought. But ecosystems are more drastically transformed by human activities. The web of ecological interdependency is fragile.
Human intervention can shatter the balance of energy production and consumption.
By knowing how ecosystems operate and change, students are able to understand the basic principles that should guide programs for environmental management. Students can understand the ways in which they are dependent on the living and nonliving systems of Earth for their survival. Knowing about ecosystems will enable them to learn how to make reasoned decisions, anticipate the consequences of their choices, and assume responsibility for the outcomes of their choices about the use of the physical environment. It is important that students become well-informed regarding ecosystem issues so they can evaluate conflicting points of view on the use of natural resources. The degree to which present and future generations understand their critical role in the natural functioning of ecosystems will determine in large measure the quality of human life on Earth.