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Drivers Cause Change in an Ecosystem
Ecosystems consist of the biological and physical components of the Earth, and their interactions with each other. They provide services to man like cleaning the air and water. Drivers cause changes in either or both of the components, and the interactions between them reduce the ecosystem's ability to provide services. The drivers can be man-made or natural. A tornado knocking down a forest would be a natural driver, while a lumber company clearing the same forest would be a man-made driver. In both cases the death of the trees changes the ecosystem. However, in the case of the lumber company, the trees are removed, creating a loss in materials from the ecosystem.
Direct Drivers Stress an Ecosystem
Direct drivers are physical or biological events that change an ecosystem. They are things like climate, land conversion, disease and invasive plants. Tsunamis, typhoons, hurricanes, fires and earthquakes are physical drivers that change an ecosystem. Floods wash plants and animals away. They also cause erosion, which reshapes the face of the landscape and removes top soil. Some examples of biological drivers are diseases and invasive organisms, such as Dutch elm disease and zebra mussels. Dutch elm disease kills trees in Europe and North America. Zebra mussels replaced native shellfish in the Great Lakes ecosystem.
Indirect Drivers of Change in an Ecosystem
Indirect drivers affect the direct drivers by altering the rate of change in an ecosystem. Indirect drivers are demographics, economics, sociopolitical, cultural, religious, scientific and technological. Demographic changes indirectly cause change to an ecosystem. For instance, the movement of people from an area of low resources to high resources changes the rate of use of ecosystem goods. In the Amazon rainforest, as farm soil loses its nutrients, the farmer moves to a new forest region, burns it and starts a new farm. Wars cause people to move, increasing the population in the new area and creating a stress on limited resources.
Ecosystem Management
Understanding the processes by which changes occur in an ecosystem provides the opportunity for policy designers to make decisions favoring sustainability. It helps land managers such as the U.S. Forest Service predict outcomes based on similar situations in other parts of the world. They can maintain ecosystem services in a sustainable fashion to meet the increased pressure from direct and indirect drivers that cause ecosystem changes.