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What is an Ecosystem?

All life on Earth exists within the biosphere. Ecosystems are human-defined areas that let scientists study small parts of the biosphere. By looking at how ecosystems work, and how they affect each other, the natural world can be understood.

Why are ecosystems important?

When investigating ecosystems, scientists take into account the ways that energy and materials flow within and through landscapes as well as the importance of species diversity. This integrated view is essential to addressing complex environmental issues like freshwater availability, air pollution, and climate change.

Ecosystems defined for study can be quite large—entire counties—or quite small, such as the organisms living under a particular rock. Even cities, such as Manhattan, have been recognized and studied as an ecosystem. The importance of the ecosystem concept is that it helps facilitate integrated scientific research.

Forests, lakes, fields, and beyond

Forest ecosystems are defined by their watershed. This is an area of forest that drains into a particular water body. To ascertain the health of a forest, ecologists measure rainwater chemistry, the movement of deer, and the level of pollutants in runoff water. Results can reveal human impacts to forests and help guide management strategies.

Lakes are among the easiest ecosystems to recognize: they are surrounded by a shoreline and they have a top and bottom boundary. By measuring rainwater inputs, runoff from the adjacent landscape, and water loss, ecologists can predict water levels and address things like nutrient-loading.

Fields can also be studied as ecosystems, in which plants transform sunlight into leaves, animals (herbivores) eat the leaves, and soil microbes decompose dead materials, releasing important nutrients for the next generation of life.

It is easy to recognize a variety of ecosystems on Cary Institute’s campus. Research into the Wappinger Creek ecosystem has revealed interesting connections between road salt application and stream salinity. Learn more about this at the Weather Station kiosk.

A freshwater marsh
Ecosystems, like this freshwater marsh in Massachusetts, are defined and studied by scientists to help us understand the natural world. Photo: David Mark