Ecological Diversity
Ecological diversity is the intricate network of different species present in local ecosystems and the dynamic interplay between them. An ecosystem consists of organisms from many different species living together in a region that are connected by the flow of energy, nutrients, and matter that occurs as the organisms of different species interact with one another. The ultimate source of energy in nearly all ecosystems is the Sun. The Sun’s radiant energy is converted to chemical energy by plants. This energy flows through the systems when animals eat the plants and then are eaten, in turn, by other animals. Fungi derive energy by decomposing organisms, releasing nutrients back into the soil as they do so. An ecosystem, then, is a collection of living components—microbes, plants, animals, and fungi—and nonliving components—climate and chemicals—that are connected by energy flow.
Removing just one species from an ecosystem damages the flow of energy of that system. For instance, in the late 19th and early 20th centuries, sea otters were hunted to near extinction in many kelp forests off the coast of the Pacific Northwest of the United States and western Canada, causing the entire ecosystem to suffer. Otters eat sea urchins, small, spiny organisms that share their habitat. When the otters disappeared, the sea urchin population exploded and started to destroy the vast beds of kelp. Without the kelp, other species that lived in the ecosystem, including many species of fish and snails and other invertebrates, began to decline in number. Efforts to restore sea otter populations brought the kelp communities back to near normal in the late 20th century.
Measuring ecological diversity is difficult because each of the Earth’s ecosystems merges into the ecosystems around it. A lake, for example, might have a distinct shoreline, but the plants fringing its edges are quite different from the aquatic plants in the middle of the lake or the trees and shrubs surrounding the lake. Beavers may live in the lake, but they construct dams from trees that grow in adjacent ecosystems. Nutrients flow into the lake via streams and rivers beyond the lake’s ecosystem.
Removing just one species from an ecosystem damages the flow of energy of that system. For instance, in the late 19th and early 20th centuries, sea otters were hunted to near extinction in many kelp forests off the coast of the Pacific Northwest of the United States and western Canada, causing the entire ecosystem to suffer. Otters eat sea urchins, small, spiny organisms that share their habitat. When the otters disappeared, the sea urchin population exploded and started to destroy the vast beds of kelp. Without the kelp, other species that lived in the ecosystem, including many species of fish and snails and other invertebrates, began to decline in number. Efforts to restore sea otter populations brought the kelp communities back to near normal in the late 20th century.
Measuring ecological diversity is difficult because each of the Earth’s ecosystems merges into the ecosystems around it. A lake, for example, might have a distinct shoreline, but the plants fringing its edges are quite different from the aquatic plants in the middle of the lake or the trees and shrubs surrounding the lake. Beavers may live in the lake, but they construct dams from trees that grow in adjacent ecosystems. Nutrients flow into the lake via streams and rivers beyond the lake’s ecosystem.
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