The biosphere is defined as the sphere or area around the planet Earth where life exists. This zone of life is vast. Most lifeforms live on or near the surface of Earth. However, some live deep within the hydrosphere (oceans, lakes and streams), while others thrive in the depths of the lithosphere (solid portion of Earth). For this reason, mapping the exact borders of the biosphere is quite challenging.

Life Affects the Landscape

The lifeforms that make up the biosphere do more than just live on Earth. They also interact with it and are responsible for making great changes in the way that the Earth has evolved.

Consider the atmosphere. Our atmosphere is comprised of approximately 21% oxygen. Where did that oxygen come from? The early Earth did not have very much oxygen in the air. Most of it had been trapped by the seas, and locked up in the rocks and soil. Slowly over millions of years, plants released oxygen into the air, greatly increasing its abundance, and making animal life possible.

Life affects the landscape in many other ways. Plant roots help keep soil from being carried away by rain water. Small rodents and reptiles dig tunnels, beavers build dams, creating temporary lakes and ponds, and humans build a variety of projects large and small.

Without life, the planet Earth would have evolved very differently indeed.