The basic nonliving components, or abiotic factors that affect ecosystems include the physical structure of rocks and soil, the availability of water, temperature, and wind

Rocks and soil provide the growing medium for the plant life in any given region, as well as homes for protists and many kinds of animals. If the area consists of solid rock, few plants will be able to grow. If the rocks are weathered into small particles and sufficient moisture is present, plants will be able to extend roots and grow. Over the years, dead plant material will mix into the rock particles, producing soil.

The pH and mineral composition of the rocks and soil will affect the distribution of plant life in the region. The distribution of plant life will, in turn, affect the animal life in the ecosystem.

Water, in the form of precipitation such as rain, snow, or hail, is a component of climate. Some ecosystems don’t get water directly from precipitation. For example, water at a desert oasis may come from rain that fell hundreds of miles away, then seeped into porous rock and soil, forming underground rivers that emerge as springs.

Without the sun’s warming rays there would be no life on Earth, and our world would be dark, cold, and barren.

As Earth makes it yearly revolution around the sun, it is tilted on its axis. It is the combination of this tilt and the yearly revolution that produces the seasons.

Because of the Earth’s tilt, some parts of our planet receive the sun’s rays more directly than others. In the Northern Hemisphere, summer is in June because that’s when the North Pole is tilted toward the sun, receiving more direct rays.

Winter is in December because the North Pole is tilted away from the sun.

At the equator, there is little variation throughout the seasons because the sun’s rays hit this region directly throughout the year.

We’ve seen that Earth’s yearly revolution around the sun produces seasonal temperature changes as different areas of Earth receive different amounts of the sun’s energy. The sun’s energy also produces daily temperature changes as the planet rotates over a 24-hour period. Let’s see how these changes affect the world’s climate patterns. The sun’s rays are most intense near the equator. Here, water evaporates into the atmosphere and produces warm, moist air, which rises and moves toward the poles. As it rises, the air cools and the water falls as rain or snow.

The rising warm air creates areas of unequal pressure. Cooler air moves in to equalize pressure, creating winds.

Because of the distribution of oceans and land masses, wind and rainfall patterns can be predicted in many regions. You’ve probably heard the term “prevailing winds” used for winds that regularly flow in a certain direction.

Variations in the landscape have strong modifying effects on climate. The temperature of the air decreases by about 6 degrees Celsius for every 1000 meters in altitude. At the top of a 5000-meter-high mountain, the air is 30 degrees cooler than it would be at sea level.

Mountain ranges also affect rainfall. As warm, moisture-filled clouds approach a mountain range, they move upward, and cool, producing rain on one side of the mountain range— a phenomenon called the orographic effect. By the time the clouds reach the mountain peaks, they contain little moisture. This creates an area known as the “rain shadow” on the opposite side of the mountain range.

Now that we’ve seen some of the global and local effects of abiotic factors on the environment, let's examine the major biomes that make up Earth’s biosphere.

Copyright 2006 The Regents of the University of California and Monterey Institute for Technology and Education