Why are trees an important part of the water cycle?


Plants do not have a heart to pump fluids through their bodies. Instead, to get water and nutrients up to their leaves, they use a process called transpiration. They let water evaporate from their leaves to create low pressure in the xylem, long tubes that carry water and nutrients up from the roots. That low pressure, plus capillary action (the same thing that causes water to soak up into a paper towel) is enough to carry water and nutrients all the way from the roots up to the top of a tree.

This process uses a lot of water. One oak tree can transpire over 100 gallons of water a day. An acre of corn can transpire 4000 gallons of water a day. That water goes into the air as part of the water cycle. About 10% of all the water vapor in the atmosphere is due to transpiration. In some areas, such as tropical rain forests, transpiration is responsible for 80% of the rain.

Learn more with the Heartless Plants video.