NewsScience Sundays


Science Sundays: How our oldest trees stay hydrated

Posted at 9:33 AM, May 01, 2022
and last updated 2022-05-01 12:33:41-04

Here in Kern County, we’re just a few hours away from some of the largest and tallest trees in the world: the giant sequoias. These trees can be over 30 feet wide and stretch hundreds of feet in the air. But how does a tree that big get water from its roots all the way to the tip of its leaves while gravity is trying to push it down?

There are a few different ways this works, but one of the most important ways is something called capillary action. That’s when water climbs up through little cracks and spaces in the wood.

Keep watching for a demonstration: 23ABC’s Chief Meteorologist, Brandon Michaels used a paper towel, took it, and twisted it up really tight. Then he took two glasses: One empty, and one filled about halfway with water and some food coloring. He put one end of the paper towel in the empty glass, and one end in the food coloring.

The paper towel is made up of fibers, just like a tree is. Over time the water went into the tiny spaces and cracks in between those fibers to climb the side of one glass, against the force of gravity, and over into the other side. That is a form of capillary action.

Here’s why it works: A molecule of water is made up of two hydrogen atoms which have a positive charge, and one oxygen atom which has a negative charge. One side is positive, and one side is just like a magnet. And just like a magnet, water likes to stick to things. In fact, if you dip your finger in some water, some of the water will stick to your finger. Inside the tree we see water sticking higher and higher up the side of those little cracks, as it climbs up the tree.