What happens to the water that tree roots absorb? We know that tree roots absorb water from the soil. But what happens to that water? Where does it go? Can we observe this happening?
Let's try the following experiment to see if we can see where all that wonderful water ends up!
Materials
Zip-top gallon bag
Time frame
3 to 5 or more days
Instructions
Find an out-of-the-way tree or bush with a branch you can reach and observe daily.
Open the zip-top gallon bag.
Put the bag around a small bush or tree limb, making sure there are about 10 to 20 leaves inside the bag.
Zip the bag closed as much as possible. Secure it with a string if necessary.
Observe the bag a few days in a row. What do you notice?
What is happening here?
Observing the bag each day, you will begin to notice water accumulating in the bottom of the bag. Why is this happening?
One way water moves from the ground to the atmosphere is transpiration. Transpiration is the evaporation of water from inside plant leaves. This water adds to the moisture in our atmosphere.
During the growing season, each leaf transpires more than its own weight. A large oak tree with all its leaves combined can transpire 40,000 gallons of water into the atmosphere each year!
One benefit leaf transpiration has on our environment is its cooling effect. When most animals get too hot, they pant. They stick out their tongues and evaporate liquid from inside their mouths. This helps them cool off. What happens to your skin when you get too hot? You sweat! Humans perspire to cool down, while plants transpire! Transpiration brings down the temperature of leaves, which is the largest organ of a plant.
Another benefit of transpiration is that plants drink up a lot of water through their roots. They absorb a lot because this water is filled with nutrients the plant needs to perform photosynthesis and grow. Just one single corn plant can absorb 53 gallons of water during the growing season. Where does all that liquid go when the plant is done with it? It transpires through the leaves and enters our atmosphere.
Take it further!
Do the same experiment with two different trees, or a tree and a bush. Does the amount of water collected vary from species to species?
Survival situation
Getting water in the wild is a very important survival skill. Water that has transpired through the leaves is safe to drink, though it may have a strong, bitter taste depending on the species of tree you use.
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