Trees: Top 10 Questions

November 2013

Thanks to Brian Jorgenson, City Forester, Boise; and Michelle Youngquist, Educational Coordinator, Idaho Forest Products Commission for the answers.

1: How come tree bark is hard?

Tree bark is designed to help protect all of the parts that are growing inside of the tree trunk. Bark protects trees from animals, sunlight and anything that could harm the tree. Some insects can get through, but the hard bark helps protect the tree from minor attacks. (From Brock at Owyhee Harbor Elementary in Boise)

2: How deep do tree roots grow?

Many people do not know. What we know more clearly is that about 90 percent of the tree roots are in about the top two percent of the soil, and they are not just right under the tree. Tree roots grow similarly to the top of the tree. They branch out and go in many different directions. Some are deeper and some are more near the surface, but they grow well beyond the actual canopy of the tree itself. Roots next to the tree trunk are large and they help support the tree in the ground. As the roots grow into the soil, they get more and more narrow, even smaller than a hair on your head. Most of the roots that absorb water are near the surface. Roots are important to the survival and health of a tree and need to be taken care of. (From James at Riverside Elementary School in Boise)

3: How does a tree grow?

Trees start to grow from a tiny, little seed that needs land and a favorable spot for it to sprout. Sunlight and water need to be just right for that seedling to sprout. It then will put down roots into the soil and start to grow. Once they get enough leaves or needles for photosynthesis, they can make more food for themselves. As they do, they are able to make more shoots that make them taller. Then they are able to make more layers of wood every year, which we see as the rings in the trunk. This allows them to become taller. They will continue to grow as long as the conditions continue to be right. (From Abbyerica at Rawson Elementary School in Melbourne, Australia)

4: Why do tree branches grow in different directions instead of straight up like the trunk?

Tree branches grow in many different directions. This allows them to gather sunlight. The leaves are factories that produce food for the tree. If they only grew up, they could only collect sunlight at a certain time of day to soak up that food. (From Alex at Owyhee Harbor Elementary School in Boise)

5: Why are there deciduous trees and non-deciduous trees?

It has to do with the huge variety of environments where trees grow. They have many different environments to cope with. If they happen to be growing in an environment that is cold and where the growing season is short, needles would be advantageous for them where they only lose a few needles a year. When a tree looses all of its leaves at once, it is a deciduous tree. These trees then grow new leaves the following spring. The leaves or needles a tree produces has to do with where the trees are growing, the different varieties of habitats, and that they may have to contend with different adaptations given their habitat. (From Olivia at Riverside Elementary School in Boise)

6: Why do leaves on some trees change color?

As yellow trees get ready for winter, they dismantle the chlorophyll, and what remains are the yellow leaves. The red leaves are a product of sunlight and the tree getting ready for winter. Some trees have a brownish color like they are cooked by the sun. There are colors in between too. (From Amanda at Owyhee Harbor Elementary School in Boise)

7: What is the tallest tree in the world?

It's a redwood tree in California. It is nicknamed Hyperion, and when I last saw it, it was 379 feet tall. (From Ike at Cynthia Mann Elementary School in Boise)

8: How can you tell how old a tree is by the rings?

Generally speaking, a tree will add a new ring to its trunk every year. You can find out how old a tree is by counting its rings. The rings also tell you about growing seasons, whether they are long or short, and the rings will look different depending on the season in which the tree grew. (From Kylie at Dalton Elementary School in Dalton Gardens)

9: How do trees make maple syrup?

Maple syrup comes from maple trees. Sugar maples can give you the best syrup. Trees are tapped in the fall and the sap comes out of the tree. It takes a lot of sap to make just one pint of syrup. Gallons of sap are boiled down to a more concentrated liquid, and that liquid becomes syrup. (From Gabby at Cynthia Mann Elementary School in Boise)

10: Why is sap found in trees?

The sap flows through the tubes from the roots to the leaves. This allows the tree to get its nutrients and grow. In photosynthesis, trees take water and nutrients from the soil, sunlight as energy, and they take in carbon dioxide through their leaves and needles. Through that process, they make all the food they need to grow. (From Amy at Cynthia Mann Elementary School in Boise)

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