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How to Tell a Tree's Age

Updated on November 2, 2014
Ancient Oak Tree at Folly Farm From the dimensions around its girth, the age of this tree has been estimated to be greater than 300 years.
Ancient Oak Tree at Folly Farm From the dimensions around its girth, the age of this tree has been estimated to be greater than 300 years. | Source

Why Ageing Trees Is Important

Trees perform a wide variety of vital functions on earth, contributing to a habitable biosphere for all other living things. Among other functions, trees are vital for:

  1. Contributing significantly to the earth's oxygen supply.
  2. They have the ability to absorb, and therefore remove from wider circulation, a number of toxins and pollutants.
  3. Trees can be blockades for unwanted noise and thus reduce noise pollution when planted strategically around your home or neighborhood.
  4. They can slow down storm water runoff, encouraging the recharging of ground water aquifers.
  5. Because they are carbon sinks, absorbing vast amounts of carbon dioxide during photosynthesis, they contribute to the removal of this green house gas from the atmosphere.
  6. Trees cleanse the air of particulates, shade and cool even on a global scale and provide windbreaks.

Understanding the age of individual trees is important for a number of reasons. Foresters use tree age data to determine:

  • age of a stand of trees
  • how quickly the trees are growing (can be extrapolated by width of individual rings)
  • the health of individual trees which is also important for urban areas where unhealthy trees suffering from internal rot could pose dangers during storms or high wind periods.
  • a site index which provides a relative measurement of the quality of that particular forest site based on the average height of dominant tree species taken at a specified age;
  • this site index helps predict future returns from this site with respect to tree harvesting and also provides a means of predicting the land productivity for both trees and wildlife
  • core samples from trees can also be used to reconstruct past climate and events
  • trees used in historically significant structures and art can be dated using techniques employed by dendrologists

Tree Growth And Age

Click thumbnail to view full-size
Illustration of a Sequoia sempervirens in sectional viewDiagram of Xylem and Phloem in a stem. 1. Xylem 2. Phloem 3. Cambium 4. Pith 5. Companion Cells
Illustration of a Sequoia sempervirens in sectional view
Illustration of a Sequoia sempervirens in sectional view | Source
Diagram of Xylem and Phloem in a stem. 1. Xylem 2. Phloem 3. Cambium 4. Pith 5. Companion Cells
Diagram of Xylem and Phloem in a stem. 1. Xylem 2. Phloem 3. Cambium 4. Pith 5. Companion Cells | Source

How A Tree Grows Can Be Used To Determine Its Age

Only 1% of a tree is actually living tissue. Just under the bark is a thin layer of living cells called the cambium. Other living cells are found in the roots, the growing tip, buds and leaves. In terms of determining tree age, the tree trunk is the key.

  • The cambium produces phloem cells, which transport food from leaves down to the roots, closest to the bark on its outside layer
  • The cambium also produces xylem cells, which transport water and nutrients from roots to leaves, on its inside layer.
  • Phloem continues to live for the life of the plant while xylem in trees lives only one season.
  • The dead xylem forms the woody support structure of a tree.

Each year's growth of xylem provides:

  • one light ring representing early spring growth with thin-walled large cells adapted for transport of large water quantities
  • and one dark ring in the summer composed of thicker walled cells adapted for strength for supporting the abundant new growth from the spring and summer.

Tree Measurement Methods

Click thumbnail to view full-size
Tree rings, Hillsborough forest. Well-defined rings on one of the logs. Drill to take samples for dendrochronology from trees
Tree rings, Hillsborough forest. Well-defined rings on one of the logs.
Tree rings, Hillsborough forest. Well-defined rings on one of the logs. | Source
 Drill to take samples for dendrochronology from trees
Drill to take samples for dendrochronology from trees | Source

How To Find Out The Age Of A Tree

1. You can tell how old a tree is by counting the pattern of dark and light rings in the tree trunk. One light ring plus the neighboring dark ring constitute one year of growth for the tree.

  • This method works well for dead trees.
  • It can also be accomplished by the utilization of an increment borer. This borer needs to be longer than the radius of the tree. The borer takes a core sample to the pith in the middle of the trunk. Tree rings can be counted in this core sample and the tree is not permanently damaged.

2. It is still possible to closely estimate the age of a tree without counting rings. Knowing the species of tree and the tree's circumference will allow for a fairly accurate determination of age.

  • Determine the correct species of tree.
  • Wrap a tape measure around the tree trunk about 4½ feet above the ground, measuring the circumference of the trunk in inches.
  • Multiply the tree's circumference by 3.14 to determine the tree's diameter in inches.
  • In the chart below, find your tree's growth factor and multiply it by the tree's diameter.

Dendrology: The Art of Estimating Tree Age

Growth Factors For Various Forest Grown Trees

Tree Species
Growth Factor
Tree Species
Growth Factor
Red maple
4.5
Aspen
2.0
Silver Maple
3.0
American Ellm
4.0
Sugar maple
5.0
Cottonwood
2.0
Black Cherry
5.0
Dogwood
7.0
River Birch
3.5
Redbud
7.0
White Birch
5.0
White Oak
5.0
Green Ash
4.0
Red Oak
4.0
Ironwood
7.0
Pin Oak
3.0
Green Ash
4.0
Shagbark Hickory
7.5
Basswood
3.0
Black Walnut
4.5

For a sugar maple:

Step 1: circumference=5 feet 4 inches

Step 2: its diameter=64 inches / 3.14 = 20.4 inches

Step 3: 5.0 (growth factor)x 20.4 inches (diameter) = 102

Therefore, this sugar maple is about 102 years old.


Resources Used

Nix, Steve. About.com Forestry. Using the Annual Tree Ring to Determine Tree Age, 2012.

Journey North. Signs of the Seasons. How Old is Your Tree?. 2012

Royal Forestry Society. Tree Biology. How Trees Grow. 2012

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    • Teresa Coppens profile image
      Author

      Teresa Coppens 11 months ago from Ontario, Canada

      You can use the method for any tree.

    • profile image

      Jake Johnson 24 months ago

      Funny, no mention of red or white pine? Probably the most common trees in Eastern Canada?

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      Susan, so glad this hub can be of help to you. We have 30 acres of forest. My husband is quite adept at accurately estimating a tree's age as he does not like to cut the really old ones for firewood. Hope you and your family have a Merry Christmas also!!

    • Just Ask Susan profile image

      Susan Zutautas 4 years ago from Ontario, Canada

      We have a few trees on our property that I've been curious to know how old they are. I'll try finding out by using a tape measure and your chart. Thanks and Merry Christmas!

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      So sorry you had to endure Sandy. One hundred year old trees are so majestic. It is so sad to see them lost to forestry or hurricanes. Thanks for reading and glad you enjoyed it!

    • shiningirisheyes profile image

      Shining Irish Eyes 4 years ago from Upstate, New York

      Wonderful job with this. Trees have always been Mother Natures majestic friends. We lost so many in Sandy. Although I am grateful for having lost very little, our hundred year old trees broke my heart.

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      Glad you enjoyed Ihchan! Cheers!

    • lhchan profile image

      lhchan 4 years ago

      Thanks for sharing this informative hub. New knowledge. Thanks.

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      Glad you learned something new prasetio. It is my aim to teach new things or at least present information in a new way. Thanks for the comment. Cheers!

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      Thanks so much billy but I have a hard time believing that you do anything other than top rate work. Thanks for the compliment.

      Cheers, Teresa

    • prasetio30 profile image

      prasetio30 4 years ago from malang-indonesia

      Very informative hub and I had never heard about the method before reading this hub. Good job, my friend. Thanks for share with us. Voted up!

      Prasetio

    • billybuc profile image

      Bill Holland 4 years ago from Olympia, WA

      Well done Teresa! I used to teach this lesson and you have done as well as I could have done....oh heck, you did better than I would have done. :)

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      Love your enthusiasm for this one rmcleave. Hope you get a chance to put the techniques to good use!

    • rmcleve profile image

      Rachael Cleveland 4 years ago from Woodbridge, VA

      Sweet! This is one of those tools I always wished to have growing up. We spent time moving around the world, and you'd see a stump here and there. I tried counting rings, but struggled to find concrete answers. All I really learned was to admire and appreciate the tenacity of our arboreal friends. :)

      Thanks for a great hub!

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      sgbrown, your property sounds devine. Enjoy the benefits. Glad you learned a thing or two. Cheers

    • Teresa Coppens profile image
      Author

      Teresa Coppens 4 years ago from Ontario, Canada

      James, so happy to read thoughts that mirror my own. Our farm has 30 acres of mostly mature hardwood forest. We do use wood to heat our home but mostly harvest trees felled by the last year's storms. My husband hasn't the heart to fell the really big ones as he knows how old they are and the history they have lived through. Trees may not be able to verbally communicate but they can reveal so much about past history - climate and other events which have impacted their growth. Thanks for the ego boost James. It's always a pleasure to hear from you. Love to see a picture of that Spanish Chestnut!

    • sgbrown profile image

      Sheila Brown 4 years ago from Southern Oklahoma

      Wonderful hub! I did not know that a core sample could be taken from a tree and it not kill it. We looked for years for property with lots of trees. We now have 40 acres that is 90% wooded. Our house is nestled in the trees and I love it! It keeps wildlife close to the house and has saved us from damaging straight line winds many times and of course the shade helps keep the house cool during the summer. Trees are a very important part of our world and we should appreciate them more. Voting this up and interesting. :)

    • JKenny profile image

      James Kenny 4 years ago from Birmingham, England

      This is a masterful job Teresa. Trees are so often dismissed as just static objects, but they're just as much alive as we are. I love standing underneath the canopy of an oak tree and looking up into the boughs and wondering what's up there. Incidentally in a park close to where I live there's a Spanish Chestnut that's over 500 years old. Its quite famous in our area, the majority of the tree is dead, but it still produces growth every year. Amazing to think that it was growing in that spot during Medieval times. If only trees could talk...