Trees are among the few living things on Earth that can grow unchecked. Under ideal conditions, some trees grow so massive that they set awe-inspiring records, stretching hundreds of feet into the air and swelling to massive circumferences.
To recognize and protect the nation’s biggest trees, the conservation organization American Forests has maintained the National Register of Big Trees since 1940. Dedicated to restoring and protecting urban and rural forests, American Forests annually honors trees that meet certain size requirements, designating them “champion trees.”
The makings of a big tree
“If a tree experiences no limitations like insufficient water, nutrients, or sunlight, and avoids getting hit by pests or lightning, it will keep growing at an ever-increasing rate,” says R.J. Laverne, a board-certified master arborist at The Davey Tree Expert Company, which has sponsored the National Big Tree Program for 25 years.
Champion trees either are taller than their peers or have an especially wide-spreading girth and crown, the latter of which refers to the length between the branches from the farthest branch on one side to the farthest on the other. “In terms of size, this can mean a gigantic 300-foot tall redwood or a wide-spreading live oak with a massive trunk and crown,” says Laverne, who notes that when it comes to being placed on the register, trees compete within their own species.
The tallest of the trees on the National Register of Big Trees is a 349-foot tall coast redwood, while the tree with the biggest crown is the California bluegum eucalyptus at 126 feet.
The fact that some trees thrive and grow quite large has to do with a combination of luck and the right genetics, says Laverne. “Trees adapt to the conditions in which they are growing. With champion trees, their seed lands in a good spot to grow and they possess the right genetics with which to adapt to that set of environmental conditions.”
One location type that consistently provides all of these requirements is cemeteries, which are generally undisturbed. “Once someone is buried, the ground is left unchanged,” says Laverne “Cemeteries also tend to have particularly deep soil, which makes tree roots happy. Trees in such situations tend to grow old and quite large amidst the graves.”
Tree preservation tips
Besides inspiring awe, big trees serve as giant filters for our air and water and provide habitat for wildlife. Help ensure that the trees in your landscape reach their full potential by keeping these cultivation tips in mind.
Avoid lawnmower damage. “All of the living cells that transport water up into the tree and transport food down through the tree are right underneath the bark,” says Laverne. “When you ram your lawnmower into the base of the tree, you cut into those critical cells. Do that just twice and the tree may start to decline. The problem can be remedied by taking out the grass at the base of the tree and replacing it with mulch.”
Prune carefully. Another tip that will help guarantee that a young tree will live to old age is performing judicious pruning when the tree is young, says Laverne. “By selecting the strongest branches on the tree and removing the weakest ones, that creates a tree that is durable and resistant to weather extremes like wind and ice.”
Provide proper maintenance. Ensure that your trees are watered during times of drought, and have a qualified arborist inspect your trees on a regular basis to see that they’re getting everything they need and aren’t infected by diseases or pests. “Just as a physician can help keep you healthy, an arborist will help keep your tree healthy,” says Laverne.
American Forests is always on the lookout for big trees. If you know of a large tree, nominate it on their website.
Julie Bawden-Davis is a garden writer and master gardener, who since 1985 has written for publications such as Organic Gardening, Wildflower, Better Homes and Gardens and The Los Angeles Times. She is the author of five books, including Fairy Gardening and Indoor Gardening the Organic Way and founder of HealthyHouseplants.com.