Which trees hold up best during a natural disaster?

Trees can withstand only a limited amount of storm-force winds before toppling. See more pictures of trees.
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­When Hurricanes Katrina and Rita bulldozed their way across the Gulf Coast in 2005, they stripped away 75 percent of the trees in New Orleans [source: Kaufman]. That's just a sliver of the 320 million trees in Louisiana and Mississippi left damaged severely by the back-to-back storms [source: Kaufman]. Sturdy pines, oaks, maples and cypresses succumbed to whipping winds, rain and flooding.

That natural disaster is an exceptional case, yet smaller-scale tree damage can be costly for property owners as well. In Georgia alone, weather-related tree problems rack up $10 million in property value losses every year [source: Coder]. If a tree or large limb snaps and lands on your roof or car, the expenses mount.

The Beaufort Wind Scale rates wind intensity, like the Fujita Scale measures tornados and Saffir-Simpson Scale measures hurricanes. When winds reach a 10 on the Beaufort Wind Scale, it means they're strong enough to damage or uproot trees. Gusts that­ powerful probably mean you're in the middle of a hurricane, tornado or other natural disaster. But fierce thunderstorms can deliver destructive blows to trees, too, especially ones that are older, weaker or ­improperly cared for.

­Unfortunately, there are no wholly weather-proof trees. First, a tree's structure cannot naturally withstand sustained hurricane or tornado-force winds. Wood fibers can shift in response to the wind, causing trees to sway, but only up to a point [source: Coder]. Also, trees with the strongest wood in the world aren't indigenous to the continental United States. You'll find those tropical hardwoods, such as teaks and ebony, in southeast Asia and other warm climates [source: Logan]. However, some commoner varieties are tougher than others when the weather kicks up. Live oaks, gingkos and sweetgum trees are among the more storm- and ice-resistant, while you'd want to avoid brittle birches, beeches and dogwoods [source: Clatterbuck]

To reduce the chances of storm-related tree damage, planting the most resilient species isn't the only option available. Assessing the health of individual trees is equally important. Properly tending to a lovely birch can help protect your property as much as replacing it with an oak. Doing so requires a little time and effort, but becoming an amateur arborist is much simpler than hauling away broken tree parts after a storm dies down.

How to Prevent Tree Damage

Trees build up a natural resistance to wind called wind firmness.
Trees build up a natural resistance to wind called wind firmness.
Tim Graham/­Getty Images

­Trees are the longest-living organisms on the Earth, but once damaged, they can't heal ­themselves like our bodies can [source: International Society of Arboriculture]. Over time, trees build a natural resistance to wind, called wind firmness [source: Coder]. For example, if wind regularly blows against a tree from the east, it will build more strength on its western side. However, wind firmness won't completely safeguard a tree from storm winds. Winter weather can also cause trees to ice over, leading to limb breakage. When brutal weather strikes, it can inflict five major tree injuries: blow-over, stem failure, crown twist, root failure and branch failure [source: Coder].

The bad news is that you can't control the weather like some omnipotent Zeus. On the other hand, there are relatively simple steps you can take to safeguard the trees on your property against those worst-case weather scenarios.

Promoting healthy trees begins before you put them in the ground. Consult your hardiness zone prior to purchasing any saplings. The hardiness zone outlines which vegetation can grow in your climate's temperature extremes. Trees planted in the wrong hardiness zone will be predisposed to poor growth. When planning where to plant trees, allow plenty of space for growth, and support trees with stakes for the first five to seven years to build wind firmness.

As your trees mature, you may need to prune them. If so, try to cut branches before they've grown larger than one inch (2.5 centimeters) in diameter. Also, don't hack long branches down to stubs -- thin, fragile branches will sprout from that point [source: Arbor Day Foundation]. Once you begin pruning the tree's crown, or leafy top, be sure not to disrupt the tree's center of gravity. If you remove too much from one side or the other, the crown will be lopsided, destabilizing the tree.

­Watch out for oversized and forked branches. Tree branches shouldn't be larger than half the total diameter of the tree. Otherwise, the tree can't support the added weight. Forked branches are also more susceptible to snapping in bad weather. Since it has to support more than one branch, the wood where the fork meets is weaker. The healthiest branches on the tree will grow at 45-degree angles to the trunk, which allows enough space between the branch and the trunk for new wood growth [source: Arbor Day Foundation].

As you would with flowers in a garden, water and fertilize your trees regularly. That schedule will vary depending on the type of tree and its hardiness zone. Also keep an eye out for signs of pests, such as pine beetles, that infect trees. If you have a damaged tree on your property and aren't sure what to do, consult an arborist.

Giving trees a little attention can help them endure the eye of the storm. And considering all that they do for us -- from sequestering carbon to releasing life-sustaining oxygen and beautifying our yards -- is that really too much to ask?

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Sources

  • Clatterbuck, Wayne K. "Storm-Damaged Residential Trees: Assessment, Care and Prevention. University of Tennesee Agricultural Extension Service. (Dec. 5, 2008)http://utextension.tennessee.edu/publications/spfiles/sp575.pdf
  • Coder, Kim. "Storm Damaged Trees: Prevention and Treatment." University of Georgia College of Agricultural and Environmental Sciences Cooperative Extension Service. February 2001. (Dec. 5, 2008)http://pubs.caes.uga.edu/caespubs/pubs/PDF/C806.pdf
  • "Fun Facts About Trees." International Society of Arboriculture. (Dec. 5, 2008)http://www.treesaregood.org/funfacts/TreeBiology.aspx
  • Kaufman, Marc. "Katrina, Rita Caused Forestry Disaster." Washington Post. Nov. 16, 2007. (Dec. 5, 2008)http://www.washingtonpost.com/wp-dyn/content/article/2007/11/15/AR2007111501359.html
  • Logan, William Bryant. "The Triumph of an Ordinary Tree." Los Angeles Times. May 30, 2005. (Dec. 5, 2008)http://articles.latimes.com/2005/may/30/opinion/oe-logan30
  • "Reducing Tree Damage in Future Storms." Arbor Day Foundation. (Dec. 5, 2008)http://www.arborday.org/media/stormrecovery/6_reducingFutureDamage.cfm