tampabay.com

Condition big trees for hurricane winds

By MARY COLLISTER
Published July 5, 2006


Hurricane season has officially started and hopefully everyone has prepared their homes.

If you're looking around your yard and wondering what should be done there, you may want to take a close look at those beautiful shade trees we all love.

Correct cultivation of these trees will help protect us during strong winds. The Hillsborough County Cooperative Extension's urban and community forestry program has launched a Web site at http://urban forestry.ifas.ufl.edu/ containing a large amount of information for Florida gardeners.

Its March 2006 newsletter has information about conditioning mature trees for storms.

The article, written by Steve Graham, parks forester for the city of Tampa, has some excellent information and I will borrow heavily from the content.

Graham said University of Florida scientists had developed lists relating tree species to relative wind tolerance by geographical area. This is helpful for new plantings, but Graham thinks the influence of environment on growth and development is important in developing wind tolerance in trees after they are in our landscape.

Fundamental factors include sunlight, gravity and exposure.

Solitary trees growing in open areas along coasts and in pastures and parks are used as an example.

"Weather-conditioned trees are shorter and stouter," he writes. "Wind speeds increase with elevation, so tree tops are pruned and energy reserves are allocated to secondary thickening in general and at key locations at the base of trunk and primary limbs."

Additionally he writes, "The trees have good crown to height ratios with branches growing very close to the ground.

"This is important in deflecting wind currents and reducing extremes in movement. The energy is dissipated by transmission through the structure of the tree and into the surrounding soil."

Graham continued by noting, "Tree crowns tend to be densely foliated from continuous tip pruning from exposure. This enables trees to more effectively deflect wind."

A bit contrary to common thought, Graham explains, "A tree with large openings in the crown will experience turbulence or rotational wind, which results in limb breakage."

Given this information, Graham recommends the following: avoid excessive pruning and concentrate on removing dead and dying branches only; height and end-weight reduction cuts will sometimes be necessary to maintain proportion and balance; pruning tips of peripheral branches will increase density of foliage; and declining trees with large openings in the crown should be removed.

With this information, many of us may want to take another look at the way we prune our shade trees.

Certainly not a scientific study, but I do have both a maple and an oak in my back yard.

Their trunks are probably not more than 30 feet apart, but I know during one of our big storms, the maple lost two large limbs and the oak tree went untouched. The maple is a very open tree, while the crown of the oak is quite dense.

I do think the maple is a weaker tree and probably more prone to wind damage, so it certainly cannot be used as a basis to advocate less pruning, but I will be watching the trees in the neighborhood and seeing which ones receive the most damage this storm season.

Now that we have all taken a long, hard look at the trees in our landscape, we can move on to other concerns we may have during high winds. Any element in your yard that is not secured in some way may easily become a projectile during a storm. This includes flowerpots, statuary, lawn furniture, hanging containers or any other loose items. It is best to move these items into the garage if high winds are forecast.

Now some good news - the rain! What a welcome relief. My grass was getting crispy in spots and the once-a-week watering was allowing it to survive but certainly not thrive. If you went into the dry season with your landscape in top shape, you probably will come out of the drought with little permanent damage, but those plant materials (especially your turf) that were unhealthy and stressed to begin with are probably dead by now. This is a good reason to use the rainy season to improve the health of your landscape plants.

If you are comfortable in guessing that the summer rains are here, you may want to add some summer color to your garden. My petunias are completely gone now and portulaca are filling in the bare spots left by the petunias' demise.

The moist soil made quick work of pulling up weeds. Spending just a few minutes alleviated much of that problem. Hope you find a few minutes to enjoy your yard this week including the blooms the rain has helped along.