Toolkit: Community Tree Care and Planning
Trees along the streets of our communities, and in our yards are vital because of the important benefits they provide. They shade the streets, sidewalks and back yards from the harsh summer sun, cooling local temperatures, while reducing household energy needs and costs. These same trees reduce flooding, promote a healthier Tampa Bay by cleaning storm water, and remove pollutants from the air we breathe (for more information see Benefits. But it is their long life, size and strength that often diverts our attention away from their need for systematic care.
Many of the problems associated with conflicts between trees and the built environment can be avoided with thoughtful planning. Making good tree care decisions starts with the proper information.
Manage Your Trees With A Plan
Undertake an inventory - systematically collect information on trees, shrubs and conservation areas. Information typically collected include:
- tree or shrub species
- tree or shrub age
- tree or shrub location
- growing space
- open growing area
- tree diameter at chest height (4.5ft above the ground)
- insect or disease problems that are visible
Without this information you will only be reacting to problems in the urban forest, not managing it. The trees under a crisis management system will suffer from lack of directed care and long range planning.
Planting Trees in Your Community - Select the Correct Trees
Hillsborough County has created a list of trees suitable to the climate and soils of the area. The University of Florida recommends that municipalities should strive for diversity of tree species. The accepted rule recommends no more than 20 percent of the trees should be from the same genus (for example oak) and no more than, 10 percent from the same species (for example live oak). For instance, a disaster could result if say 60 percent of the trees in a city were live oak and a devastating insect or disease were to strike this particular species.
While we strive for diversity on a municipal perspective; we should not plant a large variety of different trees on the same street. Instead, look to plant one section of a city or large development (several blocks) with one species, and another with a different one. This allows the development of neighborhoods which will have an identity - the trees.
Plant the Right Tree In the Right Place
Tree pruning around power lines costs several hundred dollars each year! To help reduce this cost plant only small maturing trees (less than 25 feet in height) below and within 25 feet of the line. Plant large maturing trees (greater than 25 feet in height) at least 25 feet (preferably 40 feet or more) from the lines. This will help keep utility bills in check and will provide more reliable electric service due to less tree interference with the lines.
Avoid planting large-maturing trees in areas less than 20 X 20 feet unless soil drainage is excellent. This small area will dwarf the tree so it will never reach its natural size, but it is much larger than what current standards provide. In a parking lot, trees grow much better when grouped together in several large planting islands than in numerous small islands distributed over the site. Allow at least 400 square feet of soil space for each tree.
For more information on how to plant and establish tree (see Planting a Tree).
An important investment in urban tree care is in a systematic pruning program. ( see How to Hire An Arborist) The advantages include reduced costs each time the tree is trimmed, reduced service requests, improved safety and reduced liability, improved pest control and healthier trees.
Tree pruning is a special service which should be performed by professionals. Safety and other forms of specialty pruning are best performed by a specialized crew, either in-house or contracted. Homeowners should only prune from the ground. Non-professionals should never climb a tree to prune because of the danger of falling or injury from pruning equipment.
To prevent the need for pruning at planting, purchase quality shade trees. Trees should have one central trunk and branches spaced along the trunk, not clustered at one point. Prune 2 and 5 years after planting, then place trees on a 5 to 7-year pruning cycle. (see Tree Pruning Basics)
Remove immediately any broken or dead limbs. Have an arborist remove branches which are not well attached to the trunk. These potentially hazardous branches may not be apparent from the ground.
Preventing storm damage
Major storms taught us that trees which are properly and regularly pruned are damaged less in a storm than those not regularly pruned. A potentially damaging wind passes through trees which are thinned and trained to the appropriate structure, thus helping keep them intact in a storm.
Never top a tree. Topping is the worst thing that you can do to a tree. Topping initiates decay in branches and makes the tree more dangerous than before it was pruned. It costs more in the long run, attracts insects, and is ugly. Topping does not help prevent damage during a storm.
Monitor for Insects and Diseases
Generally, a well-cared-for tree will not succumb to lethal insect or disease problems. However, some insects and diseases (such as borers and hypoxylon canker) can be deadly to trees, especially if trees are under stress from another problem. Have a professional arborist or forester check the trees regularly as part of a preventive maintenance program to help keep these and other pests from becoming problems. As with people, the best way to ensure continued health is with preventive maintenance.
Trees and Construction
Perceptions about tree roots are quite different from reality. Trees growing in urban areas seldom develop tap roots. In fact most roots are located within the top 12 inches of soil because this is where aeration, nutrients and moisture are abundant. The feeder roots grow just below the surface of the soil or mulch, or among the lawn and shrub roots. About 50 percent of the tree root system grows beyond the canopy, and the tips of the roots are three times as far from the trunk as the canopy. Construct a fence around the tree at the edge of the canopy (dripline) to reduce root damage during construction.
Due to the extent and shallowness of the roots, much of the root system is frequently removed from existing trees during construction of a home or other building. This causes decline and tree death in the years following construction. The best treatment for trees damaged by construction is irrigation. Heavy fertilizing may make the problem worse by forcing undesirable top growth, which cannot be supported by the reduced root system.