UF/IFAS Okeechobee Extension Service

This past week marks a watershed week for our local Master Gardener Program. Two more local volunteers Angela Sachson and Harold Mounts, just completed their basic class, and will soon move into their on-the job-training here at our office. And, one of last falls MG graduates has surpassed his basic commitment as a volunteer with our county Extension Service – Dick Dutton has provided 95 hours of service since his graduation last November.

I enjoy talking and learning with these folks every week, but this week Dick really moved several steps forward – he has grabbed a hold of a local problem, done his research, and instituted a plan to address the needs of the community. His community – like many others here in Okeechobee - is experiencing the construction of many new homes. Unfortunately, when homes are built and dirt is moved, often trees and wildlife pay the price. Today’s column on trees and construction was drafted by Dick Dutton. I hope you will find it useful, thought provoking and worth sharing with any new neighbors who are about to build their new homestead in Okeechobee.

In our neighborhood there has been and there will continue to be new homes built. One area in particular is a hammock, which has some beautiful oaks on the vacant lots. Most of the property owners have commented on the trees and planned on the oaks being there for their many benefits.

Trees are valuable – they are an asset to a home site, and treed lots command higher prices. Real estate agents and homebuyers typically assign 10% to 23% premium to a residence’s value when trees are on the property. Trees can reduce air conditioning energy costs, absorb noise and trap both dust in the air and keep soil on the ground.

Tree preservation during construction is assumed by the homeowner. One of the big challenges to these lovely landscapes is the construction of the house itself. Contractors may be unaware of the damage that construction can do to a tree. Property owners and builders can play a big role in preventing tree failure after a year or two.

In case of custom built homes, the property owner also may benefit from guidance to avoid damage to the trees on their new property. A little preplanning can avoid some bigger problems when a tree starts to fail or die back. Consulting with an arborist or competent tree professional can pay back dividends in keeping your trees healthy

There are three steps in keeping these valuable parts of your new home site intact: designing your site for tree survival, maintaining the root systems during construction, and remediation and monitoring after the construction is complete. Let’s look at some tips in each of these areas:

Before Construction: Pick which trees to save and design the house to accommodate them. Look for healthy trees of desirable species. Pay special attention to shade potential for the house and nearby cement/asphalt areas.

Figure 1 - The Critical Root Zone (CRZ) is as big as the canopy - don't dig it, drive over it or add fill to it. Diagram Courtesy Houston Area Urban Forestry Council

Figure 2 - Tree roots don't grow like the diagram at left. Tree roots grow like the drawing on the right - most are within the top 2 inches of the soil. Diagram Courtesy Houston Area Urban Forestry Council

Draw a line in the sand – called the Critical Root Zone (CRZ) - which is roughly a circle equal to the average drip line. (see Figure 1). Realize that while most tree roots are in the top two feet of soil, those that feed the tree are in the top few inches (see Figure 2). Fence off CRZ to prevent traffic, to keep it from storing building materials or being used as a waste deposit area. If fencing is not possible, cover the CRZ with 6-8 inches of wood-chip mulch and then a layer of thick plywood or boards to prevent soil compaction.

When underground utilities are installed, place them away from the CRZ. If digging is unavoidable, bore under the roots or hand dig to avoid severing them. Paving chokes off water and air and kills roots. Where paving is needed, place it away from CRZ or use a porous material such as pervious concrete, crushed granite, or pavers.

During Construction – Make sure all contractors and building crews do not violate the CRZ barrier. Set up substantial fences, mark access routes, storage areas and refuse sites. Keep a careful watch on the crews in action. Encourage them to keep backhoes and root destroying equipment away from roots. Allow parking in the street, not under shade trees.

If pruning is needed, use proper pruning techniques. Avoid fertilization which encourages new growth which is easier to damage. Keep the CRZ well watered during construction – a working well early in construction will be needed to saturate the top 4-6 inches of soil.

After Construction, Remediate and Monitor - Remove contaminated soil and aerate compacted soil. Keep the same grade as before construction – more than two additional inches of soil or sod can ultimately kill an otherwise healthy tree.

Monitor trees for up to five years, checking for insects or disease that can strike a weakened tree. Water trees during dry periods to help them recover from construction stress. Fertilize annually with a slow-release non-burning complete fertilizer.

If you need additional information on helping trees cope with construction, take a look at the additional references on our internet site, http://okeechobee.ifas.ufl.edu or email us at okeechobee@ifas.ufl.edu. Area residents can call us at 863-763-6469 or stop by our office at 458 Hwy 98 North in Okeechobee. You can visit with our Okeechobee County Master Gardeners on Tuesday afternoons from 1 to 5 PM.

Note: Dick Dutton was a Florida Master Gardener when he compiled this article and took these phots of an Okeechobee area homesite; he is currently a Florida Master Gardener with the Lee County Extension Service.

References

Duryea Mary L. and Malavasi, Marlene M. How Trees Grow in the Urban Environment Gainesville: UF/IFAS Circular 1093 January, 2003 http://edis.ifas.ufl.edu/FR002

Gilman, Ed. Shade tree maintenance. In UF/IFAS Woody Ornamental/Trees webpage. Gainesville: Environmental Horticulture Department website, 2004. http://hort.ufl.edu/woody/Maturetreecare/index.htm

Morgan, Robin. A Technical Guide to Urban Community Forestry: Urban and Community Forestry: Improving Our Quality of Life. Portland : World Forestry Center ,

U.S.

Department of Agriculture, Forest Service, Pacific Northwest and Pacific Southwest Regions , March 1993 http://www.na.fs.fed.us/spfo/pubs/uf/techguide/preserving.htm

The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. Florida Cooperative Extension Service / IFAS / University of Florida . Larry A. Arrington, Interim Dean. Last update: 08/22/2006 . This page is maintained by Dan Culbert


Above: topsoil has been scraped clear & palm trunk damaged by equipment Below: equipment has run over roots	Above: soil has been scraped off, exposing roots Below: fill soil has been added on top of root zone, then compacted.	Above: more exposed roots and damage to CRZ. Below: Footer has enroched on CRZ; heavy materials stored in CRZ