Trees in the hardscape require long-term aeration
By Wayne Smith
ISA Certified Arborist
Where the Pinellas Trail intersects Main Street in Dunedin, Florida, a venerable oak tree stands watch, arching its giant limbs above the trail. Its roots lie buried under asphalt paving and a strip mall's concrete foundation hardscapes.
The City of Dunedin invested in its landmark tree. By installing the W.A.N.E. Tree System , which allowed the tree's roots to breathe and to get water and nutrients, although they lie beneath the asphalt hardscape.
Paving around a tree was once a death sentence. Some trees succumbed swiftly, others lingered, but premature death was inevitable. For trees to live, their roots must breathe. They must take in oxygen and expel carbon dioxide. Paving deprives the roots of this critical exchange of gases at the interface of the soil surface.
I invented the tree feeder units, called W.A.N.E. for Water-Air-Nutrient-Exchange, in 1971. They were the first aeration devices aimed at keeping trees alive in the urban hardscape.
Each unit has a cylindrical housing that is inserted through the hardscape pavement and into the soil below. Its perforated lid, which sits flush with the pavement, allows air and water to enter the soil and carbon dioxide to be expelled. Slow-release fertilizer inside the filter provides nutrients to the roots. The number of units installed around the circumference depends upon the tree's size and condition. The perforated lids can be pulled off the units periodically to remove any accumulated debris, which maximizes the amount of oxygen getting through to the tree's roots. Nutrients can be added, as well.
The W.A.N.E. 3000 units provide portals to a tree's root system. The avenue opened for entry of oxygen and release of carbon dioxide is fundamental to the tree's survival. The water and nutrients transmitted through the units provide additional benefit.
Effective Tree Preservation with the W.A.N.E. 3000 Tree System
The Georgia Dome, the Washington D.C. Capitol Mall, and Central Florida theme parks all use W.A.N.E. 3000 Tree Units. When installed as part of a comprehensive tree preservation program, the W.A.N.E. 3000 unit is an effective aeration device. If a tree's roots have been butchered through twelve months of careless construction, popping in some W.A.N.E. 3000 units at the end will not effect a miracle cure. But in the hands of a competent arborist, who has developed, implemented and supervised a tree preservation program throughout the construction process, the W.A.N.E. 3000 unit will keep healthy trees healthy.
In downtown Clearwater, off South Fort Harrison, a grand oak tree sits in the middle of a parking lot outside the Pinellas County Utilities building. Even with the W.A.N.E. system, this tree lives in a very harsh environment. Yet it's live crown ratio remains good � although its roots have been buried under pavement for almost 30 years. Clearwater's City Forester at the time, Chris Coles, was an early advocate of the W.A.N.E. units, and the city began installing them to service the root systems of its valuable, historic trees.
Without a system to aerate it, that grand oak tree would have died. Similar live oaks two blocks away were paved over and given no aeration. Respiration diminished and toxins accumulated. The oaks exhausted their stored-up energy, roots died back, portions of the trees died back, and photosynthesis diminished, further decreasing respiration. The bleak cycle of decline played out for years. For each tree, it was a slow death.
Within blocks of each other, all these live oaks had the same potential to live. But one got an aeration system and the others did not. That is the difference.
Wayne Smith is an ISA certified arborist who has been working to preserve urban trees for 49 years. He has been a member of ISA, Florida Chapter, since its inception.