Jack Payne, Senior Vice President, Agriculture and Natural Resources, and Leader, Institute of Food and Agricultural Sciences, University of Florida
 
Your parents were wrong: Money does grow on trees.

Tampa Bay rakes up tens of millions of dollars from its urban forest annually. Leafy canopies lower summer air conditioning bills, more shade means less blade to maintain thousands of acres of grass, and trees contribute to lower asthma rates and birth defects by removing air pollutants.
 
Across the nation this Arbor Day, city foresters celebrated trees as economic drivers and get past the false dichotomy of economy versus environment.
 
Portland, New York City, Milwaukee, Atlanta, and other cities have also quantified the payoff from pines and palms, olives and oaks.
 
One of the great breakthroughs among city planners in recent decades has been awareness that a city runs not just on engineering, but on biology and ecology as well.
 
Tampa demonstrated that kind of thinking in moving its leading tree official, Kathy Beck, from the parks and recreation department onto its chief planning team. Tampa approaches trees as part of a green public works system, the living equivalent of roads and bridges. It’s a case of what Beck calls “green meets gray.”
 
Part of how Tampa gets it right on trees is that planners can shield themselves from partisanship, protest, and profit motives by relying on science. University of Florida urban forester Rob Northrop has brought to bear the expertise of UF’s Institute of Food and Agricultural Sciences on what, where, and how many trees to plant.
 
To get the biggest bang for tree planting and maintenance bucks, Tampa turns to Northrop for information on which trees provide the greatest shade, which can be planted closest to sidewalks and parking lots without root growth buckling pavement, and which species best withstand floods in a city already impacted by sea-level rise.
 
Drilling down even further, the University of South Florida has begun mapping individual trees. So planners know, for example, that the live oak on the 4200 block of Willow Drive has a 38-inch diameter and a $453 annual payoff.
 
Through the painstaking work of compiling an inventory of a city’s green infrastructure, policy makers can make more informed decisions on where to focus resources.
 
Just as the most decrepit or most used roads get more attention, key trees might get pruned or watered more often. The city has assessed the health of trees that line its evacuation routes. This kind of information would have been valuable to transportation officials in the San Francisco area, for example, before a commuter train was recently derailed when it struck a fallen tree.
 
Northrop and other natural resource scientists see intrinsic value in trees. But he recognizes the tremendous economic pressures communities are under, so he and economists collaborate to get at the straight-dollar costs and benefits.
 
The most recent study of Tampa’s trees estimated that they save the city $35 million a year in reduced costs for public health, stormwater management, energy savings, prevention of soil erosion, and other services.
 
Even within the ranks of the forestry discipline, Northrop is a rarity with his expertise in urban forestry. The Society of American Forestry didn’t start accrediting university programs in the discipline until 2005. There’s not even consensus on a definition of urban forestry, though Beck describes it as the science of addressing both people with tree problems and trees with people problems.
 
In coming years, Florida and the nation will continue to grow and urbanize. One study suggests that in the next half century, 7 million acres in Florida alone could convert from rural and natural to urban use.
 
The push into formerly natural areas will bring with it more impacts on trees. At the same time, we’ll need trees more than ever to create and maintain livable cities.
 
Let’s love our trees. More than hugs, they need science. The quiet efforts of planners and scientists are our best bet for green cities that inspire us to marvel year-round at the natural canopies above us and the ground beneath our feet. Happy Arbor Day.