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Scientists take inventory to learn how to improve Tampa's urban forest.

A truck winds along a gravel path, stopping for locked gates, crawling over deep black creeks, by fat turkeys and roseate spoonbills and leaping deer. Three researchers climb out in a clearing and follow a GPS device into the forest. One plants a stake into black muck. This is it. Their mission: to count all the trees in the surrounding 37 feet. Cypress, elms and maples. Most have likely not been seen by humans in years. Trees, not people, live in this enclave off Tampa Palms Boulevard.

This research team, from the University of Florida's local extension office, gathers data for a study being watched nationally. Throughout the summer, they will inventory trees in 201 random plots around Tampa, from the city's southernmost tip north to the far reaches of New Tampa.

Trees store carbon, shade homes and slow stormwater flow. They make us feel good. Not to mention that having the right tree in the right place, experts say, can save money.

Local officials will use the researchers' results to see how and where they can gain the greatest services from trees.

It's a huge effort, costing $250,000, and makes Tampa the nation's second city (after Washington, D.C.) to inventory its urban forest with such precision and accuracy.

But some, including UF forester Rob Northrop, say "tree science" is crucial, especially now as the area becomes more urbanized.

"Tampa is becoming one of the most prominent places in the United States in terms of the way they're assessing their urban forest."

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Boots slosh and branches crack on the dark marshy earth, but researchers spend much of their time looking up.

"What a gorgeous canopy," said Luisa Falck, gazing at a cypress 79 feet high.

This area, about one-tenth of an acre, was dry five years ago when researchers first inventoried these trees, remembers Carolyn Cheatham Rhodes, the field crew supervisor. She wraps her arms around the tree, checks a tape measure and calls out a number to Erin Gilbert, who fills in a grid.

They shoot a laser at the canopy to measure height. They gauge tree health and the span of branches.

Gilbert looks for a Quercus nigra, a water oak, recorded on her paper in the last count.

"I think it's gone," she said. "It's pretty cool to see how things change."

More than 100 years ago, much of Tampa was covered with pines and palmettos. Farms, phosphate mines and other managed lands surrounded the city and beyond that, hinterlands.

Today, the city has about 45 non-native tree varieties.

The city has been more progressive than some others in preservation.

In 1972, Tampa adopted one of the country's first tree ordinances. Joe Chillura, the City Council member who had proposed it, said the ordinance has since been modeled across the Southeast.

At the time, developers were leveling trees all over the city, said Chillura, an architect. The new law made him few friends among them. It protected certain trees from removal or trimming and required developers to attempt to work around them.

"I was known as a tree-hugger back in those days," he said. But he says the value in an oak tree's carbon storage alone is enough to merit its protection.

"There's no reason why development and nature can't share a common place in the existence of the city," he said.

The tree ordinance now includes a requirement for an urban ecological assessment every five years. The city's Tree Trust Fund, which collects fines from landowners who violate the ordinance and from developers who pay to remove trees, funded the inventory five years ago and this year's study.

Tree science is relatively new and the city has embraced it, said Kathy Beck, natural resource coordinator at the Tampa Parks and Recreation Department.

And some believe it's needed now more than ever.

At one time, people depended on the outlying lands for food and resources. Today, nature is no longer separate from humans, said Shawn Landry, a University of South Florida scientist who is working on a separate phase of the project.

"The city is essentially a human ecosystem."

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The study five years ago found that some 7.8 million trees in the city save us tens of millions of dollars.

Local scientists partnered with the U.S. Forest Service, which designed methods to collect and analyze tree data and assess the economic value of forests to people.

Aside from reducing stormwater and storing carbon, trees promote walking and add value to home sales. One study of hospital patients found they left a day earlier when they could see a tree outside their window. Another found fewer acts of domestic violence in public housing where there are trees and grass.

We often take trees for granted, said David Crawley, a member of the Mayor's Steering Committee on Urban Forest Sustainability. But research proves some unexpected values, he said. Trees attract tourism, new businesses and people, he said, attributing the effects to man's subconscious connection to nature.

Results from the last study found about 30 percent of Tampa is under a canopy of leaves and there's room for twice as many. Oaks account for 21 percent of this coverage. Of the 93 tree species documented in Tampa, about half were native to Florida. The most common tree inland: Brazilian pepper, which is non-native and invasive.

Trees can be a problem if not managed, Landry said, citing the laurel oaks that live shorter lives and tend to have more structural weaknesses than other oaks. They're likely to go down in a hurricane.

In the 1970s, developers planted these fast-growing trees, which are now maturing at the same time, said Beck with the city's parks department.

Another problem: In some areas, such as Sulphur Springs where trees abound, they are not as well maintained, Beck said.

Scientists will merge the field data with satellite imagery to identify the types of trees, how many and where they are.

After the inventories and satellite imagery is done, city officials will use the findings to create regulations and new ways of managing the area's trees. The entire process is slated to be completed in fall 2012.

But for the next few months, field researchers will travel throughout the area to spots randomly selected by computer. Some areas may have no trees at all, such as highways or residential swimming pools. No matter, the researchers will still document what they see.

At others, they will slosh through waist-high waters, crawl through thatches of Brazilian pepper trees and boat out to MacDill Air Force Base, wading into mangroves.

Elisabeth Parker can be reached at or (813) 226-3431.