June 24, 2008

Looking Past the City for the Trees

By Alan Choate



In the not-too-distant future, there will be people walking around the city of Las Vegas counting trees.

It sounds odd, as does the name of this particular endeavor: surveying the "urban forest." But a large volume of research says that, even in dry Las Vegas, the right kinds of trees are a good way to conserve water and energy and clean the air.

They look good, too.

The survey is a joint effort by the city, the Southern Nevada Water Authority and the Nevada Division of Forestry to compile an inventory of the city's public trees.

From there, the aim is to measure the benefits of the trees already in place and find places where trees need to be replaced or planted.

"It's kind of a complete rethinking of trees in the urban space for this community," said Thomas Perrigo, deputy director of the Las Vegas planning department. "Just like any other amenity or resource, we need to understand the value, the benefits and the costs. We really don't right now.

"We've never really quantified those really well."

The survey is being paid for by a $38,000 grant from the Nevada Division of Forestry, with $10,000 each from the water authority and Las Vegas. The data from the survey will be combined with aerial imagery the water authority has to generate a map and database of trees on public land across the city.

There might not be a dollar figure attached to the benefit of trees at this point, but there are many benefits attached to them.

According to the Nevada Division of Forestry:

* Trees absorb pollutants, intercept particulate matter and release oxygen.

* When placed correctly, trees shade buildings, reducing cooling costs. Shade also reduces heat buildup on asphalt and concrete surfaces, which contributes to what's known as the "heat island" effect

*\u2002Leaves, branches and roots absorb water that otherwise would become storm runoff.

* Trees tend to increase property values.

* Some studies have shown that shopping centers with trees are more successful and that apartment complexes with high levels of greenery have significantly less crime than tree-free apartments.

Trees also need to be watered, of course.

"When we first started down this path, the first thing we did was call the water authority and say, 'What is your opinion on trees?' " Perrigo said. "They loved it. They support it."

In fact, trees are an important part of a program that pays homeowners to remove lawns, said Scott Huntley, spokesman for the Southern Nevada Water Authority.

"One of the important things is not to create heat islands by ripping out grass," he said. "Trees have the ability to shade and cover and reduce that heat sink effect, especially when you're taking grass out.

"It's a very good expenditure of water."

Contact reporter Alan Choate at [email protected] or 702- 229-6435.

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